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1

Three-dimensional porous biodegradable polymeric scaffolds fabricated with biodegradable hydrogel porogens.  

PubMed

We have developed a new fabrication technique to create three-dimensional (3D) porous poly(epsilon-caprolactone fumarate) (PCLF) scaffolds using hydrogel microparticle porogens, as an alternative to overcome certain limitations of traditional scaffold fabrication techniques such as a salt leaching method. Both natural hydrogel, gelatin, and synthetic hydrogel, poly(ethylene glycol) sebacic acid diacrylate, were used as porogens to fabricate 3D porous PCLF scaffolds. Hydrogel microparticles were prepared by a single emulsion technique with the particle size in the range of 100-500 microm after equilibrium in water. The pore size distribution, porosity, pore interconnectivity, and spatial pore heterogeneity of the 3D PCLF scaffolds were assessed using micro-computed tomography and imaging analysis. Scaffolds fabricated with the hydrogel porogens had higher porosity and pore interconnectivity as well as more homogeneous spatial pore distribution, compared to the scaffolds made from the salt leaching process. Compressive moduli of the scaffolds were also measured and showed that lower porosity yielded greater modulus of the scaffolds. Overall, the new fabrication technology using hydrogel porogens may be beneficial for certain tissue engineering applications. PMID:19216632

Kim, Jinku; Yaszemski, Michael J; Lu, Lichun

2009-12-01

2

A new method for the production of gelatin microparticles for controlled protein release from porous polymeric scaffolds.  

PubMed

Tissue engineering using scaffolds and growth factors is a crucial approach in bone regeneration and repair. The combination of bioactive agents carrying microparticles with porous scaffolds can be an efficient solution when controlled release of bio-signalling molecules is required. The present study was based on a recent approach using a biodegradable scaffold and protein-loaded microparticles produced in an innovative manner in which protein loss is minimized during the loading process. Bovine serum albumin (BSA)-loaded gelatin microparticles were obtained by grinding freeze-dried membranes of gelatin and BSA. Porous scaffolds (250-355 µm pore size) produced from a polyactide (PLLA) and polycaprolactone (PCL) blend by salt leaching/supercritical CO? methods were used for the experiments. Gelatin microparticles containing three different BSA amounts were incorporated into the porous scaffolds by using a surfactant. In vitro release profiles showed up to 90% protein loading efficiency. This novel method appears to be an effective approach for producing particles that can minimize protein loss during the loading process. PMID:22499408

Ozkizilcik, Asya; Tuzlakoglu, Kadriye

2014-03-01

3

Fabrication of three dimensional polymeric scaffolds with spherical pores  

Microsoft Academic Search

This paper reports polymeric scaffolds with spherical internal macropores and relatively large external dimension. Paraffin\\u000a spheres with the diameter of several hundred microns were prepared by a suspension technique. Particulate leaching technique\\u000a based on this kind of spherical porogens was combined with room-temperature compression molding technique to fabricate biodegradable\\u000a poly(D,L-lactic-co-glycolic acid) (PLGA) porous scaffolds potentially for tissue engineering or in

Junchuan Zhang; Hong Zhang; Linbo Wu; Jiandong Ding

2006-01-01

4

Porous Collagen Scaffold Reinforced with Surfaced Activated PLLA Nanoparticles  

PubMed Central

Porous collagen scaffold is integrated with surface activated PLLA nanoparticles fabricated by lyophilizing and crosslinking via EDC treatment. In order to prepare surface-modified PLLA nanoparticles, PLLA was firstly grafted with poly (acrylic acid) (PAA) through surface-initiated polymerization of acrylic acid. Nanoparticles of average diameter 316?nm and zeta potential ?39.88?mV were obtained from the such-treated PLLA by dialysis method. Porous collagen scaffold were fabricated by mixing PLLA nanoparticles with collagen solution, freeze drying, and crosslinking with EDC. SEM observation revealed that nanoparticles were homogeneously dispersed in collagen matrix, forming interconnected porous structure with pore size ranging from 150 to 200??m, irrespective of the amount of nanoparticles. The porosity of the scaffolds kept almost unchanged with the increment of the nanoparticles, whereas the mechanical property was obviously improved, and the degradation was effectively retarded. In vitro L929 mouse fibroblast cells seeding and culture studies revealed that cells infiltrated into the scaffolds and were distributed homogeneously. Compared with the pure collagen sponge, the number of cells in hybrid scaffolds greatly increased with the increment of incorporated nanoparticles. These results manifested that the surface-activated PLLA nanoparticles effectively reinforced the porous collagen scaffold and promoted the cells penetrating into the scaffold, and proliferation. PMID:22448137

Xu, Cancan; Lu, Wei; Bian, Shaoquan; Liang, Jie; Fan, Yujiang; Zhang, Xingdong

2012-01-01

5

Porous ZrO 2 bone scaffold coated with hydroxyapatite with fluorapatite intermediate layer  

Microsoft Academic Search

Highly porous zirconia (ZrO2) bone scaffolds, fabricated by a replication technique using polymeric sponge, were coated with hydroxyapatite (HA). To prevent the chemical reactions between ZrO2 and HA, an intermediate fluorapatite (FA) layer was introduced. The strength of the porous ZrO2 was higher than that of pure HA by a factor of 7, suggesting the feasibility of ZrO2 porous scaffolds

Hae-Won Kim; Seung-Yong Lee; Chang-Jun Bae; Yoon-Jung Noh; Hyoun-Ee Kim; Hyun-Man Kim; Jea Seung Ko

2003-01-01

6

Porous chitosan scaffolds for tissue engineering  

Microsoft Academic Search

The wide array of tissue engineering applications exacerbates the need for biodegradable materials with broad potential. Chitosan, the partially deacetylated derivative of chitin, may be one such material. In this study, we examined the use of chitosan for formation of porous scaffolds of controlled microstructure in several tissue-relevant geometries. Porous chitosan materials were prepared by controlled freezing and lyophilization of

Sundararajan V. Madihally; Howard W. T. Matthew

1999-01-01

7

Nano/macro porous bioactive glass scaffold  

NASA Astrophysics Data System (ADS)

Bioactive glass (BG) and ceramics have been widely studied and developed as implants to replace hard tissues of the musculo-skeletal system, such as bones and teeth. Recently, instead of using bulk materials, which usually do not degrade rapidly enough and may remain in the human body for a long time, the idea of bioscaffold for tissue regeneration has generated much interest. An ideal bioscaffold is a porous material that would not only provide a three-dimensional structure for the regeneration of natural tissue, but also degrade gradually and, eventually be replaced by the natural tissue completely. Among various material choices the nano-macro dual porous BG appears as the most promising candidate for bioscaffold applications. Here macropores facilitate tissue growth while nanopores control degradation and enhance cell response. The surface area, which controls the degradation of scaffold can also be tuned by changing the nanopore size. However, fabrication of such 3D structure with desirable nano and macro pores has remained challenging. In this dissertation, sol-gel process combined with spinodal decomposition or polymer sponge replication method has been developed to fabricate the nano-macro porous BG scaffolds. Macropores up to 100microm are created by freezing polymer induced spinodal structure through sol-gel transition, while larger macropores (>200um) of predetermined size are obtained by the polymer sponge replication technique. The size of nanopores, which are inherent to the sol-gel method of glass fabrication, has been tailored using several approaches: Before gel point, small nanopores are generated using acid catalyst that leads to weakly-branched polymer-like network. On the other hand, larger nanopores are created with the base-catalyzed gel with highly-branched cluster-like structure. After the gel point, the nanostructure can be further modified by manipulating the sintering temperature and/or the ammonia concentration used in the solvent exchange process. Although both techniques lower the surface area of BG scaffolds, the temperature-dependent sintering process closes nanopores through densification, while the concentration-dependent solvent exchange process enlarges nanopores through Ostwald-ripening type coarsening. Therefore, nanopore size and surface area of BG scaffold are independently controlled using these methods. In vitro cell and in vivo animal tissue responses have been investigated to evaluate the performance of the nano-macro porous BG scaffold. The cells are found to migrate and penetrate deep into the 3D nano-macro porous structure, while exhibiting excellent adhesion to the bioscaffold surface. Importantly, the new tissue with both blood vessels and collagen fibers is formed deep inside the implanted scaffolds without obvious inflammatory reaction. Furthermore, our observations show biological benefits of the nanopores in the BG scaffold. In comparison to BG scaffold without nanopores, cells migrate and penetrate into nano-macro dual-porous BG scaffold faster and deeper mainly because of the increase of surface area. To study the effect of nanopore topography, we fabricated BG scaffolds with the same surface area but different nanopore sizes. It is found that the initial cell attachment is significantly enhanced on the BG scaffold with the same surface area but smaller nanopores size, indicating that the nanopore topography strongly influences the performance of BG scaffold. In conclusion, the present results demonstrate most clearly the usefulness of our nano-macro dual-porous BG as a novel and superior 3D bioscaffold for regenerative medicine and hard tissue engineering.

Wang, Shaojie

8

Additive manufacturing of wet-spun polymeric scaffolds for bone tissue engineering.  

PubMed

An Additive Manufacturing technique for the fabrication of three-dimensional polymeric scaffolds, based on wet-spinning of poly(?-caprolactone) (PCL) or PCL/hydroxyapatite (HA) solutions, was developed. The processing conditions to fabricate scaffolds with a layer-by-layer approach were optimized by studying their influence on fibres morphology and alignment. Two different scaffold architectures were designed and fabricated by tuning inter-fibre distance and fibres staggering. The developed scaffolds showed good reproducibility of the internal architecture characterized by highly porous, aligned fibres with an average diameter in the range 200-250 ?m. Mechanical characterization showed that the architecture and HA loading influenced the scaffold compressive modulus and strength. Cell culture experiments employing MC3T3-E1 preosteoblast cell line showed good cell adhesion, proliferation, alkaline phosphatase activity and bone mineralization on the developed scaffolds. PMID:22767245

Puppi, Dario; Mota, Carlos; Gazzarri, Matteo; Dinucci, Dinuccio; Gloria, Antonio; Myrzabekova, Mairam; Ambrosio, Luigi; Chiellini, Federica

2012-12-01

9

Porous ceramic scaffolds with complex architectures  

SciTech Connect

This work compares two novel techniques for the fabrication of ceramic scaffolds for bone tissue engineering with complex porosity: robocasting and freeze casting. Both techniques are based on the preparation of concentrated ceramic suspensions with suitable properties for the process. In robocasting, the computer-guided deposition of the suspensions is used to build porous materials with designed three dimensional (3-D) geometries and microstructures. Freeze casting uses ice crystals as a template to form porous lamellar ceramic materials. Preliminary results on the compressive strengths of the materials are also reported.

Saiz, Eduardo; Munch, Etienne; Franco, Jaime; Deville, Sylvain; Hunger, Phillip; Saiz, Eduardo; Tomsia, Antoni P.

2008-03-15

10

Rapid Engineering of Three-Dimensional, Multicellular Tissues With Polymeric Scaffolds  

NASA Technical Reports Server (NTRS)

A process has been developed for the rapid tissue engineering of multicellular-tissue-equivalent assemblies by the controlled enzymatic degradation of polymeric beads in a low-fluid-shear bioreactor. In this process, the porous polymeric beads serve as temporary scaffolds to support the assemblies of cells in a tissuelike 3D configuration during the critical initial growth phases of attachment of anchorage-dependent cells, aggregation of the cells, and formation of a 3D extracellular matrix. Once the cells are assembled into a 3D array and enmeshed in a structural supportive 3D extracellular matrix (ECM), the polymeric scaffolds can be degraded in the low-fluid-shear environment of the NASA-designed bioreactor. The natural 3D tissuelike assembly, devoid of any artificial support structure, is maintained in the low-shear bioreactor environment by the newly formed natural cellular/ECM. The elimination of the artificial scaffold allows normal tissue structure and function.

Gonda, Steve R.; Jordan, Jacqueline; Fraga, Denise N.

2007-01-01

11

Porous ZrO2 bone scaffold coated with hydroxyapatite with fluorapatite intermediate layer.  

PubMed

Highly porous zirconia (ZrO(2)) bone scaffolds, fabricated by a replication technique using polymeric sponge, were coated with hydroxyapatite (HA). To prevent the chemical reactions between ZrO(2) and HA, an intermediate fluorapatite (FA) layer was introduced. The strength of the porous ZrO(2) was higher than that of pure HA by a factor of 7, suggesting the feasibility of ZrO(2) porous scaffolds as load-bearing part applications. The coated HA/FA layer, with a thickness of about 30 microm, was firmly adhered to the ZrO(2) body with a bonding strength of 22MPa. The osteoblast-like cells were attached and spread well on the coating layer throughout the porous scaffolds. The alkaline phosphatase activity of the proliferated cells on the HA/FA coated ZrO(2) was comparable to that on pure HA and higher than that on pure ZrO(2). PMID:12763455

Kim, Hae-Won; Lee, Seung-Yong; Bae, Chang-Jun; Noh, Yoon-Jung; Kim, Hyoun-Ee; Kim, Hyun-Man; Ko, Jea Seung

2003-08-01

12

Living Bacterial Sacrificial Porogens to Engineer Decellularized Porous Scaffolds  

E-print Network

Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative ...

Xu, Feng

13

Evaluation of phytochemical-incorporated porous polymeric sponges for bone tissue engineering: a novel perspective.  

PubMed

Porous polymeric scaffolds are extensively studied for delivery of bone growth factors. Since phytochemicals are known to produce changes in cell signalling and other metabolic pathways, osteogenic phytochemicals, that is, extracts of Cissus quadrangularis and Butea monosperma, are incorporated into sulphonated poly(aryl ether ketone) sponges. The results have shown that the scaffolds with phytochemicals enhanced the proliferation and alkaline phosphatase activity of the cells compared to cells treated on scaffolds without phytochemicals. Hence, these phytochemicals can be evaluated to augment, if not substitute the use of bone morphogenetic proteins in scaffolds. PMID:23736994

Raghavan, Ravi N; Somanathan, N; Sastry, Thottapalli P

2013-08-01

14

Conformal encapsulation of three-dimensional, bioresorbable polymeric scaffolds using plasma-enhanced chemical vapor deposition.  

PubMed

Bioresorbable polymers such as poly(?-caprolactone) (PCL) have a multitude of potential biomaterial applications such as controlled-release drug delivery and regenerative tissue engineering. For such biological applications, the fabrication of porous three-dimensional bioresorbable materials with tunable surface chemistry is critical to maximize their surface-to-volume ratio, mimic the extracellular matrix, and increase drug-loading capacity. Here, two different fluorocarbon (FC) precursors (octofluoropropane (C3F8) and hexafluoropropylene oxide (HFPO)) were used to deposit FC films on PCL scaffolds using plasma-enhanced chemical vapor deposition (PECVD). These two coating systems were chosen with the intent of modifying the scaffold surfaces to be bio-nonreactive while maintaining desirable bulk properties of the scaffold. X-ray photoelectron spectroscopy showed high-CF2 content films were deposited on both the exterior and interior of PCL scaffolds and that deposition behavior is PECVD system specific. Scanning electron microscopy data confirmed that FC film deposition yielded conformal rather than blanket coatings as the porous scaffold structure was maintained after plasma treatment. Treated scaffolds seeded with human dermal fibroblasts (HDF) demonstrate that the cells do not attach after 72 h and that the scaffolds are noncytotoxic to HDF. This work demonstrates conformal FC coatings can be deposited on 3D polymeric scaffolds using PECVD to fabricate 3D bio-nonreactive materials. PMID:25247481

Hawker, Morgan J; Pegalajar-Jurado, Adoracion; Fisher, Ellen R

2014-10-21

15

Thermoforming techniques for manufacturing porous scaffolds for application in 3D cell cultivation.  

PubMed

Within the scientific community, there is an increasing demand to apply advanced cell cultivation substrates with increased physiological functionalities for studying spatially defined cellular interactions. Porous polymeric scaffolds are utilized for mimicking an organ-like structure or engineering complex tissues and have become a key element for three-dimensional (3D) cell cultivation in the meantime. As a consequence, efficient 3D scaffold fabrication methods play an important role in modern biotechnology. Here, we present a novel thermoforming procedure for manufacturing porous 3D scaffolds from permeable materials. We address the issue of precise thermoforming of porous polymer foils by using multilayer polymer thermoforming technology. This technology offers a new method for structuring porous polymer foils that are otherwise available for non-porous polymers only. We successfully manufactured 3D scaffolds from solvent casted and phase separated polylactic acid (PLA) foils and investigated their biocompatibility and basic cellular performance. The HepG2 cell culture in PLA scaffold has shown enhanced albumin secretion rate in comparison to a previously reported polycarbonate based scaffold with similar geometry. PMID:25686978

Borowiec, Justyna; Hampl, Jörg; Gebinoga, Michael; Elsarnagawy, Tarek; Elnakady, Yasser A; Fouad, Hassan; Almajhadi, Fahd; Fernekorn, Uta; Weise, Frank; Singh, Sukhdeep; Elsarnagawy, Dief; Schober, Andreas

2015-04-01

16

Mechanical Improvements to Reinforced Porous Silk Scaffolds  

PubMed Central

Load bearing porous biodegradable scaffolds are required to engineer functional tissues such as bone. Mechanical improvements to porogen leached scaffolds prepared from silk proteins were systematically studied through the addition of silk particles in combination with silk solution concentration, exploiting interfacial compatibility between the two components. Solvent solutions of silk up to 32 w/v% were successfully prepared in hexafluoroisopropanaol (HFIP) for the study. The mechanical properties of the reinforced silk scaffolds correlated to the material density and matched by a power law relationship, independent of the ratio of silk particles to matrix. These results were similar to the relationships previously shown for cancellous bone. The mechanism behind the increased mechanical properties was a densification effect, and not the effect of including stiffer silk particles into the softer silk continuous matrix. A continuous interface between the silk matrix and the silk particles, as well as homogeneous distribution of the silk particles within the matrix were observed. Furthermore, we note that the roughness of the pore walls was controllable by varying the ratio of particles matrix, providing a route to control topography. The rate of proteolytic hydrolysis of the scaffolds decreased with increase in mass of silk used in the matrix and with increasing silk particle content. PMID:21793193

Gil, Eun Seok; Kluge, Jonathan A.; Rockwood, Danielle N.; Rajkhowa, Rangam; Wang, Lijing; Wang, Xungai; Kaplan, David L

2012-01-01

17

Hierarchical porous polymer scaffolds from block copolymers.  

PubMed

Hierarchical porous polymer materials are of increasing importance because of their potential application in catalysis, separation technology, or bioengineering. Examples for their synthesis exist, but there is a need for a facile yet versatile conceptual approach to such hierarchical scaffolds and quantitative characterization of their nonperiodic pore systems. Here, we introduce a synthesis method combining well-established concepts of macroscale spinodal decomposition and nanoscale block copolymer self-assembly with porosity formation on both length scales via rinsing with protic solvents. We used scanning electron microscopy, small-angle x-ray scattering, transmission electron tomography, and nanoscale x-ray computed tomography for quantitative pore-structure characterization. The method was demonstrated for AB- and ABC-type block copolymers, and resulting materials were used as scaffolds for calcite crystal growth. PMID:23908232

Sai, Hiroaki; Tan, Kwan Wee; Hur, Kahyun; Asenath-Smith, Emily; Hovden, Robert; Jiang, Yi; Riccio, Mark; Muller, David A; Elser, Veit; Estroff, Lara A; Gruner, Sol M; Wiesner, Ulrich

2013-08-01

18

New paradigms in hierarchical porous scaffold design for tissue engineering.  

PubMed

This paper presented an effective method for the three-dimensional (3D) hierarchical porous scaffold design for tissue engineering. To achieve such a hierarchical porous structure with accurately controlled internal pore architectures, the recursive intersection Boolean operation (RIBO) was proposed in order to satisfy computational efficiency and biological function requirements of a porous scaffold. After generating the distance field (DF) for the given anatomic model and required pore architectures, the recursive DF modifications enable us to design hierarchical porous scaffolds with complex combinations of pore morphologies. A variety of experimental results showed that the proposed hierarchical porous scaffold design method has the potential benefits for accurately controlling both the porosity and the pore architecture gradients while preserving the advantages of triply periodic minimal surface pore geometries. PMID:23827634

Yoo, Dongjin

2013-04-01

19

Development of polycaprolactone porous scaffolds by combining solvent casting, particulate leaching, and polymer leaching techniques for bone tissue engineering.  

PubMed

Sodium chloride and polyethylene glycol (PEG) were used as water-soluble porogens for the formation of porous polycaprolactone (PCL) scaffolds. The main purpose was to prepare and evaluate in vitro efficacy of highly interconnected, three-dimensional, porous polymeric scaffolds, as obtained from the combined particulate and polymer leaching techniques. Microscopic analysis confirmed the high interconnectivity of the pores and relatively uniform pore size of 378-435 ?m. The PCL scaffolds were further characterized for their density and pore characteristics, water absorption and flow behaviors, and mechanical properties and the potential for their use as bone scaffolding materials was evaluated in vitro using mouse calvaria-derived preosteoblastic cells (MC3T3-E1). Evidently, the use of PEG as the secondary porogen not only improved the interconnectivity of the pore structures but also resulted in the PCL scaffolds that exhibited much better support for the proliferation and differentiation of the cultured bone cells. PMID:24132871

Thadavirul, Napaphat; Pavasant, Prasit; Supaphol, Pitt

2014-10-01

20

Porous Poly(?-Caprolactone) Scaffolds for Retinal Pigment Epithelium Transplantation  

PubMed Central

Purpose. Retinal pigment epithelium (RPE) transplantation is a promising strategy for the treatment of dry age-related macular degeneration (AMD). However, previous attempts at subretinal RPE cell transplantation have experienced limited success due to poor adhesion, organization, and function on aged or diseased Bruch's membrane. Instead, cell-based strategies may benefit from a synthetic scaffold that mimics the functions of healthy Bruch's membrane to promote the formation of a functional RPE monolayer while maintaining metabolite exchange between the vasculature and outer retina. Methods. This study evaluated the behavior of human RPE on nanopatterned porous poly(?-caprolactone) (PCL) film as a potential scaffold for therapeutic transplantation. Fetal human RPE (fhRPE) was cultured on porous PCL, nonporous PCL, or Costar porous polyester transwells for up to 8 weeks and assessed using light microscopy, fluorescent microscopy, transepithelial resistance, quantitative PCR, ELISAs, and phagocytosis assays. Results. fhRPE on porous PCL displayed improved markers of maturity and function compared with both porous polyester transwells and nonporous PCL, including pigmentation, increased cell density, superior barrier function, up-regulation of RPE-specific genes, and polarized growth factor secretion. Conclusions. This study indicates that porous PCL is an attractive scaffold for RPE transplantation. In addition to being biocompatible with the subretinal space, porous PCL also allows for trans-scaffold metabolite transport and significantly improves RPE cell behavior compared to nonporous PCL or porous polyester transwells. PMID:24550370

McHugh, Kevin J.; Tao, Sarah L.; Saint-Geniez, Magali

2014-01-01

21

Novel Biodegradable Porous Scaffold Applied to Skin Regeneration  

PubMed Central

Skin wound healing is an important lifesaving issue for massive lesions. A novel porous scaffold with collagen, hyaluronic acid and gelatin was developed for skin wound repair. The swelling ratio of this developed scaffold was assayed by water absorption capacity and showed a value of over 20 g water/g dried scaffold. The scaffold was then degraded in time- and dose-dependent manners by three enzymes: lysozyme, hyaluronidase and collagenase I. The average pore diameter of the scaffold was 132.5±8.4 µm measured from SEM images. With human skin cells growing for 7 days, the SEM images showed surface fractures on the scaffold due to enzymatic digestion, indicating the biodegradable properties of this scaffold. To simulate skin distribution, the human epidermal keratinocytes, melanocytes and dermal fibroblasts were seeded on the porous scaffold and the cross-section immunofluorescent staining demonstrated normal human skin layer distributions. The collagen amount was also quantified after skin cells seeding and presented an amount 50% higher than those seeded on culture wells. The in vivo histological results showed that the scaffold ameliorated wound healing, including decreasing neutrophil infiltrates and thickening newly generated skin compared to the group without treatments. PMID:23762223

Wang, Hui-Min; Chou, Yi-Ting; Wen, Zhi-Hong; Wang, Zhao-Ren; Chen, Chun-Hong; Ho, Mei-Ling

2013-01-01

22

Manufacture of degradable polymeric scaffolds for bone regeneration.  

PubMed

Many innovative technology platforms for promoting bone regeneration have been developed. A common theme among these is the use of scaffolds to provide mechanical support and osteoconduction. Scaffolds can be either ceramic or polymer-based, or composites of both classes of material. Both ceramics and polymers have their own merits and drawbacks, and a better solution may be to synergize the advantageous properties of both materials within composite scaffolds. In this current review, after a brief introduction of the anatomy and physiology of bone, different strategies of fabricating polymeric scaffolds for bone regeneration, including traditional and solid free-form fabrication, are critically discussed and compared, while focusing on the advantages and disadvantages of individual techniques. PMID:18523339

Ge, Zigang; Jin, Zhaoxia; Cao, Tong

2008-06-01

23

Design of a bioresorbable polymeric scaffold for osteoblast culture  

NASA Astrophysics Data System (ADS)

Bioresorbable polymeric scaffolds were designed for the purpose of growing rat osteosarcoma cells (ROS 17/2.8) using the compression molding method. The material used in the construction of the scaffolds was a mixture of polycaprolactone (PCL), Hydroxyapatite (HA), Glycerin (GL) and salt (NaCl) for porosity. The concentration of the several materials utilized, was determined by volume. Past research at the University of Massachusetts Lowell (UML) has successfully utilized the compression molding method for the construction of scaffolds, but was unable to accomplish the goal of long term cell survival and complete cellular proliferation throughout a three dimensional scaffold. This research investigated various concentrations of the materials and molding temperatures used for the manufacture of scaffolds in order to improve the scaffold design and address those issues. The design of the scaffold using the compression molding process is detailed in the Method and Materials section of this thesis. The porogen (salt) used for porosity was suspected as a possible source of contamination causing cell apoptosis in past studies. This research addressed the issues for cell survival and proliferation throughout a three dimensional scaffold. The leaching of the salt was one major design modification. This research successfully used ultrasonic leaching in addition to the passive method. Prior to cell culture, the scaffolds were irradiated to 2.75 Mrad, with cobalt-60 gamma radionuclide. The tissue culture consisted of two trials: (1) cell culture in scaffolds cleaned with passive leaching; (2) cell culture with scaffolds cleaned with ultrasonic leaching. Cell survival and proliferation was accomplished only with the addition of ultrasonic leaching of the scaffolds. Analysis of the scaffolds included Scanning Electron Microscopy (SEM), Nikon light microscopy and x-ray mapping of the calcium, sodium and chloride ion distribution. The cells were analyzed by Environmental Scanning Electron Microscopy (ESEM) and Nikon light microscopy. The high magnification of ESEM up to 60,000 x revealed an unexpected discovery. The osteoblasts appeared to be remodeling the PCL scaffold shown in the last two figures of this research.

Ditaranto, Vincent M., Jr.

24

Modular and Dynamic Functionalization of Polymeric Scaffolds  

Microsoft Academic Search

The design and synthesis of multifunctionalized, architecturally controlled polymers is a prerequisite for a variety of future applications of polymeric materials. On the basis of Nature's use of self-assembly in the creation of biomaterials, this Account describes concepts that were developed over the past 5 years that utilize noncovalent interactions such as hydrogen bonding, ionic interactions, electrostatic interactions, metal coordination,

Clinton R. South; Caroline Burd; Marcus Weck

2007-01-01

25

Modeling of porous scaffold deformation induced by medium perfusion.  

PubMed

In this study, we tested the possibility of calculating permeability of porous scaffolds utilized in soft tissue engineering using pore size and shape. We validated the results using experimental measured pressure drop and simulations with the inclusion of structural deformation. We prepared Polycaprolactone (PCL) and Chitosan-Gelatin (CG) scaffolds by salt leaching and freeze drying technique, respectively. Micrographs were assessed for pore characteristics and mechanical properties. Porosity for both scaffolds was nearly same but the permeability varied 10-fold. Elastic moduli were 600 and 9 kPa for PCL and CG scaffolds, respectively, while Poisson's ratio was 0.3 for PCL scaffolds and ?1.0 for CG scaffolds. A flow-through bioreactor accommodating a 10 cm diameter and 0.2 cm thick scaffold was used to determine the pressure-drop at various flow rates. Additionally, computational fluid dynamic (CFD) simulations were performed by coupling fluid flow, described by Brinkman equation, with structural mechanics using a dynamic mesh. The experimentally obtained pressure drop matched the simulation results of PCL scaffolds. Simulations were extended to a broad range of permeabilities (10(-10) m(2) to 10(-14) m(2) ), elastic moduli (10-100,000 kPa) and Poisson's ratio (0.1-0.49). The results showed significant deviation in pressure drop due to scaffold deformation compared to rigid scaffold at permeabilities near healthy tissues. Also, considering the scaffold as a nonrigid structure altered the shear stress profile. In summary, scaffold permeability can be calculated using scaffold pore characteristics and deformation could be predicted using CFD simulation. These relationships could potentially be used in monitoring tissue regeneration noninvasively via pressure drop. PMID:24259467

Podichetty, Jagdeep T; Madihally, Sundararajan V

2014-05-01

26

Laser 3D Printing with Sub-Microscale Resolution of Porous Elastomeric Scaffolds for Supporting Human Bone Stem Cells.  

PubMed

A reproducible method is needed to fabricate 3D scaffold constructs that results in periodic and uniform structures with precise control at sub-micrometer and micrometer length scales. In this study, fabrication of scaffolds by two-photon polymerization (2PP) of a biodegradable urethane and acrylate-based photoelastomer is demonstrated. This material supports 2PP processing with sub-micrometer spatial resolution. The high photoreactivity of the biophotoelastomer permits 2PP processing at a scanning speed of 1000 mm s(-1) , facilitating rapid fabrication of relatively large structures (>5 mm(3) ). These structures are custom printed for in vitro assay screening in 96-well plates and are sufficiently flexible to enable facile handling and transplantation. These results indicate that stable scaffolds with porosities of greater than 60% can be produced using 2PP. Human bone marrow stromal cells grown on 3D scaffolds exhibit increased growth and proliferation compared to smooth 2D scaffold controls. 3D scaffolds adsorb larger amounts of protein than smooth 2D scaffolds due to their larger surface area; the scaffolds also allow cells to attach in multiple planes and to completely infiltrate the porous scaffolds. The flexible photoelastomer material is biocompatible in vitro and is associated with facile handling, making it a viable candidate for further study of complex 3D-printed scaffolds. PMID:25522214

Petrochenko, Peter E; Torgersen, Jan; Gruber, Peter; Hicks, Lucas A; Zheng, Jiwen; Kumar, Girish; Narayan, Roger J; Goering, Peter L; Liska, Robert; Stampfl, Jürgen; Ovsianikov, Aleksandr

2015-04-01

27

Living Bacterial Sacrificial Porogens to Engineer Decellularized Porous Scaffolds  

PubMed Central

Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative medicine and drug discovery as viable tissue mimics. However, the existing hydrogel fabrication techniques suffer from limited control over pore interconnectivity, density and size, which leads to inefficient nutrient and oxygen transport to cells embedded in the scaffolds. Here, we demonstrated an innovative approach to develop a new platform for tissue engineered constructs using live bacteria as sacrificial porogens. E.coli were patterned and cultured in an interconnected three-dimensional (3D) hydrogel network. The growing bacteria created interconnected micropores and microchannels. Then, the scafold was decellularized, and bacteria were eliminated from the scaffold through lysing and washing steps. This 3D porous network method combined with bioprinting has the potential to be broadly applicable and compatible with tissue specific applications allowing seeding of stem cells and other cell types. PMID:21552485

Xu, Feng; Sridharan, BanuPriya; Durmus, Naside Gozde; Wang, ShuQi; Yavuz, Ahmet Sinan; Gurkan, Umut Atakan; Demirci, Utkan

2011-01-01

28

Tissue engineering scaffold material of porous nanohydroxyapatite/polyamide 66.  

PubMed

The aim of the study was to investigate a porous nanohydroxyapatite/polyamide 66 (n-HA/PA66) scaffold material that was implanted into muscle and tibiae of 16 New Zealand white rabbits to evaluate the biocompatibility and osteogenesis and osteoinductivity of the materials in vivo. The samples were harvested at 2, 4, 12 and 26 weeks respectively, and subjected to histological analysis. At 2 weeks, the experiment showed that osteogenesis was detected in porous n-HA/PA66 composite and the density of new bone formation was similar to the surrounding host bone at 12 weeks. The study indicated that three-dimensional pore structures could facilitate cell adhesion, differentiation and proliferation, and help with fibrovascular and nerve colonization. In conclusion, porous n-HA/PA66 scaffold material could be a good candidate as a bone substitute material used in clinics due to its excellent histocompatibility, osteoconductivity and osteoinductivity. PMID:20517477

Xu, Qian; Lu, Hongyan; Zhang, Jingchao; Lu, Guoyu; Deng, Zhennan; Mo, Anchun

2010-01-01

29

Porous titanium scaffolds fabricated using a rapid prototyping and powder metallurgy technique  

Microsoft Academic Search

One of the main issues in orthopaedic implant design is the fabrication of scaffolds that closely mimic the biomechanical properties of the surrounding bone. This research reports on a multi-stage rapid prototyping technique that was successfully developed to produce porous titanium scaffolds with fully interconnected pore networks and reproducible porosity and pore size. The scaffolds' porous characteristics were governed by

Garrett E. Ryan; Abhay S. Pandit; Dimitrios P. Apatsidis

2008-01-01

30

Injectable and porous PLGA microspheres that form highly porous scaffolds at body temperature  

PubMed Central

Injectable scaffolds are of interest in the field of regenerative medicine because of their minimally invasive mode of delivery. For tissue repair applications, it is essential that such scaffolds have the mechanical properties, porosity and pore diameter to support the formation of new tissue. In the current study, porous poly(dl-lactic acid-co-glycolic acid) (PLGA) microspheres were fabricated with an average size of 84 ± 24 ?m for use as injectable cell carriers. Treatment with ethanolic sodium hydroxide for 2 min was observed to increase surface porosity without causing the microsphere structure to disintegrate. This surface treatment also enabled the microspheres to fuse together at 37 °C to form scaffold structures. The average compressive strength of the scaffolds after 24 h at 37 °C was 0.9 ± 0.1 MPa, and the average Young’s modulus was 9.4 ± 1.2 MPa. Scaffold porosity levels were 81.6% on average, with a mean pore diameter of 54 ± 38 ?m. This study demonstrates a method for fabricating porous PLGA microspheres that form solid porous scaffolds at body temperature, creating an injectable system capable of supporting NIH-3T3 cell attachment and proliferation in vitro. PMID:25152354

Qutachi, Omar; Vetsch, Jolanda R.; Gill, Daniel; Cox, Helen; Scurr, David J.; Hofmann, Sandra; Müller, Ralph; Quirk, Robin A.; Shakesheff, Kevin M.; Rahman, Cheryl V.

2014-01-01

31

Highly porous 3D nanofiber scaffold using an electrospinning technique.  

PubMed

A successful 3D tissue-engineering scaffold must have a highly porous structure and good mechanical stability. High porosity and optimally designed pore size provide structural space for cell accommodation and migration and enable the exchange of nutrients between the scaffold and environment. Poly(epsilon-carprolactone) fibers were electrospun using an auxiliary electrode and chemical blowing agent (BA), and characterized according to porosity, pore size, and their mechanical properties. We also investigated the effect of the BA on the electrospinning processability. The growth characteristic of human dermal fibroblasts cells cultured in the webs showed the good adhesion with the blown web relative to a normal electrospun mat. The blown nanofiber web had good tensile properties and high porosity compared to a typical electrospun nanofiber scaffold. PMID:16924612

Kim, Geunhyung; Kim, WanDoo

2007-04-01

32

Graded Porous ?-Tricalcium Phosphate Scaffolds Enhance Bone Regeneration in Mandible Augmentation.  

PubMed

Bone augmentation requires scaffold to promote forming of natural bone structure. Currently, most of the reported bone scaffolds are porous solids with uniform pores. The aim of the currentstudy is to evaluate the effect of a graded porous ?-tricalcium phosphate scaffolds on alveolar bone augmentation. Three groups of scaffolds were fabricated by a template-casting method: (1) graded porous scaffolds with large pores in the center and small pores at theperiphery, (2) scaffolds with large uniform pores, and (3) scaffolds with small uniform pores. Bone augmentation on rabbit mandible wasinvestigated by microcomputed tomography, sequential fluorescentlabeling, and histologic examination 3 months after implantation.The result presents that all the scaffold groups maintain their augmented bone height after 3-month observation, whereas the autograftinggroup presents an obvious bone resorption. Microcomputed tomography reveals that the graded porous group has significantly greater volume of new bone (P < 0.05) and similar bone density compared with the uniform pores groups. Bone substance distributes unevenly in all the 3 experimental groups. Greater bone volume can be observed in the area closer to the bone bed. The sequential fluorescentlabeling observation reveals robust bone regeneration in the first month and faster bone growth in the graded porous scaffold group than that in the large porous scaffold group. Histologic examinationsconfirm bone structure in the aspect of distribution, activity, and maturity. We conclude that graded porous designed biodegradable?-tricalcium phosphate scaffolds are beneficial to promote bone augmentation in the aspect of bone volume. PMID:25675019

Yang, Jingwen; Kang, Yunqing; Browne, Christopher; Jiang, Ting; Yang, Yunzhi

2015-03-01

33

Ultra-porous titanium oxide scaffold with high compressive strength  

PubMed Central

Highly porous and well interconnected titanium dioxide (TiO2) scaffolds with compressive strength above 2.5 MPa were fabricated without compromising the desired pore architectural characteristics, such as high porosity, appropriate pore size, surface-to-volume ratio, and interconnectivity. Processing parameters and pore architectural characteristics were investigated in order to identify the key processing steps and morphological properties that contributed to the enhanced strength of the scaffolds. Cleaning of the TiO2 raw powder removed phosphates but introduced sodium into the powder, which was suggested to decrease the slurry stability. Strong correlation was found between compressive strength and both replication times and solid content in the ceramic slurry. Increase in the solid content resulted in more favourable sponge loading, which was achieved due to the more suitable rheological properties of the ceramic slurry. Repeated replication process induced only negligible changes in the pore architectural parameters indicating a reduced flaw size in the scaffold struts. The fabricated TiO2 scaffolds show great promise as load-bearing bone scaffolds for applications where moderate mechanical support is required. PMID:20711636

Tiainen, Hanna; Lyngstadaas, S. Petter; Ellingsen, Jan Eirik

2010-01-01

34

Phenomenological study of Au and Pt nanowires grown in porous alumina scaffolds  

E-print Network

Porous anodic aluminum oxide, commonly known as AAO, has been widely used as a scaffold to synthesize nanowires and nanotubes. The porous alumina structure can be obtained from a simple electrochemical oxidation process, ...

Shin, Yong Cheol, S.M. Massachusetts Institute of Technology

2011-01-01

35

Novel polymeric nanocomposites and porous materials prepared using organogels  

NASA Astrophysics Data System (ADS)

We propose a new method for preparing polymeric nanocomposites and porous materials using self-assembled templates formed by 1,3:2,4-dibenzylidene sorbitol (DBS) organogels. DBS is capable of self-assembling into a 3D nanofibrillar network at relatively low concentrations in some organic solvents to produce organogels. In this study, we induced the formation of such physical cross-linked networks in styrene. Subsequently, we polymerized the styrene in the presence of chemical cross-linkers, divinyl benzene (DVB), with different amounts of DBS using thermal-initiated polymerization. The resulting materials were transparent, homogeneous polystyrene (PS) nanocomposites with both physical and chemical cross-links. The porous polymeric materials were obtained by solvent extraction of the DBS nanofibrils from the PS. Brunauer-Emmett-Teller (BET) measurements show that the amounts of DBS and DVB influenced the specific surface area after the removal of the DBS fibrils.

Lai, Wei-Chi; Tseng, Shen-Chen

2009-11-01

36

Porous nanoapatite scaffolds synthesized using an approach of interfacial mineralization reaction and their bioactivity.  

PubMed

There is a growing interest in the use of calcium phosphate, used to fabricate porous scaffolds for bone tissue regeneration and repair. However, it is difficult to obtain interconnected pores with very high porosity and to engineer the topography of the pore walls for calcium phosphate ceramic scaffolds. In this study, a novelty method interfacial mineralization reaction was used to fabricate porous nano-calcium phosphate ceramic scaffolds with three-dimensional surface topography of walls, which was tuned using different surfactants; using this method, porous scaffolds with different shapes were obtained, which demonstrates that interfacial mineralization reaction is not only a good method to prepare porous ceramic scaffolds of calcium phosphate but also an efficient approach to engineer the topography of the pore walls. The as-prepared porous ceramic scaffolds have also been proved to have good biocompatibility, bioactivity, and biodegradability, which are necessary for the clinical application. In vivo experimental results revealed that not only osteoconduction but also osteoinduction was responsible for the bone formation in our scaffolds, which accelerated the formation of new bone, and that the degradation process of our porous scaffolds could match osteoinduction, mineralization of matrix and bone, and reconstruction of new bone very well, and porous scaffolds could be completely substituted by the new bone. PMID:24692259

Wang, Jianxin; Yan, Haoran; Chen, Taijun; Wang, Yingying; Li, Huiyong; Zhi, Wei; Feng, Bo; Weng, Jie; Zhu, Minghua

2014-11-01

37

Rapid prototyped porous nickel–titanium scaffolds as bone substitutes  

PubMed Central

While calcium phosphate–based ceramics are currently the most widely used materials in bone repair, they generally lack tensile strength for initial load bearing. Bulk titanium is the gold standard of metallic implant materials, but does not match the mechanical properties of the surrounding bone, potentially leading to problems of fixation and bone resorption. As an alternative, nickel–titanium alloys possess a unique combination of mechanical properties including a relatively low elastic modulus, pseudoelasticity, and high damping capacity, matching the properties of bone better than any other metallic material. With the ultimate goal of fabricating porous implants for spinal, orthopedic and dental applications, nickel–titanium substrates were fabricated by means of selective laser melting. The response of human mesenchymal stromal cells to the nickel–titanium substrates was compared to mesenchymal stromal cells cultured on clinically used titanium. Selective laser melted titanium as well as surface-treated nickel–titanium and titanium served as controls. Mesenchymal stromal cells had similar proliferation rates when cultured on selective laser melted nickel–titanium, clinically used titanium, or controls. Osteogenic differentiation was similar for mesenchymal stromal cells cultured on the selected materials, as indicated by similar gene expression levels of bone sialoprotein and osteocalcin. Mesenchymal stromal cells seeded and cultured on porous three-dimensional selective laser melted nickel–titanium scaffolds homogeneously colonized the scaffold, and following osteogenic induction, filled the scaffold’s pore volume with extracellular matrix. The combination of bone-related mechanical properties of selective laser melted nickel–titanium with its cytocompatibility and support of osteogenic differentiation of mesenchymal stromal cells highlights its potential as a superior bone substitute as compared to clinically used titanium. PMID:25383165

Hoffmann, Waldemar; Bormann, Therese; Rossi, Antonella; Müller, Bert; Schumacher, Ralf; Martin, Ivan; Wendt, David

2014-01-01

38

Preparation of Interconnected Porous Chitosan Scaffolds by Sodium Acetate Particulate Leaching  

Microsoft Academic Search

For tissue-engineering applications, a 3D porous chitosan scaffold was simply prepared from a mixture of acidic chitosan solution and sodium acetate particles as the porogen by a salt-leaching method. Differences in the porous structure in terms of pore morphology and interconnectivity between the salt-leached chitosan scaffold and phase-separated scaffold as the control were examined by using scanning electron microscopy, protein

Jin Ik Lim; Yong-Keun Lee; Jeon-Soo Shin; Kook-Jin Lim

2011-01-01

39

Porous polymeric materials for hydrogen storage  

DOEpatents

A porous polymer, poly-9,9'-spirobifluorene and its derivatives for storage of H.sub.2 are prepared through a chemical synthesis method. The porous polymers have high specific surface area and narrow pore size distribution. Hydrogen uptake measurements conducted for these polymers determined a higher hydrogen storage capacity at the ambient temperature over that of the benchmark materials. The method of preparing such polymers, includes oxidatively activating solids by CO.sub.2/steam oxidation and supercritical water treatment.

Yu, Luping; Liu, Di-Jia; Yuan, Shengwen; Yang, Junbing

2013-04-02

40

Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold.  

PubMed

The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO3 solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials. PMID:24411349

Ciobanu, Gabriela; Ilisei, Simona; Luca, Constantin

2014-02-01

41

Rapid prototyped porous nickel-titanium scaffolds as bone substitutes.  

PubMed

While calcium phosphate-based ceramics are currently the most widely used materials in bone repair, they generally lack tensile strength for initial load bearing. Bulk titanium is the gold standard of metallic implant materials, but does not match the mechanical properties of the surrounding bone, potentially leading to problems of fixation and bone resorption. As an alternative, nickel-titanium alloys possess a unique combination of mechanical properties including a relatively low elastic modulus, pseudoelasticity, and high damping capacity, matching the properties of bone better than any other metallic material. With the ultimate goal of fabricating porous implants for spinal, orthopedic and dental applications, nickel-titanium substrates were fabricated by means of selective laser melting. The response of human mesenchymal stromal cells to the nickel-titanium substrates was compared to mesenchymal stromal cells cultured on clinically used titanium. Selective laser melted titanium as well as surface-treated nickel-titanium and titanium served as controls. Mesenchymal stromal cells had similar proliferation rates when cultured on selective laser melted nickel-titanium, clinically used titanium, or controls. Osteogenic differentiation was similar for mesenchymal stromal cells cultured on the selected materials, as indicated by similar gene expression levels of bone sialoprotein and osteocalcin. Mesenchymal stromal cells seeded and cultured on porous three-dimensional selective laser melted nickel-titanium scaffolds homogeneously colonized the scaffold, and following osteogenic induction, filled the scaffold's pore volume with extracellular matrix. The combination of bone-related mechanical properties of selective laser melted nickel-titanium with its cytocompatibility and support of osteogenic differentiation of mesenchymal stromal cells highlights its potential as a superior bone substitute as compared to clinically used titanium. PMID:25383165

Hoffmann, Waldemar; Bormann, Therese; Rossi, Antonella; Müller, Bert; Schumacher, Ralf; Martin, Ivan; de Wild, Michael; Wendt, David

2014-01-01

42

High porous titanium scaffolds showed higher compatibility than lower porous beta-tricalcium phosphate scaffolds for regulating human osteoblast and osteoclast differentiation.  

PubMed

We compared osteoblast and osteoclast differentiation when using beta-tricalcium phosphate (?TCP) and titanium scaffolds by investigating human mesenchymal stem cells (hMSCs) and osteoclast progenitor cell activities. hMSCs were cultured for 7, 14, and 21days on titanium scaffolds with 60%, 73%, and 87% porosity and on ?TCP scaffolds with 60% and 75% porosity. Human osteoclast progenitor cells were cultured with osteoblast for 14 and 21days on 87% titanium and 75% ?TCP scaffolds. Viable cell numbers with 60% and 73% titanium were higher than with 87% titanium and ?TCP scaffolds (P<0.05). An 87% titanium scaffold resulted in the highest osteocalcin production with calcification on day 14 (P<0.01) in titanium scaffolds. All titanium scaffolds resulted in higher osteocalcin production on days 7 and 14 compared to ?TCP scaffolds (P<0.01). Osteoblasts cultured on 87% titanium scaffolds suppressed osteoclast differentiation on day 7 but enhanced osteoclast differentiation on day 14 compared to 75% ?TCP scaffolds (P<0.01). These findings concluded that high porosity titanium scaffolds could enhance progression of hMSC/osteoblast differentiation and regulated osteoclast differentiation cooperating with osteoblast differentiation for calcification as compared with lower porous ?TCP. PMID:25686991

Hirota, Makoto; Hayakawa, Tohru; Shima, Takaki; Ametani, Akihiro; Tohnai, Iwai

2015-04-01

43

Porous polymeric materials for hydrogen storage  

DOEpatents

Porous polymers, tribenzohexazatriphenylene, poly-9,9'-spirobifluorene, poly-tetraphenyl methane and their derivatives for storage of H.sub.2 prepared through a chemical synthesis method. The porous polymers have high specific surface area and narrow pore size distribution. Hydrogen uptake measurements conducted for these polymers determined a higher hydrogen storage capacity at the ambient temperature over that of the benchmark materials. The method of preparing such polymers, includes oxidatively activating solids by CO.sub.2/steam oxidation and supercritical water treatment.

Yu, Luping (Hoffman Estates, IL); Liu, Di-Jia (Naperville, IL); Yuan, Shengwen (Chicago, IL); Yang, Junbing (Westmont, IL)

2011-12-13

44

Fabrication and characterization of porous alginate/polyvinyl alcohol hybrid scaffolds for 3D cell culture.  

PubMed

Porous alginate/polyvinyl alcohol (PVA) hybrid scaffolds as bioartificial cell scaffolds were fabricated to improve cell compatibility as well as flexibility of the scaffolds. The alginate/PVA hybrid scaffolds with different PVA compositions up to 50 wt% were fabricated by a modified freeze-drying method including the physical cross-linking of PVA and the following chemical cross-linking of alginate. The prepared alginate/PVA hybrid scaffolds were characterized by morphology observations using scanning electron microscopy (SEM), the measurements of porosity and average pore sizes and the measurements of compressive strength and modulus. The scaffolds exhibited highly porous, open-cellular pore structures with almost the same surface and cross-sectional porosities (total porosities about 85%, regardless of PVA composition) and the pore sizes from about 290 microm to about 190 microm with increasing PVA composition. The alginate/PVA hybrid scaffolds were more soft and elastic than the control alginate scaffold without significant changes of mechanical strength. The scaffolds were examined for their in vitro cell compatibility by the culture of chondrocytes (human chondrocyte cell line) in the scaffolds and the following analyses by MTT assay and SEM observation. It was observed that the alginate/PVA scaffolds had better cell adhesion and faster growth than the control alginate scaffold. It seems that 30 wt% addition of PVA to alginate in the fabrication of the hybrid scaffolds is desirable for improving their flexibility and cell compatibility. PMID:16128229

Cho, Sang Ho; Oh, Se Heang; Lee, Jin Ho

2005-01-01

45

Gelatin-layered and multi-sized porous ?-tricalcium phosphate for tissue engineering scaffold  

NASA Astrophysics Data System (ADS)

The multi-sized porous ?-tricalcium phosphate scaffolds were fabricated by freeze drying followed by slurry coating using a multi-sized porous sponge as a template. Then, gelatin was dip coated on the multi-sized porous ?-tricalcium phosphate scaffolds under vacuum. The mechanical and biological properties of the fabricated scaffolds were evaluated and compared to the uniformly sized porous scaffolds and scaffolds that were not coated by gelatin. The compressive strength was tested by a universal testing machine, and the cell viability and differentiation behavior were measured using a cell counting kit and alkaline phosphatase activity using the MC3T3-E1 cells. In comparison, the gelatin-coated multi-sized porous ?-tricalcium phosphate scaffold showed enhanced compressive strength. After 14 days, the multi-sized pores were shown to affect cell differentiation, and gelatin coatings were shown to affect the cell viability and differentiation. The results of this study demonstrated that the multi-sized porous ?-tricalcium phosphate scaffold coated by gelatin enhanced the mechanical and biological strengths.

Kim, Sung-Min; Yi, Soon-Aei; Choi, Seong-Ho; Kim, Kwang-Mahn; Lee, Yong-Keun

2012-01-01

46

Indirect solid free form fabrication of local and global porous, biomimetic and composite 3D polymer-ceramic scaffolds  

Microsoft Academic Search

Precise control over scaffold material, porosity, and internal pore architecture is essential for tissue engineering. By coupling solid free form (SFF) manufacturing with conventional sponge scaffold fabrication procedures, we have developed methods for casting scaffolds that contain designed and controlled locally porous and globally porous internal architectures. These methods are compatible with numerous bioresorbable and non-resorbable polymers, ceramics, and biologic

J. M Taboas; R. D Maddox; P. H Krebsbach; S. J Hollister

2003-01-01

47

Physical modification of the interior surfaces of PLGA porous scaffolds using sugar fibers as template  

Microsoft Academic Search

A three-dimensional (3D) poly(D,L-lactic-co-glycolic acid) porous scaffold with microgrooves and microholes on the pore walls was fabricated by using salt particulates as main porogens and sugar fibers as modifiers. Besides macropores templated from salt particulates, microgrooves and microholes were generated after leaching sugar fibers. The resultant porous scaffolds were of high porosity over 90% and still kept good mechanical properties.

Zehua Qu; Jiandong Ding

2012-01-01

48

A microfabricated porous collagen-based scaffold as prototype for skin substitutes  

E-print Network

site area that is needed for autologous split-thickness grafts, it makes skin- replacement proceduresA microfabricated porous collagen-based scaffold as prototype for skin substitutes Curtis D. Chin of artificial skin is a tissue scaffold that allows for fast host regeneration. We present a microfabrication

Sia, Samuel K.

49

Review: Biodegradable Polymeric Scaffolds. Improvements in Bone Tissue Engineering through Controlled Drug Delivery  

Microsoft Academic Search

Recent advances in biology, medicine, and engineering have led to the discovery of new therapeutic\\u000a agents and novel materials for the repair of large bone defects caused by trauma, congenital defects, or\\u000a bone tumors. These repair strategies often utilize degradable polymeric scaffolds for the controlled localized\\u000a delivery of bioactive molecules to stimulate bone ingrowth as the scaffold degrades. Polymer composition,

Theresa A. Holland; Antonios G. Mikos

50

Biomedical Applications of Emulsion Templated Scaffolds  

E-print Network

. To this end, we have utilized emulsion templating to create injectable polyHIPE scaffolds that are biodegradable, highly porous, polymerize at body temperature, and possess appropriate and tunable mechanical properties for tissue regeneration. Poly...

Moglia, Robert Scott

2014-03-28

51

Gelatin porous scaffolds fabricated using a modified gas foaming technique: characterisation and cytotoxicity assessment.  

PubMed

The current study presents an effective and simple strategy to obtain stable porous scaffolds from gelatin via a gas foaming method. The technique exploits the intrinsic foaming ability of gelatin in the presence of CO2 to obtain a porous structure stabilised with glutaraldehyde. The produced scaffolds were characterised using physical and mechanical characterisation methods. The results showed that gas foaming may allow the tailoring of the 3-dimensional structure of the scaffolds with an interconnected porous structure. To assess the effectiveness of the preparation method in mitigating the potential cytotoxicity risk of using glutaraldehyde as a crosslinker, direct and in-direct cytotoxicity assays were performed at different concentrations of glutaraldehyde. The results indicate the potential of the gas foaming method, in the preparation of viable tissue engineering scaffolds. PMID:25579897

Poursamar, S Ali; Hatami, Javad; Lehner, Alexander N; da Silva, Cláudia L; Ferreira, Frederico Castelo; Antunes, A P M

2015-03-01

52

Porous chitosan-hyaluronic acid scaffolds as a mimic of glioblastoma microenvironment ECM  

PubMed Central

Cancer therapeutics are developed through extensive screening; however, many therapeutics evaluated with 2D in vitro cultures during pre-clinical trials suffer from lower efficacy in patients. Replicating the in vivo tumor microenvironment in vitro with three-dimensional (3D) porous scaffolds offers the possibility of generating more predictive pre-clinical models to enhance cancer treatment efficacy. We developed a chitosan and hyaluronic acid (HA) polyelectrolyte complex 3D porous scaffold and evaluated its physical properties. Chitosan-HA (C-HA) scaffolds had a highly porous network. C-HA scaffolds were compared to 2D surfaces for in vitro culture of U-118 MG human glioblastoma (GBM) cells. C-HA scaffold cultures promoted tumor spheroid formation and increased stem-like properties of GBM cells as evidenced by the upregulation of CD44, Nestin, Musashi-1, GFAP, and HIF-1? as compared with 2D cultures. Additionally, the invasiveness of GBM cells cultured in C-HA scaffolds was significantly enhanced compared to those grown in 2D cultures. C-HA scaffold cultures were also more resistant to chemotherapy drugs, which corresponded to the increased expression of ABCG2 drug efflux transporter. These findings suggest that C-HA scaffolds offer promise as an in vitro GBM platform for study and screening of novel cancer therapeutics. PMID:24075410

Jana, Soumen; Wood, David L.; Sytsma, Samara K.; Sham, Jonathan; Kievit, Forrest M.; Zhang, Miqin

2013-01-01

53

Fabrication and characterization of interconnected porous biodegradable poly(?-caprolactone) load bearing scaffolds.  

PubMed

In this study, poly(?-caprolactone) (PCL)/poly(ethylene oxide) (PEO) (50:50 wt%) immiscible blend was used as a model system to investigate the feasibility of a novel solventless fabrication approach that combines cryomilling, compression molding and porogen leaching techniques to prepare interconnected porous scaffolds for tissue engineering. PCL was cryomilled with PEO to form blend powders. Compression molding was used to consolidate and anneal the cryomilled powders. Selective dissolution of the PEO with water resulted in interconnected porous scaffolds. Sodium chloride salt (NaCl) was subsequently added to cryomilled powder to increase the porosity of scaffolds. The prepared scaffolds had homogeneous pore structures, a porosity of ~50% which was increased by mixing salt with the blend (~70% for 60% wt% NaCl), and a compressive modulus and strength (? = 10%) of 60 and 2.8 MPa, respectively. The results of the study confirm that this novel approach offers a viable alternative to fabricate scaffolds. PMID:21670998

Allaf, Rula M; Rivero, Iris V

2011-08-01

54

Fabrication of highly interconnected porous silk fibroin scaffolds for potential use as vascular grafts.  

PubMed

Silk fibroin (SF) scaffolds have been designed and fabricated for multiple organ engineering owing to SF's remarkable mechanical property, excellent biocompatibility and biodegradability, as well as its low immunogenicity. In this study, an easy-to-adopt and mild approach based on a modified freeze-drying method was developed to fabricate a highly interconnected porous SF scaffold. The physical properties of the SF scaffold, including pore morphology, pore size, porosity and compressive modulus, could be adjusted by the amount of ethanol added, the freezing temperature and the concentration of SF. Fourier transform infrared spectroscopy illustrated that treatment of the lyophilized scaffolds with 90% methanol led to a structure transition of SF from silk I (random coil) to silk II (beta-sheet), which stabilized the SF scaffolds in water. We also incorporated heparin during fabrication to obtain a heparin-loaded scaffold which possessed excellent anticoagulant property. The heparin that was incorporated into the SF scaffolds could be released in a sustain manner for approximately 7days, inhibiting the proliferation of human smooth muscle cells within the scaffold in vitro while promoting neovascularization in vivo. We therefore propose that the SF porous scaffold fabricated here may be an attractive candidate for use as a potential vascular graft for implantation based on its high porosity, excellent blood compatibility and mild fabrication process. PMID:24486642

Zhu, Meifeng; Wang, Kai; Mei, Jingjing; Li, Chen; Zhang, Jiamin; Zheng, Wenting; An, Di; Xiao, Nannan; Zhao, Qiang; Kong, Deling; Wang, Lianyong

2014-05-01

55

An experimental fatigue study of a porous scaffold for the regeneration of articular cartilage.  

PubMed

The aim of this experimental study is to predict the long-term mechanical behavior of a porous scaffold implanted in a cartilage defect for tissue engineering purpose. Fatigue studies were performed by up to 100,000 unconfined compression cycles in a polycaprolactone (PCL) scaffold with highly interconnected pores architecture. The scaffold compliance, stress-strain response and hysteresis energy have been measured after different number of fatigue cycles, while the morphology has been observed by scanning electron microscopy at the same fatigue times. To simulate the growing tissue in the scaffold/tissue construct, the scaffold was filled with an aqueous solution of polyvinyl alcohol (PVA) and subjected to repeating cycles of freezing and thawing that increase the hydrogel stiffness. Fatigue studies show that the mechanical loading provokes failure of the dry scaffold at a smaller number of deformation cycles than when it is immersed in water, and also that 100,000 compressive dynamic cycles do not affect the scaffold/gel construct. This shows the stability of the scaffold implanted in a chondral defect and gives a realistic simulation of the mechanical performance from implantation of the empty scaffold to regeneration of the new tissue inside the scaffold?s pores. PMID:25814177

Vikingsson, L; Gómez-Tejedor, J A; Gallego Ferrer, G; Gómez Ribelles, J L

2015-05-01

56

Large Scale Laser Two-Photon Polymerization Structuring for Fabrication of Artificial Polymeric Scaffolds for Regenerative Medicine  

NASA Astrophysics Data System (ADS)

We present a femtosecond Laser Two-Photon Polymerization (LTPP) system of large scale three-dimensional structuring for applications in tissue engineering. The direct laser writing system enables fabrication of artificial polymeric scaffolds over a large area (up to cm in lateral size) with sub-micrometer resolution which could find practical applications in biomedicine and surgery. Yb:KGW femtosecond laser oscillator (Pharos, Light Conversion. Co. Ltd.) is used as an irradiation source (75 fs, 515 nm (frequency doubled), 80 MHz). The sample is mounted on wide range linear motor driven stages having 10 nm sample positioning resolution (XY—ALS130-100, Z—ALS130-50, Aerotech, Inc.). These stages guarantee an overall travelling range of 100 mm into X and Y directions and 50 mm in Z direction and support the linear scanning speed up to 300 mm/s. By moving the sample three-dimensionally the position of laser focus in the photopolymer is changed and one is able to write complex 3D (three-dimensional) structures. An illumination system and CMOS camera enables online process monitoring. Control of all equipment is automated via custom made computer software "3D-Poli" specially designed for LTPP applications. Structures can be imported from computer aided design STereoLihography (stl) files or programmed directly. It can be used for rapid LTPP structuring in various photopolymers (SZ2080, AKRE19, PEG-DA-258) which are known to be suitable for bio-applications. Microstructured scaffolds can be produced on different substrates like glass, plastic and metal. In this paper, we present microfabricated polymeric scaffolds over a large area and growing of adult rabbit myogenic stem cells on them. Obtained results show the polymeric scaffolds to be applicable for cell growth practice. It exhibit potential to use it for artificial pericardium in the experimental model in the future.

Malinauskas, M.; Purlys, V.; Žukauskas, A.; Rutkauskas, M.; Danilevi?ius, P.; Paipulas, D.; Bi?kauskait?, G.; Bukelskis, L.; Baltriukien?, D.; Širmenis, R.; Gaidukevi?iut?, A.; Bukelskien?, V.; Gadonas, R.; Sirvydis, V.; Piskarskas, A.

2010-11-01

57

Large Scale Laser Two-Photon Polymerization Structuring for Fabrication of Artificial Polymeric Scaffolds for Regenerative Medicine  

SciTech Connect

We present a femtosecond Laser Two-Photon Polymerization (LTPP) system of large scale three-dimensional structuring for applications in tissue engineering. The direct laser writing system enables fabrication of artificial polymeric scaffolds over a large area (up to cm in lateral size) with sub-micrometer resolution which could find practical applications in biomedicine and surgery. Yb:KGW femtosecond laser oscillator (Pharos, Light Conversion. Co. Ltd.) is used as an irradiation source (75 fs, 515 nm (frequency doubled), 80 MHz). The sample is mounted on wide range linear motor driven stages having 10 nm sample positioning resolution (XY--ALS130-100, Z--ALS130-50, Aerotech, Inc.). These stages guarantee an overall travelling range of 100 mm into X and Y directions and 50 mm in Z direction and support the linear scanning speed up to 300 mm/s. By moving the sample three-dimensionally the position of laser focus in the photopolymer is changed and one is able to write complex 3D (three-dimensional) structures. An illumination system and CMOS camera enables online process monitoring. Control of all equipment is automated via custom made computer software ''3D-Poli'' specially designed for LTPP applications. Structures can be imported from computer aided design STereoLihography (stl) files or programmed directly. It can be used for rapid LTPP structuring in various photopolymers (SZ2080, AKRE19, PEG-DA-258) which are known to be suitable for bio-applications. Microstructured scaffolds can be produced on different substrates like glass, plastic and metal. In this paper, we present microfabricated polymeric scaffolds over a large area and growing of adult rabbit myogenic stem cells on them. Obtained results show the polymeric scaffolds to be applicable for cell growth practice. It exhibit potential to use it for artificial pericardium in the experimental model in the future.

Malinauskas, M.; Purlys, V.; Zukauskas, A.; Rutkauskas, M.; Danilevicius, P.; Paipulas, D.; Bickauskaite, G.; Gadonas, R.; Piskarskas, A. [Vilnius University, Physics Faculty, Department of Quantum Electronics, Laser Research Center, Sauletekio ave. 10, LT-10223 Vilnius (Lithuania); Bukelskis, L.; Baltriukiene, D.; Bukelskiene, V. [Institute of Biochemistry, Vivarium, Mokslininkuo str. 12, LT-08662 Vilnius (Lithuania); Sirmenis, R. [Vilnius University Hospital Santariskiuo Klinikos, Santariskiuo g. 2, LT-08661 Vilnius (Lithuania); Gaidukeviciute, A. [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, Vassilika Vouton, 711 10 Heraklion, Crete (Greece); Sirvydis, V. [Vilnius University, Faculty of Medicine, Heart Surgery Center, Santariskiuo 2, LT-08661, Vilnius (Lithuania)

2010-11-10

58

Incorporation of polymeric microparticles into collagen-hydroxyapatite scaffolds for the delivery of a pro-osteogenic peptide for bone tissue engineering  

NASA Astrophysics Data System (ADS)

Collagen-hydroxyapatite scaffolds are outstanding materials for bone tissue engineering as they are biocompatible, bioresorbable, osteoconductive, and osteoinductive. The objective of the present work was to assess the potential of increasing their regenerative capacity by functionalising the scaffolds for therapeutic delivery. This was achieved by the utilization of polymeric drug carriers. With this purpose, alginate, chitosan, gelatine, and poly(lactic-co-glycolic acid) (PLGA) microparticles eluting PTHrP 107-111, an osteogenic pentapeptide, were fabricated and tested by incorporating them into the scaffolds. Among them, PLGA microparticles show the most promising characteristics for use as drug delivery devices. Following the incorporation of the microparticles, the scaffolds maintained their interconnected porous structure and the mechanical properties of the materials were not adversely affected. In addition, the microparticles released all their PTHrP 107-111 cargo. Most importantly, the delivered peptide proved to be bioactive and promoted enhanced osteogenesis as assessed by alkaline phosphatase production and osteocalcin and osteopontin gene expression when pre-osteoblastic cells were seeded on the scaffolds. While the focus was on bone repair, the release system described in this study can be used for the delivery of therapeutics for healing and regeneration of a variety of tissue types depending on the type of collagen scaffold chosen.

López-Noriega, Adolfo; Quinlan, Elaine; Celikkin, Nehar; O'Brien, Fergal J.

2015-01-01

59

Poly(lactide-co-glycolide) porous scaffolds for tissue engineering and regenerative medicine  

PubMed Central

Porous scaffolds fabricated from biocompatible and biodegradable polymers play vital roles in tissue engineering and regenerative medicine. Among various scaffold matrix materials, poly(lactide-co-glycolide) (PLGA) is a very popular and an important biodegradable polyester owing to its tunable degradation rates, good mechanical properties and processibility, etc. This review highlights the progress on PLGA scaffolds. In the latest decade, some facile fabrication approaches at room temperature were put forward; more appropriate pore structures were designed and achieved; the mechanical properties were investigated both for dry and wet scaffolds; a long time biodegradation of the PLGA scaffold was observed and a three-stage model was established; even the effects of pore size and porosity on in vitro biodegradation were revealed; the PLGA scaffolds have also been implanted into animals, and some tissues have been regenerated in vivo after loading cells including stem cells. PMID:23741612

Pan, Zhen; Ding, Jiandong

2012-01-01

60

Palladium modified porous polymeric membranes and their performance in selective hydrogenation of propyne  

Microsoft Academic Search

The accessible pore system of polymeric ultrafiltration membranes was modified by titanium dioxide and treated further with palladium acetate to yield catalytically active, porous nanofiltration membranes. This procedure is in general applicable for any polymeric ultrafiltration membrane. To overcome the drawback of low thermal stability of common polymeric membranes, new ultrafiltration membranes were developed, based on a polyamideimide containing up

Silke Ziegler; Juliane Theis; Detlev Fritsch

2001-01-01

61

Hydrolytic degradation of porous scaffolds for tissue engineering from terpolymer of L-lactide, ?-caprolactone and glycolide  

NASA Astrophysics Data System (ADS)

Segmental terpolymer of L-lactide, ?-caprolactone and glycolide have been synthesized by ring-opening polymerization with the use of zirconium acetylacetonate as a biocompatible initiator. Porous scaffolds aimed at tissue engineering have been prepared from resulting terpolymer by solvent casting/particulate leaching technique. Sieved sodium citrate particles of 500-700 ?m size have been used as porogens. The obtained scaffolds have been submitted to degradation in phosphate buffered saline (PBS) at 37 °C for 26 weeks and characterized as a function of incubation time by: Fourier transform infrared spectroscopy in the attenuated total reflection mode (FTIR-ATR), nuclear magnetic resonance ( 1H NMR), gel permeation chromatography (GPC) and scanning electron microscopy (SEM). The scaffolds start to degrade immediately after contact with PBS, as demonstrated by decrease in molecular weights ( Mn and Mw). In the first stage (6 weeks in PBS) when the scaffolds are still dimensionally stable, the degradation is generally due to cleavage of ester bonds between glycolidyl (GG) and caproyl (Cap) groups present in chain sequences such as -GGCapCap-, -GGGCap-, as shown by 1H NMR. The analysis of FTIR spectra of the initial scaffolds and after 6 week immersion in PBS reveals a shift of the band attributed to C dbnd6 O vibrations and considerable changes in the shape of the bands attributed to C-O and C-O-C vibrations. These changes are due to chain-scission of polyester bonds in hydrolysis reaction. Subsequently, when the concentration of sequences containing glycol, glycolidyl and caproyl groups decreases, the influence of cleavage of polyester bonds between longer lactyl microblocks on the degradation increases gradually. As a result, two separate polymer fractions are formed.

Pamu?a, El?bieta; Dobrzy?ski, Piotr; Bero, Maciej; Paluszkiewicz, Czes?awa

2005-06-01

62

A transient cell-shielding method for viable MSC delivery within hydrophobic scaffolds polymerized in situ.  

PubMed

Cell-based therapies have emerged as promising approaches for regenerative medicine. Hydrophobic poly(ester urethane)s offer the advantages of robust mechanical properties, cell attachment without the use of peptides, and controlled degradation by oxidative and hydrolytic mechanisms. However, the application of injectable hydrophobic polymers to cell delivery is limited by the challenges of protecting cells from reaction products and creating a macroporous architecture post-cure. We designed injectable carriers for cell delivery derived from reactive, hydrophobic polyisocyanate and polyester triol precursors. To overcome cell death caused by reaction products from in situ polymerization, we encapsulated bone marrow-derived stem cells (BMSCs) in fastdegrading, oxidized alginate beads prior to mixing with the hydrophobic precursors. Cells survived the polymerization at >70% viability, and rapid dissolution of oxidized alginate beads after the scaffold cured created interconnected macropores that facilitated cellular adhesion to the scaffold in vitro. Applying this injectable system to deliver BMSCs to rat excisional skin wounds showed that the scaffolds supported survival of transplanted cells and infiltration of host cells, which improved new tissue formation compared to both implanted, pre-formed scaffolds seeded with cells and acellular controls. Our design is the first to enable injectable delivery of settable, hydrophobic scaffolds where cell encapsulation provides a mechanism for both temporary cytoprotection during polymerization and rapid formation of macropores post-polymerization. This simple approach provides potential advantages for cell delivery relative to hydrogel technologies, which have weaker mechanical properties and require incorporation of peptides to achieve cell adhesion and degradability. PMID:25907036

Guo, Ruijing; Ward, Catherine L; Davidson, Jeffrey M; Duvall, Craig L; Wenke, Joseph C; Guelcher, Scott A

2015-06-01

63

Porous poly(para-phenylene) scaffolds for load-bearing orthopedic applications.  

PubMed

The focus of this study was to fabricate and investigate the mechanical behavior of porous poly(para-phenylene) (PPP) for potential use as a load-bearing orthopedic biomaterial. PPPs are known to have exceptional mechanical properties due to their aromatic backbone; however, the manufacturing and properties of PPP porous structures have not been previously investigated. Tailored porous structures with either small (150-250µm) or large (420-500µm) pore sizes were manufactured using a powder-sintering/salt-leaching technique. Porosities were systematically varied using 50 to 90vol%. Micro-computed tomography (µCT) and scanning electron microscopy (SEM) were used to verify an open-cell structure and investigate pore morphology of the scaffolds. Uniaxial mechanical behavior of solid and porous PPP samples was characterized through tensile and compressive testing. Both modulus and strength decreased with increasing porosity and matched well with foam theory. Porous scaffolds showed a significant decrease in strain-to-failure (<4%) under tensile loading and experienced linear elasticity, plastic deformation, and densification under compressive loading. Over the size ranges tested, pore size did not significantly influence the mechanical behavior of the scaffolds on a consistent basis. These results are discussed in regards to use of porous PPP for orthopedic applications and a prototype porous interbody fusion cage is presented. PMID:24374261

DiRienzo, Amy L; Yakacki, Christopher M; Frensemeier, Mareike; Schneider, Andreas S; Safranski, David L; Hoyt, Anthony J; Frick, Carl P

2014-02-01

64

Label-free magnetic resonance imaging to locate live cells in three-dimensional porous scaffolds  

PubMed Central

Porous scaffolds are widely tested materials used for various purposes in tissue engineering. A critical feature of a porous scaffold is its ability to allow cell migration and growth on its inner surface. Up to now, there has not been a method to locate live cells deep inside a material, or in an entire structure, using real-time imaging and a non-destructive technique. Herein, we seek to demonstrate the feasibility of the magnetic resonance imaging (MRI) technique as a method to detect and locate in vitro non-labelled live cells in an entire porous material. Our results show that the use of optimized MRI parameters (4.7 T; repetition time = 3000 ms; echo time = 20 ms; resolution 39 × 39 µm) makes it possible to obtain images of the scaffold structure and to locate live non-labelled cells in the entire material, with a signal intensity higher than that obtained in the culture medium. In the current study, cells are visualized and located in different kinds of porous scaffolds. Moreover, further development of this MRI method might be useful in several three-dimensional biomaterial tests such as cell distribution studies, routine qualitative testing methods and in situ monitoring of cells inside scaffolds. PMID:22442095

Abarrategi, A.; Fernandez-Valle, M. E.; Desmet, T.; Castejón, D.; Civantos, A.; Moreno-Vicente, C.; Ramos, V.; Sanz-Casado, J. V.; Martínez-Vázquez, F. J.; Dubruel, P.; Miranda, P.; López-Lacomba, J. L.

2012-01-01

65

Fabrication and in vitro degradation of porous fumarate-based polymer\\/alumoxane nanocomposite scaffolds for bone tissue engineering  

Microsoft Academic Search

In this work, the fabrication and in vitro degradation of porous fumarate-based\\/alumoxane nanocomposites were evaluated for their potential as bone tissue engineering scaffolds. The biodegradable polymer poly (propylene fumarate)\\/propylene fumarate-diacrylate (PPF\\/PF-DA), a macrocomposite composed of PPF\\/PF-DA and boehmite microparticles, and a nanocomposite composed of PPF\\/PF-DA and surface-modified alumoxane nanoparticles were used to fabricate porous scaffolds by photo-crosslinking and salt-leaching. Scaffolds

A. S. Mistry; S. H. Cheng; T. Yeh; E. Christenson; J. A. Jansen; A. G. Mikos

2009-01-01

66

Effective method for multi-scale gradient porous scaffold design and fabrication.  

PubMed

Function-based modeling is a highly flexible porous scaffold design approach for use in tissue engineering. It was recently proposed as a valid tool for constructing cellular structures by providing a compact representation of complex structures. However, current approaches have some limitations with regard to combining multiple function-based substructures. In this short communication, we propose an effective method for combination operations of multiple substructures based on given substructures and boundaries. With this proposed method, a functional gradient porous scaffold (FGPS) with multi-scale substructures could be easily constructed and directly fabricated by using additive manufacturing techniques. PMID:25175242

Yang, Nan; Zhou, Kuntao

2014-10-01

67

Interfacing polymeric scaffolds with primary pancreatic ductal adenocarcinoma cells to develop 3D cancer models.  

PubMed

We analyzed the interactions between human primary cells from pancreatic ductal adenocarcinoma (PDAC) and polymeric scaffolds to develop 3D cancer models useful for mimicking the biology of this tumor. Three scaffold types based on two biocompatible polymeric formulations, such as poly(vinyl alcohol)/gelatin (PVA/G) mixture and poly(ethylene oxide terephthalate)/poly(butylene terephthalate) (PEOT/PBT) copolymer, were obtained via different techniques, namely, emulsion and freeze-drying, compression molding followed by salt leaching, and electrospinning. In this way, primary PDAC cells interfaced with different pore topographies, such as sponge-like pores of different shape and size or nanofiber interspaces. The aim of this study was to investigate the influence played by the scaffold architecture over cancerous cell growth and function. In all scaffolds, primary PDAC cells showed good viability and synthesized tumor-specific metalloproteinases (MMPs) such as MMP-2, and MMP-9. However, only sponge-like pores, obtained via emulsion-based and salt leaching-based techniques allowed for an organized cellular aggregation very similar to the native PDAC morphological structure. Differently, these cell clusters were not observed on PEOT/PBT electrospun scaffolds. MMP-2 and MMP-9, as active enzymes, resulted to be increased in PVA/G and PEOT/PBT sponges, respectively. These findings suggested that spongy scaffolds supported the generation of pancreatic tumor models with enhanced aggressiveness. In conclusion, primary PDAC cells showed diverse behaviors while interacting with different scaffold types that can be potentially exploited to create stage-specific pancreatic cancer models likely to provide new knowledge on the modulation and drug susceptibility of MMPs. PMID:25482337

Ricci, Claudio; Mota, Carlos; Moscato, Stefania; D'Alessandro, Delfo; Ugel, Stefano; Sartoris, Silvia; Bronte, Vincenzo; Boggi, Ugo; Campani, Daniela; Funel, Niccola; Moroni, Lorenzo; Danti, Serena

2014-01-01

68

Adipogenic differentiation of stem cells in three-dimensional porous bacterial nanocellulose scaffolds.  

PubMed

There is an increased interest in developing adipose tissue for in vitro and in vivo applications. Current two-dimensional (2D) cell-culture systems of adipocytes are limited, and new methods to culture adipocytes in three-dimensional (3D) are warranted as a more life-like model to study metabolic diseases such as obesity and diabetes. In this study, we have evaluated different porous bacterial nanocellulose scaffolds for 3D adipose tissue. In an initial pilot study, we compared adipogenic differentiation of mice mesenchymal stem cells from a cell line on 2D and 3D scaffolds of bacterial nanocellulose. The 3D scaffolds were engineered by crosslinking homogenized cellulose fibrils using alginate and freeze drying the mixture to obtain a porous structure. Quenching the scaffolds in liquid nitrogen resulted in smaller pores compared to slower freezing using isopropanol. We found that on 2D surfaces, the cells were scarcely distributed and showed limited formation of lipid droplets, whereas cells grown in macroporous 3D scaffolds contained more cells growing in clusters, containing large lipid droplets. All four types of scaffolds contained a lot of adipocytes, but scaffolds with smaller pores contained larger cell clusters than scaffolds with bigger pores, with viable adipocytes present even 4 weeks after differentiation. Scaffolds with lower alginate fractions retained their pore integrity better. We conclude that 3D culturing of adipocytes in bacterial nanocellulose macroporous scaffolds is a promising method for fabrication of adipose tissue as an in vitro model for adipose biology and metabolic disease. PMID:24819827

Krontiras, Panagiotis; Gatenholm, Paul; Hägg, Daniel A

2015-01-01

69

Repairing a critical-sized bone defect with highly porous modified and unmodified baghdadite scaffolds.  

PubMed

This is the first reported study to prepare highly porous baghdadite (Ca?ZrSi?O?) scaffolds with and without surface modification and investigate their ability to repair critical-sized bone defects in a rabbit radius under normal load. The modification was carried out to improve the mechanical properties of the baghdadite scaffolds (particularly to address their brittleness) by coating their surfaces with a thin layer (?400 nm) of polycaprolactone (PCL)/bioactive glass nanoparticles (nBGs). The ?-tricalcium phosphate/hydroxyapatite (TCP/HA) scaffolds with and without modification were used as the control groups. All of the tested scaffolds had an open and interconnected porous structure with a porosity of ?85% and average pore size of 500 ?m. The scaffolds (six per scaffold type and size of 4 mm × 4 mm × 15 mm) were implanted (press-fit) into the rabbit radial segmental defects for 12 weeks. Micro-computed tomography and histological evaluations were used to determine bone ingrowth, bone quality, and implant integration after 12 weeks of healing. Extensive new bone formation with complete bridging of the radial defect was evident with the baghdadite scaffolds (modified/unmodified) at the periphery and in close proximity to the ceramics within the pores, in contrast to TCP/HA scaffolds (modified/unmodified), where bone tended to grow between the ulna adjacent to the implant edge. Although the modification of the baghdadite scaffolds significantly improved their mechanical properties, it did not show any significant effect on in vivo bone formation. Our findings suggest that baghdadite scaffolds with and without modification can serve as a potential material to repair critical sized bone defects. PMID:22842031

Roohani-Esfahani, S I; Dunstan, C R; Davies, B; Pearce, S; Williams, R; Zreiqat, H

2012-11-01

70

Characteristics and osteogenic effect of zirconia porous scaffold coated with ?-TCP/HA  

PubMed Central

PURPOSE The purpose of this study was to evaluate the properties of a porous zirconia scaffold coated with bioactive materials and compare the in vitro cellular behavior of MC3T3-E1 preosteoblastic cells to titanium and zirconia disks and porous zirconia scaffolds. MATERIALS AND METHODS Titanium and zirconia disks were prepared. A porous zirconia scaffold was fabricated with an open cell polyurethane disk foam template. The porous zirconia scaffolds were coated with ?-TCP, HA and a compound of ?-TCP and HA (BCP). The characteristics of the specimens were evaluated using scanning electron microscopy (SEM), energy dispersive x-ray spectrometer (EDX), and x-ray diffractometry (XRD). The dissolution tests were analyzed by an inductively coupled plasma spectrometer (ICP). The osteogenic effect of MC3T3-E1 cells was assessed via cell counting and reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS The EDX profiles showed the substrate of zirconia, which was surrounded by the Ca-P layer. In the dissolution test, dissolved Ca2+ ions were observed in the following decreasing order; ?-TCP > BCP > HA (P<.05). In the cellular experiments, the cell proliferation on titanium disks appeared significantly lower in comparison to the other groups after 5 days (P<.05). The zirconia scaffolds had greater values than the zirconia disks (P<.05). The mRNA level of osteocalcin was highest on the non-coated zirconia scaffolds after 7 days. CONCLUSION Zirconia had greater osteoblast cell activity than titanium. The interconnecting pores of the zirconia scaffolds showed enhanced proliferation and cell differentiation. The activity of osteoblast was more affected by microstructure than by coating materials. PMID:25177472

Song, Young-Gyun

2014-01-01

71

Physiologically-Relevant Oxidative Degradation of Oligo(proline)-Crosslinked Polymeric Scaffolds  

PubMed Central

Chronic inflammation-mediated oxidative stress is a common mechanism of implant rejection and failure. Therefore, polymer scaffolds that can degrade slowly in response to this environment may provide a viable platform for implant site-specific, sustained release of immunomodulatory agents over a long time period. In this work, proline oligomers of varying lengths (Pn) were synthesized and exposed to oxidative environments, and their accelerated degradation under oxidative conditions was verified via high performance liquid chromatography and gel permeation chromatography. Next, diblock copolymers of poly(ethylene glycol) (PEG) and poly(?-caprolactone) (PCL) were carboxylated to form 100 kDa terpolymers of 4%PEG-86%PCL-10%cPCL (cPCL = poly(carboxyl-?-caprolactone); i% indicates molar ratio). The polymers were then crosslinked with bi-aminated PEG-Pn-PEG chains—where Pn indicates the length of the proline oligomer flanked by PEG chains. Salt-leaching of the polymeric matrices created scaffolds of macroporous and microporous architecture as observed by scanning electron microscopy. The degradation of scaffolds was accelerated under oxidative conditions, as evidenced by mass loss and differential scanning calorimetry measurements. Immortalized murine bone marrow-derived macrophages were then seeded on the scaffolds, and activated through the addition of ?-interferon and lipopolysaccharide throughout the 9-day study period. This treatment promoted the release of H2O2 by the macrophages, and the degradation of proline-containing scaffolds compared to the control scaffolds. The accelerated degradation was evidenced by increased scaffold porosity, as visualized through scanning electron microscoopy and X-ray microtomography imaging. The current study provides insight into the development of scaffolds that respond to oxidative environments through gradual degradation, for the controlled release of therapeutics targeted to diseases that feature chronic inflammation and oxidative stress. PMID:22017359

Yu, Shann S.; Koblin, Rachel L.; Zachman, Angela L.; Perrien, Daniel S.; Hofmeister, Lucas H.; Giorgio, Todd D.; Sung, Hak-Joon

2011-01-01

72

Porous ovalbumin scaffolds with tunable properties: a resource-efficient biodegradable material for tissue engineering applications.  

PubMed

Natural materials are promising alternatives to synthetic materials used in tissue engineering applications as they have superior biocompatibility and promote better cell attachment and proliferation. Ovalbumin, a natural polymer found in avian egg white, is an example of a nature-derived material. Despite the availability and reported biocompatibility of ovalbumin, limited research has been carried out to investigate the efficacy of ovalbumin-based scaffolds for adipose tissue engineering applications. Hence, the current study was carried out to investigate the effect of different crosslinkers on ovalbumin scaffold properties as first step towards the development of ovalbumin-based scaffolds for adipose tissue engineering applications. In this study, highly porous three-dimensional scaffolds were fabricated by using three different crosslinkers: glutaraldehyde, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and 1,4-butanediol diglycidyl ether. Results showed that the overall scaffold properties such as morphology, pore size and mechanical properties could be modulated based on the type and concentration of crosslinkers used during the fabrication process. Subsequently, the efficacy of the different scaffolds for supporting cell proliferation was investigated. In vitro degradation was also carried on for the best scaffold based on the mechanical and cellular results. Overall, this study is a demonstration of the viability of ovalbumin-based scaffolds as cell carriers for soft tissue engineering applications. PMID:25158688

Luo, Baiwen; Choong, Cleo

2015-01-01

73

Porous anodic aluminum oxide scaffolds; formation mechanisms and applications  

E-print Network

Nanoporous anodic aluminium oxide (AAO) can be created with pores that self-assemble into ordered configurations. Nanostructured metal oxides have proven to be very useful as scaffolds for growth of nanowires and nanotubes ...

Oh, Jihun

2010-01-01

74

A Porous Tissue Engineering Scaffold Selectively Degraded by Cell-Generated Reactive Oxygen Species  

PubMed Central

Biodegradable tissue engineering scaffolds are commonly fabricated from poly(lactide-co-glycolide) (PLGA) or similar polyesters that degrade by hydrolysis. PLGA hydrolysis generates acidic breakdown products that trigger an accelerated, autocatalytic degradation mechanism that can create mismatched rates of biomaterial breakdown and tissue formation. Reactive oxygen species (ROS) are key mediators of cell function in both health and disease, especially at sites of inflammation and tissue healing, and induction of inflammation and ROS are natural components of the in vivo response to biomaterial implantation. Thus, polymeric biomaterials that are selectively degraded by cell-generated ROS may have potential for creating tissue engineering scaffolds with better matched rates of tissue in-growth and cell-mediated scaffold biodegradation. To explore this approach, a series of poly(thioketal) (PTK) urethane (PTK-UR) biomaterial scaffolds were synthesized that degrade specifically by an ROS-dependent mechanism. PTK-UR scaffolds had significantly higher compressive moduli than analogous poly(ester urethane) (PEUR) scaffolds formed from hydrolytically-degradable ester-based diols (p < 0.05). Unlike PEUR scaffolds, the PTK-UR scaffolds were stable under aqueous conditions out to 25 weeks but were selectively degraded by ROS, indicating that their biodegradation would be exclusively cell-mediated. The in vitro oxidative degradation rates of the PTK-URs followed first-order degradation kinetics, were significantly dependent on PTK composition (p < 0.05), and correlated to ROS concentration. In subcutaneous rat wounds, PTK-UR scaffolds supported cellular infiltration and granulation tissue formation, followed first-order degradation kinetics over 7 weeks, and produced significantly greater stenting of subcutaneous wounds compared to PEUR scaffolds. These combined results indicate that ROS-degradable PTK-UR tissue engineering scaffolds have significant advantages over analogous polyester-based biomaterials and provide a robust, cell-degradable substrate for guiding new tissue formation. PMID:24491510

Martin, John R.; Gupta, Mukesh K.; Page, Jonathan M.; Yu, Fang; Davidson, Jeffrey M.; Guelcher, Scott A.

2014-01-01

75

Porous poly(?-caprolactone) scaffolds for load-bearing tissue regeneration: solventless fabrication and characterization.  

PubMed

Three-dimensional interconnected porous poly(?-caprolactone) scaffolds have been prepared by a novel solventless scaffold fabrication approach combining cryomilling and compression molding/porogen leaching techniques. This study investigated the effects of processing parameters on scaffold morphology and properties for tissue regeneration. Specifically, the effects of molding temperature, cryomilling time, and porogen mix were examined. Fifty percentage of porous scaffolds were fabricated with a range of properties: mean pore size from ?40 to 125 ?m, water uptake from ?50 to 86%, compressive modulus from ?45 to 84 MPa, and compressive strength at 10% strain from ?3 to 4 MPa. Addition of 60 wt % NaCl salt resulted in a ?50% increase in porosity in multimodal pore-size structures that depended on the method of NaCl addition. Water uptake ranged from ?61 to 197%, compressive modulus from ?4 to 8.6 MPa, and compressive strength at 10% strain from ?0.36 to 0.40 MPa. Results suggest that this approach provides a controllable strategy for the design and fabrication of 3D interconnected porous biodegradable scaffolds for load-bearing tissue regeneration. PMID:23559444

Allaf, Rula M; Rivero, Iris V; Abidi, Noureddine; Ivanov, Ilia N

2013-08-01

76

[Study on the development of Ag-nano-hydroxyapatite/polyamide66 porous scaffolds with surface mineralization].  

PubMed

Bacterial infection after implantation of bone tissue engineering scaffolds is still a serious clinical problem. Ag-nano-hydroxyapatite/polyamide66 (Ag-nHA/PA66) antibacterial composite scaffold were prepared with phase-inversion method in this study. The scaffolds were mineralized in saturated calcium phosphate solution at 37 degrees C for 1 day. The microstructure and the newly formed nano-apatite deposition on the scaffolds before and after mineralization were observed using scanning electron microscopy (SEM). In order to investigate the release behaviors of Ag+, the Ag-nHA/PA66 scaffolds were immersed into 5 ml PBS at 37 degrees C for a different period between 3 h and 168 h before and after mineralization. Then the samples were cultured with E. coli (8099) to test the antibacterial effect of the scaffolds. The results showed that, after mineralization, Ag-nHA/PA66 porous scaffolds still possessed a good inter-connection and a new apatite layer was formed on the surface of the scaffolds. The average macropore size was 626.61 +/- 141.94 microm, the porosity was 76.89 +/- 8.21% and the compressive strength was 2.94 +/- 1.12 MPa. All these physical parameters had no significant difference from those of the un-mineralized scaffolds. The Ag+ release of the scaffolds with and without mineralization was fast within 1 day and then kept slow and stable after 1 day. The antibacterial test confirmed that after mineralization the scaffolds had good antibacterial effects on E. coli. PMID:23469542

Fan, Jianbo; Chang, Shan; Dong, Mina; Huang, Di; Li, Jidong; Jiang, Dianming

2012-12-01

77

Selective laser melting-produced porous titanium scaffolds regenerate bone in critical size cortical bone defects.  

PubMed

Porous titanium scaffolds have good mechanical properties that make them an interesting bone substitute material for large bone defects. These scaffolds can be produced with selective laser melting, which has the advantage of tailoring the structure's architecture. Reducing the strut size reduces the stiffness of the structure and may have a positive effect on bone formation. Two scaffolds with struts of 120-µm (titanium-120) or 230-µm (titanium-230) were studied in a load-bearing critical femoral bone defect in rats. The defect was stabilized with an internal plate and treated with titanium-120, titanium-230, or left empty. In vivo micro-CT scans at 4, 8, and 12 weeks showed more bone in the defects treated with scaffolds. Finally, 18.4?±?7.1?mm(3) (titanium-120, p?=?0.015) and 18.7?±?8.0?mm(3) (titanium-230, p?=?0.012) of bone was formed in those defects, significantly more than in the empty defects (5.8?±?5.1?mm(3) ). Bending tests on the excised femurs after 12 weeks showed that the fusion strength reached 62% (titanium-120) and 45% (titanium-230) of the intact contralateral femurs, but there was no significant difference between the two scaffolds. This study showed that in addition to adequate mechanical support, porous titanium scaffolds facilitate bone formation, which results in high mechanical integrity of the treated large bone defects. PMID:23255164

Van der Stok, Johan; Van der Jagt, Olav P; Amin Yavari, Saber; De Haas, Mirthe F P; Waarsing, Jan H; Jahr, Holger; Van Lieshout, Esther M M; Patka, Peter; Verhaar, Jan A N; Zadpoor, Amir A; Weinans, Harrie

2013-05-01

78

Fabrication and characterization of gelatin-based biocompatible porous composite scaffold for bone tissue engineering.  

PubMed

In this study, composite scaffolds were prepared with polyethylene oxide (PEO)-linked gelatin and tricalcium phosphate (TCP). Chitosan, a positively charged polysaccharide, was introduced into the scaffolds to improve the properties of the artificial bone matrix. The chemical and thermal properties of composite scaffolds were investigated by Fourier transform infrared spectroscopy, thermogravimetric analyzer, differential thermal analyzer. In vitro cytotoxicity of the composite scaffold was also evaluated and the sample showed no cytotoxic effect. The morphology was studied by SEM and light microscopy. It was observed that the prepared scaffold had an open interconnected porous structure with pore size of 230-354 ?m, which is suitable for osteoblast cell proliferation. The mechanical properties were assessed and it was found that the composite had compressive modulus of 1200 MPa with a strength of 5.2 MPa and bending modulus of 250 MPa having strength of 12.3 MPa. The porosity and apparent density were calculated and it was found that the incorporation of TCP can reduce the porosity and water absorption. It was revealed from the study that the composite had a 3D porous microstructure and TCP particles were dispersed evenly among the crosslinked gelatin/chitosan scaffold. PMID:22707185

Khan, M Nuruzzaman; Islam, Jahid M M; Khan, Mubarak A

2012-11-01

79

Osteoblast-Like Cell Behavior on Porous Scaffolds Based on Poly(styrene) Fibers  

PubMed Central

Scaffolds of nonresorbable biomaterials can represent an interesting alternative for replacing large bone defects in some particular clinical cases with massive bone loss. Poly(styrene) microfibers were prepared by a dry spinning method. They were partially melted to provide 3D porous scaffolds. The quality of the material was assessed by Raman spectroscopy. Surface roughness was determined by atomic force microscopy and vertical interference microscopy. Saos-2 osteoblast-like cells were seeded on the surface of the fibers and left to proliferate. Cell morphology, evaluated by scanning electron microscopy, revealed that they can spread and elongate on the rough microfiber surface. Porous 3D scaffolds made of nonresorbable poly(styrene) fibers are cytocompatible biomaterials mimicking allogenic bone trabeculae and allowing the growth and development of osteoblast-like cells in vitro. PMID:25045688

Serafim, Andrada; Mallet, Romain; Pascaretti-Grizon, Florence

2014-01-01

80

Uniform Deposition of Protein Incorporated Mineral Layer on Three-Dimensional Porous Polymer Scaffolds  

PubMed Central

Inorganic–organic hybrid materials designed to facilitate bone tissue regeneration use a calcium phosphate mineral layer to encourage cell adhesion, proliferation, and osteogenic differentiation. Mineral formed on porous materials is often discontinuous through the thickness of the scaffold. This study aimed to uniformly coat the pores of three-dimensional (3D) porous, polymer scaffolds with a bone-like mineral layer in addition to uniformly incorporating a model protein within this mineral layer. A filtration system designed to induce simulated body fluid flow through the interstices of 3D polylactic-co-glycolic acid scaffolds (10-mm diameter × 2-mm thickness) illustrated that a uniform, continuous mineral layer can be precipitated on the pore surfaces of a 3D porous structure within 5 days. MicroCT analysis showed increased mineral volume percent (MV%) (7.86 ± 3.25 MV%, p = 0.029) and continuous mineralization of filtered scaffolds compared with two static control groups (floating, 0.16 ± 0.26 MV% and submerged, 0.20 ± 0.01 MV%). Furthermore, the system was effective in coprecipitating a model protein, bone sialoprotein (BSA), within the mineral layer. A 10-fold increase in BSA incorporation was seen when coprecipitated filtered scaffolds (1308 ± 464 ?g) were compared to a submerged static control group (139 ± 45 ?g), p < 0.001. Confocal microscopy visually confirmed uniform coprecipitation of BSA throughout the thickness of the filtration scaffolds. The designed system enables 3D mineralization through the thickness of porous materials, and provides the option of including coprecipitated biomolecular cues within the mineral layer. This approach of providing a 3D conductive and osteoinductive environment could be conducive to bone tissue regeneration. PMID:17618505

Segvich, Sharon; Smith, Hayes C.; Luong, Linh N.; Kohn, David H.

2009-01-01

81

Label-free Raman monitoring of extracellular matrix formation in three-dimensional polymeric scaffolds.  

PubMed

Monitoring extracellular matrix (ECM) components is one of the key methods used to determine tissue quality in three-dimensional scaffolds for regenerative medicine and clinical purposes. Raman spectroscopy can be used for non-invasive sensing of cellular and ECM biochemistry. We have investigated the use of conventional (confocal and semiconfocal) Raman microspectroscopy and fibre-optic Raman spectroscopy for in vitro monitoring of ECM formation in three-dimensional poly(ethylene oxide terephthalate)-poly(butylene terephthalate) (PEOT/PBT) scaffolds. Chondrocyte-seeded PEOT/PBT scaffolds were analysed for ECM formation by Raman microspectroscopy, biochemical analysis, histology and scanning electron microscopy. ECM deposition in these scaffolds was successfully detected by biochemical and histological analysis and by label-free non-destructive Raman microspectroscopy. In the spectra collected by the conventional Raman set-ups, the Raman bands at 937 and at 1062 cm(-1) which, respectively, correspond to collagen and sulfated glycosaminoglycans could be used as Raman markers for ECM formation in scaffolds. Collagen synthesis was found to be different in single chondrocyte-seeded scaffolds when compared with microaggregate-seeded samples. Normalized band-area ratios for collagen content of single cell-seeded samples gradually decreased during a 21-day culture period, whereas collagen content of the microaggregate-seeded samples significantly increased during this period. Moreover, a fibre-optic Raman set-up allowed for the collection of Raman spectra from multiple pores inside scaffolds in parallel. These fibre-optic measurements could give a representative average of the ECM Raman signal present in tissue-engineered constructs. Results in this study provide proof-of-principle that Raman microspectroscopy is a promising non-invasive tool to monitor ECM production and remodelling in three-dimensional porous cartilage tissue-engineered constructs. PMID:23825118

Kunstar, Aliz; Leferink, Anne M; Okagbare, Paul I; Morris, Michael D; Roessler, Blake J; Otto, Cees; Karperien, Marcel; van Blitterswijk, Clemens A; Moroni, Lorenzo; van Apeldoorn, Aart A

2013-09-01

82

Surface modification of biodegradable porous Mg bone scaffold using polycaprolactone/bioactive glass composite.  

PubMed

A reduction in the degradation rate of magnesium (Mg) and its alloys is in high demand to enable these materials to be used in orthopedic applications. For this purpose, in this paper, a biocompatible polymeric layer reinforced with a bioactive ceramic made of polycaprolactone (PCL) and bioactive glass (BG) was applied on the surface of Mg scaffolds using dip-coating technique under low vacuum. The results indicated that the PCL-BG coated Mg scaffolds exhibited noticeably enhanced bioactivity compared to the uncoated scaffold. Moreover, the mechanical integrity of the Mg scaffolds was improved using the PCL-BG coating on the surface. The stable barrier property of the coatings effectively delayed the degradation activity of Mg scaffold substrates. Moreover, the coatings induced the formation of apatite layer on their surface after immersion in the SBF, which can enhance the biological bone in-growth and block the microcracks and pore channels in the coatings, thus prolonging their protective effect. Furthermore, it was shown that a three times increase in the concentration of PCL-BG noticeably improved the characteristics of scaffolds including their degradation resistance and mechanical stability. Since bioactivity, degradation resistance and mechanical integrity of a bone substitute are the key factors for repairing and healing fractured bones, we suggest that PCL-BG is a suitable coating material for surface modification of Mg scaffolds. PMID:25686970

Yazdimamaghani, Mostafa; Razavi, Mehdi; Vashaee, Daryoosh; Tayebi, Lobat

2015-04-01

83

Porous magnesium/PLGA composite scaffolds for enhanced bone regeneration following tooth extraction.  

PubMed

Sixty percent of implant-supported dental prostheses require bone grafting to enhance bone quantity and quality prior to implant placement. We have developed a metallic magnesium particle/PLGA composite scaffold to overcome the limitations of currently used dental bone grafting materials. This is the first report of porous metallic magnesium/PLGA scaffolds synthesized using a solvent casting, salt leaching method. We found that incorporation of varying amounts of magnesium into the PLGA scaffolds increased the compressive strength and modulus, as well as provided a porous structure suitable for cell infiltration, as measured by mercury intrusion porosimetry. Additionally, combining basic-degrading magnesium with acidic-degrading PLGA led to an overall pH buffering effect and long-term release of magnesium over the course of a 10-week degradation assay, as measured with inductively coupled plasma-atomic emission spectroscopy. Using an indirect proliferation assay adapted from ISO 10993:5, it was found that extracts of medium from degrading magnesium/PLGA scaffolds increased bone marrow stromal cell proliferation in vitro, a phenomenon observed by other groups investigating magnesium's impact on cells. Finally, magnesium/PLGA scaffold biocompatibility was assessed in a canine socket preservation model. Micro-computed tomography and histological analysis showed the magnesium/PLGA scaffolds to be safer and more effective at preserving bone height than empty controls. Three-dimensional magnesium/PLGA composite scaffolds show promise for dental socket preservation and also, potentially, orthopedic bone regeneration. These scaffolds could decrease inflammation observed with clinically used PLGA devices, as well as enhance osteogenesis, as observed with previously studied magnesium devices. PMID:25234156

Brown, Andrew; Zaky, Samer; Ray, Herbert; Sfeir, Charles

2015-01-01

84

A polycaprolactone/cuttlefish bone-derived hydroxyapatite composite porous scaffold for bone tissue engineering.  

PubMed

Cuttlefish bone (CB) is an attractive natural biomaterial source to obtain hydroxyapatite (HAp). In this study, a porous polycaprolactone (PCL) scaffold incorporating CB-derived HAp (CB-HAp) powder was fabricated using the solvent casting and particulate leaching method. The presence of CB-HAp in PCL/CB-HAp scaffold was confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) and porosity analysis showed that the average pore dimension of the fabricated scaffold was approximately 200-300 ?m, with ?85% porosity, and that the compressive modulus increased after addition of CB-HAp powders. In vitro tests such as cell proliferation assay, cytotoxicity analysis, cell attachment observations, and alkaline phosphatase activity assays showed that the PCL/CB-HAp scaffold could improve the proliferation, viability, adherence, and osteoblast differentiation rate of MG-63 cells. When surgically implanted into rabbit calvarial bone defects, consistent with the in vitro results, PCL/CB-HAp scaffold implantation resulted in significantly higher new bone formation than did implantation of PCL alone. These findings suggest that addition of CB-HAp powder to the PCL scaffold can improve cellular response and that the PCL/CB-HAp composite scaffold has great potential for use in bone tissue engineering. PMID:24259295

Kim, Beom-Su; Yang, Sun-Sik; Lee, Jun

2014-07-01

85

Bone formation on the apatite-coated zirconia porous scaffolds within a rabbit calvarial defect.  

PubMed

Previously, a strong and bioactive ceramic scaffold consisting of a porous zirconia body coated with apatite double layers (fluorapatite (FA) as an inner layer and hydroxyapatite (HA) as an outer layer) was successfully fabricated. In this contribution, the authors investigate the in vivo performance of the engineered bioceramic scaffolds using a rabbit calvarial defect model. In particular, the porosity and pore size of the scaffolds are varied in order to observe the geometrical effects of the scaffolds on their bone formation behaviors. The scaffolds supported on a zirconia framework can be produced with an extremely high porosity (approximately 84-87%), while retaining excellent compressive strength (approximately 7-8 MPa), which has been unachievable in the case of pure apatite scaffolds (approximately 74% porosity with approximately 2 MPa strength). The experimental groups used in this study include three types of zirconia scaffolds coated with apatite; high porosity (approximately 87%) with large pore size (approximately 500- 700 microm): AZ-HL, high porosity (approximately 84%) with small pore size (approximately 150-200 microm): AZ-HS, and low porosity (approximately 75%) with large pore size (approximately 500-700 microm): AZ-LL, as well as one type of HA porous scaffold: low porosity (approximately 74%) with a large pore size (approximately 500-700 microm) for the purpose of comparison. The scaffolds prepared with dimensions of approximately 10 mm (diameter) x 1.2 mm (thickness) are grafted in rabbit calvaria defects. The histological sections are made at 4 and 12 weeks after surgery and immunohistochemical analyses are performed on the samples. All of the specimens show a good healing response without adverse tissue reactions. Good healing is shown at 4 weeks post-surgery with the ingrowth of new bone into the macropore-channels of the scaffolds. The newly formed bone amounts to approximately 19.9-24.2% of the initial defect area, depending on the scaffold type, but there is no statistical significance between the scaffold groups. However, the defects without the scaffolds (control group) show a significantly lower bone formation ratio (approximately 4.3%). At twelve weeks after surgery, the extent of new bone formation is more pronounced in all of the scaffold groups. All of the scaffold groups show significantly higher bone formation ratios (26.7-46.9%) with respect to the control without the graft. In the comparison between the scaffold groups, those with high porosities (AZ-HL and AZ-HS) exhibit significantly higher bone formation as compared to the scaffold with low porosity (AZ-LL). Based on the present in vivo test performed within a rabbit calvaria defect model, it is concluded that the apatite-coated zirconia scaffolds show good bone forming ability and are considered to be a promising scaffolding material for bone regeneration since they possess a high level of both mechanical and biological properties. PMID:17494967

Kim, Hae-Won; Shin, Seung-Yun; Kim, Hyoun-Ee; Lee, Yong-Moo; Chung, Chong-Pyoung; Lee, Hae-Hyoung; Rhyu, In-Chul

2008-05-01

86

Porous molecularly imprinted polymer membranes and polymeric particles.  

PubMed

Porous free-standing molecularly imprinted polymer membranes were synthesised by the method of in situ polymerisation using the principle of synthesis of interpenetrating polymer networks and tested in solid-phase extraction of triazine herbicides from aqueous solutions. Atrazine-specific MIP membranes were obtained by the UV-initiated co-polymerisation of methacrylic acid, tri(ethylene glycol) dimethacrylate, and oligourethane acrylate in the presence of a template (atrazine). Addition of oligourethane acrylate provided formation of the highly cross-linked MIP in a form of a free-standing 60 microm thick flexible membrane. High water fluxes through the MIP membranes were achieved due to addition of linear polymers (polyethylene glycol M(w) 20,000 and polyurethane M(w) 40,000) to the initial mixture of monomers before the polymerization. As a result, typical semi-interpenetrating polymer networks (semi-IPNs) have been formed, where the cross-linked polymer was represented by the atrazine-specific molecularly imprinted polymer, while the linear one was represented by polyethylene glycol/polyurethane. Extraction of the linear polymers from the fully formed semi-IPNs resulted in formation of large pores in the membrane structure. At the same time, extraction of the template molecules lead to formation of the sites in the polymeric network, which in shape and arrangement of functional groups are complementary to atrazine. Reference polymeric membranes were prepared from the same mixture of monomers but in the absence of the template. Recognition properties of the MIP membranes were estimated in solid-phase extraction by their ability to selective re-adsorbtion of atrazine from 10(-8) to 10(-4) M aqueous solutions. The imprinting effect was demonstrated for both types of the MIP membranes and the influence of the type of the linear compound on their recognition properties was estimated. The recognition properties of the MIP membranes were compared to those of the MIP particles of the same composition. Morphology of the MIP membranes was investigated using the SEM microscopy. High fluxes of the developed membranes together with high affinity and adsorption capability make them an attractive alternative to MIP particles in separation processes. PMID:17386508

Sergeyeva, T A; Brovko, O O; Piletska, E V; Piletsky, S A; Goncharova, L A; Karabanova, L V; Sergeyeva, L M; El'skaya, A V

2007-01-23

87

Macro-scale Topology Optimization for Controlling Internal Shear Stress in a Porous Scaffold Bioreactor  

E-print Network

Shear stress is an important physical factor that regulates proliferation, migration and morphogenesis. In particular, the homeostasis of blood vessels is dependent on shear stress. To mimic this process ex vivo, efforts have been made to seed scaffolds with vascular and other cell types in the presence of growth factors and under pulsatile flow conditions. However, the resulting bioreactors lack information on shear stress and flow distributions within the scaffold. Consequently, it is difficult to interpret the effects of shear stress on cell function. Such knowledge would enable researchers to improve upon cell culture protocols. Recent work has focused on optimizing the microstructural parameters of the scaffold to fine tune the shear stress. In this study, we have adopted a different approach whereby flows are redirected throughout the bioreactor along channels patterned in the porous scaffold to yield shear stress distributions that are optimized for uniformity centered on a target value. A topology optimization algorithm coupled to computational fluid dynamics simulations was devised to this end. The channel topology in the porous scaffold was varied using a combination of genetic algorithm and fuzzy logic. The method is validated by experiments using magnetic resonance imaging (MRI) readouts of the flow field.

K. Youssef; J. J. Mack; M. L. Iruela-Arispe; L. -S. Bouchard

2012-01-09

88

Porous chitosan tubular scaffolds with knitted outer wall and controllable inner structure for nerve tissue engineering.  

PubMed

In this study, a novel method was developed to create porous tubular scaffolds with desirable mechanical properties and controllable inner structure from chitosan, for nerve tissue engineering. Chitosan fiber-based yarns were first used to create porous hollow tubes, which served as the outer wall of the scaffolds, through an industrial knitting process. Then, an innovative molding technique was developed and used to produce inner matrices with multiple axially oriented macrochannels and radially interconnected micropores. Acupuncture needles were used as mandrels during molding to improve the safety and controllability of the process. In vitro characterization demonstrated that the scaffolds possessed suitable mechanical strength, porosity, swelling, and biodegradability for applications in nerve tissue engineering. In vitro cell culture experiments showed that differentiated Neuro-2a cells grew along the oriented macrochannels and the interconnected micropores were beneficial for nutrient diffusion and cell ingrowth to the scaffold's interior. Collectively, the well-defined architectural features in addition to the desirable mechanical and biological properties of the scaffolds make them promising for nerve tissue engineering. PMID:16758450

Wang, Aijun; Ao, Qiang; Cao, Wenling; Yu, Mingzhi; He, Qing; Kong, Lijun; Zhang, Ling; Gong, Yandao; Zhang, Xiufang

2006-10-01

89

MC3T3-E1 osteoblast attachment and proliferation on porous hydroxyapatite scaffolds fabricated with nanophase powder  

PubMed Central

Porous bone tissue engineering scaffolds were fabricated using both nano hydroxyapatite (nano HA) powder (20 nm average particle size) and micro HA powder (10 ?m average particle size), resulting in sintered scaffolds of 59 vol% porosity and 8.6±1.9 ?m average grain size and 72 vol% porosity and 588±55 nm average grain size, respectively. Scanning electron microscopy was used to measure both the grain size and pore size. MC3T3-E1 osteoblast (OB) attachment and proliferation on both nano HA and micro HA porous scaffolds were quantified. As expected, OB cell number was greater on nano HA scaffolds compared with similarly processed micro HA scaffolds 5 days after seeding, while OB attachment did not appear greater on the nano HA scaffolds (p<0.05). PMID:17722535

Smith, Ian O; McCabe, Laura R; Baumann, Melissa J

2006-01-01

90

Porous Hydroxyapatite Bioceramic Scaffolds for Drug Delivery and Bone Regeneration  

NASA Astrophysics Data System (ADS)

The conventional methods of supplying a patient with pharmacologic active substances suffer from being very poorly selective, so that damage can occurs to the healthy tissues and organs, different from the intended target. In addition, high drug doses can be required to achieve the desired effect. An alternative approach is based on the use of implantable delivery tools, able to release the active substance in a controlled way. In the current research local drug delivery devices containing 8mg of gentamicin sulphate were prepared using custom developed vacuum impregnation technique. In vitro dissolution tests showed that gentamicin release was sustained for 12h. In order to decrease gentamicin release rate, biopolymer coatings were applied and coating structure investigated. The results showed that gentamicin release can be sustained for more than 70h for poly(epsilon-caprolactone) coated calcium phosphate scaffolds. From poly lactic acid and polyvinyl alcohol coated scaffolds gentamicin was released within 20h and 50h, respectively.

Loca, Dagnija; Locs, Janis; Salma, Kristine; Gulbis, Juris; Salma, Ilze; Berzina-Cimdina, Liga

2011-10-01

91

Reinforced Portland cement porous scaffolds for load-bearing bone tissue engineering applications.  

PubMed

Modified Portland cement porous scaffolds with suitable characteristics for load-bearing bone tissue engineering applications were manufactured by combining the particulate leaching and foaming methods. Non-crosslinked polydimethylsiloxane was evaluated as a potential reinforcing material. The scaffolds presented average porosities between 70 and 80% with mean pore sizes ranging from 300 ?m up to 5.0 mm. Non-reinforced scaffolds presented compressive strengths and elastic modulus values of 2.6 and 245 MPa, respectively, whereas reinforced scaffolds exhibited 4.2 and 443 MPa, respectively, an increase of ?62 and 80%. Portland cement scaffolds supported human osteoblast-like cell adhesion, spreading, and propagation (t = 1-28 days). Cell metabolism and alkaline phosphatase activity were found to be enhanced at longer culture intervals (t ? 14 days). These results suggest the possibility of obtaining strong and biocompatible scaffolds for bone repair applications from inexpensive, yet technologically advanced materials such as Portland cement. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 501-507, 2012. PMID:22121151

Higuita-Castro, Natalia; Gallego-Perez, Daniel; Pelaez-Vargas, Alejandro; García Quiroz, Felipe; Posada, Olga M; López, Luis E; Sarassa, Carlos A; Agudelo-Florez, Piedad; Monteiro, Fernando J; Litsky, Alan S; Hansford, Derek J

2012-02-01

92

Direct Ink Writing of Highly Porous and Strong Glass Scaffolds for Load-bearing Bone Defects Repair and Regeneration  

PubMed Central

The quest for synthetic materials to repair load-bearing bone lost because of trauma, cancer, or congenital bone defects requires development of porous and high-performance scaffolds with exceptional mechanical strength. However, the low mechanical strength of porous bioactive ceramic and glass scaffolds, compared with that of human cortical bone, has limited their use for these applications. In the present work, bioactive 6P53B glass scaffolds with superior mechanical strength were fabricated using a direct ink writing technique. The rheological properties of Pluronic® F-127 (referred to hereafter simply as F-127) hydrogel-based inkswere optimized for the printing of features as fine as 30 ?m and of the three-dimensional scaffolds. The mechanical strength and in vitro degradation of the scaffolds were assessed in a simulated body fluid (SBF). The sintered glass scaffolds show a compressive strength (136 ± 22 MPa) comparable to that of human cortical bone (100-150 MPa), while the porosity (60%) is in the range of that of trabecular bone (50-90%).The strength is ~100 times that of polymer scaffolds and 4–5 times that of ceramic and glass scaffolds with comparable porosities. Despite the strength decrease resulting from weight loss during immersion in an SBF, the value (77 MPa) is still far above that of trabecular bone after three weeks. The ability to create both porous and strong structures opens a new avenue for fabricating scaffolds for load-bearing bone defect repair and regeneration. PMID:21745606

Fu, Qiang; Saiz, Eduardo; Tomsia, Antoni P.

2011-01-01

93

Direct ink writing of highly porous and strong glass scaffolds for load-bearing bone defects repair and regeneration.  

PubMed

The quest for synthetic materials to repair load-bearing bone lost because of trauma, cancer, or congenital bone defects requires the development of porous, high-performance scaffolds with exceptional mechanical strength. However, the low mechanical strength of porous bioactive ceramic and glass scaffolds, compared with that of human cortical bone, has limited their use for these applications. In the present work bioactive 6P53B glass scaffolds with superior mechanical strength were fabricated using a direct ink writing technique. The rheological properties of Pluronic® F-127 (referred to hereafter simply as F-127) hydrogel-based inks were optimized for the printing of features as fine as 30 ?m and of three-dimensional scaffolds. The mechanical strength and in vitro degradation of the scaffolds were assessed in a simulated body fluid (SBF). The sintered glass scaffolds showed a compressive strength (136 ± 22 MPa) comparable with that of human cortical bone (100-150 MPa), while the porosity (60%) was in the range of that of trabecular bone (50-90%). The strength is ~100-times that of polymer scaffolds and 4-5-times that of ceramic and glass scaffolds with comparable porosities. Despite the strength decrease resulting from weight loss during immersion in SBF, the value (77 MPa) is still far above that of trabecular bone after 3 weeks. The ability to create both porous and strong structures opens a new avenue for fabricating scaffolds for load-bearing bone defect repair and regeneration. PMID:21745606

Fu, Qiang; Saiz, Eduardo; Tomsia, Antoni P

2011-10-01

94

High resolution x-ray imaging of dynamic solute transport in cyclically deformed porous tissue scaffolds  

NASA Astrophysics Data System (ADS)

The objective was to develop a method for high-resolution imaging of dynamic solute transport in cyclically deforming porous scaffolds for tissue engineering applications. A flexible cubic scaffold with single cylindrical channel was fabricated from a biodegradable polymer blend using a combined 3D printing and injection molding technique. The scaffold was attached to the bottom of a fluid reservoir mounted underneath a compression apparatus placed inside the X-ray scanner. The scaffold was positioned with the channel axis perpendicular to the X-ray beam. The container was filled with glycerin, and a solution of the contrast agent sodium iodide (NaI) in glycerin was injected into the scaffold channel. Intervals of compression cycles (14.5 +/- 2.1 % compression at 1.0 Hz) were applied to the top face of the scaffold. After each interval the compression was temporarily paused to obtain a two-dimensional image at 20 ?m pixel resolution. A series of images was also obtained without application of the compression cycles to quantify the effect of passive diffusional removal of NaI from the channel. The average NaI concentration in the channel decreased by 82% after 300 cycles (5 min.) of compression, by 40% after 60 min. of passive removal. Spatial profiles of the NaI concentration along the channel axis indicated that compression-induced transport preferentially removed the contrast agent at the pore openings. We conclude that convective transport induced by cyclic mechanical deformation of artificial tissue scaffolds could significantly contribute to the rate and depth of nutrient transport inside the scaffold, as compared to slow diffusive transport alone.

Op Den Buijs, Jorn; Lee, Kee-Won; Jorgensen, Steven M.; Wang, Shanfeng; Yaszemski, Michael J.; Ritman, Erik L.

2008-03-01

95

Dissolution control and cellular responses of calcium phosphate coatings on zirconia porous scaffold.  

PubMed

Different types of calcium phosphates [hydroxyapatite (HA), fluorapatite (FA), tricalcium phosphate (TCP), and their composites (HA + FA, HA + TCP)] were coated on a zirconia (ZrO(2)) porous scaffold using a powder slurry method. The ZrO(2) porous scaffold was intended for a load-bearing implant, and the apatite layers were coated to improve osteoconductivity. The insertion of an FA intermediate layer between the coating layer and ZrO(2) scaffold effectively suppressed the reaction between the calcium phosphate and ZrO(2) and maintained the coating layer at the initial powder composition. The obtained coating layer, of a thickness of approximately 30 microm, was relatively microporous and firmly adherent to the ZrO(2) scaffold. Dissolution tests in physiological solution showed typical differences depending on the coating layers, with the dissolution rate increasing in the order TCP > HA + TCP > HA > HA + FA > FA. This result suggests the functional coating of the calcium phosphates in view of tailoring the solubility. Osteoblast-like cells, MG63 and HOS, responded similarly in terms of cell growth, morphology, and proliferation rate regardless of the coating types, indicating favorable and comparable cell viability. However, the alkaline phosphatase (ALP) activity of the cells on the pure HA and HA composite coatings (HA + FA and HA + TCP) expressed at higher levels compared to those on pure FA and pure TCP coatings for both MG63 and HOS cells, suggesting a selective cell activity depending on the coating types. All the calcium phosphate-coated-ZrO(2) scaffolds showed higher ALP levels compared to pure ZrO(2) scaffold. PMID:14762932

Kim, Hae-Won; Kim, Hyoun-Ee; Salih, Vehid; Knowles, Jonathan C

2004-03-01

96

Development and Characterization of Novel Porous 3D Alginate-Cockle Shell Powder Nanobiocomposite Bone Scaffold  

PubMed Central

A novel porous three-dimensional bone scaffold was developed using a natural polymer (alginate/Alg) in combination with a naturally obtained biomineral (nano cockle shell powder/nCP) through lyophilization techniques. The scaffold was developed in varying composition mixture of Alg-nCP and characterized using various evaluation techniques as well as preliminary in vitro studies on MG63 human osteoblast cells. Morphological observations using SEM revealed variations in structures with the use of different Alg-nCP composition ratios. All the developed scaffolds showed a porous structure with pore sizes ideal for facilitating new bone growth; however, not all combination mixtures showed subsequent favorable characteristics to be used for biological applications. Scaffolds produced using the combination mixture of 40% Alg and 60% nCP produced significantly promising results in terms of mechanical strength, degradation rate, and increased cell proliferation rates making it potentially the optimum composition mixture of Alg-nCP with future application prospects. PMID:25110655

Bharatham, B. Hemabarathy; Abu Bakar, Md. Zuki; Perimal, Enoch Kumar; Yusof, Loqman Mohamed; Hamid, Muhajir

2014-01-01

97

Porous scaffold of gelatin-starch with nanohydroxyapatite composite processed via novel microwave vacuum drying.  

PubMed

Hydroxyapatite (HA) is a fundamental mineral-based biomaterial, used for preparing composites for bone repair and regeneration. Gelatin blended with starch results in scaffold composites with enhanced mechanical properties. A gelatin-starch blend reinforced with HA nanocrystals (nHA) gave biocompatible composites with enhanced mechanical properties. In this study, a porous scaffold of gelatin-starch-nHA composites was fabricated through microwave vacuum drying and crosslinking using trisodium citrate. Three different composite scaffolds were prepared at three different percentages of nHA: 20%, 30% and 40%. The microstructures and compositions of the composites were analyzed. Within the porous structure, the nHA crystals were observed to precipitate. The interaction between the gelatin-starch network film and nHA crystalline material was studied using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction analysis (XRD). XRD reflections showed that there are two different minerals present in the scaffold composite. There were strong reflection peaks close to the 26 degrees and 32 degrees 2theta angles of HA, and close to the 8 degrees and 49 degrees 2theta angles for sodium citrate minerals. The FTIR result suggested that carboxyl groups, C=O and amino groups play crucial roles in HA formation on the surface of a gelatin network. PMID:18325862

Sundaram, Jaya; Durance, Timothy D; Wang, Rizhi

2008-07-01

98

Porous Silk Scaffolds for Delivery of Growth Factors and Stem Cells to Enhance Bone Regeneration  

PubMed Central

Stem cell-based tissue engineering shows promise for bone regeneration and requires artificial microenvironments to enhance the survival, proliferation and differentiation of the seeded cells. Silk fibroin, as a natural protein polymer, has unique properties for tissue regeneration. The present study aimed to evaluate the influence of porous silk scaffolds on rat bone marrow stem cells (BMSCs) by lenti-GFP tracking both in vitro and in vivo in cranial bone defects. The number of cells seeded within silk scaffolds in rat cranial bone defects increased from 2 days to 2 weeks after implantation, followed by a decrease at eight weeks. Importantly, the implanted cells survived for 8 weeks in vivo and some of the cells might differentiate into endothelial cells and osteoblasts induced by the presence of VEGF and BMP-2 in the scaffolds to promote angiogenesis and osteogenesis. The results demonstrate that porous silk scaffolds provide a suitable niche to maintain long survival and function of the implanted cells for bone regeneration. PMID:25050556

Xu, Ling; Zhang, Xiaochen; Wu, Qianju; Zhang, Xiuli; Kaplan, David L.; Jiang, Xinquan

2014-01-01

99

Porous silk scaffolds for delivery of growth factors and stem cells to enhance bone regeneration.  

PubMed

Stem cell-based tissue engineering shows promise for bone regeneration and requires artificial microenvironments to enhance the survival, proliferation and differentiation of the seeded cells. Silk fibroin, as a natural protein polymer, has unique properties for tissue regeneration. The present study aimed to evaluate the influence of porous silk scaffolds on rat bone marrow stem cells (BMSCs) by lenti-GFP tracking both in vitro and in vivo in cranial bone defects. The number of cells seeded within silk scaffolds in rat cranial bone defects increased from 2 days to 2 weeks after implantation, followed by a decrease at eight weeks. Importantly, the implanted cells survived for 8 weeks in vivo and some of the cells might differentiate into endothelial cells and osteoblasts induced by the presence of VEGF and BMP-2 in the scaffolds to promote angiogenesis and osteogenesis. The results demonstrate that porous silk scaffolds provide a suitable niche to maintain long survival and function of the implanted cells for bone regeneration. PMID:25050556

Zhang, Wenjie; Zhu, Chao; Ye, Dongxia; Xu, Ling; Zhang, Xiaochen; Wu, Qianju; Zhang, Xiuli; Kaplan, David L; Jiang, Xinquan

2014-01-01

100

Rat bone marrow stromal cells-seeded porous gelatin/tricalcium phosphate/oligomeric proanthocyanidins composite scaffold for bone repair.  

PubMed

Repair of bone defects remains a major challenge in orthopaedic surgery. Bone tissue engineering is an attractive approach for treating bone loss in various shapes and amounts. The aim of this study was to prepare and evaluate the feasibility of a porous scaffold, which was composed of oligomeric proanthocyanidin crosslinked gelatin mixed with ?-tricalcium phosphate (GTP) and was seeded with bone marrow stromal cells (BMSCs) as a bone substitute. GTP scaffolds were made porous using a salt-leaching method. The physicochemical properties of the scaffold were evaluated to determine the optimal salt:composite weight ratio. The results indicated that the GTP scaffold had a favourable macroporous structure and higher porosity when the salt:composite weight ratio was 4:1. Cytotoxic tests demonstrated that extracts from the GTP scaffolds promoted the proliferation of BMSCs. Rat BMSCs were seeded on a GTP scaffold and cultured in a spinner flask. After 2 weeks of culture, scanning electron microscopy observation showed that the cells adhered well to the surfaces of the pores in the scaffold. Moreover, this study explored the biological response of rat calvarial bone to the scaffold to evaluate its potential in bone tissue engineering. Bone defects were filled with BMSC-seeded GTP scaffold and acellular GTP scaffold. After 8 weeks, the scaffold induced new bone formation at a bone defect, as was confirmed by X-ray microradiography and histology. The BMSC-seeded scaffold induced more new bone formation than did an acellular scaffold. These observations suggest that the BMSCs-seeded GTP scaffold can promote the regeneration of defective bone tissue. PMID:22392838

Chen, Kuo-Yu; Chung, Chia-Mei; Chen, Yueh-Sheng; Bau, Da-Tian; Yao, Chun-Hsu

2013-09-01

101

Fabrication of Porous Hydroxyapatite Scaffolds as Artificial Bone Preform and its Biocompatibility Evaluation  

PubMed Central

In this study, a novel porous hydroxyapatite scaffold was designed and fabricated to imitate natural bone through a multipass extrusion process. The conceptual design manifested unidirectional microchannels at the exterior part of the scaffold to facilitate rapid biomineralization and a central canal that houses the bone marrow. External and internal fissures were minimized during microwave sintering at 1,100°C. No deformation was noted, and a mechanically stable scaffold was fabricated. Detailed microstructure of the fabricated artificial bone was examined by scanning electron microscope and X-ray diffractometer, and material properties like compressive strength were evaluated. The initial biocompatibility was examined by the cell proliferation of MG-63 osteoblast-like cells using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Preliminary in vivo investigation in a rabbit model after 4 weeks and 8 weeks of implantation showed full osteointegration of the scaffold with the native tissue, and formation of bone tissue within the pore network, as examined by microcomputed tomography analyses and histological staining. Osteon-like bone microarchitecture was observed along the unidirectional channel with microblood vessels. These confirm a biomimetic regeneration model in the implanted bone scaffold, which can be used as an artificial alternative for damaged bone. PMID:24399056

2014-01-01

102

Performance of PRP Associated with Porous Chitosan as a Composite Scaffold for Regenerative Medicine  

PubMed Central

This study aimed to evaluate the in vitro performance of activated platelet-rich plasma associated with porous sponges of chitosan as a composite scaffold for proliferation and osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells. The sponges were prepared by controlled freezing (?20, ?80, or ?196°C) and lyophilization of chitosan solutions (1, 2, or 3% w/v). The platelet-rich plasma was obtained from controlled centrifugation of whole blood and activated with calcium and autologous serum. The composite scaffolds were prepared by embedding the sponges with the activated platelet-rich plasma. The results showed the performance of the scaffolds was superior to that of activated platelet-rich plasma alone, in terms of delaying the release of growth factors and increased proliferation of the stem cells. The best preparation conditions of chitosan composite scaffolds that coordinated the physicochemical and mechanical properties and cell proliferation were 3% (w/v) chitosan and a ?20°C freezing temperature, while ?196°C favored osteogenic differentiation. Although the composite scaffolds are promising for regenerative medicine, the structures require stabilization to prevent the collapse observed after five days.

Shimojo, Andréa Arruda Martins; Perez, Amanda Gomes Marcelino; Galdames, Sofia Elisa Moraga; Brissac, Isabela Cambraia de Souza; Santana, Maria Helena Andrade

2015-01-01

103

Fabrication of porous titanium scaffolds by stack sintering of microporous titanium spheres produced with centrifugal granulation technology.  

PubMed

Microporosity plays a key role in bioactivity and osteoinductivity of a biomaterial scaffold. A simple new approach to fabricating load-bearing porous titanium (Ti) scaffolds with uniform porous structure, highly controllable pore size and excellent biocompatibility was developed in the present study. This method was based on stack sintering of microporous Ti spheres produced with centrifugal granulation of commercial Ti powders. Macropores (180.0-341.8 ?m) and micropores (6.1-11.8 ?m) of the scaffolds were dependent on the sizes of the Ti spheres and the Ti powders, respectively. The compressive strength of the scaffolds (83.4-108.9 MPa) was high enough for the repair of load-bearing bone defects. Besides, the abundant micropores occurred on the rough and convex surface of the Ti spheres in the scaffolds were more favorable for adsorption of serum proteins, and thus promoted the growth of mesenchymal stem cells (MSCs). PMID:25175203

Chen, Hongjie; Wang, Chunli; Zhu, Xiangdong; Zhang, Kai; Fan, Yujiang; Zhang, Xingdong

2014-10-01

104

Direct fabrication of high-resolution three-dimensional polymeric scaffolds using electrohydrodynamic hot jet plotting  

NASA Astrophysics Data System (ADS)

This paper presents the direct three-dimensional (3D) fabrication of polymer scaffolds with sub-10 µm structures using electrohydrodynamic jet (EHD-jet) plotting of melted thermoplastic polymers. Traditional extrusion-based fabrication approaches of 3D periodic porous structures are very limited in their resolution, due to the excessive pressure requirement for extruding highly viscous thermoplastic polymers. EHD-jet printing has become a high-resolution alternative to other forms of nozzle deposition-based fabrication approaches by generating micro-scale liquid droplets or a fine jet through the application of a large electrical voltage between the nozzle and the substrate. In this study, we successfully apply EHD-jet plotting technology with melted biodegradable polymer (polycaprolactone, or PCL) for the fabrication of 2D patterns and 3D periodic porous scaffold structures in potential tissue engineering applications. Process conditions (e.g. electrical voltage, pressure, plotting speed) have been thoroughly investigated to achieve reliable jet printing of fine filaments. We have demonstrated for the first time that the EHD-jet plotting process is capable of the fabrication of 3D periodic structures with sub-10 µm resolution, which has great potential in advanced biomedical applications, such as cell alignment and guidance.

Wei, Chuang; Dong, Jingyan

2013-02-01

105

Porous Shape Memory Polymers  

PubMed Central

Porous shape memory polymers (SMPs) include foams, scaffolds, meshes, and other polymeric substrates that possess porous three-dimensional macrostructures. Porous SMPs exhibit active structural and volumetric transformations and have driven investigations in fields ranging from biomedical engineering to aerospace engineering to the clothing industry. The present review article examines recent developments in porous SMPs, with focus given to structural and chemical classification, methods of characterization, and applications. We conclude that the current body of literature presents porous SMPs as highly interesting smart materials with potential for industrial use. PMID:23646038

Hearon, Keith; Singhal, Pooja; Horn, John; Small, Ward; Olsovsky, Cory; Maitland, Kristen C.; Wilson, Thomas S.; Maitland, Duncan J.

2013-01-01

106

Conductive porous scaffolds as potential neural interface materials.  

SciTech Connect

Our overall intent is to develop improved prosthetic devices with the use of nerve interfaces through which transected nerves may grow, such that small groups of nerve fibers come into close contact with electrode sites, each of which is connected to electronics external to the interface. These interfaces must be physically structured to allow nerve fibers to grow through them, either by being porous or by including specific channels for the axons. They must be mechanically compatible with nerves such that they promote growth and do not harm the nervous system, and biocompatible to promote nerve fiber growth and to allow close integration with biological tissue. They must exhibit selective and structured conductivity to allow the connection of electrode sites with external circuitry, and electrical properties must be tuned to enable the transmission of neural signals. Finally, the interfaces must be capable of being physically connected to external circuitry, e.g. through attached wires. We have utilized electrospinning as a tool to create conductive, porous networks of non-woven biocompatible fibers in order to meet the materials requirements for the neural interface. The biocompatible fibers were based on the known biocompatible material poly(dimethyl siloxane) (PDMS) as well as a newer biomaterial developed in our laboratories, poly(butylene fumarate) (PBF). Both of the polymers cannot be electrospun using conventional electrospinning techniques due to their low glass transition temperatures, so in situ crosslinking methodologies were developed to facilitate micro- and nano-fiber formation during electrospinning. The conductivity of the electrospun fiber mats was controlled by controlling the loading with multi-walled carbon nanotubes (MWNTs). Fabrication, electrical and materials characterization will be discussed along with initial in vivo experimental results.

Hedberg-Dirk, Elizabeth L.; Cicotte, Kirsten N.; Buerger, Stephen P.; Reece, Gregory; Dirk, Shawn M.; Lin, Patrick P.

2011-11-01

107

In vitro comparison of three rifampicin loading methods in a reinforced porous ?-tricalcium phosphate scaffold.  

PubMed

The antibiotic compound, rifampicin (RFP), was loaded into porous reinforced ?-tricalcium phosphate (?-TCP) scaffolds using three different solution adsorption methods. This resulted in drug delivery systems (DDS) generated by vacuum adsorption (VA), dynamic adsorption (DA), and static adsorption (SA). In vitro examination of the drug loading and release profiles of the DDS indicated that the unit mass of RFP loaded into the scaffold by the VA method (0.44 mg/g) was higher than that achieved by SA (0.42 mg/g) or DA (0.38 mg/g) (P < 0.05). The mechanical strength had no significant change after RFP-loading (P > 0.05). Moreover, there were no significant differences among the mechanical strength of three ?-TCP DDS generated by loading RFP using SA, DA, and VA (P > 0.05). In vitro release testing showed an initial burst release of RFP from the three different DDS within the first 3 h and in the first 51 h, the cumulative release of RFP from VA-DDS, DA-DDS, and SA-DDS had reached 56.2, 83.6, and 88.6 %, respectively. Complete RFP release had occurred from VA-DDS, DA-DDS, and SA-DDS after 23, 17, and 15 days, respectively. As the VA-DDS method showed improved RFP loading and a more sustained drug release, this method is recommended for solution adsorption drug loading into porous ?-TCP scaffolds to form a DDS. PMID:25820665

Yuan, Junjie; Wang, Baoxin; Han, Chen; Lu, Xiao; Sun, Wei; Wang, Dezhi; Lu, Jianxi; Zhao, Jie; Zhang, Chao; Xie, Youzhuan

2015-04-01

108

Facile fabrication of hierarchical porous resins via high internal phase emulsion and polymeric porogen  

NASA Astrophysics Data System (ADS)

To achieve the dual features of fast oil absorption rate and high oil absorbency for the practical application in emergency treatment of spilled chemical pollutants, hierarchical porous resins were synthesized. The polymerization of high internal phase emulsion was applied to fabricate the porous structure for the purpose of high oil absorbency. Polymeric porogens were proposed to adjust the second-order or interconnected pore structure for fast oil absorption rate. SEM revealed the hierarchical porous structure. Molecular weight and dose of polymeric porogen were investigated for the effect on the formation of porous structure and absorption features. Optimized resins have 31.5 g/g or 17.1 g/g absorbency for chloroform and toluene, respectively, and only 5 min is needed to reach their saturation absorption. Besides, the porous resins demonstrated high oil retention under pressure. The absorption/desorption cycling results revealed the high repeatability of recovered resins. All these tests predicted the potential applications of porous resins of this kind particularly in the emergency treatment of oil and chemical pollution.

Ma, Libin; Luo, Xiaogang; Cai, Ning; Xue, Yanan; Zhu, San; Fu, Zhen; Yu, Faquan

2014-06-01

109

Enhanced osteoblastic activity and bone regeneration using surface-modified porous bioactive glass scaffolds.  

PubMed

The potential use as a bone substitute material of a three-dimensional bioactive glass fiber scaffold composed of Na(2)O-K(2)O-MgO-CaO-B(2)O(3)-P(2)O(5)-SiO(2) (BG1) was investigated in this work. Scaffolds were pre-treated with simulated body fluid (SBF) to promote the formation of two different bone-like apatite layers on their surfaces. The topography and roughness of the deposited layers were assessed by scanning electron microscopy (SEM), while the chemical composition and structure using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, respectively. Based on surface analysis, the bioactive glass surfaces were ranked from smoothest to roughest: 0 SBF (untreated), 1x SBF and 2x SBF. A calcium-deficient carbonated hydroxyapatite (HCA) layer was present on both SBF-treated scaffolds, with higher number and larger bone-like apatite nodule formation in the 2x SBF case. MC3T3-E1 preosteoblasts showed a more flattened morphology and higher cell proliferation on the nontreated scaffolds; whereas, cells were more elongated and had higher osteoblastic activity on SBF-treated samples. In vivo results in a rabbit calvarial bone defect model showed enhanced bone formation with SBF pretreated scaffolds, compared with untreated ones, commercially available Perioglass particles and empty defects. Our findings demonstrate that the formation of a rough HCA layer on bioactive glass porous scaffolds enhanced preosteoblast maturation in vitro, as well as bone formation in vivo. PMID:20694969

San Miguel, Blanca; Kriauciunas, Rytis; Tosatti, Samuele; Ehrbar, Martin; Ghayor, Chafik; Textor, Marcus; Weber, Franz E

2010-09-15

110

Biomechanical stability of novel mechanically adapted open-porous titanium scaffolds in metatarsal bone defects of sheep.  

PubMed

Open-porous titanium scaffolds for large segmental bone defects offer advantages like early weight-bearing and limited risk of implant failure. The objective of this experimental study was to determine the biomechanical behavior of novel open-porous titanium scaffolds with mechanical-adapted properties in vivo. Two types of the custom-made, open-porous scaffolds made of Ti6Al4V (Young's modulus: 6-8 GPa and different pore sizes) were implanted into a 20 mm segmental defect in the mid-diaphysis of the metatarsus of sheep, and were stabilized with an osteosynthesis plate. After 12 and 24 weeks postoperatively, torsional testing was performed on the implanted bone and compared to the contralateral non-treated side. Maximum torque, maximum angle, torsional stiffness, fracture energy, shear modulus and shear stress were investigated. Furthermore, bone mineral density (BMD) of the newly formed bone was determined. Mechanical loading capabilities for both scaffolds were similar and about 50% after 12 weeks (e.g., max. torque of approximately 20 Nm). A further increase after 24 weeks was found for most of the investigated parameters. Results for torsional stiffness and shear modulus as well as bone formation depended on the type of scaffold. Increased BMD after 24 weeks was found for one scaffold type but remained constant for the other one. The present data showed the capability of mechanically adapted open-porous titanium scaffolds to function as bone scaffolds for large segmental defects and the influence of the scaffold's stiffness. A further increase in the biomechanical stability can be assumed for longer observation periods of greater than six months. PMID:25678114

Wieding, Jan; Lindner, Tobias; Bergschmidt, Philipp; Bader, Rainer

2015-04-01

111

Modeling Vascularized Bone Regeneration Within a Porous Biodegradable CaP Scaffold Loaded with Growth Factors  

PubMed Central

Osteogenetic microenvironment is a complex constitution in which extracellular matrix (ECM) molecules, stem cells and growth factors each interact to direct the coordinate regulation of bone tissue development. Importantly, angiogenesis improvement and revascularization are critical for osteogenesis during bone tissue regeneration processes. In this study, we developed a three-dimensional (3D) multi-scale system model to study cell response to growth factors released from a 3D biodegradable porous calcium phosphate (CaP) scaffold. Our model reconstructed the 3D bone regeneration system and examined the effects of pore size and porosity on bone formation and angiogenesis. The results suggested that scaffold porosity played a more dominant role in affecting bone formation and angiogenesis compared with pore size, while the pore size could be controlled to tailor the growth factor release rate and release fraction. Furthermore, a combination of gradient VEGF with BMP2 and Wnt released from the multi-layer scaffold promoted angiogenesis and bone formation more readily than single growth factors. These results demonstrated that the developed model can be potentially applied to predict vascularized bone regeneration with specific scaffold and growth factors. PMID:23566802

Sun, X; Kang, Y; Bao, J; Zhang, Y; Yang, Y; Zhou, X

2013-01-01

112

Biocompatible, biodegradable and porous liquid crystal elastomer scaffolds for spatial cell cultures.  

PubMed

Here we report on the modular synthesis and characterization of biodegradable, controlled porous, liquid crystal elastomers (LCE) and their use as three-dimensional cell culture scaffolds. The elastomers were prepared by cross-linking of star block-co-polymers with pendant cholesterol units resulting in the formation of smectic-A LCEs as determined by polarized optical microscopy, DSC, and X-ray diffraction. Scanning electron microscopy revealed the porosity of the as-prepared biocompatible LCEs, making them suitable as 3D cell culture scaffolds. Biodegradability studies in physiological buffers at varying pH show that these scaffolds are intact for about 11 weeks after which degradation sets in at an exponential rate. Initial results from cell culture studies indicate that these smectic LCEs are compatible with growth, survival, and expansion of cultured neuroblastomas and myoblasts when grown on the LCEs for extended time periods (about a month). These preliminary cell studies focused on characterizing the elastomer-based scaffolds' biocompatibility and the successful 3D incorporation as well as growth of cells in 60 to 150-?m thick elastomer sheets. PMID:25303674

Sharma, Anshul; Neshat, Abdollah; Mahnen, Cory J; Nielsen, Alek D; Snyder, Jacob; Stankovich, Tory L; Daum, Benjamin G; LaSpina, Emily M; Beltrano, Gabrielle; Gao, Yunxiang; Li, Shuo; Park, Byung-Wook; Clements, Robert J; Freeman, Ernest J; Malcuit, Christopher; McDonough, Jennifer A; Korley, LaShanda T J; Hegmann, Torsten; Hegmann, Elda

2015-02-01

113

Surface functionalization of 3D glass-ceramic porous scaffolds for enhanced mineralization in vitro  

NASA Astrophysics Data System (ADS)

Bone reconstruction after tissue loosening due to traumatic, pathological or surgical causes is in increasing demand. 3D scaffolds are a widely studied solution for supporting new bone growth. Bioactive glass-ceramic porous materials can offer a three-dimensional structure that is able to chemically bond to bone. The ability to surface modify these devices by grafting biologically active molecules represents a challenge, with the aim of stimulating physiological bone regeneration with both inorganic and organic signals. In this research work glass ceramic scaffolds with very high mechanical properties and moderate bioactivity have been functionalized with the enzyme alkaline phosphatase (ALP). The material surface was activated in order to expose hydroxyl groups. The activated surface was further grafted with ALP both via silanization and also via direct grafting to the surface active hydroxyl groups. Enzymatic activity of grafted samples were measured by means of UV-vis spectroscopy before and after ultrasonic washing in TRIS-HCl buffer solution. In vitro inorganic bioactivity was investigated by soaking the scaffolds after the different steps of functionalization in a simulated body fluid (SBF). SEM observations allowed the monitoring of the scaffold morphology and surface chemical composition after soaking in SBF. The presence of ALP enhanced the in vitro inorganic bioactivity of the tested material.

Ferraris, Sara; Vitale-Brovarone, Chiara; Bretcanu, Oana; Cassinelli, Clara; Vernè, Enrica

2013-04-01

114

3D printing of porous hydroxyapatite scaffolds intended for use in bone tissue engineering applications.  

PubMed

A systematic characterisation of bone tissue scaffolds fabricated via 3D printing from hydroxyapatite (HA) and poly(vinyl)alcohol (PVOH) composite powders is presented. Flowability of HA:PVOH precursor materials was observed to affect mechanical stability, microstructure and porosity of 3D printed scaffolds. Anisotropic behaviour of constructs and part failure at the boundaries of interlayer bonds was highlighted by compressive strength testing. A trade-off between the ability to facilitate removal of PVOH thermal degradation products during sintering and the compressive strength of green parts was revealed. The ultimate compressive strength of 55% porous green scaffolds printed along the Y-axis and dried in a vacuum oven for 6h was 0.88 ± 0.02 MPa. Critically, the pores of 3D printed constructs could be user designed, ensuring bulk interconnectivity, and the imperfect packing of powder particles created an inherent surface roughness and non-designed porosity within the scaffold. These features are considered promising since they are known to facilitate osteoconduction and osteointegration in-vivo. Characterisation techniques utilised in this study include two funnel flow tests, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), compressive strength testing and computed tomography (CT). PMID:25492194

Cox, Sophie C; Thornby, John A; Gibbons, Gregory J; Williams, Mark A; Mallick, Kajal K

2015-02-01

115

Porous scaffolds support extrahepatic human islet transplantation, engraftment, and function in mice.  

PubMed

Islet transplantation as a therapy or cure for type 1 diabetes has significant promise but has been limited by islet mass requirements and long-term graft failure. The intrahepatic and intravascular site may be responsible for significant loss of transplanted islets. Nonencapsulating biomaterial scaffolds provide a strategy for architecturally defining and modulating extrahepatic sites beyond the endogenous milieu to enhance islet survival and function. We utilized scaffolds to transplant human islets into the intraperitoneal fat of immunodeficient mice. A smaller human islet mass than previously reported reversed murine diabetes and restored glycemic control at human blood glucose levels. Graft function was highly dependent on the islet number transplanted and directly correlated to islet viability, as determined by the ATP-to-DNA ratio. Islets engrafted and revascularized in host tissue, and glucose tolerance testing indicated performance equivalent to healthy mice. Addition of extracellular matrix, specifically collagen IV, to scaffold surfaces improved graft function compared to serum-supplemented media. Porous scaffolds can facilitate efficient human islet transplantation and provide a platform for modulating the islet microenvironment, in ways not possible with current clinical strategies, to enhance islet engraftment and function. PMID:22507300

Gibly, Romie F; Zhang, Xiaomin; Lowe, William L; Shea, Lonnie D

2013-01-01

116

Controlled Preparation of Porous Scaffolds by Gas Foaming of Heterogeneous Blends  

NASA Astrophysics Data System (ADS)

Blending two different immiscible polymers is one of the most efficient strategies to prepare materials with improved performances. Recently, this multi-phase systems have been used in tissue engineering aiming at the preparation of porous scaffolds for cell culture. In this study, thermoplastic biodegradable and biocompatible multi-phase blends with co-continuous micro-structures have been prepared by melt mixing poly(?-caprolactone) (PCL) with thermoplastic gelatin (TG), a thermoplastic material prepared by mixing gelatin with glycerol. The blend have been prepared by selecting the composition into the 60/40 to 40/60 wt-% PCL-TG range. Dynamic mechanical analysis was performed in order to asses the achievement of an heterogeneous micro-structure while, gravimetric measurements and scanning electron micrograph analysis, performed after the selective extraction of the different phases, were used to evaluate the co-continuity of the different systems prepared. Finally, the PCL/TG blends have been further processed by the gas foaming technique, in order to create porous materials with well controlled open-pore microarchitectures, suitable as 3D porous scaffolds for tissue engineering applications.

Salerno, A.; Oliviero, M.; Di Maio, E.; Iannace, S.; Netti, P.

2008-08-01

117

Fabrication and Dynamic Mechanical Analysis of Hydroxyapatite Nanoparticle/Gelatin Porous Scaffolds  

NASA Astrophysics Data System (ADS)

The application of engineered biomaterial scaffolds for hard tissue repair critically depends on the scaffold's internal architecture at various length scales. The pore size, shape, surface morphology, and pore connectivity are among the most important factors that affect the scaffold's mechanical properties and biointegration. Reported in this thesis are the results of the investigation of porous constructs fabricated by a freeze-drying process from synthetic nanosized hydroxyapatite / gelatin (nanoHA/Gel) dispersions with different nanoHA/Gel ratios (nanoHA loading was varied from 0 to 50 % by weight). The fabricated scaffolds had porosity up to 90% with pore size in the range of 100 - 500 im, and good distribution of HA nanoparticles within the gelatin matrix. Such porosity is considered to be close to optimal to promote a good cell adhesion in the potential applications of prepared constructs. The fabricated scaffolds have been investigated using X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Dynamic Mechanical Analysis (DMA). Dynamic mechanical analysis of as-fabricated scaffolds revealed that the scaffolds achieved maximum bending and tensile moduli up to 1.28 GPa and 1.5 GPa, respectively, when nanoHA loading was around 30 % by weight. The bending modulus increases by a factor of 1.6, while the Tension modulus increased by a factor of 0.8 after the cross-linking of polymer. Higher nanoHA loading above 50 % by weight results in bending modulus of about 700 MPa and Tension modulus of about 200 MPa only. However, the cross-linking still enhanced the bending up to 1 GPa while it did not affect much the Tension modulus in 50% nanoHA/gelatin constructs. It has been shown that the cross-linking with glutaraldehyde solution improves the morphological structure of the scaffolds, while there was no apparent effect of the cross-linking on the chemical changes in both organic and inorganic content during the processing. The results of this study can be useful for further development of nanoparticulate bioceramic / biopolymer constructs for applications in biomedical field. Keywords: Gelatin, Nano HA, Mechanical, Morphological, Modulus, Crosslinking.

Ghossein, Hicham

118

Chondrogenic regeneration using bone marrow clots and a porous polycaprolactone-hydroxyapatite scaffold by three-dimensional printing.  

PubMed

Scaffolds play an important role in directing three-dimensional (3D) cartilage regeneration. Our recent study reported the potential advantages of bone marrow clots (MC) in promoting extracellular matrix (ECM) scaffold chondrogenic regeneration. The aim of this study is to build a new scaffold for MC, with improved characteristics in mechanics, shaping, and biodegradability, compared to our previous study. To address this issue, this study prepared a 3D porous polycaprolactone (PCL)-hydroxyapatite (HA) scaffold combined with MC (Group A), while the control group (Group B) utilized a bone marrow stem cell seeded PCL-HA scaffold. The results of in vitro cultures and in vivo implantation demonstrated that although an initial obstruction of nutrient exchange caused by large amounts of fibrin and erythrocytes led to a decrease in the ratio of live cells in Group A, these scaffolds also showed significant improvements in cell adhesion, proliferation, and chondrogenic differentiation with porous recanalization in the later culture, compared to Group B. After 4 weeks of in vivo implantation, Group A scaffolds have a superior performance in DNA content, Sox9 and RunX2 expression, cartilage lacuna-like cell and ECM accumulation, when compared to Group B. Furthermore, Group A scaffold size and mechanics were stable during in vitro and in vivo experiments, unlike the scaffolds in our previous study. Our results suggest that the combination with MC proved to be a highly efficient, reliable, and simple new method that improves the biological performance of 3D PCL-HA scaffold. The MC-PCL-HA scaffold is a candidate for future cartilage regeneration studies. PMID:25530453

Yao, Qingqiang; Wei, Bo; Liu, Nancy; Li, Chenshuang; Guo, Yang; Shamie, Arya Nick; Chen, James; Tang, Cheng; Jin, Chengzhe; Xu, Yan; Bian, Xiuwu; Zhang, Xinli; Wang, Liming

2015-04-01

119

Porous nano-HA\\/collagen\\/PLLA scaffold containing chitosan microspheres for controlled delivery of synthetic peptide derived from BMP2  

Microsoft Academic Search

It is advantageous to incorporate controlled growth factor delivery into tissue engineering strategies. The purpose of the present study was to develop a novel tissue engineering scaffold with the capability of controlled releasing BMP-2-derived synthetic peptide. Porous nano-hydroxyapatite\\/collagen\\/poly(L-lactic acid)\\/chitosan microspheres (nHAC\\/PLLA\\/CMs) composite scaffolds containing different quantities of chitosan microspheres (CMs) were prepared by a thermally induced phase separation method. Dioxane

Xufeng Niu; Qingling Feng; Mingbo Wang; Xiaodong Guo; Qixin Zheng

2009-01-01

120

In vitro degradation of three-dimensional porous poly( d, l-lactide- co-glycolide) scaffolds for tissue engineering  

Microsoft Academic Search

In vitro degradation behaviors of three-dimensional tissue engineering porous scaffolds made from amorphous poly(d,l-lactide-co-glycolide) with three different formulations have been systematically investigated up to 26 weeks in phosphate buffer saline solution at 37°C. The following properties of the scaffolds were measured as a function of degradation time: dimensions, weight, compressive strength and modulus, polymer molecular weight and its distribution, and

Linbo Wu; Jiandong Ding

2004-01-01

121

Subcritical CO2 Sintering of Microspheres of Different Polymeric Materials to Fabricate Scaffolds for Tissue Engineering  

PubMed Central

The aim of this study was to use CO2 at sub-critical pressures as a tool to sinter 3D, macroporous, microsphere-based scaffolds for bone and cartilage Tissue Engineering Porous scaffolds composed of ~200 µm microspheres of either poly(lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL) were prepared using dense phase CO2 sintering, which were seeded with rat bone marrow mesenchymal stromal cells (rBMSCs), and exposed to either osteogenic (PLGA, PCL) or chondrogenic (PLGA) conditions for 6 weeks. Under osteogenic conditions, the PLGA constructs produced over an order of magnitude more calcium than the PCL constructs, whereas the PCL constructs had far superior mechanical and structural integrity (125 times stiffer than PLGA constructs) at week 6, along with twice the cell content of the PLGA constructs. Chondrogenic cell performance was limited in PLGA constructs, perhaps as a result of the polymer degradation rate being too high. The current study represents the first long-term culture of CO2-sintered microsphere-based scaffolds, and has established important thermodynamic differences in sintering between the selected formulations of PLGA and PCL, with the former requiring adjustment of pressure only, and the latter requiring the adjustment of both pressure and temperature. Based on more straightforward sintering conditions and more favorable cell performance, PLGA may be the material of choice for microspheres in a CO2 sintering application, although a different PLGA formulation with the encapsulation of growth factors, extracellular matrix-derived nanoparticles, and/or buffers in the microspheres may be advantageous for achieving a more superior cell performance than observed here. PMID:24094202

Bhamidipati, Manjari; Sridharan, BanuPriya; Scurto, Aaron M; Detamore, Michael S.

2013-01-01

122

Strategies for the chemical analysis of highly porous bone scaffolds using secondary ion mass spectrometry.  

PubMed

Understanding the distribution of critical elements (e.g. silicon and calcium) within silica-based bone scaffolds synthesized by different methods is central to the optimization of these materials. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used to determine this information due to its very high surface sensitivity and its ability to map all the elements and compounds in the periodic table with high spatial resolution. The SIMS image data can also be combined with depth profiles to construct three-dimensional chemical maps. However, the scaffolds have interconnected pore networks, which are very challenging structures for the SIMS technique. To overcome this problem two experimental methodologies have been developed. The first method involved the use of the focused ion beam technique to obtain clear images of the regions of interest and subsequently mark them by introducing fiducial marks; the samples were then analysed using the ToF-SIMS technique to yield the chemical analyses of the regions of interest. The second method involved impregnating the pores using a suitable reagent so that a flat surface could be achieved, and this was followed by secondary ion mapping and 3D chemical imaging with ToF-SIMS. The samples used in this work were sol-gel 70S30C foam and electrospun fibres and calcium-containing silica/gelatin hybrid scaffolds. The results demonstrate the feasibility of both these experimental methodologies and indicate that these methods can provide an opportunity to compare various artificial bone scaffolds, which will be of help in improving scaffold synthesis and processing routes. The techniques are also transferable to many other types of porous material. PMID:24457328

Wang, Daming; Poologasundarampillai, Gowsihan; van den Bergh, Wouter; Chater, Richard J; Kasuga, Toshihiro; Jones, Julian R; McPhail, David S

2014-02-01

123

A comparison study of different physical treatments on cartilage matrix derived porous scaffolds for tissue engineering applications  

NASA Astrophysics Data System (ADS)

Native cartilage matrix derived (CMD) scaffolds from various animal and human sources have drawn attention in cartilage tissue engineering due to the demonstrable presence of bioactive components. Different chemical and physical treatments have been employed to enhance the micro-architecture of CMD scaffolds. In this study we have assessed the typical effects of physical cross-linking methods, namely ultraviolet (UV) light, dehydrothermal (DHT) treatment, and combinations of them on bovine articular CMD porous scaffolds with three different matrix concentrations (5%, 15% and 30%) to assess the relative strengths of each treatment. Our findings suggest that UV and UV–DHT treatments on 15% CMD scaffolds can yield architecturally optimal scaffolds for cartilage tissue engineering.

Moradi, Ali; Pramanik, Sumit; Ataollahi, Forough; Khalil, Alizan Abdul; Kamarul, Tunku; Pingguan-Murphy, Belinda

2014-12-01

124

Stress-strain analysis of porous scaffolds made from titanium alloys synthesized via SLS method  

NASA Astrophysics Data System (ADS)

A layer-by-layer selective laser sintering (SLS) technology seems to be greatly promising for solving the plastic surgery problems, particularly those pertaining to the facial reconstruction. Made from titanium-based alloys (titanium or nitinol, i.e. NiTi-intermetallic phase), the porous scaffolds for cranioplasty are an efficient tool for rectifying the face defects and for the dental orthopedic surgery. The progress in the oral surgery and teeth implantation is caused by the problem of an osteointegration on the one hand, and by achievements of the implant synthesis techniques, on the other hand. An important problem thereby is a profound study of the stress-strain behavior of porous implants under the masticatory load or pressure. In the present study the ways for the optimization of the porous implant structural and strength properties as the function of the laser synthesis parameters are described. The finite element approach (ANSYS) was used here for a complex dowel description and numerical simulations. In order to evaluate the processes in the porous implant under the external loading, a CAD 3D model was built for different internal and external configurations of the implant and/or initial shape of powdered particles. The stress-strain dependences were calculated that displayed the irregularity of the stress distribution by the implant volume in the bone tissue. Most of the values are concentrated in places of object contact.

Shishkovsky, I.

2009-09-01

125

Porous matrix of calcium alginate/gelatin with enhanced properties as scaffold for cell culture.  

PubMed

Hydrophilic polysaccharides can be used to prepare porous matrices with a range of possible applications. One such application involves acting as scaffolds for cell culture. A new homogeneous and highly porous biopolymeric porous matrix (BPM) of calcium alginate/gelatin was produced by following a simple process. The key to this process was the selection of the porogen (aerated gelatin). The preparation technique comprises the following steps: incorporating the porogen into the solution of alginate (3%), molding, cross-linking the alginate in 1.41% CaCl2 (maximum gel strength; Cuadros et al., 2012. Carbohydr. Polym. 89, 1198-1206), molding, leaching and lyophilization. Cylinders of BPM were shown to have a relative density of 0.0274±0.002, porosity of 97.26±0.18%, an average internal pore size of 204±58µm and enhanced mechanical properties, while imbibing more than 11 times their dry weight in water. In vitro cell culture testing within BPM using mesenchymal stem cells was demonstrated by MTT assays and expression of alkaline phosphatase. The BPM provided a suitable microenvironment for seeding, adhesion, proliferation and osteogenic differentiation of cells. The preparation technique and resulting porous matrix represent potential tools for future study and further applications. PMID:25661688

Cuadros, Teresa R; Erices, Alejandro A; Aguilera, José M

2015-06-01

126

Reverse freeze casting: a new method for fabricating highly porous titanium scaffolds with aligned large pores.  

PubMed

Highly porous titanium with aligned large pores up to 500 ?m in size, which is suitable for scaffold applications, was successfully fabricated using the reverse freeze casting method. In this process we have newly developed, the Ti powders migrated spontaneously along the pre-aligned camphene boundaries at a temperature of 45.5°C and formed a titanium-camphene mixture with an aligned structure; this was followed by freeze drying and sintering. As the casting time increased from 24 to 48 h, the initial columnar structures turned into lamellar structures, with the porosity decreasing from 69 to 51%. This reduction in porosity caused the compressive yield strength to increase from 121 to 302 MPa, with an elastic modulus of the samples being in the range of 2-5 GPa. In addition, it was demonstrated that reverse freeze casting can also be successfully applied to various other raw powders, suggesting that the method developed in this work opens up new avenues for the production of a range of porous metallic and ceramic scaffolds with highly aligned pores. PMID:22421310

Yook, Se-Won; Jung, Hyun-Do; Park, Chang-Hoon; Shin, Kwan-Ha; Koh, Young-Hag; Estrin, Yuri; Kim, Hyoun-Ee

2012-07-01

127

Icariin delivery porous PHBV scaffolds for promoting osteoblast expansion in vitro.  

PubMed

How cells could proliferate quickly and maintain their biological activity by using appropriate scaffolds remains a big challenge for tissue engineering. By integrating icariin, a bioactive ingredient of traditional Chinese medicine (TCM) Epimedii herba, with PHBV scaffolds, novel icariin delivery porous PHBV scaffolds (IDPPSs) were fabricated with a combination of the solvent casting and salt leaching techniques. IDPPSs displayed a high porosity, 88.80%, and appropriate mechanical properties which were required for 3-D cell culture. IDPPSs significantly promoted the proliferation of human osteoblast-like MG-63 cells and the pre-osteoblast MC3T3-E1 cells, while IDPPSs containing 0.1% icariin (wt.%) showed the highest effect compared with other samples. Although IDPPSs continuously released icariin to the solution in 28 days, cells attached to IDPPSs received an enhanced growth stimulation compared with which were not physically in contact with IDPPSs. Up-regulated transcription of growth factor genes and extracellular matrix genes, including BMP2, BMP6, BMP7 and BGN, was observed in IDPPS-cultured MG-63 cells, illustrating that enhanced cellular proliferation results from alteration of gene transcription. These results implied the potential commercial use of IDPPSs in tissue engineering. PMID:23706245

Xia, Leilei; Li, Yongsheng; Zhou, Zheng; Dai, Yao; Liu, Hongbo; Liu, Hairong

2013-08-01

128

Influences of environmental factors on bacterial extracellular polymeric substances production in porous media  

NASA Astrophysics Data System (ADS)

Bioclogging of natural porous media occurs frequently under a wide range of conditions. It may influence the performance of permeable reactive barrier and constructed wetland. It is also one of the factors that determine the effect of artificial groundwater recharge and in situ bioremediation process. In this study, a series of percolation column experiments were conducted to simulate bioclogging process in porous media. The predominant bacteria in porous media which induced clogging were identified to be Methylobacterium, Janthinobacterium, Yersinia, Staphylococcus and Acidovorax, most of which had been shown to effectively produce viscous extracellular polymeric substances (EPS). The column in which EPS production was maximized also coincided with the largest reduction in saturated hydraulic conductivity of porous media. In addition, carbon concentration was the most significant factor to affect polysaccharide, protein and EPS secretion, followed by phosphorus concentration and temperature. The coupled effect of carbon and phosphorus concentration was also very important to stimulate polysaccharide and EPS production.

Xia, Lu; Zheng, Xilai; Shao, Haibing; Xin, Jia; Peng, Tao

2014-11-01

129

Bone regeneration in strong porous bioactive glass (13–93) scaffolds with an oriented microstructure implanted in rat calvarial defects  

PubMed Central

There is a need for synthetic bone graft substitutes to repair large bone defects resulting from trauma, malignancy, and congenital diseases. Bioactive glass has attractive properties as a scaffold material but factors that influence its ability to regenerate bone in vivo are not well understood. In the present work, the ability of strong porous scaffolds of 13–93 bioactive glass with an oriented microstructure to regenerate bone was evaluated in vivo using a rat calvarial defect model. Scaffolds with an oriented microstructure of columnar pores (porosity = 50%; pore diameter = 50–150 µm) showed mostly osteoconductive bone regeneration, and new bone formation, normalized to the available pore area (volume) of the scaffolds, increased from 37% at 12 weeks to 55% at 24 weeks. Scaffolds of the same glass with a trabecular microstructure (porosity = 80%; pore width = 100–500 µm), used as the positive control, showed bone regeneration in the pores of 25% and 46% at 12 and 24 weeks, respectively. The brittle mechanical response of the as-fabricated scaffolds changed markedly to an elasto-plastic response in vivo at both implantation times. These results indicate that both groups of 13–93 bioactive glass scaffolds could potentially be used to repair large bone defects, but scaffolds with the oriented microstructure could also be considered for the repair of loaded bone. PMID:22922251

Liu, Xin; Rahaman, Mohamed N.; Fu, Qiang

2012-01-01

130

Preparation of porous and nonporous biodegradable polymeric hollow microspheres  

Microsoft Academic Search

A simple method to prepare various porous and nonporous hollow microspheres composed of poly(d,l-lactic-co-glycolic acid) using a water\\/oil\\/water (W\\/O\\/W) multiple emulsion solvent evaporation technique is described. The volume of the inner aqueous phase was varied to observe the effect on microsphere morphology. Hollow microspheres possessing dense, nonporous polymer shell layers were prepared when an initial inner aqueous phase volume fraction

George Crotts; Tae Gwan Park

1995-01-01

131

Graded porous polyurethane foam: A potential scaffold for oro-maxillary bone regeneration.  

PubMed

Bone tissue engineering applications demand for biomaterials offering a substrate for cell adhesion, migration, and proliferation, while inferring suitable mechanical properties to the construct. In the present study, polyurethane (PU) foams were synthesized to develop a graded porous material-characterized by a dense shell and a porous core-for the treatment of oro-maxillary bone defects. Foam was synthesized via a one-pot reaction starting from a polyisocyanate and a biocompatible polyester diol, using water as a foaming agent. Different foaming conditions were examined, with the aim of creating a dense/porous functional graded material that would perform at the same time as an osteoconductive scaffold for bone defect regeneration and as a membrane-barrier to gingival tissue ingrowth. The obtained PU was characterized in terms of morphological and mechanical properties. Biocompatibility assessment was performed in combination with bone-marrow-derived human mesenchymal stromal cells (hBMSCs). Our findings confirm that the material is potentially suitable for guided bone regeneration applications. PMID:25842142

Giannitelli, S M; Basoli, F; Mozetic, P; Piva, P; Bartuli, F N; Luciani, F; Arcuri, C; Trombetta, M; Rainer, A; Licoccia, S

2015-06-01

132

Collagen-poly(dialdehyde) guar gum based porous 3D scaffolds immobilized with growth factor for tissue engineering applications.  

PubMed

Here we report the preparation of collagen-poly(dialdehyde) guar gum based hybrid functionalized scaffolds covalently immobilized with platelet derived growth factor - BB for tissue engineering applications. Poly(dialdehyde) guar gum was synthesized from selective oxidation of guar gum using sodium periodate. The synthesized poly(dialdehyde) guar gum not only promotes crosslinking of collagen but also immobilizes the platelet derived growth factor through imine bonds. The covalent crosslinking formed in collagen improves thermal, swelling and biodegradation properties of the hybrid scaffolds. The prepared hybrid scaffolds show 3D interconnected honeycomb porous structure when viewed under a microscope. The release of immobilized platelet derived growth factor was seen up to 13th day of incubation thereby proving its sustained delivery. The developed hybrid scaffold leads to a quantum increase in NIH 3T3 fibroblast cell density and proliferation thereby demonstrating its potential for tissue engineering applications. PMID:25263907

Ragothaman, Murali; Palanisamy, Thanikaivelan; Kalirajan, Cheirmadurai

2014-12-19

133

Stabilization of resveratrol immobilized in monodisperse cyano-functionalized porous polymeric microspheres  

Microsoft Academic Search

To preserve the high anti-oxidant activity of resveratrol for a long period of time, porous particles were utilized. The porosity of these substrate particles was controlled by DVB content and toluene\\/heptane ratios in the seeded polymerization. The influence of porosity on the anti-oxidant activity of the immobilized resveratrol was investigated. From SEM and CLSM analysis, it was confirmed that the

Jeong-Beom Nam; Jee-Hyun Ryu; Jin-Woong Kim; Ih-Scop Chang; Kyung-Do Suh

2005-01-01

134

Porous polymeric structures for tissue engineering prepared by a coagulation, compression moulding and salt leaching technique  

Microsoft Academic Search

A technique for the preparation of porous polymeric structures involving coagulation, compression moulding and particulate leaching has been developed. The technique combines the advantages of thermal processing methods and particulate leaching. A high molecular weight polymer solution in an organic solvent containing dispersed water-soluble salt particles is precipitated into an excess of non-solvent. The polymer–salt composite is then processed by

Qingpu Hou; Dirk W. Grijpma; Jan Feijen

2003-01-01

135

Preparation and characterization of 3D porous ceramic scaffolds based on portland cement for bone tissue engineering.  

PubMed

There is a constant need for bone substitutes. This work was focused on developing a porous substrate based on Portland cement with air-voids introduced by outgassing reaction product from lime and aluminum powder. The structures were obtained through two routes of raw-materials and processing. Water absorption and compressive strength measurements and scanning electron microscopy, X-ray diffraction, and Fourier Transformed Infrared Spectroscopy assays were conducted in order to characterize the porous substrates. The substrates have shown pore size structure compatible with bone tissue colonization. Also, the mechanical strength exhibited by the scaffolds fall in the normal ranges for trabecular bone. These characteristics indicate potential use of the developed porous scaffold for bone tissue engineering which was endorsed by in vitro experiments via cell culture. PMID:18949538

Mansur, Alexandra A P; Mansur, Herman S

2009-02-01

136

The Study on Biocompatibility of Porous nHA/PLGA Composite Scaffolds for Tissue Engineering with Rabbit Chondrocytes In Vitro  

PubMed Central

Objective. To examine the biocompatibility of a novel nanohydroxyapatite/poly[lactic-co-glycolic acid] (nHA/PLGA) composite and evaluate its feasibility as a scaffold for cartilage tissue engineering. Methods. Chondrocytes of fetal rabbit were cultured with nHA/PLGA scaffold in vitro and the cell viability was assessed by MTT assay first. Cells adhering to nHA/PLGA scaffold were then observed by inverted microscope and scanning electron microscope (SEM). The cell cycle profile was analyzed by flow cytometry. Results. The viability of the chondrocytes on the scaffold was not affected by nHA/PLGA comparing with the control group as it was shown by MTT assay. Cells on the surface and in the pores of the scaffold increased in a time-dependent manner. Results obtained from flow cytometry showed that there was no significant difference in cell cycle profiles between the coculture group and control (P > 0.05). Conclusion. The porous nHA/PLGA composite scaffold is a biocompatible and good kind of scaffold for cartilage tissue engineering. PMID:24380082

Chen, Lei; Zhu, Wei-Min; Fei, Zhi-Qiang; Chen, Jie-Lin; Xiong, Jian-Yi; Zhang, Ju-Feng; Duan, Li; Huang, Jianghong; Liu, Zhiyong; Wang, Daping; Zeng, Yanjun

2013-01-01

137

Biomineral Coating Increases Bone Formation by Ex Vivo BMP-7 Gene Therapy in Rapid Prototyped Poly(l-lactic acid) (PLLA) and Poly(?-caprolactone) (PCL) Porous Scaffolds.  

PubMed

Porousbiodegradable polymer scaffolds are widely utilized for bone tissue engineering, but are not osteoconductive like calcium phosphate scaffolds. We combine indirect solid freeform fabrication (SFF), ex vivo gene therapy, with biomineral coating to compare the effect of biomineral coating on bone regeneration for Poly (l-lactic acid) (PLLA) and Poly (?-caprolactone) (PCL) scaffolds with the same porous architecture. Scanning electron microscope (SEM) and micro-computed tomography (?-CT) demonstrate PLLA and PCL scaffolds have the same porous architecture and are completely coated. All scaffolds are seeded with human gingival fibroblasts (HGF) transduced with adenovirus encoded with either bone morphogenetic protein 7 (BMP-7) or green fluorescent protein (GFP), and implanted into mice subcutaneously for 3 and 10 weeks. Only scaffolds with BMP-7 transduced HGFs show mineralized tissue formation. At 3 weeks some blood vessel-like structures are observed in coated PLLA and PCL scaffolds, but there is no significant difference in bone ingrowth between the coated and uncoated scaffolds for either PLLA or PCL. At 10 weeks, however, coated scaffolds (both PLLA and PCL) have significantly more bone ingrowth than uncoated scaffolds, which have more fibrous tissue. Coated PLLA scaffolds have improved mechanical properties compared with uncoated PLLA scaffolds due to increased bone ingrowth. PMID:25515846

Saito, Eiji; Suarez-Gonzalez, Darilis; Murphy, William L; Hollister, Scott J

2015-03-01

138

Porous collagen-hydroxyapatite scaffolds with mesenchymal stem cells for bone regeneration.  

PubMed

Current bone grafting materials have significant limitations for repairing maxillofacial and dentoalveolar bone deficiencies. An ideal bone tissue-engineering construct is still lacking. The purpose of the present study was first to synthesize and develop a collagen-hydroxyapatite (Col-HA) composite through controlled in situ mineralization on type I collagen fibrils with nanometer-sized apatite crystals, and then evaluate their biologic properties by culturing with mouse and human mesenchymal stem cells (MSCs). We synthesized Col-HA scaffolds with different Col:HA ratios. Mouse C3H10T1/2 MSCs and human periodontal ligament stem cells (hPDSCs) were cultured with scaffolds for cell proliferation and biocompatibility assays. We found that the porous Col-HA composites have good biocompatibility and biomimetic properties. The Col-HA composites with ratios 80:20 and 50:50 composites supported the attachments and proliferations of mouse MSCs and hPDSCs. These findings indicate that Col-HA composite complexes have strong potentials for bone tissue regeneration. PMID:23574526

Ning, Li; Malmström, Hans; Ren, Yan-Fang

2015-02-01

139

Morphostructural analysis of human follicular stem cells on highly porous bone hydroxyapatite scaffold.  

PubMed

In this study we investigated the in vitro behaviour, morphostructure and extracellular matrix synthesis of human dental follicular stem cells (hDFSCs) isolated from human dental bud, which resulted to be positive for mesenchymal markers (CD29, CD90, CD146 and CD166) by FACS analysis. Cells were analysed by light and electronic microscopy to evaluate their biological response either at week 1, that is before differentiation, or at weeks 3-6, when they had been cultured in osteogenic medium onto a highly porous natural scaffold material (Bio-Oss). Microscopy analysis of primary culture cells showed they had a mesenchymal stem cell-like morphostructure, spindle shaped, similar to the culture of mesenchymal stem cells derived from adult bone marrow. Also, after osteogenic differentiation, these analyses indicate typical osteoblast morphostructure and reveale a tri-dimensional organization of the cells and deposition of extracellular matrix (ECM) in close contact with biomaterial. This approach would allow to personalize the scaffold for bone tissue engineering in order to accelerate the process of osteogenesis. PMID:18179737

Tetè, S; Mastrangelo, F; Carone, L; Nargi, E; Costanzo, G; Vinci, R; Burruano, F; Tortorici, S; Dadorante, V; Caciagli, F; Traini, T; Gherlone, E; Caraffa, A; Salini, V; Conti, P; Ciccarelli, R

2007-01-01

140

Olefin polymerization from single site catalysts confined within porous media  

NASA Astrophysics Data System (ADS)

Single Site Catalysts (SSCs) have been utilized for olefin polymerization. Altering the metal-ligand architecture in the SSCs, polyolefin properties can be enhanced in a rational manner. This influence of the ligands in the SSC on the property of polyolefins prepared can be referred to as the primary ligand influence. Extending this understanding and subsequent control of the metal-ligand framework to the interaction of SSCs within organic and inorganic supports is vital for the synthesis of polyolefins with tailored properties. The motivation behind this thesis was to explore the support influence on the reactivity of the SSC tethered to a support matrix during ethylene homo and copolymerization. In order to address this question of the support influence on the final polyolefin properties, synthetic routes to covalently bind SSCs on different matrices have been explored. Two distinct supported SSCs have been used to prepare branched polyethylenes. Branched polyethylenes can be prepared by either copolymerization (ethylene and alpha-olefin) or oligomerization/copolymerization processes (ethylene and in situ generated alpha-olefin). Synthetic routes to prepare precursor catalysts to Constrained Geometry Catalysts (CGCs) by silyl elimination chemistry have been developed (Chapter 2). Efficient synthetic protocols to assemble CGCs on aminomethylpolysytrene matrices (Chapter 3) and amine-functionalized mesoporous silica (Chapter 4) are also reported. These supported catalysts, with appropriate cocatalysts have been used to prepare ethylene homo and copolymers, the polymer thermal properties and microstructures were analyzed by various analytical techniques. Branched polyethylenes (LLDPE) can be prepared by copolymerization chemistry. It has been observed is that the influence of the support is seen in the production of lower crystalline forms of high density polyethylene (HDPE, 20--50% crystalline), while homogeneous polymerization of analogous soluble CGCs afford HDPE of higher percent crystallinity (greater than 60% crystalline). High-density polyethylene with crystallinity of 40--60% can be prepared by using cocatalysts tethered to AMPS or silica in conjunction with analogous soluble, homogeneous CGCs (Chapter 6). Preparative methods to assemble piano stool complexes on hydroxy polystyrenes have been designed. These supported catalysts in conjunction with cocatalysts act as both oligomerization and copolymerization catalysts and allow the preparation of branched polyethylenes from ethylene only feed (Chapter 7).

Kasi, Rajeswari M.

141

Fabrication and in vitro degradation of porous fumarate-based polymer/alumoxane nanocomposite scaffolds for bone tissue engineering.  

PubMed

In this work, the fabrication and in vitro degradation of porous fumarate-based/alumoxane nanocomposites were evaluated for their potential as bone tissue engineering scaffolds. The biodegradable polymer poly (propylene fumarate)/propylene fumarate-diacrylate (PPF/PF-DA), a macrocomposite composed of PPF/PF-DA and boehmite microparticles, and a nanocomposite composed of PPF/PF-DA and surface-modified alumoxane nanoparticles were used to fabricate porous scaffolds by photo-crosslinking and salt-leaching. Scaffolds then underwent 12 weeks of in vitro degradation in phosphate buffered saline at 37 degrees C. The presence of boehmite microparticles and alumoxane nanoparticles in the polymer inhibited scaffold shrinkage during crosslinking. Furthermore, the incorporation of alumoxane nanoparticles into the polymer limited salt-leaching, perhaps due to tighter crosslinking within the nanocomposite. Analysis of crosslinking revealed that the acrylate and overall double bond conversions in the nanocomposite were higher than in the PPF/PF-DA polymer alone, though these differences were not significant. During 12 weeks of in vitro degradation, the nanocomposite lost 5.3% +/- 2.4% of its mass but maintained its compressive mechanical properties and porous architecture. The addition of alumoxane nanoparticles into the fumarate-based polymer did not significantly affect the degradation of the nanocomposite compared with the other materials in terms of mass loss, compressive properties, and porous structure. These results demonstrate the feasibility of fabricating degradable nanocomposite scaffolds for bone tissue engineering by photo-crosslinking and salt-leaching mixtures of fumarate-based polymers, alumoxane nanoparticles, and salt microparticles. PMID:18428800

Mistry, Amit S; Cheng, Stacy H; Yeh, Tiffany; Christenson, Elizabeth; Jansen, John A; Mikos, Antonios G

2009-04-01

142

Nanogel tectonic porous gel loading biologics, nanocarriers, and cells for advanced scaffold.  

PubMed

We developed a new self-assembled amphiphilic nanogel-crosslinked porous (NanoCliP) gel that can trap proteins, liposomes, and cells. The NanoCliP gel was prepared by Michael addition of a self-assembled nanogel of acryloyl group-modified cholesterol-bearing pullulan to pentaerythritol tetra (mercaptoethyl) polyoxyethylene, followed by freezing-induced phase separation. Dynamic rheological analysis revealed that the storage modulus (G') of the NanoCliP gel was approximately 10 times greater than that of a nonporous nanogel-crosslinked gel. Two-photon excitation deep imaging revealed that the NanoCliP gel comprises interconnected pores of several hundred micrometers in diameter. The NanoCliP gel trapped proteins and liposomes via hydrophobic interactions because its amphiphilic nanogels exhibit chaperone-like activity. Mouse embryonic fibroblasts penetrated the interconnected pores and adhered to the porous surface of fibronectin-complexed NanoCliP gel. In vivo, the NanoCliP gel enhanced cell infiltration, tissue ingrowth, and neovascularization without requiring exogenous growth factors, suggesting that the NanoCliP gel is a promising scaffold for tissue engineering. PMID:25453324

Hashimoto, Yoshihide; Mukai, Sada-atsu; Sawada, Shin-ichi; Sasaki, Yoshihiro; Akiyoshi, Kazunari

2015-01-01

143

Tough and flexible CNT-polymeric hybrid scaffolds for engineering cardiac constructs.  

PubMed

In the past few years, a considerable amount of effort has been devoted toward the development of biomimetic scaffolds for cardiac tissue engineering. However, most of the previous scaffolds have been electrically insulating or lacked the structural and mechanical robustness to engineer cardiac tissue constructs with suitable electrophysiological functions. Here, we developed tough and flexible hybrid scaffolds with enhanced electrical properties composed of carbon nanotubes (CNTs) embedded aligned poly(glycerol sebacate):gelatin (PG) electrospun nanofibers. Incorporation of varying concentrations of CNTs from 0 to 1.5% within the PG nanofibrous scaffolds (CNT-PG scaffolds) notably enhanced fiber alignment and improved the electrical conductivity and toughness of the scaffolds while maintaining the viability, retention, alignment, and contractile activities of cardiomyocytes (CMs) seeded on the scaffolds. The resulting CNT-PG scaffolds resulted in stronger spontaneous and synchronous beating behavior (3.5-fold lower excitation threshold and 2.8-fold higher maximum capture rate) compared to those cultured on PG scaffold. Overall, our findings demonstrated that aligned CNT-PG scaffold exhibited superior mechanical properties with enhanced CM beating properties. It is envisioned that the proposed hybrid scaffolds can be useful for generating cardiac tissue constructs with improved organization and maturation. PMID:24927679

Kharaziha, Mahshid; Shin, Su Ryon; Nikkhah, Mehdi; Topkaya, Seda Nur; Masoumi, Nafiseh; Annabi, Nasim; Dokmeci, Mehmet R; Khademhosseini, Ali

2014-08-01

144

Osteogenic Differentiation of Human Mesenchymal Stem Cells in 3-D Zr-Si Organic-Inorganic Scaffolds Produced by Two-Photon Polymerization Technique  

PubMed Central

Two-photon polymerization (2PP) is applied for the fabrication of 3-D Zr-Si scaffolds for bone tissue engineering. Zr-Si scaffolds with 150, 200, and 250 ?m pore sizes are seeded with human bone marrow stem cells (hBMSCs) and human adipose tissue derived stem cells (hASCs) and cultured in osteoinductive and control media for three weeks. Osteogenic differentiation of hASCs and hBMSCs and formation of bone matrix is comparatively analyzed via alkaline phosphatase activity (ALP), calcium quantification, osteocalcin staining and scanning electron microscopy (SEM). It is observed that the 150 ?m pore size Zr-Si scaffolds support the strongest matrix mineralization, as confirmed by calcium deposition. Analysis of ALP activity, osteocalcin staining and SEM observations of matrix mineralization reveal that mesenchymal stem cells cultured on 3-D scaffolds without osteogenic stimulation spontaneously differentiate towards osteogenic lineage. Nanoindentation measurements show that aging of the 2PP-produced Zr-Si scaffolds in aqueous or alcohol media results in an increase in the scaffold Young’s modulus and hardness. Moreover, accelerated formation of bone matrix by hASCs is noted, when cultured on the scaffolds with lower Young’s moduli and hardness values (non aged scaffolds) compared to the cells cultured on scaffolds with higher Young’s modulus and hardness values (aged scaffolds). Presented results support the potential application of Zr-Si scaffolds for autologous bone tissue engineering. PMID:25706270

Koroleva, Anastasia; Deiwick, Andrea; Nguyen, Alexander; Schlie-Wolter, Sabrina; Narayan, Roger; Timashev, Peter; Popov, Vladimir; Bagratashvili, Viktor; Chichkov, Boris

2015-01-01

145

Numerical optimization of open-porous bone scaffold structures to match the elastic properties of human cortical bone.  

PubMed

Treatment of large segmental bone defects, especially in load bearing areas, is a complex procedure in orthopedic surgery. The usage of additive manufacturing processes enables the creation of customized bone implants with arbitrary open-porous structure satisfying both the mechanical and the biological requirements for a sufficient bone ingrowth. Aim of the present numerical study was to optimize the geometrical parameters of open-porous titanium scaffolds to match the elastic properties of human cortical bone with respect to an adequate pore size. Three different scaffold designs (cubic, diagonal and pyramidal) were numerically investigated by using an optimization approach. Beam elements were used to create the lattice structures of the scaffolds. The design parameters strut diameter and pore size ranged from 0.2 to 1.5mm and from 0 to 3.0mm, respectively. In a first optimization step, the geometrical parameters were varied under uniaxial compression to obtain a structural modulus of 15GPa (Young?s modulus of cortical bone) and a pore size of 800µm was aimed to enable cell ingrowth. Furthermore, the mechanical behavior of the optimized structures under bending and torsion was investigated. Results for bending modulus were between 9.0 and 14.5GPa. In contrast, shear modulus was lowest for cubic and pyramidal design of approximately 1GPa. Here, the diagonal design revealed a modulus of nearly 20GPa. In a second step, large-sized bone scaffolds were created and placed in a biomechanical loading situation within a 30mm segmental femoral defect, stabilized with an osteosynthesis plate and loaded with physiological muscle forces. Strut diameter for the 17 sections of each scaffold was optimized independently in order to match the biomechanical stability of intact bone. For each design, highest strut diameter was found at the dorsal/medial site of the defect and smallest strut diameter in the center. In conclusion, we demonstrated the possibility of providing optimized open-porous scaffolds for bone regeneration by considering both mechanical and biological aspects. Furthermore, the results revealed the need of the investigation and comparison of different load scenarios (compression, bending and torsion) as well as complex biomechanical loading for a profound characterization of different scaffold designs. The usage of a numerical optimization process was proven to be a feasible tool to reduce the amount of the required titanium material without influencing the biomechanical performance of the scaffold negatively. By using fully parameterized models, the optimization approach is adaptable to other scaffold designs and bone defect situations. PMID:24942627

Wieding, Jan; Wolf, Andreas; Bader, Rainer

2014-09-01

146

Design and application of chitosan/biphasic calcium phosphate porous scaffolds for bone tissue engineering  

NASA Astrophysics Data System (ADS)

For the restoration of maxillofacial bone tissue, design of novel tissue engineering scaffolds capable of inducing bone remodeling through the delivery of mesenchymal stem cells (MSCs) and an angiogenic growth factor, directly at the site of the defect was investigated in order to replace autogenous cancellous bone grafts with synthetic materials. Porous, three dimensional scaffolds were fabricated by a freeze drying method. In culture media, biphasic calcium phosphate particles within chitosan produced a surface reprecipitate of a composition similar to natural apatite that led to a uniform distribution of cells and mineralized ECM through chemotaxis. Further, the reprecipitation regulated the differentiation pathway and phenotype commitment of stem cells by altering the initial cell attachment morphology and actin cytoskeleton organization. In order to induce neovascularization after implantation, constructs were designed to be loaded with gelatin microspheres that delivered basic fibroblast growth factor (bFGF), a potent angiogenic factor. In vitro proliferation tests performed on fibroblastic cells showed no detectible loss of bFGF activity when delivered through enzymatic degradation of gelatin. Laser scanning confocal microscopy was used to demonstrate that gelatin microspheres can be injected evenly into cell-scaffold constructs owing to the spongy characteristics of the scaffold. To examine the binding interactions of bFGF with surface bound gelatin, a label free biosensor system, Biomolecular INteraction Detection sensor (BIND) was used. Results confirm that the principal interaction that takes place between bFGF and gelatin is electrostatic. Cell loaded tissue engineered constructs were produced in vitro at clinically relevant sizes and implanted with and without bFGF into a porcine mandibular defect model. Tissue engineered constructs facilitated the healing of mandibular defects only if combined with delivery of bFGF via gelatin microspheres. bFGF release from the constructs improved neovascularization in the defect area and subsequently enhanced new bone formation. Although the rate and extent of bone formation was similar in bFGF group to those in empty defects for the period of the study, existence of woven bone in bFGF group suggests that bone formation is continuing while the lamellar structure in empty defects indicates that bone formation in that group was finalized.

Sendemir-Urkmez, Aylin

147

Computational modeling of flow-induced shear stresses within 3D salt-leached porous scaffolds imaged via micro-CT  

Microsoft Academic Search

Flow-induced shear stresses have been found to be a stimulatory factor in pre-osteoblastic cells seeded in 3D porous scaffolds and cultured under continuous flow perfusion. However, due to the complex internal structure of porous scaffolds, analytical estimation of the local shear forces is impractical. The primary goal of this work is to investigate the shear stress distributions within Poly(l-lactic acid)

Roman Voronov; Samuel VanGordon; Vassilios I. Sikavitsas; Dimitrios V. Papavassiliou

2010-01-01

148

Effects of low temperature hydrogen peroxide gas on sterilization and cytocompatibility of porous poly( d, l-lactic- co-glycolic acid) scaffolds  

Microsoft Academic Search

Biodegradable poly(d,l-lactic-co-glycolic acid) (PLGA) has been widely used as a scaffold in tissue engineering due to its excellent biocompatibility. However, PLGA scaffolds become structurally deformed during the sterilization process since they were hydrolytically unstable. In this study, the effects of hydrogen peroxide gas (HPG) were investigated on the deformation, sterilization and cytocompatibility of porous PLGA scaffolds and compared with those

Mi Hee Lee; Hye-Lee Kim; Chang Hwa Kim; Sun Ho Lee; Jeong Koo Kim; Seung Jin Lee; Jong-Chul Park

2008-01-01

149

Synthesis of composite gelatin-hyaluronic acid-alginate porous scaffold and evaluation for in vitro stem cell growth and in vivo tissue integration.  

PubMed

Engineering three-dimensional (3-D) porous scaffolds with precise bio-functional properties is one of the most important issues in tissue engineering. In the present study, a three-dimensional gelatin-hyaluronic acid-alginate (GHA) polymeric composite was synthesized by freeze-drying, which was followed by ionic crosslinking using CaCl2, and evaluated for its suitability in bone tissue engineering applications. The obtained matrix showed high porosity (85%), an interconnected pore morphology and a rapid swelling behavior. The rheological analysis of GHA showed a viscoelastic characteristic, which suggested a high load bearing capacity without fractural deformation. The influence of the GHA matrix on cell growth and on modulating the differentiation ability of mesenchymal stem cells was evaluated by different biochemical and immunostaining assays. The monitoring of cells over a period of four weeks showed increased cellular proliferation and osteogenic differentiation without external growth factors, compared with control (supplemented with osteogenic differentiation medium). The in vivo matrix implantation showed higher matrix-tissue integration and cell infiltration as the duration of the implant increased. These results suggest that a porous GHA matrix with suitable mechanical integrity and tissue compatibility is a promising substrate for the osteogenic differentiation of stem cells for bone tissue engineering applications. PMID:24572494

Singh, Deepti; Tripathi, Anuj; Zo, Sunmi; Singh, Dolly; Han, Sung Soo

2014-04-01

150

Femtosecond laser two-photon polymerization of three-dimensional scaffolds for tissue engineering and regenerative medicine applications  

NASA Astrophysics Data System (ADS)

Recent studies have shown that mechanical factors can direct stem cell fate in vitro, even in the absence of biochemical factors. Two-photon laser polymerization was applied here to fabricate ultra-precise 3D micro-scaffolds with different architectures and pore sizes able to structurally interact with cells at the single-cell scale. Our experiments have shown that randomly seeded mesenchymal stem cells systematically colonize the internal volumes of 3D scaffolds and proliferate, while showing a roundish morphology. Even if stem cell mechanobiology is a very complex field, this study shows how mechanical interactions studied in a 3D micro-architecture at a single cell scale may influence stem cells response.

Aprile, V.; Eaton, S. M.; Laganà, M.; Cerullo, G.; Raimondi, M. T.; Osellame, R.

2012-01-01

151

Nano SiO2 and MgO Improve the Properties of Porous ?-TCP Scaffolds via Advanced Manufacturing Technology.  

PubMed

Nano SiO2 and MgO particles were incorporated into ?-tricalcium phosphate (?-TCP) scaffolds to improve the mechanical and biological properties. The porous cylindrical ?-TCP scaffolds doped with 0.5 wt % SiO2, 1.0 wt % MgO, 0.5 wt % SiO2 + 1.0 wt % MgO were fabricated via selective laser sintering respectively and undoped ?-TCP scaffold was also prepared as control. The phase composition and mechanical strength of the scaffolds were evaluated. X-ray diffraction analysis indicated that the phase transformation from ?-TCP to ?-TCP was inhibited after the addition of MgO. The compressive strength of scaffold was improved from 3.12 ± 0.36 MPa (?-TCP) to 5.74 ± 0.62 MPa (?-TCP/SiO2), 9.02 ± 0.55 MPa (?-TCP/MgO) and 10.43 ± 0.28 MPa (?-TCP/SiO2/MgO), respectively. The weight loss and apatite-forming ability of the scaffolds were evaluated by soaking them in simulated body fluid. The results demonstrated that both SiO2 and MgO dopings slowed down the degradation rate and improved the bioactivity of ?-TCP scaffolds. In vitro cell culture studies indicated that SiO2 and MgO dopings facilitated cell attachment and proliferation. Combined addition of SiO2 and MgO were found optimal in enhancing both the mechanical and biological properties of ?-TCP scaffold. PMID:25815597

Gao, Chengde; Wei, Pingpin; Feng, Pei; Xiao, Tao; Shuai, Cijun; Peng, Shuping

2015-01-01

152

Comprehensive Genetic Analysis of Early Host Body Reactions to the Bioactive and Bio-Inert Porous Scaffolds  

PubMed Central

To design scaffolds for tissue regeneration, details of the host body reaction to the scaffolds must be studied. Host body reactions have been investigated mainly by immunohistological observations for a long time. Despite of recent dramatic development in genetic analysis technologies, genetically comprehensive changes in host body reactions are hardly studied. There is no information about host body reactions that can predict successful tissue regeneration in the future. In the present study, porous polyethylene scaffolds were coated with bioactive collagen or bio-inert poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB) and were implanted subcutaneously and compared the host body reaction to those substrates by normalizing the result using control non-coat polyethylene scaffold. The comprehensive analyses of early host body reactions to the scaffolds were carried out using a DNA microarray assay. Within numerous genes which were expressed differently among these scaffolds, particular genes related to inflammation, wound healing, and angiogenesis were focused upon. Interleukin (IL)-1? and IL-10 are important cytokines in tissue responses to biomaterials because IL-1? promotes both inflammation and wound healing and IL-10 suppresses both of them. IL-1? was up-regulated in the collagen-coated scaffold. Collagen-specifically up-regulated genes contained both M1- and M2-macrophage-related genes. Marked vessel formation in the collagen-coated scaffold was occurred in accordance with the up-regulation of many angiogenesis-inducible factors. The DNA microarray assay provided global information regarding the host body reaction. Interestingly, several up-regulated genes were detected even on the very bio-inert PMB-coated surfaces and those genes include inflammation-suppressive and wound healing-suppressive IL-10, suggesting that not only active tissue response but also the inert response may relates to these genetic regulations. PMID:24454803

Ehashi, Tomo; Takemura, Taro; Hanagata, Nobutaka; Minowa, Takashi; Kobayashi, Hisatoshi; Ishihara, Kazuhiko; Yamaoka, Tetsuji

2014-01-01

153

In vitro degradation of porous poly(propylene fumarate)\\/poly( dl-lactic- co-glycolic acid) composite scaffolds  

Microsoft Academic Search

This study investigated the in vitro degradation of porous poly(propylene fumarate) (PPF-based) composites incorporating microparticles of blends of poly(DL-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) during a 26-week period in pH 7.4 phosphate-buffered saline at 37°C. Using a fractional factorial design, four formulations of composite scaffolds were fabricated with varying PEG content of the microparticles, microparticle mass fraction of the

Elizabeth L. Hedberg; Charles K. Shih; Jeremy J. Lemoine; Mark D. Timmer; Michael A. K. Liebschner; John A. Jansen; Antonios G. Mikos

2005-01-01

154

Preparation of interconnected poly(?-caprolactone) porous scaffolds by a combination of polymer and salt particulate leaching  

Microsoft Academic Search

This paper examines a new technique for the preparation of porous scaffolds by combining selective polymer leaching in a co-continuous blend and salt particulate leaching. In the first step of this technique, a co-continuous blend of two biodegradable polymers, poly(?-caprolactone) (PCL) and polyethylene oxide (PEO), and a certain amount of sodium chloride salt particles are melt blended using a twin

Joël Reignier; Michel A. Huneault

2006-01-01

155

Enhanced biological stability of collagen porous scaffolds by using amino acids as novel cross-linking bridges  

Microsoft Academic Search

Collagen porous scaffolds have been widely employed as a dermal equivalent to induce fibroblasts infiltration and dermal regeneration. To eliminate the disadvantageous drawback of the fast degradation speed, a cross-linking method was adopted by using a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDAC) and N-hydroxysuccinimide (NHS) in the presence of amino acids (glycin, glutamic acid or lysine), which function as cross-linking bridge between

Lie Ma; Changyou Gao; Zhengwei Mao; Jie Zhou; Jiacong Shen

2004-01-01

156

Surface modification of porous polycaprolactone/biphasic calcium phosphate scaffolds for bone regeneration in rat calvaria defect.  

PubMed

In this study, polycaprolactone scaffolds fabricated by a salt-leaching process were loaded with biphasic calcium phosphate successfully to improve the osteoconductivity in bone regeneration. The surface of polycaprolactone/biphasic calcium phosphate scaffolds was aminolyzed by 1,6-hexamethylenediamine to introduce amino groups onto the surface, which was verified qualitatively by ninhyrin staining. Collagen was further immobilized on the aminolyzed porous polycaprolactone via N-ethyl-N'-(3-dimethylaminopropy) carbodiimide hydrochloride/hydroxy-2,5-dioxopyrolidine-3-sulfonic acid sodium cross-linking. The pore size of polycaprolactone/biphasic calcium phosphate-collagen scaffolds was 200-300?µm, which was suitable for bone in-growth. The X-ray photoelectron spectroscopy confirmed the coupling of collagen immobilized on the surface of polycaprolactone/biphasic calcium phosphate. In vitro results demonstrated that the spreading and viability of MC3T3-E1 cells were remarkably improved in the polycaprolactone/biphasic calcium phosphate-collagen scaffolds. The in vivo study was carried out by implanting the porous polycaprolactone, polycaprolactone/biphasic calcium phosphate, and polycaprolactone/biphasic calcium phosphate-collagen to the skulls of rats. Although the addition of biphasic calcium phosphate particles in the polycaprolactone scaffolds does not have a strong effect on the new bone formation, the immobilization of collagen on the polycaprolactone/biphasic calcium phosphate scaffolds significantly improved the bone regeneration even though the implantation time was short, 6 weeks. The present results provide more evidence that functionalizing polycaprolactone with biphasic calcium phosphate and collagen may be a feasible way to improve the osteoconduction in bone regeneration. PMID:24939961

Kim, Ji-Hyun; Linh, Nguyen T B; Min, Young K; Lee, Byong-Taek

2014-10-01

157

Porous aromatic frameworks with anion-templated pore apertures serving as polymeric sieves  

NASA Astrophysics Data System (ADS)

Owing to environmental pollution and energy depletion, efficient separation of energy gases has attracted widespread attention. Low-cost and efficient adsorbents for gas separation are greatly needed. Here we report a family of quaternary pyridinium-type porous aromatic frameworks with tunable channels. After carefully choosing and adjusting the sterically hindered counter ions via a facile ion exchange approach, the pore diameters are tuned at an angstrom scale in the range of 3.4-7?Å. The designed pore sizes may bring benefits to capturing or sieving gas molecules with varied diameters to separate them efficiently by size-exclusive effects. By combining their specific separation properties, a five-component (hydrogen, nitrogen, oxygen, carbon dioxide and methane) gas mixture can be separated completely. The porous aromatic frameworks may hold promise for practical and commercial applications as polymeric sieves.

Yuan, Ye; Sun, Fuxing; Li, Lina; Cui, Peng; Zhu, Guangshan

2014-06-01

158

A porous scaffold for bone tissue engineering\\/45S5 Bioglass ® derived porous scaffolds for co-culturing osteoblasts and endothelial cells  

Microsoft Academic Search

One of the major factors in the therapeutic success of bone tissue engineered scaffolds is the ability of the construct to\\u000a vascularise post implantation. One of the approaches for improving vascularisation within scaffolds has been to co-culture\\u000a human umbilical vein endothelial cells (HUVECS) with human osteoblasts (HOBS), which may then promote vascularisation and\\u000a facilitate tissue regeneration. However, in order to

Sanjukta Deb; Ramin Mandegaran; Lucy Di Silvio

2010-01-01

159

Enhanced bone regeneration of cortical segmental bone defects using porous titanium scaffolds incorporated with colloidal gelatin gels for time- and dose-controlled delivery of dual growth factors.  

PubMed

Porous titanium scaffolds are a promising class of biomaterials for grafting large bone defects, because titanium provides sufficient mechanical support, whereas its porous structure allows bone ingrowth resulting in good osseointegration. To reinforce porous titanium scaffolds with biological cues that enhance and continue bone regeneration, scaffolds can be incorporated with bioactive gels for time- and dose-controlled delivery of multiple growth factors (GFs). In this study, critical femoral bone defects in rats were grafted with porous titanium scaffolds incorporated with nanostructured colloidal gelatin gels. Gels were loaded with bone morphogenetic protein-2 (BMP-2, 3??g), fibroblast growth factor-2 (FGF-2, 0.6??g), BMP-2, and FGF-2 (BMP-2/FGF-2, ratio 5:1) or were left unloaded. GF delivery was controlled by fine tuning the crosslinking density of oppositely charged nanospheres. Grafted femurs were evaluated using in vivo and ex vivo micro-CT, histology, and three-point bending tests. All porous titanium scaffolds containing GF-loaded gels accelerated and enhanced bone regeneration: BMP-2 gels gave an early increase (0-4 weeks), and FGF-2 gels gave a late increase (8-12 weeks). Interestingly, stimulatory effects of 0.6??g FGF-2 were similar to a fivefold higher dose of BMP-2 (3??g). BMP-2/FGF-2 gels gave more bone outside the porous titanium scaffolds than gels with only BMP-2 or FGF-2, resulted in bridging of most defects and showed superior bone-implant integrity in three-point bending tests. In conclusion, incorporation of nanostructured colloidal gelatin gels capable of time- and dose-controlled delivery of BMP-2 and FGF-2 in porous titanium scaffolds is a promising strategy to enhance and continue bone regeneration of large bone defects. PMID:23822814

van der Stok, Johan; Wang, Huanan; Amin Yavari, Saber; Siebelt, Michiel; Sandker, Marjan; Waarsing, Jan H; Verhaar, Jan A N; Jahr, Holger; Zadpoor, Amir A; Leeuwenburgh, Sander C G; Weinans, Harrie

2013-12-01

160

Image-Based Three-Dimensional Analysis to Characterize the Texture of Porous Scaffolds  

PubMed Central

The aim of the present study is to characterize the microstructure of composite scaffolds for bone tissue regeneration containing different ratios of chitosan/gelatin blend and bioactive glasses. Starting from realistic 3D models of the scaffolds reconstructed from micro-CT images, the level of heterogeneity of scaffold architecture is evaluated performing a lacunarity analysis. The results demonstrate that the presence of the bioactive glass component affects not only macroscopic features such as porosity, but mainly scaffold microarchitecture giving rise to structural heterogeneity, which could have an impact on the local cell-scaffold interaction and scaffold performances. The adopted approach allows to investigate the scale-dependent pore distribution within the scaffold and the related structural heterogeneity features, providing a comprehensive characterization of the scaffold texture. PMID:24995272

Pennella, Francesco; Gallo, Diego; Ciardelli, Gianluca; Bignardi, Cristina; Audenino, Alberto; Morbiducci, Umberto

2014-01-01

161

Selective separation of lambdacyhalothrin by porous/magnetic molecularly imprinted polymers prepared by Pickering emulsion polymerization.  

PubMed

Porous/magnetic molecularly imprinted polymers (PM-MIPs) were prepared by Pickering emulsion polymerization. The reaction was carried out in an oil/water emulsion using magnetic halloysite nanotubes as the stabilizer instead of a toxic surfactant. In the oil phase, the imprinting process was conducted by radical polymerization of functional and cross-linked monomers, and porogen chloroform generated steam under the high reaction temperature, which resulted in some pores decorated with easily accessible molecular binding sites within the as-made PM-MIPs. The characterization demonstrated that the PM-MIPs were porous and magnetic inorganic-polymer composite microparticles with magnetic sensitivity (M(s) = 0.7448 emu/g), thermal stability (below 473 K) and magnetic stability (over the pH range of 2.0-8.0). The PM-MIPs were used as a sorbent for the selective binding of lambdacyhalothrin (LC) and rapidly separated under an external magnetic field. The Freundlich isotherm model gave a good fit to the experimental data. The adsorption kinetics of the PM-MIPs was well described by pseudo-second-order kinetics, indicating that the chemical process could be the rate-limiting step in the adsorption of LC. The selective recognition experiments exhibited the outstanding selective adsorption effect of the PM-MIPs for target LC. Moreover, the PM-MIPs regeneration without significant loss in adsorption capacity was demonstrated by at least four repeated cycles. PMID:23894024

Hang, Hui; Li, Chunxiang; Pan, Jianming; Li, Linzi; Dai, Jiangdong; Dai, Xiaohui; Yu, Ping; Feng, Yonghai

2013-10-01

162

Effect of cryomilling times on the resultant properties of porous biodegradable poly(e-caprolactone)/poly(glycolic acid) scaffolds for articular cartilage tissue engineering.  

PubMed

The aim of this research is to develop a parametric investigation of the fabrication of poly(e-caprolactone) (PCL)/poly(glycolic acid) (PGA) scaffolds to decipher the influence of cryomilling time on the scaffolds' resultant physical, morphological and mechanical characteristics. Scaffolds were fabricated via solid-state cryomilling to prepare a homogeneous blend along with conventional compression molding and porogen leaching yielding interconnected porous scaffolds. PCL/PGA scaffolds fabricated through this technique demonstrated high porosity at all cryomilling times. Morphological analysis revealed a co-continuous interconnected pore network. While mean pore size decreased, water uptake and compressive properties increased with increasing cryomilling times. Porous scaffolds cryomilled for 12min exhibited a mean pore size within the optimal range for tissue engineering and chondrocyte ingrowth. And the compressive modulus of scaffolds cryomilled for 12, 30 and 60min matched the compressive modulus of human articular cartilage. In addition, scaffolds exhibited water uptake, a key requirement in tissue engineering. A 60 day in vitro degradation study revealed mass loss starting from day 10 and increasing through day 60, while notable reduction in compressive properties was observed. The results indicated that cryomilling times affected the resultant properties of PCL/PGA scaffolds and will be interesting candidates for articular cartilage tissue engineering. PMID:25194523

Jonnalagadda, John B; Rivero, Iris V

2014-12-01

163

Preparation of porous hydroxyapatite scaffolds by combination of the gel-casting and polymer sponge methods  

Microsoft Academic Search

A new technique of combining the gel-casting and polymer sponge methods is introduced in this study to prepare macroporous hydroxyapatite scaffolds, which provides a better control over the microstructures of scaffolds and enhances their mechanical properties. With this technique, we were able to produce scaffolds with mechanical and structural properties that cannot be attained by either the polymer sponge or

Hassna Rehman Ramay; Miqin Zhang

2003-01-01

164

Retention of Insulin-like Growth Factor I Bioactivity during Fabrication of Sintered Polymeric Scaffolds  

PubMed Central

The use of growth factors in tissue engineering offers an added benefit to cartilage regeneration. Growth factors, such as insulin-like growth factor I (IGF-I), increase cell proliferation and can therefore decrease the time it takes for cartilage tissue to regrow. In this study, IGF-I was released from poly(lactic-co-glycolic) acid (PLGA) scaffolds that were designed to have a decreased burst release often associated with tissue engineering scaffolds. The scaffolds were fabricated from IGF-I-loaded PLGA microspheres by a double emulsion (W1/O/W2) technique. The microspheres were then compressed, sintered at 49°C, and salt leached. The bioactivity of soluble IGF-I was verified after being heat treated at 37, 43, 45, 49, and 60°C. Additionally, the bioactivity of IGF-I was confirmed after being released from the sintered scaffolds. The triphasic release lasted 120 days resulting in 20%, 55% and 25% of the IGF-I being released during days 1-3, 4-58, and 59-120, respectively. Seeding bone marrow cells directly onto the IGF-I loaded scaffolds showed an increase in cell proliferation, based on DNA content, leading to an increased glycosaminoglycan (GAG) production. The present results demonstrated that IGF-I remains active after being incorporated into heat-treated scaffolds, further enhancing tissue regeneration possibilities. PMID:24565886

Clark, Amanda; Milbrandt, Todd A.; Hilt, J. Zach; Puleo, David A.

2014-01-01

165

Ingrowth of Human Mesenchymal Stem Cells into Porous Silk Particle Reinforced Silk Composite Scaffolds: An In Vitro Study  

PubMed Central

Silk fibroin protein is biodegradable and biocompatible, exhibiting excellent mechanical properties for various biomedical applications. However, porous 3D silk fibroin scaffolds, or silk sponges, usually fall short in matching the initial mechanical requirements for bone tissue engineering. In the present study, silk sponge matrices were reinforced with silk microparticles to generate protein-protein composite scaffolds with desirable mechanical properties for in vitro osteogenic tissue formation. It was found that increasing the silk microparticle loading led to a substantial increase in the scaffold compressive modulus from 0.3 MPa (nonreinforced) to 1.9 MPa for 1:2 (matrix:particle) reinforcement loading by dry mass. Biochemical, gene expression, and histological assays were employed to study the possible effects of increasing composite scaffold stiffness, due to microparticle reinforcement, on in vitro osteogenic differentiation of human mesenchymal stem cells (hMSCs). Increasing silk microparticle loading increased the osteogenic capability of hMSCs in the presence of bone morphogenic protein-2 (BMP-2) and other osteogenic factors in static culture for up to six weeks. The calcium adsorption increased dramatically with increasing loading, as observed from biochemical assays, histological staining, and microCT (?CT) analysis. Specifically, calcium content in the scaffolds increased by 0.57, 0.71, and 1.27 mg (per ?g of DNA) from 3 to 6 weeks for matrix to particle dry mass loading ratios of 1:0, 1:1 and 1:2, respectively. In addition, ?CT imaging revealed that at 6 weeks, bone volume fraction increased from 0.78% for nonreinforced to 7.1% and 6.7% for 1:1 and 1:2 loading, respectively. Our results support the hypothesis that scaffold stiffness may strongly influence the 3D in vitro differentiation capabilities of hMSCs, providing a means to improve osteogenic outcomes. PMID:20656075

Rockwood, Danielle N.; Gil, Eun Seok; Park, Sang-Hyug; Kluge, Jonathan A.; Grayson, Warren; Bhumiratana, Sarindr; Rajkhowa, Rangam; Wang, Xungai; Kim, Sung Jun; Vunjak-Novakovic, Gordana; Kaplan, David L

2010-01-01

166

Improving Osteointegration and Osteogenesis of Three-Dimensional Porous Ti6Al4V Scaffolds by Polydopamine-Assisted Biomimetic Hydroxyapatite Coating.  

PubMed

Titanium alloys with various porous structures can be fabricated by advanced additive manufacturing techniques, which are attractive for use as scaffolds for bone defect repair. However, modification of the scaffold surfaces, particularly inner surfaces, is critical to improve the osteointegration of these scaffolds. In this study, a biomimetic approach was employed to construct polydopamine-assisted hydroxyapatite coating (HA/pDA) onto porous Ti6Al4V scaffolds fabricated by the electron beam melting method. The surface modification was characterized with the field emission scanning electron microscopy, energy dispersive spectroscopy, water contact angle measurement, and confocal laser scanning microscopy. Attachment and proliferation of MC3T3-E1 cells on the scaffold surface were significantly enhanced by the HA/pDA coating compared to the unmodified surfaces. Additionally, MC3T3-E1 cells grown on the HA/pDA-coated Ti6Al4V scaffolds displayed significantly higher expression of runt-related transcription factor-2, alkaline phosphatase, osteocalcin, osteopontin, and collagen type-1 compared with bare Ti6Al4V scaffolds after culture for 14 days. Moreover, microcomputed tomography analysis and Van-Gieson staining of histological sections showed that HA/pDA coating on surfaces of porous Ti6Al4V scaffolds enhanced osteointegration and significantly promoted bone regeneration after implantation in rabbit femoral condylar defects for 4 and 12 weeks. Therefore, this study provides an alternative to biofunctionalized porous Ti6Al4V scaffolds with improved osteointegration and osteogenesis functions for orthopedic applications. PMID:25711714

Li, Yong; Yang, Wei; Li, Xiaokang; Zhang, Xing; Wang, Cairu; Meng, Xiangfei; Pei, Yifeng; Fan, Xiangli; Lan, Pingheng; Wang, Chunhui; Li, Xiaojie; Guo, Zheng

2015-03-18

167

Mimic of the Green Fluorescent Protein ?-Barrel: Photophysics and Dynamics of Confined Chromophores Defined by a Rigid Porous Scaffold.  

PubMed

Chromophores with a benzylidene imidazolidinone core define the emission profile of commonly used biomarkers such as the green fluorescent protein (GFP) and its analogues. In this communication, artificially engineered porous scaffolds have been shown to mimic the protein ?-barrel structure, maintaining green fluorescence response and conformational rigidity of GFP-like chromophores. In particular, we demonstrated that the emission maximum in our artificial scaffolds is similar to those observed in the spectra of the natural GFP-based systems. To correlate the fluorescence response with a structure and perform a comprehensive analysis of the prepared photoluminescent scaffolds, (13)C cross-polarization magic angle spinning solid-state (CP-MAS) NMR spectroscopy, powder and single-crystal X-ray diffraction, and time-resolved fluorescence spectroscopy were employed. Quadrupolar spin-echo solid-state (2)H NMR spectroscopy, in combination with theoretical calculations, was implemented to probe low-frequency vibrational dynamics of the confined chromophores, demonstrating conformational restrictions imposed on the coordinatively trapped chromophores. Because of possible tunability of the introduced scaffolds, these studies could foreshadow utilization of the presented approach toward directing a fluorescence response in artificial GFP mimics, modulating a protein microenvironment, and controlling nonradiative pathways through chromophore dynamics. PMID:25654319

Williams, Derek E; Dolgopolova, Ekaterina A; Pellechia, Perry J; Palukoshka, Andrei; Wilson, Thomas J; Tan, Rui; Maier, Josef M; Greytak, Andrew B; Smith, Mark D; Krause, Jeanette A; Shustova, Natalia B

2015-02-18

168

Biocompatibility and bone-repairing effects: comparison between porous poly-lactic-co-glycolic acid and nano-hydroxyapatite/poly(lactic acid) scaffolds.  

PubMed

Copolymer composite scaffolds and bioceramic/polymer composite scaffolds are two representative forms of composite scaffolds used for bone tissue engineering. Studies to compare biocompatibility and bone-repairing effects between these two scaffolds are significant for selecting or improving the scaffold for clinical application. We prepared two porous scaffolds comprising poly-lactic-acid/poly-glycolic-acid (PLGA) and poly-lactic-acid/nano-hydroxyapatite (nHAP/PLA) respectively, and examined their biocompatibility with human bone marrow-derived mesenchymal stem cells (hMSCs) through evaluating adhesion, proliferation and osteogenic differentiation potentials of hMSCs in the scaffold. Then, the PLGA scaffold with hMSCs (PM construct) and the nHAP/PLA scaffold with hMSCs (HPM construct) were transplanted into the rat calvarial defect areas to compare their effects on the bone reconstruction. The results showed that the nHAP/PLA scaffold was in favor of adhesion, matrix deposition and osteogenic differentiation of hMSCs. For in vivo transplantation, both HPM and PM constructs led to mineralization and osteogenesis in the defect area of rat. However, the area grafted with PM construct showed a better formation of mature bone than that with HPM construct. In addition, the evaluation of in vitro and in vivo degradation indicated that the degradation rate of nHAP/PLA scaffold was much lower than that of PLGA scaffold. It is inferred that the lower degradation of nHAP/PLA scaffold should result in its inferior bone reconstruction in rat calvaria. Therefore, the preparation of an ideal composite scaffold for bone tissue engineering should be taken into account of the balance between its biocompatibility, degradation rate, osteoconductivity and mechanical property. PMID:24749403

Zong, Chen; Qian, Xiaodan; Tang, Zihua; Hu, Qinghong; Chen, Jiarong; Gao, Changyou; Tang, Ruikang; Tong, Xiangmin; Wang, Jinfu

2014-06-01

169

Microfabrication of complex porous tissue engineering scaffolds using 3D projection stereolithography  

PubMed Central

The success of tissue engineering will rely on the ability to generate complex, cell seeded three-dimensional (3D) structures. Therefore, methods that can be used to precisely engineer the architecture and topography of scaffolding materials will represent a critical aspect of functional tissue engineering. Previous approaches for 3D scaffold fabrication based on top-down and process driven methods are often not adequate to produce complex structures due to the lack of control on scaffold architecture, porosity, and cellular interactions. The proposed projection stereolithography (PSL) platform can be used to design intricate 3D tissue scaffolds that can be engineered to mimic the microarchitecture of tissues, based on computer aided design (CAD). The PSL system was developed, programmed and optimized to fabricate 3D scaffolds using gelatin methacrylate (GelMA). Variation of the structure and prepolymer concentration enabled tailoring the mechanical properties of the scaffolds. A dynamic cell seeding method was utilized to improve the coverage of the scaffold throughout its thickness. The results demonstrated that the interconnectivity of pores allowed for uniform human umbilical vein endothelial cells (HUVECs) distribution and proliferation in the scaffolds, leading to high cell density and confluency at the end of the culture period. Moreover, immunohistochemistry results showed that cells seeded on the scaffold maintained their endothelial phenotype, demonstrating the biological functionality of the microfabricated GelMA scaffolds. PMID:22365811

Gauvin, Robert; Chen, Ying-Chieh; Lee, Jin Woo; Soman, Pranav; Zorlutuna, Pinar; Nichol, Jason W.; Bae, Hojae; Chen, Shaochen; Khademhosseini, Ali

2013-01-01

170

Improvement of dual-leached polycaprolactone porous scaffolds by incorporating with hydroxyapatite for bone tissue regeneration.  

PubMed

Polycaprolactone (PCL)/hydroxyapatite (HA) composite scaffolds were prepared by combining solvent casting and salt particulate leaching with a polymer leaching technique. The hydrophilicity of the dual-leached scaffold was improved by alkaline (NaOH) treatment. Well-defined interconnected pores were detected by scanning electron microscopy. The water absorption capacity of the NaOH-treated PCL/HA dual-leached scaffold increased greatly, confirming that the hydrophilicity of the scaffold was improved by NaOH treatment. The compressive modulus of the PCL/HA dual-leached scaffold was greatly increased by the addition of HA particles. An indirect evaluation of the cytotoxicity of all PCL dual-leached scaffolds with mouse fibroblastic cells (L929) and mouse calvaria-derived pre-osteoblastic cells (MC3T3-E1) indicated that the PCL dual-leached scaffolds are non-toxic to cells. The ability of the scaffolds to support mouse calvaria-derived pre-osteoblastic cell (MC3T3-E1) attachment, proliferation, differentiation, and mineralization was also evaluated. Although the viability of cells was lower on the PCL/HA dual-leached scaffold than on the tissue-culture polystyrene plates (TCPS) and on the other substrates at early time points, both the PCL and NaOH-treated PCL/HA dual-leached scaffolds supported the attachment of MC3T3-E1 at significantly higher levels than TCPS. During the proliferation period (days 1-3), all of the PCL dual-leached scaffolds were able to support the proliferation of MC3T3-E1 at higher levels than the TCPS; in addition, the cells grown on NaOH-treated PCL/HA dual-leached scaffolds proliferated more rapidly. The cells cultured on the surfaces of NaOH-treated PCL/HA dual-leached scaffolds had the highest rate of mineral deposition. PMID:25291106

Thadavirul, Napaphat; Pavasant, Prasit; Supaphol, Pitt

2014-01-01

171

Fabrication and structural characterization of porous biodegradable poly( dl-lactic- co-glycolic acid) scaffolds with controlled range of pore sizes  

Microsoft Academic Search

Biodegradable polymer scaffolds play a major role in the field of tissue engineering as they provide a three-dimensional template to regenerate desirable tissues for different applications. In this study, porous poly(dl-lactic-co-glycolic acid) (PLGA) scaffolds with four different pore sizes (150–180?m, 180–250?m, 250–280?m and 280–400?m) were fabricated using paraffin-spheres-dissolution technique. Paraffin spheres with the stated size range were bonded into a

Anita W. T. Shum; Jiashen Li; Arthur F. T. Mak

2005-01-01

172

Synthesis of porous zirconia spheres for HPLC by polymerization-induced colloid aggregation (PICA)  

SciTech Connect

Porous, spherical zirconia particles with a narrow particle size distribution, which are useful as chromatographic packing materials for high performance liquid chromatography (HPLC), were synthesized by polymerization-induced colloid aggregation (PICA) first described by Iler and McQueston (US Patent 4,010,242, 1977.) and the effects of a number of crucial processing variables were examined. In this method, an aqueous zirconia sol consisting of 700 [angstrom] (mean diameter) particles is mixed with urea and formaldehyde polymer adsorbs onto the ZrO[sub 2] colloids, entraining the colloids in the precipitation of the polymer gel and thus alloying the colloids to aggregate. Features of the aggregation process are elucidated from responses of the process to variations in temperature, reaction mixture composition, and solvent polarity. Results suggest that the aggregation process resembles those reported for the bridging flocculation of colloids by adsorbed polymers. Porous zirconia particles obtained after polymer combustion and sintering of the aggregates are 3.5 [mu]m in diameter with a surface area of 13 m[sup 2]/g, a porosity of 29% and pores ranging from <50 to 350 [angstrom] in diameter. The particles are strong enough to withstand the packing of a HPLC column.

Sun, L.; Annen, M.J.; Lorenzano-Porras, F.; Carr, P.W.; McCormick, A.V. (Univ. of Minnesota, Minneapolis, MN (United States))

1994-03-15

173

Seeding of mesenchymal stem cells into inner part of interconnected porous biodegradable scaffold by a new method with a filter paper.  

PubMed

An appropriate physical support provided by scaffolds creates a supportive environment that directs proliferation and differentiation of stem cells. However, it is difficult to homogenously inoculate stem cells into the inner part of scaffolds at high cell densities. In this study, mesenchymal stem cells were seeded into a hydroxyapatite/poly (D, L-lactic-co-glycolic acid) (HAP/PLGA) scaffold that had enough mechanical strength and porous 3-D structure. With an aid of a filter paper placed under the bottom of a HAP/PLGA block, the cells suspended in a culture medium flowed from the top to the bottom through interconnected pores in the scaffold, and distributed almost homogenously, as compared to cell distribution near the surface of the block by the conventional method using centrifugation or reduced pressure. This simple method with a filter paper may be useful in preparation of cell-scaffold complexes for tissue engineering. PMID:25748462

Yamanaka, Katsuyuki; Yamamoto, Katsushi; Sakai, Yuhiro; Suda, Youko; Shigemitsu, Yusuke; Kaneko, Tadashi; Kato, Koichi; Kumagai, Tomohiro; Kato, Yukio

2015-02-01

174

Porous beta tricalcium phosphate scaffolds used as a BMP2 delivery system for bone tissue engineering  

Microsoft Academic Search

Macroporous beta tricalcium phosphate (?-TCP) scaffolds were evaluated as potential carriers and delivery systems for bone morphogenetic protein-2 (BMP-2). Chemical etching was performed to increase the available surface and thus the protein loading. X-ray diffraction and infrared spectrocopy analyses confirmed the preparation of pure ?-TCP scaffolds. Scanning electron microscopy revealed interconnected porosity (64%) and a microporous surface after chemical etching.

Jerome Sohier; Guy Daculsi; Sophie Sourice; Groot de Klaas; Pierre Layrolle

2009-01-01

175

A novel porous bioceramics scaffold by accumulating hydroxyapatite spherulites for large bone tissue engineering in vivo. II. Construct large volume of bone grafts.  

PubMed

In vivo engineering of bone autografts using bioceramic scaffolds with appropriate porous structures is a potential approach to prepare autologous bone grafts for the repair of critical-sized bone defects. This study investigated the evolutionary process of osteogenesis, angiogenesis, and compressive strength of bioceramic scaffolds implanted in two non-osseous sites of dogs: the abdominal cavity and the dorsal muscle. Hydroxyapatite (HA) sphere-accumulated scaffolds with controlled porous structures were prepared and placed in the two sites for up to 6 months. Analyses of retrieved scaffolds found that osteogenesis and angiogenesis were faster in scaffolds implanted in dorsal muscles compared with those placed in abdominal cavities. The abdominal cavity, however, can accommodate larger bone grafts with designed shape. Analyses of scaffolds implanted in abdominal cavities [an environment of a low mesenchymal stem cell (MSC) density] further demonstrated that angiogenesis play critical roles during osteogenesis in the scaffolds, presumably by supplying progenitor cells and/or MSCs as seed cells. This study also examined the relationship between the volume of bone grafts and the physiological environment of in vivo bioreactor. These results provide basic information for the selection of appropriate implanting sites and culture time required to engineer autologous bone grafts for the clinical bone defect repair. Based on these positive results, a pilot study has applied the grafts constructed in canine abdominal cavity to repair segmental bone defect in load-bearing sites (limbs). PMID:23946164

Zhi, Wei; Zhang, Cong; Duan, Ke; Li, Xiaohong; Qu, Shuxin; Wang, Jianxin; Zhu, Zhuoli; Huang, Peng; Xia, Tian; Liao, Ga; Weng, Jie

2014-08-01

176

Bone Tissue Engineering with Premineralized Silk Scaffolds  

PubMed Central

Silks fibroin biomaterials are being explored as novel protein-based systems for cell and tissue culture. In the present study, biomimetic growth of calcium phosphate on porous silk fibroin polymeric scaffolds was explored to generate organic/inorganic composites as scaffolds for bone tissue engineering. Aqueous-derived silk fibroin scaffolds were prepared with the addition of polyaspartic acid during processing, followed by the controlled deposition of calcium phosphate by exposure to CaCl2 and Na2HPO4. These mineralized protein-composite scaffolds were subsequently seeded with human bone marrow stem cells (hMSC) and cultured in vitro for 6 weeks under osteogenic conditions with or without BMP-2. The extent of osteoconductivity was assessed by cell numbers, alkaline phosphatase and calcium deposition, along with immunohistochemistry for bone related outcomes. The results suggest increased osteoconductive outcomes with an increase in initial content of apatite and BMP-2 in the silk fibroin porous scaffolds. The premineralization of these highly porous silk fibroin protein scaffolds provided enhanced outcomes for the bone tissue engineering. PMID:18387349

Kim, Hyeon Joo; Kim, Ung-Jin; Kim, Hyun Suk; Li, Chunmei; Wada, Masahisa; Leisk, Gary G.; Kaplan, David L.

2009-01-01

177

Bone tissue engineering with premineralized silk scaffolds.  

PubMed

Silk fibroin biomaterials are being explored as novel protein-based systems for cell and tissue culture. In the present study, biomimetic growth of calcium phosphate on porous silk fibroin polymeric scaffolds was explored to generate organic/inorganic composites as scaffolds for bone tissue engineering. Aqueous-derived silk fibroin scaffolds were prepared with the addition of polyaspartic acid during processing, followed by the controlled deposition of calcium phosphate by exposure to CaCl(2) and Na(2)HPO(4). These mineralized protein-composite scaffolds were subsequently seeded with human bone marrow stem cells (hMSC) and cultured in vitro for 6 weeks under osteogenic conditions with or without BMP-2. The extent of osteoconductivity was assessed by cell numbers, alkaline phosphatase and calcium deposition, along with immunohistochemistry for bone-related outcomes. The results suggest increased osteoconductive outcomes with an increase in initial content of apatite and BMP-2 in the silk fibroin porous scaffolds. The premineralization of these highly porous silk fibroin protein scaffolds provided enhanced outcomes for the bone tissue engineering. PMID:18387349

Kim, Hyeon Joo; Kim, Ung-Jin; Kim, Hyun Suk; Li, Chunmei; Wada, Masahisa; Leisk, Gary G; Kaplan, David L

2008-06-01

178

Preparation of tissue engineering porous scaffold with poly(lactic acid) and polyethylene glycol solution blend by solvent-casting/particulate-leaching  

NASA Astrophysics Data System (ADS)

Polyethylene glycol/poly(lactic acid) solution blend is employed as the raw materials to prepare porous scaffold of potential usage in tissue engineering. The solution blend can be naturally introduced in the classical solvent casting/particular leaching technique in porous matrix preparation. The PEG presence is to modify the degradation behavior of scaffolds to fit particular requirements in tissue engineering. The porous matrix of PEG/PLA with various weight ratios are made with pores size ˜ 250 ? m. The SEM characterizations have been done to investigate the porous morphology of products, the results indicate that though with the clear semi-miscibility feature of PEG/PLA blends, the macro-structure is not significantly affected by the PEG content percentage. The degradation results show an enhanced weight loss rate with the presence of PEG as expected.

Huang, Ran; Zhu, Xiaomin; Zhao, Tingting; Wan, Ajun

2014-12-01

179

Fabrication of three-dimensional porous scaffolds with controlled filament orientation and large pore size via an improved E-jetting technique.  

PubMed

Biodegradable polymeric scaffolds have been widely used in tissue engineering as a platform for cell proliferation and subsequent tissue regeneration. Conventional microextrusion methods for three-dimensional (3D) scaffold fabrication were limited by their low resolution. Electrospinning, a form of electrohydrodynamic (EHD) printing, is an attractive method due to its capability of fabricating high-resolution scaffolds at the nanometer/micrometer scale level. However, the scaffold was composed of randomly orientated filaments which could not guide the cells in a specific direction. Furthermore, the pores of the electrospun scaffold were small, thus preventing cell infiltration. In this study, an alternative EHD jet printing (E-jetting) technique has been developed and employed to fabricate 3D polycaprolactone (PCL) scaffolds with desired filament orientation and pore size. The effect of PCL solution concentration was evaluated. Results showed that solidified filaments were achieved at concentration >70% (w/v). Uniform filaments of diameter 20 ?m were produced via the E-jetting technique, and X-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopic analyses revealed that there was no physicochemical changes toward PCL. Scaffold with a pore size of 450 ?m and porosity level of 92%, was achieved. A preliminary in vitro study illustrated that live chondrocytes were attaching on the outer and inner surfaces of collagen-coated E-jetted PCL scaffolds. E-jetted scaffolds increased chondrocytes extracellular matrix secretion, and newly formed matrices from chondrocytes contributed significantly to the mechanical strength of the scaffolds. All these results suggested that E-jetting is an alternative scaffold fabrication technique, which has the capability to construct 3D scaffolds with aligned filaments and large pore sizes for tissue engineering applications. PMID:24155124

Li, Jin Lan; Cai, Yan Li; Guo, Yi Lin; Fuh, Jerry Ying Hsi; Sun, Jie; Hong, Geok Soon; Lam, Ruey Na; Wong, Yoke San; Wang, Wilson; Tay, Bee Yen; Thian, Eng San

2014-05-01

180

Improvement of the compressive strength of a cuttlefish bone-derived porous hydroxyapatite scaffold via polycaprolactone coating.  

PubMed

Cuttlefish bones (CBs) have emerged as attractive biomaterials because of their porous structure and components that can be converted into hydroxyapatite (HAp) via a hydrothermal reaction. However, their brittleness and low strength restrict their application in bone tissue engineering. Therefore, to improve the compressive strength of the scaffold following hydrothermal conversion to a HAp form of CB (CB-HAp), the scaffold was coated using a polycaprolactone (PCL) polymer at various concentrations. In this study, raw CB was successfully converted into HAp via a hydrothermal reaction. We then evaluated their surface properties and composition by scanning electron microscopy and X-ray diffraction analysis. The CB-HAp coated with PCL showed improved compressive performance and retained a microporous structure. The compressive strength was significantly increased upon coating with 5 and 10% PCL, by 2.09- and 3.30-fold, respectively, as compared with uncoated CB-HAp. However, coating with 10% PCL resulted in a reduction in porosity. Furthermore, an in vitro biological evaluation demonstrated that MG-63 cells adhered well, proliferated and were able to be differentiated on the PCL-coated CB-HAp scaffold, which was noncytotoxic. These results suggest that a simple coating method is useful to improve the compressive strength of CB-HAp for bone tissue engineering applications. PMID:23661509

Kim, Beom-Su; Kang, Hyo Jin; Lee, Jun

2013-10-01

181

Hierarchical polymeric scaffolds support the growth of MC3T3-E1 cells.  

PubMed

Tissue engineering makes use of the principles of biology and engineering to sustain 3D cell growth and promote tissue repair and/or regeneration. In this study, macro/microporous scaffold architectures have been developed using a hybrid solid freeform fabrication/thermally induced phase separation (TIPS) technique. Poly(lactic-co-glycolic acid) (PLGA) dissolved in 1,4-dioxane was used to generate a microporous matrix by the TIPS method. The 3D-bioplotting technique was used to fabricate 3D macroporous constructs made of polyethylene glycol (PEG). Embedding the PEG constructs inside the PLGA solution prior to the TIPS process and subsequent extraction of PEG following solvent removal (1,4-dioaxane) resulted in a macro/microporous structure. These hierarchical scaffolds with a bimodal pore size distribution (<50 and >300 ?m) contained orthogonally interconnected macro-channels generated by the extracted PEG. The diameter of the macro-channels was varied by tuning the dispensing parameters of the 3D bioplotter. The in vitro cell culture using murine MC3T3-E1 cell line for 21 days demonstrated that these scaffolds could provide a favorable environment to support cell adhesion and growth. PMID:25665851

Akbarzadeh, Rosa; Minton, Joshua A; Janney, Cara S; Smith, Tyler A; James, Paul F; Yousefi, Azizeh-Mitra

2015-02-01

182

Incorporation of growth factor containing Matrigel promotes vascularization of porous PLGA scaffolds.  

PubMed

In tissue engineering, rapid ingrowth of blood vessels into scaffolds is a major prerequisite for the survival of three-dimensional tissue constructs. In the present study, we investigated whether the vascularization of implanted poly-D,L-lactic-co-glycolic acid (PLGA) scaffolds may be accelerated by incorporation of Matrigel. For this purpose, we investigated in the aortic ring assay the proangiogenic properties of growth factor reduced Matrigel (GFRM) and growth factor containing Matrigel (GFCM), which were then incorporated into the pores of PLGA scaffolds. Subsequently, we analyzed vascularization, biocompatibility, and incorporation of these scaffolds during 14 days after implantation into dorsal skinfold chambers of balb/c mice by means of intravital microscopy, histology, and immunohistochemistry. Matrigel-free scaffolds served as controls. In the aortic ring assay, GFCM stimulated the development of a network of tubular vessel structures with a significantly increased sprout area and density when compared with GFRM. Accordingly, GFCM accelerated and improved in vivo the ingrowth of new blood vessels into scaffolds, resulting in the formation of a pericyte-coated vascular network with an increased functional capillary density in comparison to the GFRM and control group. Besides, analysis of leukocyte-endothelial cell interaction in host tissue venules located in close vicinity to the scaffolds showed no marked differences in numbers of rolling and adherent leukocytes between the observation groups, indicating that incorporation of Matrigel did not affect biocompatibility of PLGA scaffolds. These findings demonstrate that the combination of proangiogenic extracellular matrices with solid scaffold biomaterials may represent a novel approach to accelerate adequate vascularization of tissue engineering constructs. PMID:17688245

Laschke, M W; Rücker, M; Jensen, G; Carvalho, C; Mülhaupt, R; Gellrich, N-C; Menger, M D

2008-05-01

183

Accurate Fabrication of Hydroxyapatite Bone Models with Porous Scaffold Structures by Using Stereolithography  

NASA Astrophysics Data System (ADS)

Computer graphic models of bioscaffolds with four-coordinate lattice structures of solid rods in artificial bones were designed by using a computer aided design. The scaffold models composed of acryl resin with hydroxyapatite particles at 45vol. % were fabricated by using stereolithography of a computer aided manufacturing. After dewaxing and sintering heat treatment processes, the ceramics scaffold models with four-coordinate lattices and fine hydroxyapatite microstructures were obtained successfully. By using a computer aided analysis, it was found that bio-fluids could flow extensively inside the sintered scaffolds. This result shows that the lattice structures will realize appropriate bio-fluid circulations and promote regenerations of new bones.

Maeda, Chiaki; Tasaki, Satoko; Kirihara, Soshu

2011-05-01

184

The application of type II collagen and chondroitin sulfate grafted PCL porous scaffold in cartilage tissue engineering.  

PubMed

This study investigates a poly(epsilon-caprolactone)-graft-type II collagen-graft-chondroitin sulfate (PCL-g-COL-g-CS) biomaterial as a scaffold for cartilage tissue engineering. Biodegradable polyester, PCL, was utilized to fabricate three-dimensional (3D) porous scaffolds by particulate leaching. The PCL scaffold was then surface modified by chemical bonding of 1,6-hexanediamine and the grafting of a bioactive polymer layer of COL and CS with the help of 1-ethyl-3-(3-dimethyl- aminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS) on the modified PCL surface to produce PCL-g-COL and PCL-g-COL-g-CS, respectively. The characteristics of these modified and grafted matrices were examined by ESCA, aminolysis, collagen and CS assay, porosity and water-binding capacity. Grafted COL and CS markedly increased water-binding capacity, and promoted the spreading and growth of chondrocytes. During a 4-week culture period, PCL-g-COL and PCL-g-COL-g-CS matrices both provided more cell proliferation, as determined by measuring the DNA assay. Additionally, a larger amount of secreted collagen and glycosaminoglycans (GAGs) appeared in the PCL-g-COL-g-CS matrices than in the control (PCL) as indicated by the histochemical sections via Hematoxylin and eosin (H&E) stain, Masson trichrome stain and Safranin-O stain. The chondrocytes were induced to function normally; the cell phenotype was maintained, and the GAGs and collagen in the PCL-g-COL-g-CS scaffold were secreted in vitro. These results serve as a basis for future studies of the fabrication process and reveal the potential biocompatibility of the biomimetic matrix for regenerating articular cartilage or other organs. PMID:19274722

Chang, Kuo-Yung; Hung, Li-Han; Chu, I-Ming; Ko, Chih-Shen; Lee, Yu-Der

2010-02-01

185

The promotion of angiogenesis induced by three-dimensional porous beta-tricalcium phosphate scaffold with different interconnection sizes via activation of PI3K/Akt pathways  

PubMed Central

The porous architectural characteristics of biomaterials play an important role in scaffold revascularization. However, no consensus exists regarding optimal interconnection sizes for vascularization and its scaffold bioperformance with different interconnection sizes. Therefore, a series of disk-type beta-tricalcium phosphates with the same pore sizes and variable interconnections were produced to evaluate how the interconnection size influenced biomaterial vascularization in vitro and in vivo. We incubated human umbilical vein endothelial cells on scaffolds with interconnections of various sizes. Results showed that scaffolds with a 150??m interconnection size ameliorated endothelial cell function evidenced by promoting cell adhesion and migration, increasing cell proliferation and enhancing expression of platelet-endothelial cell adhesion molecules and vascular endothelial growth factor. In vivo study was performed on rabbit implanted with scaffolds into the bone defect on femoral condyles. Implantation with scaffolds with 150??m interconnection size significantly improved neovascularization as shown by micro-CT as compared to scaffolds with 100 and 120??m interconnection sizes. Moreover, the aforementioned positive effects were abolished by blocking PI3K/Akt/eNOS pathway with LY-294002. Our study explicitly demonstrates that the scaffold with 150??m interconnection size improves neovascularization via the PI3K/Akt pathway and provides a target for biomaterial inner structure modification to attain improved clinical performance in implant vascularization. PMID:25797242

Xiao, Xin; Wang, Wei; Liu, Dong; Zhang, Haoqiang; Gao, Peng; Geng, Lei; Yuan, Yulin; Lu, Jianxi; Wang, Zhen

2015-01-01

186

Fabrication of Porous Scaffolds with a Controllable Microstructure and Mechanical Properties by Porogen Fusion Technique  

PubMed Central

Macroporous scaffolds with controllable pore structure and mechanical properties were fabricated by a porogen fusion technique. Biodegradable material poly (d, l-lactide) (PDLLA) was used as the scaffold matrix. The effects of porogen size, PDLLA concentration and hydroxyapatite (HA) content on the scaffold morphology, porosity and mechanical properties were investigated. High porosity (90% and above) and highly interconnected structures were easily obtained and the pore size could be adjusted by varying the porogen size. With the increasing porogen size and PDLLA concentration, the porosity of scaffolds decreases, while its mechanical properties increase. The introduction of HA greatly increases the impact on pore structure, mechanical properties and water absorption ability of scaffolds, while it has comparatively little influence on its porosity under low HA contents. These results show that by adjusting processing parameters, scaffolds could afford a controllable pore size, exhibit suitable pore structure and high porosity, as well as good mechanical properties, and may serve as an excellent substrate for bone tissue engineering. PMID:21541032

Tan, Qinggang; Li, Songgang; Ren, Jie; Chen, Chu

2011-01-01

187

A 1-min method for homogenous cell seeding in porous scaffolds.  

PubMed

The aim of this study was to develop and evaluate a simple and rapid cell seeding procedure for both calcium phosphate ceramic scaffolds and polymer scaffolds. Poly(d,l-lactic acid) and ?-tri-calcium phosphate scaffolds were seeded with MC3T3-E1 cells in a syringe. Scaffolds were put in the syringe. After replacing the plunger, the cell suspension was drawn into the syringe. The syringe was closed and the plunger was retracted to the volume of the cell suspension to create a vacuum. This was done for 3?×?10?s. By this procedure, cells were homogenously distributed throughout the scaffold. The efficiency of cell seeding was approximately 60% for both scaffolds independent of the initial cell density. The hypotension the cells experienced for 3?×?10?s did not affect the proliferation capacity of the cells. In conclusion, this method of syringe-vacuum cell seeding is easy, quick, cheap, and easily to perform at an operating theatre. PMID:21123281

Tan, Lijun; Ren, Yijin; Kuijer, Roel

2012-03-01

188

Biomimetic mineralisation of polymeric scaffolds using a combined soaking approach: adaptation with various mineral salts.  

PubMed

Biomimetic strategies which utilise hydrogels have been targeted due to favourable hydrogel characteristics such as the presentation of a large surface area for crystal nucleation within a structured yet responsive scaffold. Chitosan hydrogels were prepared and mineralised using a combined method which involves alternate soaking of the films with precursor solutions, followed by treatment with saturated mineral solution. This method has been shown to be effective for the synthesis of calcium carbonate-chitosan composite materials with tensile strength comparable to nacre. The ratio of organic to inorganic is readily controlled through the presoaking solution concentrations. The ubiquity of this method is shown here with respect to switching out both the anion (CaHPO(4)) and the cation (BaSO(4)). Cation doping is also readily achieved allowing formation of Mg-rich CaCO(3). Poly(acrylic acid) added to (Mg,Ca)CO(3)-chitosan systems induces the formation of two polymorphs (vaterite and calcite) which coexist within the composite material. The mineralised scaffolds were analysed by SEM and powder XRD. The successful mineralisation of chitosan templates with various inorganic compounds shows that this combined approach is widely applicable as a biomimetic approach. PMID:21829842

Munro, Natasha H; McGrath, Kathryn M

2011-09-28

189

Direct laser writing and geometrical analysis of scaffolds with designed pore architecture for three-dimensional cell culturing  

NASA Astrophysics Data System (ADS)

Traditional scaffold fabrication methods used in tissue engineering enable only limited control over essential parameters such as porosity, pore size and pore interconnectivity. In this study, we designed and fabricated five different types of three-dimensionally interconnected, highly porous scaffolds with precise control over the scaffold characteristics. We used two-photon polymerization (2PP) with a commercial polymer-ceramic material (Ormocomp®) for scaffold fabrication. Also for the first time, we analyzed the 2PP fabrication accuracy with respect to scaffold design parameters. Our results showed that the porosity values decreased up to 13% compared to the design specifications due to the fabrication process and the shrinkage of the material. Finally, we showed that our scaffolds supported human adipose stem cell adhesion and proliferation in a six day culture. By precise tuning of scaffold parameters, our design and fabrication method provides a novel approach for studying the effect of scaffold architecture on cell behavior in vitro.

Käpylä, Elli; Aydogan, Dogu Baran; Virjula, Sanni; Vanhatupa, Sari; Miettinen, Susanna; Hyttinen, Jari; Kellomäki, Minna

2012-11-01

190

Polymeric molecular sieve membranes via in situ cross-linking of non-porous polymer membrane templates  

NASA Astrophysics Data System (ADS)

High-performance polymeric membranes for gas separation are attractive for molecular-level separations in industrial-scale chemical, energyand environmental processes. Molecular sieving materials are widely regarded as the next-generation membranes to simultaneously achieve high permeability and selectivity. However, most polymeric molecular sieve membranes are based on a few solution-processable polymers such as polymers of intrinsic microporosity. Here we report an in situ cross-linking strategy for the preparation of polymeric molecular sieve membranes with hierarchical and tailorable porosity. These membranes demonstrate exceptional performance as molecular sieves with high gas permeabilities and selectivities for smaller gas molecules, such as carbon dioxide and oxygen, over larger molecules such as nitrogen. Hence, these membranes have potential for large-scale gas separations of commercial and environmental relevance. Moreover, this strategy could provide a possible alternative to ‘classical’ methods for the preparation of porous membranes and, in some cases, the only viable synthetic route towards certain membranes.

Qiao, Zhen-An; Chai, Song-Hai; Nelson, Kimberly; Bi, Zhonghe; Chen, Jihua; Mahurin, Shannon M.; Zhu, Xiang; Dai, Sheng

2014-04-01

191

A METHOD OF FABRICATION OF POROUS CARBONATED HYDROXYAPATITE SCAFFOLDS FOR BONE TISSUE ENGINEERING  

Microsoft Academic Search

A method to produce porous carbonated hydroxyapatite ceramics was developed which is based on vacuum impregnation of cellular polyurethane (PU) matrixes with a ceramic slip. The polyurethane foams were burnt off and the samples were converted into porous carbonated hydroxyapatite (CHA) ceramics by sintering in a furnace at 600 to 650°C using a sintering additive. The ceramics had 60-90% interconnected

N. V. Bakunova; V. S. Komlev; A. Y. Fedotov; I. V. Fadeeva; V. V. Smirnov; L. I. Shvorneva; A. N. Gurin; S. M. Barinov

192

Rapid prototyping: porous titanium alloy scaffolds produced by selective laser melting for bone tissue engineering.  

PubMed

Selective laser melting (SLM), a method used in the nuclear, space, and racing industries, allows the creation of customized titanium alloy scaffolds with highly defined external shape and internal structure using rapid prototyping as supporting external structures within which bone tissue can grow. Human osteoblasts were cultured on SLM-produced Ti6Al4V mesh scaffolds to demonstrate biocompatibility using scanning electron microscopy (SEM), fluorescence microscopy after cell vitality staining, and common biocompatibility tests (lactate dihydrogenase (LDH), 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), 5-bromo-2-deoxyuridine (BrdU), and water soluble tetrazolium (WST)). Cell occlusion of pores of different widths (0.45-1.2 mm) was evaluated. Scaffolds were tested for resistance to compressive force. SEM investigations showed osteoblasts with well-spread morphology and multiple contact points. Cell vitality staining and biocompatibility tests confirmed osteoblast vitality and proliferation on the scaffolds. Pore overgrowth increased during 6 weeks' culture at pore widths of 0.45 and 0.5 mm, and in the course of 3 weeks for pore widths of 0.55, 0.6, and 0.7 mm. No pore occlusion was observed on pores of width 0.9-1.2 mm. Porosity and maximum compressive load at failure increased and decreased with increasing pore width, respectively. In summary, the scaffolds are biocompatible, and pore width influences pore overgrowth, resistance to compressive force, and porosity. PMID:19072196

Warnke, Patrick H; Douglas, Timothy; Wollny, Patrick; Sherry, Eugene; Steiner, Martin; Galonska, Sebastian; Becker, Stephan T; Springer, Ingo N; Wiltfang, Jörg; Sivananthan, Sureshan

2009-06-01

193

Comparative Study of Bone Repair Using Porous Hydroxyapatite/ ?-Tricalcium Phosphate and Xenograft Scaffold in Rabbits with Tibia Defect  

PubMed Central

Background: Bone tissue engineering requires materials that are biocompatible, mechanically suited for bone function, integrated with the host skeleton, and support osteoinduction of the implanted cells for new bone formation. The aim of this study was to compare the osteogenic potential of xenograft with hydroxyapatite/?- tricalcium phosphate (HA/?-TCP) scaffold. Methods: New Zealand rabbits (n = 9) were divided into 3 groups. Osteoblast cells were originally isolated from rabbit iliac crest and cultured in DMEM/F12. After creating a critical-sized defect (2 × 3 cm) in rabbit tibia bone, the defect was filled with an implant of HA/TCP with osteoblasts and xenograft in the hole of left (as control) and right tibia, respectively. The new bone formation and the development of bone union within the defect were evaluated by x-ray images and eosine and hematoxylin staining at 4, 8, and 12 weeks post-operation. Results: The bone partially formed in both groups was filled with osteoblast cultured on porous implants at 4 weeks. Over time, progressive bone regeneration was observed inside the pores. Moreover, a progressive vascular ingrowth and progressive integration with the host bone were obvious in xenograft when compared to HA/?-TCP. A good integration between the xenograft implants and the bone was observed radiographically and confirmed by histological section. Conclusion: The result showed that the bone defect can be repaired using both synthetic and xenograft implants. However, the xenograft showed a better osteointegration as compared to HA/?-TCP scaffold. PMID:22562028

Bagher, Zohreh; Rajaei, Farzad; Shokrgozar, Mohammadali

2012-01-01

194

Methods for Producing Scaffold-Free Engineered Cartilage Sheets from Auricular and Articular Chondrocyte Cell Sources and Attachment to Porous Tantalum  

PubMed Central

Abstract Scaffold-free cartilage engineering techniques may provide a simple alternative to traditional methods employing scaffolds. We previously reported auricular chondrocyte-derived constructs for use in an engineered trachea model; however, the construct generation methods were not reported in detail. In this study, methods for cartilage construct generation from auricular and articular cell sources are described in detail, and the resulting constructs are compared for use in a joint resurfacing model. Attachment of cartilage sheets to porous tantalum is also investigated as a potential vehicle for future attachment to subchondral bone. Large scaffold-free cartilage constructs were produced from culture-expanded chondrocytes from skeletally mature rabbits, and redifferentiated in a chemically-defined culture medium. Auricular constructs contained more glycosaminoglycan (39.6±12.7 vs. 9.7±1.9??g/mg wet weight, mean and standard deviation) and collagen (2.7±0.45 vs. 1.1±0.2??g/mg wet weight, mean and standard deviation) than articular constructs. Aggregate modulus was also higher for auricular constructs vs. articular constructs (0.23±0.07 vs. 0.12±0.03?MPa, mean and standard deviation). Attachment of constructs to porous tantalum was achieved by neocartilage ingrowth into tantalum pores. These results demonstrate that large scaffold-free neocartilage constructs can be produced from mature culture-expanded chondrocytes in a chemically-defined medium, and that these constructs can be attached to porous tantalum. PMID:23514898

Mera, Hisashi; Weidenbecher, Mark; Awadallah, Amad; Mansour, Joseph M.; Dennis, James E.

2012-01-01

195

The Encapsulation of Rat Aortic Smooth Muscle Cells Within Porous Scaffold  

E-print Network

for the cells. Cells are encapsulated in rapidly degrading polyethylene glycol (PEG) bead-shaped gels. These beads are then encapsulated in a cross-linked PEG rectangular scaffold. In time, the beads degrade while the cells remain intact. In essence, this allows...

Iacob, Alexandra

2009-09-30

196

Endocultivation: 3D printed customized porous scaffolds for heterotopic bone induction  

Microsoft Academic Search

The aim of this study was to evaluate the ability of computer assisted designed (CAD) synthetic hydroxyapatite and tricalciumphosphate blocks to serve as precise scaffolds for intramuscular bone induction in a rat model. A central channel to allow for vessel pedicle or nerve integration was added. Natural bovine hydroxyapatite blocks served as controls to evaluate and compare biocompatibility of the

Stephan T. Becker; Hendrik Bolte; Oliver Krapf; Hermann Seitz; Timothy Douglas; Sureshan Sivananthan; Jörg Wiltfang; Eugene Sherry; Patrick H. Warnke

2009-01-01

197

Endocultivation: 3D printed customized porous scaffolds for heterotopic bond induction  

Microsoft Academic Search

The aim of this study was to evaluate the ability of computer assisted designed (CAD) synthetic hydroxyapatite and tricalciumphosphate blocks to serve as precise scaffolds for intramuscular bone induction in a rat model. A central channel to allow for vessel pedicle or nerve integration was added. Natural bovine hydroxyapatite blocks served as controls to evaluate and compare biocompatibility of the

Stephan T. Becker; Hendrik Bolte; Oliver Krapf; Hermann Seitz; Timothy Douglas; Sureshan Sivananthan; Jörg Wiltfang; Eugene Sherry; Patrick H. Warnke

2009-01-01

198

The scale-up of a tissue engineered porous hydroxyapatite polymer composite scaffold for use in bone repair: An ovine femoral condyle defect study.  

PubMed

The development of an osteogenic bone graft substitute has important practical and cost implications in many branches of medicine where bone regeneration is required. Previous in vitro and small animal (murine) in vivo studies highlighted a porous hydroxyapatite/poly (dl-lactic acid) composite scaffold in combination with skeletal stem cells (SSCs) as a potential bone graft substitute candidate. The aim of the current study was to scale up the bone cell-scaffold construct to large animals and examine the potential for repair of a critical-sized defect via an ovine model. SSC seeded scaffolds (and unseeded scaffold controls) were implanted bilaterally into ovine femoral condyle critical defects for 3 months. A parallel in vitro analysis of ovine SSC seeded scaffolds was also performed. Post mortem mechanical indentation testing showed the bone strengths of the defect sites were 20% (controls) and 11% (SSC seeded scaffolds) those of normal cancellous bone (p?scaffolds over the SSC seeded scaffolds (p?=?0.14). Histological examination confirmed these findings, with enhanced quality new bone within the control defects. This study highlights important issues and steps to overcome in scale-up and translation of tissue engineered products. The scaffold demonstrated encouraging results as an osteoconductive matrix; however, further work is required with cellular protocols before any human trials. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1346-1356, 2015. PMID:25044983

Tayton, Edward; Purcell, Matthew; Smith, James O; Lanham, Stuart; Howdle, Steven M; Shakesheff, Kevin M; Goodship, Allen; Blunn, Gordon; Fowler, Darren; Dunlop, Douglas G; Oreffo, Richard O C

2015-04-01

199

Biomimetic mineralisation of polymeric scaffolds using a combined soaking and Kitano approach.  

PubMed

Chitosan hydrogels are of considerable interest in synthetic biomimetic mineralisation strategies due to their favourable characteristics such as the presentation of a large surface area for crystal nucleation within a structured yet responsive scaffold. Chitosan hydrogels were prepared and subsequently calcium carbonate mineralisation was initiated using a method which combines alternate soaking of the films with precursor solutions followed by treatment with Kitano solution. This combined approach allows for increased extent of mineralisation, inducement of mineralisation uniformly throughout the hydrogel rather than only at the peripheral surface and ready scalability and shape manipulation. The base synthetic system is readily modified through the introduction of additives that manipulate the nucleation and growth of the calcium carbonate. Addition of poly(acrylic acid) inhibits nucleation and induces tangential crystal growth along the internal and external interfaces of the hydrogel. The resulting composite is comprised of stacked overlapping plates of calcium carbonate intercalated with carbohydrate. The method is applicable in combination with a variety of hydrogels including macroporous chitosan, chitosan-alginate bilayers and pure alginate hydrogels. The composite materials were analysed by SEM, XRD, microRaman spectroscopy and mechanical strength testing. PMID:21829841

Munro, Natasha H; Green, David W; Dangerfield, Ashley; McGrath, Kathryn M

2011-09-28

200

In vitro and in vivo evaluation of porous PCL-PLLA 3D polymer scaffolds fabricated via salt leaching method for bone tissue engineering applications.  

PubMed

Three dimensional porous scaffolds composed of various ratios of polycaprolactone and poly(L-lactic acid) (PLLA) were prepared using salt leaching method for bone regeneration applications. Surfaces of the scaffolds were visualized using scanning electron microscope (SEM) and the combination of the polymers was confirmed by FT-IR. Addition of PLLA increased the porosity and pore sizes of the scaffolds and also the scaffolds' compressive strength initially. Osteoblast-like cells were used and it was found that the samples' cell biocompatibility was further promoted with the increase in PLLA content as observed via cell proliferation assays using MTT, gene expression with RT-PCR, and micrographs from SEM and confocal microscopy. Samples were then implanted into male rabbits for 2 months, and histological staining and micro-CT histomorphometry show that new bone formations were detected in the site containing the implants of the scaffolds and that bone regeneration was further promoted with the increased concentration of PLLA in the scaffold. PMID:24138179

Sadiasa, Alexander; Nguyen, Thi Hiep; Lee, Byong-Taek

2014-01-01

201

Electrospun nanofiber scaffolds and plasma polymerization: a promising combination towards complete, stable endothelial lining for vascular grafts.  

PubMed

In the quest to reduce risk of thrombosis in vascular grafts, it is essential to provide a surface with morphological and mechanical properties close to those of the extracellular matrix beneath the luminal endothelium, and to favor the growth of a confluent, stable monolayer of endothelial cells. This is accomplished here by combining electrospun poly(ethylene terephthalate) (PET) mats with an amine-rich thin plasma-polymerized coating, designated "L-PPE:N." Its deposition does not modify the open, highly porous mats and leads only to small changes in mechanical properties. L-PPE:N significantly improves the adhesion and growth of human umbilical vein endothelial cells (HUVEC) and their resistance to flow-induced shear stress. These properties favor the formation of desired confluent HUVEC monolayers on the topmost surface, unlike conventional vascular grafts (ePTFE or woven PET), where cells migrate inside the material. This combination is therefore highly advantageous for the pre-endothelialization of the luminal side of small-diameter vascular prostheses. PMID:24740559

Savoji, Houman; Hadjizadeh, Afra; Maire, Marion; Ajji, Abdellah; Wertheimer, Michael R; Lerouge, Sophie

2014-08-01

202

Porous chitosan scaffolds with surface micropatterning and inner porosity and their effects on Schwann cells.  

PubMed

Chitosan is found to promote the regeneration of peripheral nerve system in our previous studies, whereas the regeneration speed is not satisfied with clinical request. Micropatterning could promote cell orientation and growth, however, the effect of porous chitosan micropatterning on nerve regeneration is rarely reported. In this study, the porous chitosan micropatterning with surface ridge/groove and inner porosity structure was fabricated using a combination of micromodeling and lyophilization method. The morphology and stability of the prepared chitosan micropatterning were evaluated, the regulation of Schwann cells behavior by chitosan micropatterning was evaluated. The results showed that the chitosan micropatterning displayed stripe-like structure with a clear and complete edge. The micropatterning with 30/30 ?m was more stable than 20/20 ?m sample. Schwann cells on chitosan micropatterning showed orientation adhesion and began to grow along a certain direction after culture for 2 h, and displayed the minimal orientation angle and the largest length/width ratio on 30/30 ?m micropatterning after further culture for 3 d and 5 d, indicating the most obvious cell orientation. Moreover, the secretion of nerve growth factor (NGF) demonstrated that the micropatterned chitosan had no negative influence on the physiological function of Schwann cells. Thus, the results indicate that the porous chitosan micropatterning can regulate Schwann cell growth well, which may have potential application in nerve regeneration. The study provides an important basis for constructing porous nerve conduit with micropatterning structure in the inner wall. PMID:25002265

Li, Guicai; Zhao, Xueying; Zhao, Weixin; Zhang, Luzhong; Wang, Caiping; Jiang, Maorong; Gu, Xiaosong; Yang, Yumin

2014-10-01

203

Immobilization of cell adhesive RGD peptide onto the surface of highly porous biodegradable polymer scaffolds fabricated by a gas foaming\\/salt leaching method  

Microsoft Academic Search

A cell adhesive peptide moiety, Gly-Arg-Gly-Asp-Tyr (GRGDY), was immobilized onto the surface of highly porous biodegradable polymer scaffolds for enhancing cell adhesion and function. A carboxyl terminal end of poly(d,l-lactic-co-glycolic acid) (PLGA) was functionalized with a primary amine group by conjugating hexaethylene glycol-diamine. The PLGA-NH2 was blended with PLGA in varying ratios to prepare films by solvent casting or to

Jun Jin Yoon; Soon Ho Song; Doo Sung Lee; Tae Gwan Park

2004-01-01

204

In vitro degradation and release behavior of porous poly(lactic acid) scaffolds containing chitosan microspheres as a carrier for BMP2-derived synthetic peptide  

Microsoft Academic Search

To develop a novel tissue engineering scaffold with the capability of controlled releasing BMP-2-derived synthetic peptide, porous poly(lactic acid)\\/chitosan microspheres (PLA\\/CMs) composites containing different quantities of chitosan microspheres were prepared by a thermally induced phase separation method. FTIR analysis revealed that there were strong hydrogen bond interactions between the PLA and chitosan component. Introduction of less than 30% CMs (on

Xufeng Niu; Qingling Feng; Mingbo Wang; Xiaodong Guo; Qixin Zheng

2009-01-01

205

Challenges for Nerve Repair Using Chitosan-Siloxane Hybrid Porous Scaffolds  

PubMed Central

The treatment of peripheral nerve injuries remains one of the greatest challenges of neurosurgery, as functional recover is rarely satisfactory in these patients. Recently, biodegradable nerve guides have shown great potential for enhancing nerve regeneration. A major advantage of these nerve guides is that no foreign material remains after the device has fulfilled its task, which spares a second surgical intervention. Recently, we studied peripheral nerve regeneration using chitosan-?-glycidoxypropyltrimethoxysilane (chitosan-GPTMS) porous hybrid membranes. In our studies, these porous membranes significantly improved nerve fiber regeneration and functional recovery in rat models of axonotmetic and neurotmetic sciatic nerve injuries. In particular, the number of regenerated myelinated nerve fibers and myelin thickness were significantly higher in rat treated with chitosan porous hybrid membranes, whether or not they were used in combination with mesenchymal stem cells isolated from the Wharton's jelly of the umbilical cord. In this review, we describe our findings on the use of chitosan-GPTMS hybrids for nerve regeneration. PMID:25054129

Shirosaki, Yuki; Hayakawa, Satoshi; Osaka, Akiyoshi; Lopes, Maria A.; Santos, José D.; Geuna, Stefano; Mauricio, Ana C.

2014-01-01

206

A new method for the preparation of polymeric porous layer open tubular columns for GC application  

NASA Technical Reports Server (NTRS)

A new method to prepare polymeric PLOT columns by using in situ polymerization technology is described. The method involves a straightforward in situ polymerization of the monomer. The polymer produced is directly coated on the metal tubing. This eliminates many of the steps needed in conventional polymeric PLOT column preparation. Our method is easy to operate and produces very reproducible columns, as shown previously (T. C. Shen. J. Chromatogr. Sci. 30, 239, 1992). The effects of solvents, tubing pretreatments, initiators and reaction temperatures in the preparation of PLOT columns are studied. Several columns have been developed to separate (1) highly polar compounds, such as water and ammonia or water and HCN, and (2) hydrocarbons and inert gases. A recent improvement has allowed us to produce bonded polymeric PLOT columns. These were studied, and the results are included also.

Shen, T. C.; Wang, M. L.

1995-01-01

207

Porous poly(alpha-hydroxyacid)/Bioglass composite scaffolds for bone tissue engineering. I: Preparation and in vitro characterisation.  

PubMed

Highly porous composites scaffolds of poly-D,L-lactide (PDLLA) and poly(lactide-co-glycolide) (PLGA) containing different amounts (10, 25 and 50 wt%) of bioactive glass (45S5 Bioglass)were prepared by thermally induced solid-liquid phase separation (TIPS) and subsequent solvent sublimation. The addition of increasing amounts of Bioglass into the polymer foams decreased the pore volume. Conversely, the mechanical properties of the polymer materials were improved. The composites were incubated in phosphate buffer saline at 37 degrees C to study the in vitro degradation of the polymer by measurement of water absorption, weight loss as well as changes in the average molecular weight of the polymer and in the pH of the incubation medium as a function of the incubation time. The addition of Bioglass to polymer foams increased the water absorption and weight loss compared to neat polymer foams. However, the polymer molecular weight, determined by size exclusion chromatography, was found to decrease more rapidly and to a larger extent in absence of Bioglass. The presence of the bioactive filler was therefore found to delay the degradation rate of the polymer as compared to the neat polymer foams. Formation of hydroxyapatite on the surface of composites, as an indication of their bioactivity, was recorded by EDXA, X-ray diffractometry and confirmed by Raman spectroscopy. PMID:15046908

Maquet, V; Boccaccini, A R; Pravata, L; Notingher, I; Jérôme, R

2004-08-01

208

Spatial control of bone formation using a porous polymer scaffold co-delivering anabolic rhBMP-2 and anti-resorptive agents.  

PubMed

Current clinical delivery of recombinant human bone morphogenetic proteins (rhBMPs) utilises freeze-dried collagen. Despite effective new bone generation, rhBMP via collagen can be limited by significant complications due to inflammation and uncontrolled bone formation. This study aimed to produce an alternative rhBMP local delivery system to permit more controllable and superior rhBMP-induced bone formation. Cylindrical porous poly(lactic-co-glycolic acid) (PLGA) scaffolds were manufactured by thermally-induced phase separation. Scaffolds were encapsulated with anabolic rhBMP-2 (20 µg) ± anti-resorptive agents: zoledronic acid (5 µg ZA), ZA pre-adsorbed onto hydroxyapatite microparticles, (5 µg ZA/2% HA) or IkappaB kinase (IKK) inhibitor (10 µg PS-1145). Scaffolds were inserted in a 6-mm critical-sized femoral defect in Wistar rats, and compared against rhBMP-2 via collagen. The regenerate region was examined at 6 weeks by 3D microCT and descriptive histology. MicroCT and histology revealed rhBMP-induced bone was more restricted in the PLGA scaffolds than collagen scaffolds (-92.3% TV, p < 0.01). The regenerate formed by PLGA + rhBMP-2/ZA/HA showed comparable bone volume to rhBMP-2 via collagen, and bone mineral density was +9.1% higher (p < 0.01). Local adjunct ZA/HA or PS-1145 significantly enhanced PLGA + rhBMP-induced bone formation by +78.2% and +52.0%, respectively (p ? 0.01). Mechanistically, MG-63 human osteoblast-like cells showed cellular invasion and proliferation within PLGA scaffolds. In conclusion, PLGA scaffolds enabled superior spatial control of rhBMP-induced bone formation over clinically-used collagen. The PLGA scaffold has the potential to avoid uncontrollable bone formation-related safety issues and to customise bone shape by scaffold design. Moreover, local treatment with anti-resorptive agents incorporated within the scaffold further augmented rhBMP-induced bone formation. PMID:24488823

Yu, N Y C; Gdalevitch, M; Murphy, C M; Mikulec, K; Peacock, L; Fitzpatrick, J; Cantrill, L C; Ruys, A J; Cooper-White, J J; Little, D G; Schindeler, A

2014-01-01

209

Polymeric molecular sieve membranes via in situ cross-linking of non-porous polymer membrane templates.  

PubMed

High-performance polymeric membranes for gas separation are attractive for molecular-level separations in industrial-scale chemical, energy and environmental processes. Molecular sieving materials are widely regarded as the next-generation membranes to simultaneously achieve high permeability and selectivity. However, most polymeric molecular sieve membranes are based on a few solution-processable polymers such as polymers of intrinsic microporosity. Here we report an in situ cross-linking strategy for the preparation of polymeric molecular sieve membranes with hierarchical and tailorable porosity. These membranes demonstrate exceptional performance as molecular sieves with high gas permeabilities and selectivities for smaller gas molecules, such as carbon dioxide and oxygen, over larger molecules such as nitrogen. Hence, these membranes have potential for large-scale gas separations of commercial and environmental relevance. Moreover, this strategy could provide a possible alternative to 'classical' methods for the preparation of porous membranes and, in some cases, the only viable synthetic route towards certain membranes. PMID:24739439

Qiao, Zhen-An; Chai, Song-Hai; Nelson, Kimberly; Bi, Zhonghe; Chen, Jihua; Mahurin, Shannon M; Zhu, Xiang; Dai, Sheng

2014-01-01

210

HA/nylon 6,6 porous scaffolds fabricated by salt-leaching/solvent casting technique: effect of nano-sized filler content on scaffold properties.  

PubMed

Nanohydroxyapatite (n-HA)/nylon 6,6 composite scaffolds were produced by means of the salt-leaching/solvent casting technique. NaCl with a distinct range size was used with the aim of optimizing the pore network. Composite powders with different n-HA contents (40%, 60%) for scaffold fabrication were synthesized and tested. The composite scaffolds thus obtained were characterized for their microstructure, mechanical stability and strength, and bioactivity. The microstructure of the composite scaffolds possessed a well-developed interconnected porosity with approximate optimal pore size ranging from 200 to 500 ?m, ideal for bone regeneration and vascularization. The mechanical properties of the composite scaffolds were evaluated by compressive strength and modulus tests, and the results confirmed their similarity to cortical bone. To characterize bioactivity, the composite scaffolds were immersed in simulated body fluid for different lengths of time and results monitored by scanning electron microscopy and energy dispersive X-ray microanalysis to determine formation of an apatite layer on the scaffold surface. PMID:21904455

Mehrabanian, Mehran; Nasr-Esfahani, Mojtaba

2011-01-01

211

HA/nylon 6,6 porous scaffolds fabricated by salt-leaching/solvent casting technique: effect of nano-sized filler content on scaffold properties  

PubMed Central

Nanohydroxyapatite (n-HA)/nylon 6,6 composite scaffolds were produced by means of the salt-leaching/solvent casting technique. NaCl with a distinct range size was used with the aim of optimizing the pore network. Composite powders with different n-HA contents (40%, 60%) for scaffold fabrication were synthesized and tested. The composite scaffolds thus obtained were characterized for their microstructure, mechanical stability and strength, and bioactivity. The microstructure of the composite scaffolds possessed a well-developed interconnected porosity with approximate optimal pore size ranging from 200 to 500 ?m, ideal for bone regeneration and vascularization. The mechanical properties of the composite scaffolds were evaluated by compressive strength and modulus tests, and the results confirmed their similarity to cortical bone. To characterize bioactivity, the composite scaffolds were immersed in simulated body fluid for different lengths of time and results monitored by scanning electron microscopy and energy dispersive X-ray microanalysis to determine formation of an apatite layer on the scaffold surface. PMID:21904455

Mehrabanian, Mehran; Nasr-Esfahani, Mojtaba

2011-01-01

212

Bioactive glass-based composites for the production of dense sintered bodies and porous scaffolds.  

PubMed

Recently several attempts have been made to combine calcium phosphates, such as ?-tricalcium phosphate (?-TCP) and, most of all, hydroxyapatite (HA), with bioactive glasses of different composition, in order to develop composites with improved biological and mechanical performance. Unfortunately, the production of such systems usually implies a high-temperature treatment (up to 1300 °C), which may result in several drawbacks, including crystallization of the original glass, decomposition of the calcium phosphate phase and/or reactions between the constituent phases, with non-trivial consequences in terms of microstructure, bioactivity and mechanical properties of the final samples. In the present contribution, novel binary composites have been obtained by sintering a bioactive glass, characterized by a low tendency to crystallize, with the addition of HA or ?-TCP as the second phase. In particular, the composites have been treated at a relatively low temperature (818 °C and 830 °C, depending on the sample), thus preserving the amorphous structure of the glass and minimizing the interaction between the constituent phases. The effects of the glass composition, calcium phosphate nature and processing conditions on the composite microstructure, mechanical properties and in vitro bioactivity have been systematically discussed. To conclude, a feasibility study to obtain scaffolds for bone tissue regeneration has been proposed. PMID:23498242

Bellucci, D; Sola, A; Cannillo, V

2013-05-01

213

Fabrication of porous carbon/TiO? composites through polymerization-induced phase separation and use as an anode for Na-ion batteries.  

PubMed

Polymerization-induced phase separation of nanoparticle-filled solution is demonstrated as a simple approach to control the structure of porous composites. These composites are subsequently demonstrated as the active component for sodium ion battery anode. To synthesize the composites, we dissolved/dispersed titanium oxide (anatase) nanoparticles (for sodium insertion) and poly(hydroxybutyl methacrylate) (PHBMA, porogen) in furfuryl alcohol (carbon precursor) containing a photoacid generator (PAG). UV exposure converts the PAG to a strong acid that catalyzes the furfuryl alcohol polymerization. This polymerization simultaneously decreases the miscibility of the PHBMA and reduces the mobility in the mixture to kinetically trap the phase separation. Carbonization of this polymer composite yields a porous nanocomposite. This nanocomposite exhibits nearly 3-fold greater gravimetric capacity in Na-ion batteries than the same titanium oxide nanoparticles that have been coated with carbon. This improved performance is attributed to the morphology as the carbon content in the composite is five times that of the coated nanoparticles. The porous composite materials exhibit stable cyclic performance. Moreover, the battery performance using materials from this polymerization-induced phase separation method is reproducible (capacity within 10% batch-to-batch). This simple fabrication methodology may be extendable to other systems and provides a facile route to generate reproducible hierarchical porous morphology that can be beneficial in energy storage applications. PMID:25397899

Lee, Jeongwoo; Chen, Yu-Ming; Zhu, Yu; Vogt, Bryan D

2014-12-10

214

Stem cell engineered bone with calcium-phosphate coated porous titanium scaffold or silicon hydroxyapatite granules for revision total joint arthroplasty.  

PubMed

Aseptic loosening in total joint replacements (TJRs) is mainly caused by osteolysis which leads to a reduction of the bone stock necessary for implant fixation in revision TJRs. Our aim was to develop bone tissue-engineered constructs based on scaffolds of clinical relevance in revision TJRs to reconstitute the bone stock at revision operations by using a perfusion bioreactor system (PBRS). The hypothesis was that a PBRS will enhance mesenchymal stem cells (MSCs) proliferation and osteogenic differentiation and will provide an even distribution of MSCs throughout the scaffolds when compared to static cultures. A PBRS was designed and implemented. Scaffolds, silicon substituted hydroxyapatite granules and calcium-phosphate coated porous TiAl6V4 cylinders, were seeded with MSCs and cultured either in static conditions or in the PBRS at 0.75 mL/min. Statistically significant increased cell proliferation and alkaline phosphatase activity was found in samples cultured in the PBRS. Histology revealed a more even cell distribution in the perfused constructs. SEM showed that cells arranged in sheets. Long cytoplasmic processes attached the cells to the scaffolds. We conclude that a novel tissue engineering approach to address the issue of poor bone stock at revision operations is feasible by using a PBRS. PMID:24519756

García-Gareta, Elena; Hua, Jia; Rayan, Faizal; Blunn, Gordon W

2014-06-01

215

A multistep procedure to prepare pre-vascularized cardiac tissue constructs using adult stem sells, dynamic cell cultures, and porous scaffolds  

PubMed Central

The vascularization of tissue engineered products represents a key issue in regenerative medicine which needs to be addressed before the translation of these protocols to the bedside can be foreseen. Here we propose a multistep procedure to prepare pre-vascularized three-dimensional (3D) cardiac bio-substitutes using dynamic cell cultures and highly porous biocompatible gelatin scaffolds. The strategy adopted exploits the peculiar differentiation potential of two distinct subsets of adult stem cells to obtain human vascularized 3D cardiac tissues. In the first step of the procedure, human mesenchymal stem cells (hMSCs) are seeded onto gelatin scaffolds to provide interconnected vessel-like structures, while human cardiomyocyte progenitor cells (hCMPCs) are stimulated in vitro to obtain their commitment toward the cardiac phenotype. The use of a modular bioreactor allows the perfusion of the whole scaffold, providing superior performance in terms of cardiac tissue maturation and cell survival. Both the cell culture on natural-derived polymers and the continuous medium perfusion of the scaffold led to the formation of a densely packaged proto-tissue composed of vascular-like and cardiac-like cells, which might complete maturation process and interconnect with native tissue upon in vivo implantation. In conclusion, the data obtained through the approach here proposed highlight the importance to provide stem cells with complementary signals in vitro able to resemble the complexity of cardiac microenvironment. PMID:24917827

Pagliari, Stefania; Tirella, Annalisa; Ahluwalia, Arti; Duim, Sjoerd; Goumans, Marie-Josè; Aoyagi, Takao; Forte, Giancarlo

2014-01-01

216

The double porogen approach as a new technique for the fabrication of interconnected poly(L-lactic acid) and starch based biodegradable scaffolds  

Microsoft Academic Search

One of the most widely used fabrication methods of three dimensional porous scaffolds involves compression moulding of a polymer\\u000a salt mixture, followed by salt leaching. However, the scaffolds prepared by this technique have typically limited interconnectivity.\\u000a In this study, besides salt particles, an additional polymeric porogen, poly(ethylene oxide), PEO, was added to poly(L-lactic\\u000a acid), PLLA, to enhance the interconnectivity of

S. Ghosh; J. C. Viana; R. L. Reis; J. F. Mano

2007-01-01

217

Release profiles of tricalcium phosphate nanoparticles from poly(L-lactic acid) electrospun scaffolds with single component, core-sheath, or porous fiber morphologies: effects on hASC viability and osteogenic differentiation.  

PubMed

Functional PLA scaffolds are created with single component, core-sheath, or porous fiber morphology and doped with TCP nanoparticles to study the release profiles for use in bone tissue engineering applications. Pharmacokinetic analyses are performed for the three different nanofibrous structures after doping with TCP. Results indicate that single component and porous fiber scaffolds exhibit an initial-burst release profile whereas core-sheath fibers show a steady release. All scaffolds are then seeded with human adipose-derived stem cells (hASC), which remain viable and continue proliferation on all nanofibrous morphologies for up to 21 d. Osteogenic differentiation of hASC and cell-mediated calcium accretion are largest on porous fibers. PMID:22648935

Asli, Mahsa Mohiti; Pourdeyhimi, Behnam; Loboa, Elizabeth G

2012-07-01

218

A hypothesis-driven parametric study of effects of polymeric scaffold properties on tissue engineered neovessel formation.  

PubMed

Continued advances in the tissue engineering of vascular grafts have enabled a paradigm shift from the desire to design for adequate suture retention, burst pressure and thrombo-resistance to the goal of achieving grafts having near native properties, including growth potential. Achieving this far more ambitious outcome will require the identification of optimal, not just adequate, scaffold structure and material properties. Given the myriad possible combinations of scaffold parameters, there is a need for a new strategy for reducing the experimental search space. Toward this end, we present a new modeling framework for in vivo neovessel development that allows one to begin to assess in silico the potential consequences of different combinations of scaffold structure and material properties. To restrict the number of parameters considered, we also utilize a non-dimensionalization to identify key properties of interest. Using illustrative constitutive relations for both the evolving fibrous scaffold and the neotissue that develops in response to inflammatory and mechanobiological cues, we show that this combined non-dimensionalization computational approach predicts salient aspects of neotissue development that depend directly on two key scaffold parameters, porosity and fiber diameter. We suggest, therefore, that hypothesis-driven computational models should continue to be pursued given their potential to identify preferred combinations of scaffold parameters that have the promise of improving neovessel outcome. In this way, we can begin to move beyond a purely empirical trial-and-error search for optimal combinations of parameters and instead focus our experimental resources on those combinations that are predicted to have the most promise. PMID:25288519

Miller, Kristin S; Khosravi, Ramak; Breuer, Christopher K; Humphrey, Jay D

2015-01-01

219

Injectable PolyMIPE Scaffolds for Soft Tissue Regeneration  

PubMed Central

Injury caused by trauma, burns, surgery, or disease often results in soft tissue loss leading to impaired function and permanent disfiguration. Tissue engineering aims to overcome the lack of viable donor tissue by fabricating synthetic scaffolds with the requisite properties and bioactive cues to regenerate these tissues. Biomaterial scaffolds designed to match soft tissue modulus and strength should also retain the elastomeric and fatigue-resistant properties of the tissue. Of particular design importance is the interconnected porous structure of the scaffold needed to support tissue growth by facilitating mass transport. Adequate mass transport is especially true for newly implanted scaffolds that lack vasculature to provide nutrient flux. Common scaffold fabrication strategies often utilize toxic solvents and high temperatures or pressures to achieve the desired porosity. In this study, a polymerized medium internal phase emulsion (polyMIPE) is used to generate an injectable graft that cures to a porous foam at body temperature without toxic solvents. These poly(ester urethane urea) scaffolds possess elastomeric properties with tunable compressive moduli (20–200 kPa) and strengths (4–60 kPa) as well as high recovery after the first conditioning cycle (97–99%). The resultant pore architecture was highly interconnected with large voids (0.5–2 mm) from carbon dioxide generation surrounded by water-templated pores (50–300 ?m). The ability to modulate both scaffold pore architecture and mechanical properties by altering emulsion chemistry was demonstrated. Permeability and form factor were experimentally measured to determine the effects of polyMIPE composition on pore interconnectivity. Finally, initial human mesenchymal stem cell (hMSC) cytocompatibility testing supported the use of these candidate scaffolds in regenerative applications. Overall, these injectable polyMIPE foams show strong promise as a biomaterial scaffold for soft tissue repair. PMID:24563552

Moglia, Robert S.; Robinson, Jennifer L.; Muschenborn, Andrea D.; Touchet, Tyler J.; Maitland, Duncan J.; Cosgriff-Hernandez, Elizabeth

2013-01-01

220

In vitro chondrocyte behavior on porous biodegradable poly (e-caprolactone)/polyglycolic acid scaffolds for articular chondrocyte adhesion and proliferation.  

PubMed

In this study, poly(e-caprolactone)/polyglycolic acid (PCL/PGA) scaffolds for repairing articular cartilage were fabricated via solid-state cryomilling along with compression molding and porogen leaching. Four distinct scaffolds were fabricated using this approach by four independent cryomilling times. These scaffolds were assessed for their suitability to promote articular cartilage regeneration with in vitro chondrocyte cell culture studies. The scaffolds were characterized for pore size, porosity, swelling ratio, compressive, and thermal properties. Cryomilling time proved to significantly affect the physical, mechanical, and morphological properties of the scaffolds. In vitro bovine chondrocyte culture was performed dynamically for 1, 7, 14, 28, and 35 days. Chondrocyte viability and adhesion were tested using MTT assay and scanning electron microscopy micrographs. Glycosaminoglycan (GAG) and DNA assays were performed to investigate the extracellular matrix (ECM) formation and cell proliferation, respectively. PCL/PGA scaffolds demonstrated high porosity for all scaffold types. Morphological analysis and poly(ethylene oxide) continuity demonstrated the existence of a co-continuous network of interconnected pores with pore sizes appropriate for tissue engineering and chondrocyte ingrowth. While mean pore size decreased, water uptake and compressive properties increased with increasing cryomilling times. Compressive modulus of 12, 30, and 60 min scaffolds matched the compressive modulus of human articular cartilage. Viable cells increased besides increase in cell proliferation and ECM formation with progress in culture period. Chondrocytes exhibited spherical morphology on all scaffold types. The pore size of the scaffold affected chondrocyte adhesion, proliferation, and GAG secretion. The results indicated that the 12 min scaffolds delivered promising results for applications in articular cartilage repair. PMID:25671317

Jonnalagadda, John B; Rivero, Iris V; Dertien, Janet S

2015-05-01

221

Metal filled porous carbon  

DOEpatents

A porous carbon scaffold with a surface and pores, the porous carbon scaffold containing a primary metal and a secondary metal, where the primary metal is a metal that does not wet the surface of the pores of the carbon scaffold but wets the surface of the secondary metal, and the secondary metal is interspersed between the surface of the pores of the carbon scaffold and the primary metal.

Gross, Adam F. (Los Angeles, CA); Vajo, John J. (West Hills, CA); Cumberland, Robert W. (Malibu, CA); Liu, Ping (Irvine, CA); Salguero, Tina T. (Encino, CA)

2011-03-22

222

Three-Dimensional Culture of Human Periodontal Ligament Cells on Highly Porous Polyglycolic Acid Scaffolds in vitro  

Microsoft Academic Search

Periodontal tissue engineering represents a possible approach to regenerate the human periodontal ligament (PDL) around dental implants. The aim of this study was to observe the morphological and biological property of the human periodontal ligament cells that were three-dimensional (3D) cultured onto PGA scaffolds in vitro. The human periodontal ligament cells were seeded and cultured onto PGA 3D scaffolds, and

Yining Wang; Haibin Xia; Yan Zhao; Tao Jiang

2005-01-01

223

Porous carbon nanotube electrodes supported by natural polymeric membranes for PEMFC  

Microsoft Academic Search

A new type of porous multiwalled carbon nanotube (MWCNT) electrode with a macroporous networking inner-structure was prepared. First, the MWCNTs were homogeneously introduced inside and outside of a bacterial cellulose membrane with a 3D inter-connected network structure using ultrasound treatment and vacuum filtration in order to form the GDL. Second, the CL was formed on the surface of the GDL

Young Soo Yun; Hyeonseong Bak; Hyoung-Joon Jin

2010-01-01

224

Chitin Scaffolds in Tissue Engineering  

PubMed Central

Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue engineering biomaterial lies in that it can be easily processed into gel and scaffold forms for a variety of biomedical applications. Moreover, chitin has been shown to enhance some biological activities such as immunological, antibacterial, drug delivery and have been shown to promote better healing at a faster rate and exhibit greater compatibility with humans. This review provides an overview of the current status of tissue engineering/regenerative medicine research using chitin scaffolds for bone, cartilage and wound healing applications. We also outline the key challenges in this field and the most likely directions for future development and we hope that this review will be helpful to the researchers working in the field of tissue engineering and regenerative medicine. PMID:21673928

Jayakumar, Rangasamy; Chennazhi, Krishna Prasad; Srinivasan, Sowmya; Nair, Shantikumar V.; Furuike, Tetsuya; Tamura, Hiroshi

2011-01-01

225

Active scaffolds for on-demand drug and cell delivery  

E-print Network

Porous biomaterials have been widely used as scaffolds in tissue engineering and cell-based therapies. The release of biological agents from conventional porous scaffolds is typically governed by molecular diffusion, ...

Zhao, Xuanhe

226

Solvent/Non-Solvent Sintering To Make Microsphere Scaffolds  

NASA Technical Reports Server (NTRS)

A solvent/non-solvent sintering technique has been devised for joining polymeric microspheres to make porous matrices for use as drug-delivery devices or scaffolds that could be seeded with cells for growing tissues. Unlike traditional sintering at elevated temperature and pressure, this technique is practiced at room temperature and pressure and, therefore, does not cause thermal degradation of any drug, protein, or other biochemical with which the microspheres might be loaded to impart properties desired in a specific application. Also, properties of scaffolds made by this technique are more reproducible than are properties of comparable scaffolds made by traditional sintering. The technique involves the use of two miscible organic liquids: one that is and one that is not a solvent for the affected polymer. The polymeric microspheres are placed in a mold having the size and shape of the desired scaffold, then the solvent/non-solvent mixture is poured into the mold to fill the void volume between the microspheres, then the liquid mixture is allowed to evaporate. Some of the properties of the resulting scaffold can be tailored through choice of the proportions of the liquids and the diameter of the microspheres.

Laurencin, Cato T.; Brown, Justin L.; Nair, Lakshmi

2011-01-01

227

Poly (D,L-lactide)/nano-hydroxyapatite composite scaffolds for bone tissue engineering and biocompatibility evaluation.  

PubMed

Biodegradable polymer/bioceramic composite scaffolds can overcome the limitations of conventional ceramic bone substitutes such as brittleness and difficulty in shaping. However, conventional methods for fabricating polymer/bioceramic composite scaffolds often use organic solvents (e.g., the solvent casting and particulate leaching (SC/PL) method), which might be harmful to cells or tissues. In this study, Poly (D,L-lactide)/nano-hydroxyapatite (PDLLA/NHA) composites were prepared by in-situ polymerization, and highly porous scaffolds were fabricated using a novel method, supercritical CO2/salt-leaching method (SC CO2/SL). The materials and scaffolds were investigated by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and gel permeation chromatography (GPC). GPC showed that the molecular weight of composites decreased with increase of NHA content. However, the water absorption and compressive strength increased dramatically. The SEM micrographs showed that the scaffolds with pore size about 250 microm were obtained by controlling parameters of SC CO2/SL. The biocompatibility of PDLLA/NHA porous scaffolds were evaluated in vitro and in vivo. The evaluation on the cytotoxicity were carried out by cell relative growth rate (RGR) method and cell direct contact method. The cytotoxicity of these scaffolds was in grade I according to ISO 10993-1. There was no toxicosis and death cases observed in acute systemic toxicity test. And histological observation of the tissue response (1 and 9 weeks after the implantation) showed that there are still some slight inflammation responses. PMID:17701303

Ren, Jie; Zhao, Peng; Ren, Tianbin; Gu, Shuying; Pan, Kefeng

2008-03-01

228

Biomimetic nanoclay scaffolds for bone tissue engineering  

NASA Astrophysics Data System (ADS)

Tissue engineering offers a significant potential alternative to conventional methods for rectifying tissue defects by evoking natural regeneration process via interactions between cells and 3D porous scaffolds. Imparting adequate mechanical properties to biodegradable scaffolds for bone tissue engineering is an important challenge and extends from molecular to macroscale. This work focuses on the use of sodium montmorillonite (Na-MMT) to design polymer composite scaffolds having enhanced mechanical properties along with multiple interdependent properties. Materials design beginning at the molecular level was used in which Na-MMT clay was modified with three different unnatural amino acids and further characterized using Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD). Based on improved bicompatibility with human osteoblasts (bone cells) and intermediate increase in d-spacing of MMT clay (shown by XRD), 5-aminovaleric acid modified clay was further used to prepare biopolymer (chitosan-polygalacturonic acid complex) scaffolds. Osteoblast proliferation in biopolymer scaffolds containing 5-aminovaleric acid modified clay was similar to biopolymer scaffolds containing hydroxyapatite (HAP). A novel process based on biomineralization in bone was designed to prepare 5-aminovaleric acid modified clay capable of imparting multiple properties to the scaffolds. Bone-like apatite was mineralized in modified clay and a novel nanoclay-HAP hybrid (in situ HAPclay) was obtained. FTIR spectroscopy indicated a molecular level organic-inorganic association between the intercalated 5-aminovaleric acid and mineralized HAP. Osteoblasts formed clusters on biopolymer composite films prepared with different weight percent compositions of in situ HAPclay. Human MSCs formed mineralized nodules on composite films and mineralized extracellular matrix (ECM) in composite scaffolds without the use of osteogenic supplements. Polycaprolactone (PCL), a synthetic polymer, was used for preparing composites (films and scaffolds) containing in situ HAPclay. Composite films showed significantly improved nanomechanical properties. Human MSCs formed mineralized ECM on films in absence of osteogenic supplements and were able to infiltrate the scaffolds. Atomic force microscopy imaging of mineralized ECM formed on composite films showed similarities in dimensions, arrangement of collagen and apatite with their natural bone counterparts. This work indicates the potential of in situ HAPclay to impart polymeric scaffolds with osteoinductive, osteoconductive abilities and improve their mechanical properties besides emphasizing nanoclays as cell-instructive materials.

Ambre, Avinash Harishchandra

229

Protein adsorption characteristics of porous and tentacle anion-exchange membrane prepared by radiation-induced graft polymerization  

NASA Astrophysics Data System (ADS)

A polymer chain containing a diethylamino group was grafted onto the pore surface of a porous hollow-fiber membrane by radiation-induced graft polymerization. Dependence of the protein binding capacity of the membrane on environmental parameters such as salt concentration, pH and temperature was investigated. Saturation capacity of protein bound onto the graft chain containing ion-exchange group was governed by the conformation of the graft chain and the intensity of ion-exchange interaction. The conformation of the graft chain was investigated based on the pore radius of the membrane estimated from the permeation flux of a buffer solution through the membrane. By sufficiently permeating a bovine serum albumin (BSA) solution within the concentration range of 0.2-10 mg-BSA/ml through the membrane, the BSA binding capacity was determined. With increasing salt concentration or pH of the protein buffer solution, the graft chain shrank and BSA binding capacity decreased. On the other hand, the BSA binding capacity slightly increased with increasing temperature, and the conformation of the graft chain was insensitive to temperature in the range from 278 to 303 K. The bound BSA could be quantitatively eluted by permeating a buffer solution containing 0.5 M NaCl, and no deterioration in the BSA binding capacity was observed during five cycles of adsorption, elution and conditioning.

Tsuneda, Satoshi; Saito, Kyoichi; Sugo, Takanobu; Makuuchi, Keizo

1995-08-01

230

Fast and continuous preparation of high polymerization degree cellulose nanofibrils and their three-dimensional macroporous scaffold fabrication  

NASA Astrophysics Data System (ADS)

C6-carboxy-cellulose with a carboxylate content of 0.8 mmol g-1 was obtained by oxidation of once-dried cellulose, using the 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)/NaClO/NaClO2 system at pH 6.8 and 60 °C for 16 h. This method, with the addition of reagents in the order TEMPO, NaClO and NaClO2, was 38 h faster than a previously published method. Individualized cellulose nanofibrils with a width of 3-5 nm and a length of several hundred nanometers were prepared by homogenizing the C6-carboxy-cellulose-water suspension. Macroporous cellulose nanofibril/poly(vinyl alcohol) scaffolds with interconnected large pores of 20-100 ?m diameter and small pores of 2-10 ?m diameter were fabricated. The cellulose nanofilaments formed nanofibrous structures on the surface of the PVA wall, which was similar to that of the collagen skeleton of the extracellular matrix. NIH/3T3 cells were cultured in the scaffolds for 4 weeks, SEM observation showed that the cells were anchored and clustered on the cellulose nanofilaments, forming spherical colonies. The extracellular matrix (ECM) was filled with mineralized particles.

Song, Jiankang; Tang, Aimin; Liu, Tingting; Wang, Jufang

2013-02-01

231

Expansion of mouse hematopoietic progenitor cells in three-dimensional cocultures on frozen-thawed stromal cell layers formed within porous scaffolds.  

PubMed

To establish a highly efficient method of ex vivo expansion of hematopoietic cells (HCs), three-dimensional (3D) cocultures of HCs and stromal cell lines were performed using porous polymer scaffolds. Hematopoietic cells derived from mouse fetal livers were expanded by two successive cultures without the use of exogenous cytokines, namely, 3D cultures of stromal cells (DAS 104-8 cell line) to form stromal layers within the scaffolds, and, subsequently, by cocultures of the HCs on the stromal cell layers for 2 weeks. To expand the HCs more conveniently, in some experiments the stromal layers formed within the scaffolds were frozen (3D freezing) before the cocultures, then stored and applied to the cocultures after thawing. When the HCs were cocultured on the stromal layers of the DAS 104-8 cells, primitive HCs (c-kit(+) and CD34(+) cells) were expanded several fold during the cocultures. In contrast, the expansion of these primitive HCs was remarkably enhanced in the cocultures using the 3D frozen-thawed DAS 104-8 stromal layers (c-kit(+) cells > fifteenfold and CD34(+) cells > thirtyfold), and these expansions were significantly higher than those without the 3D freezing. The expansions enhanced by cocultures on the 3D frozen-thawed stromal layers were also observed in the cocultures with another stromal cell line (DAS 104-4). Because 3D frozen-thawed stromal cell lines are easy to handle, 3D coculture of HCs on frozen-thawed stromal cell lines may be an effective and convenient method for expanding primitive HCs. PMID:25461256

Miyoshi, Hirotoshi; Morita, Misa; Ohshima, Norio; Sato, Chiaki

2015-02-01

232

Three-dimensional porous alginate scaffolds provide a conducive environment for generation of well-vascularized embryoid bodies from human embryonic stem cells.  

PubMed

Differentiation of human embryonic stem cells (hESCs) can be instigated through the formation of embryo-like aggregates in suspension, termed human embryoid bodies (hEBs). Controlling cell aggregation and agglomeration during hEBs formation has a profound effect on the extent of cell proliferation and differentiation. In a previous work, we showed that control over hEBs formation and differentiation can be achieved via cultivation of hESC suspensions in a rotating bioreactor system. We now report that hEBs can be generated directly from hESC suspensions within three-dimensional (3D) porous alginate scaffolds. The confining environments of the alginate scaffold pores enabled efficient formation of hEBs with a relatively high degree of cell proliferation and differentiation; encouraged round, small-sized hEBs; and induced vasculogenesis in the forming hEBs to a greater extent than in static or rotating cultures. We therefore conclude that differentiation of hEBs can be induced and directed by physical constraints in addition to chemical cues. PMID:15486935

Gerecht-Nir, Sharon; Cohen, Smadar; Ziskind, Anna; Itskovitz-Eldor, Joseph

2004-11-01

233

Synergetic effect based gel-emulsions and their utilization for the template preparation of porous polymeric monoliths.  

PubMed

A polymerizable cholesteryl derivative (COA) was synthesized and used as a stabilizer for creating gel-emulsions with water in polymerizable monomers, of which they are styrene (ST), tert-butyl methacrylate (t-BMA), ethylene glycol dimethyl acrylate (EGDMA), and methyl methacrylate (MMA), etc. Interestingly, in addition to COA, the presence of a small amount of Span-80 is a necessity for the formation of the monomers containing gel-emulsions. Unlike conventional ones, the volume fraction of the dispersed phase in the gel-emulsions as created could be much lower than 74%, a critical value for routine gel-emulsions. Stabilization of these gel-emulsions as created has been attributed to the synergetic effect between COA, a typical low-molecular-mass gelator (LMMG), and Span-80, a surfactant, of which the former gels the continuous phase and the latter minimizes the interfacial energy of the continuous phase and the dispersed phase. SEM observation confirmed the network structures of COA in the gel-emulsions. Rheological tests demonstrated that the storage modulus, G', and the yield stress of the gel-emulsions decrease along with increasing the volume fraction of the dispersed phase, water, provided it is not greater than 74%-a result inconsistent with the theory explaining formation of routine gel-emulsions and in support of the conclusion that the systems under study follow a different mechanism. Furthermore, unlike LMMG-based stabilizers reported earlier, the gelator, COA, created in the present study has been functioning not only as a stabilizer but also a monomer. To illustrate the conceptual advantages, the gel-emulsions of water in ST/DVB/AIBN were polymerized. As expected, the densities and internal structures of the monoliths as prepared are highly adjustable, functionalization of the materials with cholesterol has been realized, and at the same time the problem of stabilizer leaking has been avoided. A preliminary test for gas adsorption demonstrated that the monoliths as prepared are good adsorbents for some volatile organic compounds (VOCs), in particular benzene, toluene, ethylbenzene, and xylene-the famous and toxic BTEX. It is believed that the findings reported in the present work provide not only a new strategy for creating novel gel-emulsions but also a new route for functionalizing porous polymeric monoliths. PMID:25338107

Miao, Qing; Chen, Xiangli; Liu, Lingling; Peng, Junxia; Fang, Yu

2014-11-18

234

Influence of 3D porous galactose containing PVA/gelatin hydrogel scaffolds on three-dimensional spheroidal morphology of hepatocytes.  

PubMed

Three-dimensional liver scaffolds are temporary framework that mimics native ECM architecture and positively influence hepatocyte lodging, proliferation with retention of metabolic activities. The aim of the current study is to develop galactose containing physical cross-linked polyvinyl alcohol/gelatin (P/G 8:2 and 9:1) hydrogel scaffolds via freeze/thaw technique. The 8:2 and 9:1 P/G hydrogels exhibited comparable pore size and porosity (P > 0.05). The tensile strength of the fabricated 8:2 and 9:1 P/G hydrogel scaffolds were found to be in accordance with native human liver. Pore interconnectivity of both the P/G hydrogel scaffolds was confirmed by scanning electron micrographs and liquid displacement method. Further galactose containing hydrogel promoted cell-cell and cell-hydrogel interaction, aiding cellular aggregation leading to spheroids formation compared to void P/G hydrogel by 7 days. Hence, galactose containing P/G hydrogel could be more promising substrate as it showed significantly higher cell proliferation and albumin secretion for 21 days when compared to non-galactose P/G hydrogels (P < 0.05). PMID:25578699

Vasanthan, Kirthanashri S; Subramaniam, Anuradha; Krishnan, Uma Maheswari; Sethuraman, Swaminathan

2015-01-01

235

Mechanical and biodegradable properties of porous titanium filled with poly-L-lactic acid by modified in situ polymerization technique.  

PubMed

Porous titanium (pTi) can possess a low Young's modulus equal to that of human bone, depending on its porosity. However, the mechanical strength of pTi deteriorates greatly with increasing porosity. On the other hand, certain medical polymers exhibit biofunctionalities, which are not possessed intrinsically by metallic materials. Therefore, a biodegradable medical polymer, poly-L-lactic acid (PLLA), was used to fill in the pTi pores using a modified in-situ polymerization technique. The mechanical and biodegradable properties of pTi filled with PLLA (pTi/PLLA) as fabricated by this technique and the effects of the PLLA filling were evaluated in this study. The pTi pores are almost completely filled with PLLA by the developed process (i.e., technique). The tensile strength and tensile Young's modulus of pTi barely changes with the PLLA filling. However, the PLLA filling improves the compressive 0.2% proof stress of pTi having any porosity and increases the compressive Young's modulus of pTi having relatively high porosity. This difference between the tensile and compressive properties of pTi/PLLA is considered to be caused by the differing resistances of PLLA in the pores to tensile and compressive deformations. The PLLA filled into the pTi pores degrades during immersion in Hanks' solution at 310 K. The weight loss due to PLLA degradation increases with increasing immersion time. However, the rate of weight loss of pTi/PLLA during immersion decreases with increasing immersion time. Hydroxyapatite formation is observed on the surface of pTi/PLLA after immersion for ?8 weeks. The decrease in the weight-loss rate may be caused by weight gain due to hydroxyapatite formation and/or the decrease in contact area with Hanks' solution caused by its formation on the surface of pTi/PLLA. PMID:21783129

Nakai, Masaaki; Niinomi, Mitsuo; Ishii, Daisuke

2011-10-01

236

Microwave sintering and in vitro study of defect-free stable porous multilayered HAp-ZrO2 artificial bone scaffold  

NASA Astrophysics Data System (ADS)

Continuously porous hydroxyapatite (HAp)/t-ZrO2 composites containing concentric laminated frames and microchanneled bodies were fabricated by an extrusion process. To investigate the mechanical properties of HAp/t-ZrO2 composites, the porous composites were sintered at different temperatures using a microwave furnace. The microstructure was designed to imitate that of natural bone, particularly small bone, with both cortical and spongy bone sections. Each microchannel was separated by alternating lamina of HAp, HAp-(t-ZrO2) and t-ZrO2. HAp and ZrO2 phases existed on the surface of the microchannel and the core zone to increase the biocompatibility and mechanical properties of the HAp-ZrO2 artificial bone. The sintering behavior was evaluated and the optimum sintering temperature was found to be 1400 °C, which produced a stable scaffold. The material characteristics, such as the microstructure, crystal structure and compressive strength, were evaluated in detail for different sintering temperatures. A detailed in vitro study was carried out using MTT assay, western blot analysis, gene expression by polymerase chain reaction and laser confocal image analysis of cell proliferation. The results confirmed that HAp-ZrO2 performs as an artificial bone, showing excellent cell growth, attachment and proliferation behavior using osteoblast-like MG63 cells.

Jang, Dong-Woo; Nguyen, Thi-Hiep; Sarkar, Swapan Kumar; Lee, Byong-Taek

2012-06-01

237

Effect of silicon level on rate, quality and progression of bone healing within silicate-substituted porous hydroxyapatite scaffolds  

Microsoft Academic Search

The osseous response to silicon (Si) level (0, 0.2, 0.4, 0.8 and 1.5wt% Si) within 5 batches of matched porosity silicate-substituted hydroxyapatite (SA) scaffold was assessed by implantation of 4.6mm diameter cylinders in the femoral intercondylar notch of New Zealand White rabbits for periods of 1, 3, 6 and 12 weeks. Histological evaluation and histomorphometric quantification of bone ingrowth and

Karin A. Hing; Peter A. Revell; Nigel Smith; Thomas Buckland

2006-01-01

238

Ectopic osteochondral formation of biomimetic porous PVA-n-HA/PA6 bilayered scaffold and BMSCs construct in rabbit.  

PubMed

In this work, the novel poly vinyl alcohol/gelatin-nano-hydroxyapatite/polyamide6 (PVA-n-HA/PA6) bilayered scaffold with biomimetic properties for articular cartilage and subchondral bone is developed. Furthermore, when these osteochondral scaffolds were seeded with induced bone mesenchymal stem cells (BMSCs) and implanted at ectopic sites, showed the potential for an engineered cartilage tissue and the corresponding subchondral bone. BMSCs were expanded in vitro and induced to chondrogenic or osteogenic potential by culturing in suitable media for 14 days. Subsequently, these induced cells were seeded into PVA-n-HA/PA6 separately, and the constructs were implanted into the rabbit muscle pouch for upto 12 weeks. Ectopic neocartilage formation in the PVA layer and reconstitution of the subchondral bone which remained confined within the n-HA/PA6 layer with the alteration of the cellular phenotype were identified with Masson's trichrome stain. Simultaneously, the RT-PCR results confirmed the expression of specific extracellular matrix (ECM) markers for cartilaginous tissue, such as collagen type II (Col-II), or alternatively, markers for osteoid tissue, such as collagen type I (Col-I) at the corresponding layers. During ectopic implantation, the underlying subchondral bone layer was completely integrated with the cartilage layer. The result from the ectopic osteochondral scaffolds implantation suggests that PVA-n-HA/PA6 with induced BMSCs is a possible substitute with potential in cartilage repair strategies. PMID:20967773

Qu, Dan; Li, Jihua; Li, Yubao; Khadka, Ashish; Zuo, Yi; Wang, Hang; Liu, Yiming; Cheng, Lin

2011-01-01

239

Fabrication of porous scaffolds by three-dimensional plotting of a pasty calcium phosphate bone cement under mild conditions.  

PubMed

The major advantage of hydroxyapatite (HA)-forming calcium phosphate cements (CPCs) used as bone replacement materials is their setting under physiological conditions without the necessity for thermal treatment that allows the incorporation of biological factors. In the present study, we have combined the biocompatible consolidation of CPCs with the potential of rapid prototyping (RP) techniques to generate calcium phosphate-based scaffolds with defined inner and outer morphology. We demonstrate the application of the RP technique three-dimensional (3D) plotting for the fabrication of HA cement scaffolds. This was realized by utilizing a paste-like CPC (P-CPC) which is stable as a malleable paste and whose setting reaction is initiated only after contact with aqueous solutions. The P-CPC showed good processability in the 3D plotting process and allowed the fabrication of stable?3D structures of different geometries with adequate mechanical stability and compressive strength. The cytocompatibility of the plotted P-CPC scaffolds was demonstrated in a cell culture experiment with human mesenchymal stem cells. The mild conditions during 3D plotting and post-processing and the realization of the whole procedure under sterile conditions make this approach highly attractive for fabrication of individualized implants with respect to patient-specific requirements by simultaneous plotting of biological components. PMID:22933381

Lode, Anja; Meissner, Katrin; Luo, Yongxiang; Sonntag, Frank; Glorius, Stefan; Nies, Berthold; Vater, Corina; Despang, Florian; Hanke, Thomas; Gelinsky, Michael

2014-09-01

240

Functionalized ultra-porous titania nanofiber membranes as nuclear waste separation and sequestration scaffolds for nuclear fuels recycle.  

SciTech Connect

Advanced nuclear fuel cycle concept is interested in reducing separations to a simplified, one-step process if possible. This will benefit from the development of a one-step universal getter and sequestration material so as a simplified, universal waste form was proposed in this project. We have developed a technique combining a modified sol-gel chemistry and electrospinning for producing ultra-porous ceramic nanofiber membranes with controllable diameters and porous structures as the separation/sequestration materials. These ceramic nanofiber materials have been determined to have high porosity, permeability, loading capacity, and stability in extreme conditions. These porous fiber membranes were functionalized with silver nanoparticles and nanocrystal metal organic frameworks (MOFs) to introduce specific sites to capture gas species that are released during spent nuclear fuel reprocessing. Encapsulation into a durable waste form of ceramic composition was also demonstrated.

Liu, Haiqing; Bell, Nelson Simmons; Cipiti, Benjamin B.; Lewis, Tom Goslee,; Sava, Dorina Florentina; Nenoff, Tina Maria

2012-09-01

241

Dose Effect of Tumor Necrosis Factor-? on In Vitro Osteogenic Differentiation of Mesenchymal Stem Cells on Biodegradable Polymeric Microfiber Scaffolds  

PubMed Central

This study presents a first step in the development of a bone tissue engineering strategy to trigger enhanced osteogenesis by modulating inflammation. This work focused on characterizing the effects of the concentration of a pro-inflammatory cytokine, tumor necrosis factor alpha (TNF-?), on osteogenic differentiation of mesenchymal stem cells (MSCs) grown in a 3D culture system. MSC osteogenic differentiation is typically achieved in vitro through a combination of osteogenic supplements that include the anti-inflammatory corticosteroid dexamethasone. Although simple, the use of dexamethasone is not clinically realistic, and also hampers in vitro studies of the role of inflammatory mediators in wound healing. In this study, MSCs were pre-treated with dexamethasone to induce osteogenic differentiation, and then cultured in biodegradable electrospun poly(?-caprolactone) (PCL) scaffolds, which supported continued MSC osteogenic differentiation in the absence of dexamethasone. Continuous delivery of 0.1 ng/mL of recombinant rat TNF-? suppressed osteogenic differentiation of rat MSCs over 16 days, which was likely the result of residual dexamethasone antagonizing TNF-? signaling. Continuous delivery of a higher dose, 5 ng/mL TNF-?, stimulated osteogenic differentiation for a few days, and 50 ng/mL TNF-? resulted in significant mineralized matrix deposition over the course of the study. These findings suggest that the pro-inflammatory cytokine TNF-? stimulates osteogenic differentiation of MSCs, an effect that can be blocked by the presence of anti-inflammatory agents like dexamethasone, with significant implications on the interplay between inflammation and tissue regeneration. PMID:19963268

Mountziaris, Paschalia M.; Tzouanas, Stephanie; Mikos, Antonios G.

2009-01-01

242

Novel bioactive polyester scaffolds prepared from unsaturated resins based on isosorbide and succinic acid.  

PubMed

In this study new biodegradable materials obtained by crosslinking poly(3-allyloxy-1,2-propylene succinate) (PSAGE) with oligo(isosorbide maleate) (OMIS) and small amount of methyl methacrylate were investigated. The porous scaffolds were obtained in the presence of a foaming system consisted of calcium carbonate/carboxylic acid mixture, creating in situ porous structure during crosslinking of liquid formulations. The maximum crosslinking temperature and setting time, the cured porous materials morphology as well as the effect of their porosity on mechanical properties and hydrolytic degradation process were evaluated. It was found that the kind of carboxylic acid used in the foaming system influenced compressive strength and compressive modulus of porous scaffolds. The MTS cytotoxicity assay was carried out for OMIS using hFOB1.19 cell line. OMIS resin was found to be non-toxic in wide range of concentrations. On the ground of scanning electron microscopy (SEM) observations and energy X-ray dispersive analysis (EDX) it was found that hydroxyapatite (HA) formation at the scaffolds surfaces within short period of soaking in phosphate buffer solution occurs. After 3h immersion a compact layer of HA was observed at the surface of the samples. The obtained results suggest potential applicability of resulted new porous crosslinked polymeric materials as temporary bone void fillers. PMID:25491802

Smiga-Matuszowicz, Monika; Janicki, Bartosz; Jaszcz, Katarzyna; ?ukaszczyk, Jan; Kaczmarek, Marcin; Lesiak, Marta; Siero?, Aleksander L; Simka, Wojciech; Mierzwi?ski, Maciej; Kusz, Damian

2014-12-01

243

MESENCHYMAL STEM CELL DELIVERY INTO RAT INFARCTED MYOCARDIUM USING A POROUS POLYSACCHARIDE-BASED SCAFFOLD: A QUANTITATIVE  

E-print Network

1 MESENCHYMAL STEM CELL DELIVERY INTO RAT INFARCTED MYOCARDIUM USING A POROUS POLYSACCHARIDE myocardial infarction model. Cellular engraftment was measured by quantitative RT-PCR using MSCs previously in the peri-infarct area, mainly phenotypically consistent with immature MSCs. Functional assessment

Paris-Sud XI, Université de

244

Novel synthesis strategies for natural polymer and composite biomaterials as potential scaffolds for tissue engineering  

PubMed Central

Recent developments in tissue engineering approaches frequently revolve around the use of three-dimensional scaffolds to function as the template for cellular activities to repair, rebuild and regenerate damaged or lost tissues. While there are several biomaterials to select as three-dimensional scaffolds, it is generally agreed that a biomaterial to be used in tissue engineering needs to possess certain material characteristics such as biocompatibility, suitable surface chemistry, interconnected porosity, desired mechanical properties and biodegradability. The use of naturally derived polymers as three-dimensional scaffolds has been gaining widespread attention owing to their favourable attributes of biocompatibility, low cost and ease of processing. This paper discusses the synthesis of various polysaccharide-based, naturally derived polymers, and the potential of using these biomaterials to serve as tissue engineering three-dimensional scaffolds is also evaluated. In this study, naturally derived polymers, specifically cellulose, chitosan, alginate and agarose, and their composites, are examined. Single-component scaffolds of plain cellulose, plain chitosan and plain alginate as well as composite scaffolds of cellulose–alginate, cellulose–agarose, cellulose–chitosan, chitosan–alginate and chitosan–agarose are synthesized, and their suitability as tissue engineering scaffolds is assessed. It is shown that naturally derived polymers in the form of hydrogels can be synthesized, and the lyophilization technique is used to synthesize various composites comprising these natural polymers. The composite scaffolds appear to be sponge-like after lyophilization. Scanning electron microscopy is used to demonstrate the formation of an interconnected porous network within the polymeric scaffold following lyophilization. It is also established that HeLa cells attach and proliferate well on scaffolds of cellulose, chitosan or alginate. The synthesis protocols reported in this study can therefore be used to manufacture naturally derived polymer-based scaffolds as potential biomaterials for various tissue engineering applications. PMID:20308112

Ko, Hsu-Feng; Sfeir, Charles; Kumta, Prashant N.

2010-01-01

245

Antitumor activity of docetaxel-loaded polymeric nanoparticles fabricated by Shirasu porous glass membrane-emulsification technique  

PubMed Central

Docetaxel (DTX) has excellent efficiency against a wide spectrum of cancers. However, the current clinical formulation has limited its usage, as it causes some severe side effects. Various polymeric nanoparticles have thus been developed as alternative formulations of DTX, but they have been mostly fabricated on a laboratory scale. Previously, we synthesized a novel copolymer, poly(lactide)-D-?-tocopheryl polyethylene glycol 1000 succinate (PLA-TPGS), and found that it exhibited great potential in drug delivery with improved properties. In this study, we applied the Shirasu porous glass (SPG) membrane-emulsification technique to prepare the DTX-loaded PLA-TPGS nanoparticles on a pilot scale. The effect of several formulation variables on the DTX-loaded nanoparticle properties, including particle size, zeta potential, and drug-encapsulation efficiency, were investigated based on surfactant type and concentration in the aqueous phase, organic/aqueous phase volumetric ratio, membrane-pore size, transmembrane cycles, and operation pressure. The DTX-loaded nanoparticles were obtained with sizes of 306.8 ± 5.5 nm and 334.1 ± 2.7 nm (mean value ± standard deviation), and drug-encapsulation efficiency of 81.8% ± 4.5% and 64.5% ± 2.7% for PLA-TPGS and poly(lactic-co-glycolic acid) (PLGA) nanoparticles, respectively. In vivo pharmacokinetic study exhibited a significant advantage of PLA-TPGS nanoparticles over PLGA nanoparticles and Taxotere. Drug-loaded PLA-TPGS nanoparticles exhibited 1.78-, 6.34- and 3.35-fold higher values for area under the curve, half-life, and mean residence time, respectively, compared with those of PLGA nanoparticles, and 2.23-, 13.2-, 8.51-fold higher than those of Taxotere, respectively. In vivo real-time distribution of nanoparticles was measured on tumor-bearing mice by near-infrared fluorescence imaging, which demonstrated that the PLA-TPGS nanoparticles achieved much higher concentration and longer retention in tumors than PLGA nanoparticles after intravenous injection. This is consistent with the pharmacokinetic behavior of the nanoparticles. The tumor-inhibitory effect of DTX-loaded nanoparticles was observed in vivo in an H22 tumor-bearing mice model via intravenous administration. This indicated that PLA-TPGS nanoparticles are a feasible drug-delivery formulation with a pilot fabrication technique and have superior pharmacokinetic and anticancer effects compared to the commercially available Taxotere. PMID:23935362

Yu, Yunni; Tan, Songwei; Zhao, Shuang; Zhuang, Xiangting; Song, Qingle; Wang, Yuliang; Zhou, Qin; Zhang, Zhiping

2013-01-01

246

Antitumor activity of docetaxel-loaded polymeric nanoparticles fabricated by Shirasu porous glass membrane-emulsification technique.  

PubMed

Docetaxel (DTX) has excellent efficiency against a wide spectrum of cancers. However, the current clinical formulation has limited its usage, as it causes some severe side effects. Various polymeric nanoparticles have thus been developed as alternative formulations of DTX, but they have been mostly fabricated on a laboratory scale. Previously, we synthesized a novel copolymer, poly(lactide)-D-?-tocopheryl polyethylene glycol 1000 succinate (PLA-TPGS), and found that it exhibited great potential in drug delivery with improved properties. In this study, we applied the Shirasu porous glass (SPG) membrane-emulsification technique to prepare the DTX-loaded PLA-TPGS nanoparticles on a pilot scale. The effect of several formulation variables on the DTX-loaded nanoparticle properties, including particle size, zeta potential, and drug-encapsulation efficiency, were investigated based on surfactant type and concentration in the aqueous phase, organic/aqueous phase volumetric ratio, membrane-pore size, transmembrane cycles, and operation pressure. The DTX-loaded nanoparticles were obtained with sizes of 306.8 ± 5.5 nm and 334.1 ± 2.7 nm (mean value ± standard deviation), and drug-encapsulation efficiency of 81.8% ± 4.5% and 64.5% ± 2.7% for PLA-TPGS and poly(lactic-co-glycolic acid) (PLGA) nanoparticles, respectively. In vivo pharmacokinetic study exhibited a significant advantage of PLA-TPGS nanoparticles over PLGA nanoparticles and Taxotere. Drug-loaded PLA-TPGS nanoparticles exhibited 1.78-, 6.34- and 3.35-fold higher values for area under the curve, half-life, and mean residence time, respectively, compared with those of PLGA nanoparticles, and 2.23-, 13.2-, 8.51-fold higher than those of Taxotere, respectively. In vivo real-time distribution of nanoparticles was measured on tumor-bearing mice by near-infrared fluorescence imaging, which demonstrated that the PLA-TPGS nanoparticles achieved much higher concentration and longer retention in tumors than PLGA nanoparticles after intravenous injection. This is consistent with the pharmacokinetic behavior of the nanoparticles. The tumor-inhibitory effect of DTX-loaded nanoparticles was observed in vivo in an H22 tumor-bearing mice model via intravenous administration. This indicated that PLA-TPGS nanoparticles are a feasible drug-delivery formulation with a pilot fabrication technique and have superior pharmacokinetic and anticancer effects compared to the commercially available Taxotere. PMID:23935362

Yu, Yunni; Tan, Songwei; Zhao, Shuang; Zhuang, Xiangting; Song, Qingle; Wang, Yuliang; Zhou, Qin; Zhang, Zhiping

2013-01-01

247

3D Porous Calcium-Alginate Scaffolds Cell Culture System Improved Human Osteoblast Cell Clusters for Cell Therapy  

PubMed Central

Age-related orthopedic disorders and bone defects have become a critical public health issue, and cell-based therapy is potentially a novel solution for issues surrounding bone tissue engineering and regenerative medicine. Long-term cultures of primary bone cells exhibit phenotypic and functional degeneration; therefore, culturing cells or tissues suitable for clinical use remain a challenge. A platform consisting of human osteoblasts (hOBs), calcium-alginate (Ca-Alginate) scaffolds, and a self-made bioreactor system was established for autologous transplantation of human osteoblast cell clusters. The Ca-Alginate scaffold facilitated the growth and differentiation of human bone cell clusters, and the functionally-closed process bioreactor system supplied the soluble nutrients and osteogenic signals required to maintain the cell viability. This system preserved the proliferative ability of cells and cell viability and up-regulated bone-related gene expression and biological apatite crystals formation. The bone-like tissue generated could be extracted by removal of calcium ions via ethylenediaminetetraacetic acid (EDTA) chelation, and exhibited a size suitable for injection. The described strategy could be used in therapeutic application and opens new avenues for surgical interventions to correct skeletal defects.

Chen, Ching-Yun; Ke, Cherng-Jyh; Yen, Ko-Chung; Hsieh, Hui-Chen; Sun, Jui-Sheng; Lin, Feng-Huei

2015-01-01

248

Effect of calcium phosphate coating and rhBMP-2 on bone regeneration in rabbit calvaria using poly(propylene fumarate) scaffolds.  

PubMed

Various calcium phosphate based coatings have been evaluated for better bony integration of metallic implants and are currently being investigated to improve the surface bioactivity of polymeric scaffolds. The aim of this study was to evaluate the role of calcium phosphate coating and simultaneous delivery of recombinant human bone morphogenetic protein-2 (rhBMP-2) on the in vivo bone regeneration capacity of biodegradable, porous poly(propylene fumarate) (PPF) scaffolds. PPF scaffolds were coated with three different calcium phosphate formulations: magnesium-substituted ?-tricalcium phosphate (?-TCMP), carbonated hydroxyapatite (synthetic bone mineral, SBM) and biphasic calcium phosphate (BCP). In vivo bone regeneration was evaluated by implantation of scaffolds in a critical-sized rabbit calvarial defect loaded with different doses of rhBMP-2. Our data demonstrated that scaffolds with each of the calcium phosphate coatings were capable of sustaining rhBMP-2 release and retained an open porous structure. After 6weeks of implantation, micro-computed tomography revealed that the rhBMP-2 dose had a significant effect on bone formation within the scaffolds and that the SBM-coated scaffolds regenerated significantly greater bone than BCP-coated scaffolds. Mechanical testing of the defects also indicated restoration of strength in the SBM and ?-TCMP with rhBMP-2 delivery. Histology results demonstrated bone growth immediately adjacent to the scaffold surface, indicating good osteointegration and osteoconductivity for coated scaffolds. The results obtained in this study suggest that the coated scaffold platform demonstrated a synergistic effect between calcium phosphate coatings and rhBMP-2 delivery and may provide a promising platform for the functional restoration of large bone defects. PMID:25575855

Dadsetan, Mahrokh; Guda, Teja; Runge, M Brett; Mijares, Dindo; LeGeros, Racquel Z; LeGeros, John P; Silliman, David T; Lu, Lichun; Wenke, Joseph C; Brown Baer, Pamela R; Yaszemski, Michael J

2015-05-01

249

Fabrication of mullite-bonded porous SiC ceramics from multilayer-coated SiC particles through sol-gel and in-situ polymerization techniques  

NASA Astrophysics Data System (ADS)

In this work, mullite-bonded porous silicon carbide (SiC) ceramics were prepared via a reaction bonding technique with the assistance of a sol-gel technique or in-situ polymerization as well as a combination of these techniques. In a typical procedure, SiC particles were first coated by alumina using calcined powder and alumina sol via a sol-gel technique followed by drying and passing through a screen. Subsequently, they were coated with the desired amount of polyethylene via an in-situ polymerization technique in a slurry phase reactor using a Ziegler-Natta catalyst. Afterward, the coated powders were dried again and passed through a screen before being pressed into a rectangular mold to make a green body. During the heating process, the polyethylene was burnt out to form pores at a temperature of about 500°C. Increasing the temperature above 800°C led to the partial oxidation of SiC particles to silica. At higher temperatures (above 1400°C) derived silica reacted with alumina to form mullite, which bonds SiC particles together. The porous SiC specimens were characterized with various techniques. The first part of the project was devoted to investigating the oxidation of SiC particles using a Thermogravimetric analysis (TGA) apparatus. The effects of particle size (micro and nano) and oxidation temperature (910°C--1010°C) as well as the initial mass of SiC particles in TGA on the oxidation behaviour of SiC powders were evaluated. To illustrate the oxidation rate of SiC in the packed bed state, a new kinetic model, which takes into account all of the diffusion steps (bulk, inter and intra particle diffusion) and surface oxidation rate, was proposed. Furthermore, the oxidation of SiC particles was analyzed by the X-ray Diffraction (XRD) technique. The effect of different alumina sources (calcined Al2O 3, alumina sol or a combination of the two) on the mechanical, physical, and crystalline structure of mullite-bonded porous SiC ceramics was studied in the second part of the project. Alumina sol was synthesized by the hydrolysis of Aluminum isopropoxide using the Yoldas method. Alumina sol was homogenous and had a needle-like shape with a thickness of 2--3 nm. Crystalline changes during the heating process of alumina sol were studied using XRD. In addition, Fourier transform infrared (FTIR) spectroscopy was performed to identify the functional groups on the alumina sol surface as a function of temperature. In the third part of the project, the feasibility of the in-situ polymerization technique was investigated to fabricate porous SiC ceramics. In this part, the mixture of SiC and calcined alumina powders were coated by polyethylene via in-situ polymerizing referred to as the polymerization compounding process in a slurry phase. The polymerization was conducted under very moderate operational conditions using the Ziegler-Natta catalyst system. Differential scanning calorimetry (DSC) and TGA analysis and morphological studies (SEM and TEM) revealed the presence of a high density of polyethylene on the surface of SiC and alumina powders. The amount of polymer was controlled by the polymerization reaction time. Most parts of particles were coated by a thin layer of polyethylene and polymer. The porous SiC ceramics, which were fabricated by these treated particles showed higher mechanical and physical properties compared to the samples made without any treatment. The relative intensity of mullite was higher compared to the samples prepared by the traditional process. The effects of the sintering temperature, forming pressure and polymer content were also studied on the physical and mechanical properties of the final product. In the last phase of this research work, the focus of the investigation was to take advantage of both the sol-gel processing and in-situ polymerization method to develop a new process to manufacture mullite-bonded porous SiC ceramic with enhanced mechanical and physical properties. Therefore, first the SiC particles and alumina nano powders were mixed in alumina sol to adjust the alumina weight to 35

Ebrahimpour, Omid

250

Translating textiles to tissue engineering: Creation and evaluation of microporous, biocompatible, degradable scaffolds using industry relevant manufacturing approaches and human adipose derived stem cells.  

PubMed

Polymeric scaffolds have emerged as a means of generating three-dimensional tissues, such as for the treatment of bone injuries and nonunions. In this study, a fibrous scaffold was designed using the biocompatible, degradable polymer poly-lactic acid in combination with a water dispersible sacrificial polymer, EastONE. Fibers were generated via industry relevant, facile scale-up melt-spinning techniques with an islands-in-the-sea geometry. Following removal of EastONE, a highly porous fiber remained possessing 12 longitudinal channels and pores throughout all internal and external fiber walls. Weight loss and surface area characterization confirmed the generation of highly porous fibers as observed via focused ion beam/scanning electron microscopy. Porous fibers were then knit into a three-dimensional scaffold and seeded with human adipose-derived stem cells (hASC). Confocal microscopy images confirmed hASC attachment to the fiber walls and proliferation throughout the knit structure. Quantification of cell-mediated calcium accretion following culture in osteogenic differentiation medium confirmed hASC differentiation throughout the porous constructs. These results suggest incorporation of a sacrificial polymer within islands-in-the-sea fibers generates a highly porous scaffold capable of supporting stem cell viability and differentiation with the potential to generate large three-dimensional constructs for bone regeneration and/or other tissue engineering applications. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014. PMID:25229198

Haslauer, Carla M; Avery, Matthew R; Pourdeyhimi, Behnam; Loboa, Elizabeth G

2014-09-17

251

A design protocol for tailoring ice-templated scaffold structure  

E-print Network

In this paper, we show, for the first time, the key link between scaffold architecture and latent heat evolution during the production of porous biomedical collagen structures using freeze-drying. Collagen scaffolds are used widely in the biomedical...

Pawelec, K. A.; Husmann, A.; Best, Serena Michelle; Cameron, Ruth Elizabeth

2014-03-06

252

Development of a new pre-vascularized tissue-engineered construct using pre-differentiated rADSCs, arteriovenous vascular bundle and porous nano-hydroxyapatide-polyamide 66 scaffold  

PubMed Central

Background Development of a pre-vascularized tissue-engineered construct with intrinsic vascular system for cell growth and tissue formation still faces many difficulties due to the complexity of the vascular network of natural bone tissue. The present study was to design and form a new vascularized tissue-engineered construct using pre-differentiated rADSCs, arteriovenous vascular bundle and porous nHA-PA 66 scaffold. Methods rADSCs were pre-differentiated to endothelial cells (rADSCs-Endo) and then incorporated in nHA-PA 66 scaffolds in vitro. Subsequently, in vivo experiments were carried out according to the following groups: Group A (rADSCs-Endo/nHA-PA 66 scaffold with arteriovenous vascular bundle), Group B (rADSCs/nHA-PA 66 scaffold with arteriovenous vascular bundle); Group C (nHA-PA66 scaffold with arteriovenous vascular bundle), Group D (nHA-PA 66 scaffold only). The vessel density and vessel diameter were measured based on histological and immunohistochemical evaluation, furthermore, the VEGF-C, FGF-2 and BMP-2 protein expressions were also evaluated by western blot analysis. Results The results of in vivo experiments showed that the vessel density and vessel diameter in group A were significantly higher than the other three groups. Between Group B and C, no statistical difference was observed at each time point. In accordance with the results, there were dramatically higher expressions of VEGF-C and FGF-2 protein in Group A than that of Group B, C and D at 2 or 4 weeks. Statistical differences were not observed in VEGF-C and FGF-2 expression between Group B and C. BMP-2 was not expressed in any group at each time point. Conclusions Compared with muscular wrapping method, arteriovenous vascular bundle implantation could promote vascularization of the scaffold; and the angiogenesis of the scaffold was significantly accelerated when pre-differentiated rADSCs (endothelial differentiation) were added. These positive results implicate the combination of pre-differentiated rADSCs (endothelial differentiation) and arteriovenous vascular bundle may achieve rapidly angiogenesis of biomaterial scaffold. PMID:24209783

2013-01-01

253

An Open Source Image Processing Method to Quantitatively Assess Tissue Growth after Non-Invasive Magnetic Resonance Imaging in Human Bone Marrow Stromal Cell Seeded 3D Polymeric Scaffolds  

PubMed Central

Monitoring extracellular matrix (ECM) components is one of the key methods used to determine tissue quality in three-dimensional (3D) scaffolds for regenerative medicine and clinical purposes. This is even more important when multipotent human bone marrow stromal cells (hMSCs) are used, as it could offer a method to understand in real time the dynamics of stromal cell differentiation and eventually steer it into the desired lineage. Magnetic Resonance Imaging (MRI) is a promising tool to overcome the challenge of a limited transparency in opaque 3D scaffolds. Technical limitations of MRI involve non-uniform background intensity leading to fluctuating background signals and therewith complicating quantifications on the retrieved images. We present a post-imaging processing sequence that is able to correct for this non-uniform background intensity. To test the processing sequence we investigated the use of MRI for in vitro monitoring of tissue growth in three-dimensional poly(ethylene oxide terephthalate)–poly(butylene terephthalate) (PEOT/PBT) scaffolds. Results showed that MRI, without the need to use contrast agents, is a promising non-invasive tool to quantitatively monitor ECM production and cell distribution during in vitro culture in 3D porous tissue engineered constructs. PMID:25502022

Leferink, Anne M.; Fratila, Raluca M.; Koenrades, Maaike A.; van Blitterswijk, Clemens A.; Velders, Aldrik; Moroni, Lorenzo

2014-01-01

254

High-precision flexible fabrication of tissue engineering scaffolds using distinct polymers  

SciTech Connect

Three-dimensional porous structures using biodegradable materials with excellent biocompatibility are critically important for tissue engineering applications. We present a multi-nozzle-based versatile deposition approach to flexibly construct porous tissue engineering scaffolds using distinct polymeric biomaterials such as thermoplastic and photo-crosslinkable polymers. We first describe the development of the deposition system and fabrication of scaffolds from two types of biodegradable polymers using this system. The thermoplastic sample is semi-crystalline poly({var_epsilon}-caprolactone) (PCL) that can be processed at a temperature higher than its melting point and solidifies at room temperature. The photo-crosslinkable one is polypropylene fumarate (PPF) that has to be dissolved in a reactive solvent as a resin for being cured into solid structures. Besides the direct fabrication of thermoplastic PCL scaffolds, we specifically develop a layer molding approach for the fabrication of crosslinkable polymers, which traditionally can only be fabricated by stereolithography. In this approach, a thermoplastic supporting material (paraffin wax) is first deposited to make a mold for each specific layer, and then PPF is deposited on demand to fill the mold and cured by the UV light. The supporting material can be removed to produce a porous scaffold of crosslinked PPF. Both PCL and crosslinked PPF scaffolds fabricated using the developed system have been characterized in terms of compressive mechanical properties, morphology, pore size and porosity. Mouse MC3T3-E1 pre-osteoblastic cell studies on the fabricated scaffolds have been performed to demonstrate their capability of supporting cell proliferation and ingrowth, aiming for bone tissue engineering applications.

Wei, Chuang [North Carolina State University; Cai, Lei [ORNL; Sonawane, Bhushan [North Carolina State University; Wang, Shanfeng [ORNL; Dong, Jingyan [North Carolina State University

2012-01-01

255

A biodegradable polymeric system for peptide–protein delivery assembled with porous microspheres and nanoparticles, using an adsorption/infiltration process  

PubMed Central

A biodegradable polymeric system is proposed for formulating peptides and proteins. The systems were assembled through the adsorption of biodegradable polymeric nanoparticles onto porous, biodegradable microspheres by an adsorption/infiltration process with the use of an immersion method. The peptide drug is not involved in the manufacturing of the nanoparticles or in obtaining the microspheres; thus, contact with the organic solvent, interfaces, and shear forces required for the process are prevented during drug loading. Leuprolide acetate was used as the model peptide, and poly(d,l-lactide-co-glycolide) (PLGA) was used as the biodegradable polymer. Leuprolide was adsorbed onto different amounts of PLGA nanoparticles (25 mg/mL, 50 mg/mL, 75 mg/mL, and 100 mg/mL) in a first stage; then, these were infiltrated into porous PLGA microspheres (100 mg) by dipping the structures into a microsphere suspension. In this way, the leuprolide was adsorbed onto both surfaces (ie, nanoparticles and microspheres). Scanning electron microscopy studies revealed the formation of a nanoparticle film on the porous microsphere surface that becomes more continuous as the amount of infiltrated nanoparticles increases. The adsorption efficiency and release rate are dependent on the amount of adsorbed nanoparticles. As expected, a greater adsorption efficiency (~95%) and a slower release rate were seen (~20% of released leuprolide in 12 hours) when a larger amount of nanoparticles was adsorbed (100 mg/mL of nanoparticles). Leuprolide acetate begins to be released immediately when there are no infiltrated nanoparticles, and 90% of the peptide is released in the first 12 hours. In contrast, the systems assembled in this study released less than 44% of the loaded drug during the same period of time. The observed release profiles denoted a Fickian diffusion that fit Higuchi’s model (t1/2). The manufacturing process presented here may be useful as a potential alternative for formulating injectable depots for sensitive hydrophilic drugs such as peptides and proteins, among others. PMID:23788833

Alcalá-Alcalá, Sergio; Urbán-Morlán, Zaida; Aguilar-Rosas, Irene; Quintanar-Guerrero, David

2013-01-01

256

Osteogenesis and angiogenesis induced by porous ?-CaSiO(3)/PDLGA composite scaffold via activation of AMPK/ERK1/2 and PI3K/Akt pathways.  

PubMed

As a potential bioactive material, ?-calcium silicate (?-CS) has attracted particular attention in the field of bone regeneration. In this study, porous ?-CS/Poly-D,L-Lactide-Glycolide (PDLGA) composite scaffolds were developed with the goals of controlling the degradation rate and improving the mechanical and biological properties. The compressive strength and toughness were significantly enhanced by PDLGA modification of porous ?-CS ceramic scaffolds. The effects of the ionic extract from ?-CS/PDLGA composite scaffolds on osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (rBMSCs), proliferation of human umbilical vein endothelial cells (HUVECs) and the related mechanisms were investigated. It was shown that bioactive ions from ?-CS/PDLGA scaffolds could enhance cell viability, alkaline phosphatase (ALP) activity, calcium mineral deposition, and mRNA expression levels of osteoblast-related genes of rBMSCs without addition of extra osteogenic reagents. The activation in AMP-activated protein kinase (AMPK), extracellular signal-related kinases (ERK) 1/2 and RUNX-2 were observed in rBMSCs cultured in the extract of ?-CS/PDLGA, and these effects could be blocked by AMPK inhibitor Compound C. The extracts of ?-CS/PDLGA composites stimulated HUVECs proliferation that was associated with phosphorylation of protein kinase B (Akt) and endothelial nitric oxide synthase (eNOS) as well as an increase in nitric oxide (NO) production and secretion of vascular endothelial growth factor (VEGF). The inductions were abolished by the addition of phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. The composite scaffolds were implanted in critical sized rabbit femur defects (6 × 10 mm) for 4, 12 and 20 weeks with ?-tricalcium phosphate (?-TCP) as controls. Sequential histological evaluations and radiographs revealed that ?-CS/PDLGA dramatically stimulated new bone formation and angiogenesis. The biodegradation rate of the ?-CS/PDLGA scaffolds was lower than that of ?-TCP at each time point examined, and matched the new bone formation rates. These data suggest that ?-CS/PDLGA could promote bone regeneration in vivo, which might be ascribed to the enhanced osteogenic differentiation of mesenchymal stem cells (MSCs) and increased angiogenic activity of endothelial cells (ECs). PMID:23069715

Wang, Chen; Lin, Kaili; Chang, Jiang; Sun, Jiao

2013-01-01

257

In situ synthesis of molecularly imprinted nanoparticles in porous support membranes using high-viscosity polymerization solvents.  

PubMed

There is a growing need in membrane separations for novel membrane materials providing selective retention. Molecularly imprinted polymers (MIPs) are promising candidates for membrane functionalization. In this work, a novel approach is described to prepare composite membrane adsorbers incorporating molecularly imprinted microparticles or nanoparticles into commercially available macroporous filtration membranes. The polymerization is carried out in highly viscous polymerization solvents, and the particles are formed in situ in the pores of the support membrane. MIP particle composite membranes selective for terbutylazine were prepared and characterized by scanning electron microscopy and N? porosimetry. By varying the polymerization solvent microparticles or nanoparticles with diameters ranging from several hundred nanometers to 1 µm could be embedded into the support. The permeability of the membranes was in the range of 1000 to 20,000 Lm?² ?hr?¹ ?bar?¹. The imprinted composite membranes showed high MIP/NIP (nonimprinted polymer) selectivity for the template in organic media both in equilibrium-rebinding measurements and in filtration experiments. The solid phase extraction of a mixture of the template, its analogs, and a nonrelated compound demonstrated MIP/NIP selectivity and substance selectivity of the new molecularly imprinted membrane. The synthesis technique offers a potential for the cost-effective production of selective membrane adsorbers with high capacity and high throughput. PMID:22641529

Renkecz, Tibor; László, Krisztina; Horváth, Viola

2012-06-01

258

Porous nitrogen-doped carbon microspheres derived from microporous polymeric organic frameworks for high performance electric double-layer capacitors.  

PubMed

This research presents a simple and efficient method to synthesize porous nitrogen-doped carbon microspheres (PNCM) by the carbonization of microporous poly(terephthalaldehyde-pyrrole) organic frameworks (PtpOF). The common KOH activation process is used to tune the porous texture of the PNCM and produce an activated-PNCM (A-PNCM). The PNCM and A-PNCM with specific surface area of 921 and 1303 m(2) ?g(-1) , respectively, are demonstrated as promising candidates for EDLCs. At a current density of 0.5 A g(-1) , the specific capacitances of the PNCM and A-PNCM are 248 and 282 F g(-1) , respectively. At the relatively high current density of 20 A?g(-1) , the capacitance remaining is 95 and 154 F g(-1) , respectively. Capacity retention of the A-PNCM is more than 92% after 10000 charge/discharge cycles at a current density of 2 A g(-1) . PMID:25469994

Han, Jinpeng; Xu, Guiyin; Dou, Hui; MacFarlane, Douglas R

2015-02-01

259

Porous carbon anodes for a high capacity lithium-ion battery obtained by incorporating silica into benzoxazine during polymerization.  

PubMed

Porous carbon anodes with a controllable Vmes /Vmic ratio were synthesized through the self-assembly of poly(benzoxazine-co-resol) and the simultaneous hydrolysis of tetraethyl orthosilicate (TEOS) followed by carbonization and removal of silica. The Vmes /Vmic ratio of the carbon can be controlled in the range of approximately 1.3-32.6 through tuning the amount of TEOS. For lithium-ion battery anodes, a correlation between the electrochemical performance and Vmes /Vmic ratio has been established. A high Vmes /Vmic ratio in porous carbons is favorable for enhancing the accessibility of Li ions to active sites provided by the micropores and for achieving good lithium storage performance. The obtained porous carbon exhibits a high reversible capacity of 660?mAh?g(-1) after 70 cycles at a current density of 100?mA?g(-1) . Moreover, at a high current density of 3000?mA?g(-1) , the capacity still remains at 215?mAh?g(-1) , showing a fast charge-discharge potential. This synthesis method relying on modified benzoxazine chemistry with the hydrolysis of TEOS may provide a new route for the development of mesoporous carbon-based electrode materials. PMID:25428788

Guo, De-Cai; Han, Fei; Lu, An-Hui

2015-01-19

260

Biodegradable porous sheet-like scaffolds for soft-tissue engineering using a combined particulate leaching of salt particles and magnetic sugar particles.  

PubMed

Scaffolds serving as artificial extracellular matrixes (ECMs) play a pivotal role in the process of tissue regeneration by providing optimal cellular environments for penetration, ingrowth, and vascularization. Stacks of sheet-like scaffold can be engineered to become artificial ECMs, suggesting a great potential for achieving complex 3-D tissue regeneration to support cell survival and growth. In this study, we proposed and investigated a combined particulate leaching of magnetic sugar particles (MSPs) and salt particles for the development of a sheet-like scaffold. MSPs were fabricated by encapsulating NdFeB particles inside sugar spheres and were controlled using magnetic fields as a porogen to control pore size, pore structure and pore density while fabricating the scaffold. We studied the influence of the strength of the magnetic fields in controlling the coating thickness of the unmagnetized MSPs during the fabrication of the sheet-like scaffolds. The experimental relationship between magnetic flux density and the thickness of the MSP layer was illustrated. Furthermore, we investigated the infiltration capacity of different concentrations of poly(L-lactide-co-?-caprolactone) (PLCL) as a scaffold material on MSP clusters. Following polymer casting and removal of the sugar template, spherical pores were generated inside the scaffolds. Cultivation of NIH/3T3 fibroblasts on the fabricated scaffold proves that the proposed method can be applied in the cell sheet fabrication. PMID:23462200

Hu, Chengzhi; Tercero, Carlos; Ikeda, Seiichi; Nakajima, Masahiro; Tajima, Hirotaka; Shen, Yajing; Fukuda, Toshio; Arai, Fumihito

2013-07-01

261

Three-dimensional cellular distribution in polymeric scaffolds for bone regeneration: a microCT analysis compared to SEM, CLSM and DNA content.  

PubMed

In orthopaedic surgery the tissues damaged by injury or disease could be replaced using constructs based on biocompatible materials, cells and growth factors. Scaffold design, porosity and early colonization are key components for the implant success. From biological point of view, attention may be also given to the number, type and size of seeded cells, as well as the seeding technique and cell morphological and volumetric alterations. This paper describes the use of the microCT approach (to date used principally for mineralized matrix quantification) to observe construct colonization in terms of cell localization, and make a direct comparison of the microtomographic sections with scanning electron microscopy images and confocal laser scanning microscope analysis. Briefly, polycaprolactone scaffolds were seeded at different cell densities with MG63 osteoblastic-like cells. Two different endpoints, 1 and 2 weeks, were selected for the three-dimensional colonization and proliferation analysis of the cells. By observing all images obtained, in addition to a more extensive distribution of cells on scaffolds surfaces than in the deeper layers, cell volume increased at 2 weeks compared to 1 week after seeding. Combining the cell number quantification by deoxyribonucleic acid analysis and the single cell volume changes by confocal laser scanning microscope, we validated the microCT segmentation method by finding no statistical differences in the evaluation of the cell volume fraction of the scaffold. Furthermore, the morphological results of this study suggest that an effective scaffold colonization requires a precise balance between different factors, such as number, type and size of seeded cells in addition to scaffold porosity. PMID:24802370

Parrilli, A; Pagani, S; Maltarello, M C; Santi, S; Salerno, A; Netti, P A; Giardino, R; Rimondini, L; Fini, M

2014-07-01

262

RhBMP-2-loaded calcium silicate/calcium phosphate cement scaffold with hierarchically porous structure for enhanced bone tissue regeneration.  

PubMed

Calcium phosphate cement scaffold (CPC) has been widely used as bone graft substitutes, but undesirable osteoinductivity and slow degradability greatly hamper their clinic application. To address these problems, a recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded calcium silicate/calcium phosphate cement scaffold (CSPC) with hierarchical pores was developed in this study. The CSPC scaffold with both interconnected macropores on the order of 200-500 ?m and micropores of 2-5 ?m was synthesized from CPC and calcium silicate (CS) by a NaCl particulate-leaching method. In vitro cell culture with C2C12 model cells, in vivo ectopic bone formation and rabbit femur cavity defect repair were performed to evaluate the osteogeneic capacity of the CSPC/rhBMP-2 scaffold. CPC, CSPC and CPC/rhBMP-2 scaffolds were parallelly investigated for comparison. The results demonstrated that the hierarchical macro/microporous structure, whether in presence of CS or rhBMP-2, highly favored the adhesion of C2C12 cells and bone in-growth into the CPC-based scaffolds. But, in comparison to the CPC-based scaffolds with CS or rhBMP-2 alone, the CSPC/rhBMP-2 scaffold strongly promoted osteogenic differentiation in vitro and osteogenetic efficacy in vivo. Further studies demonstrated that Si ions derived from CSPC contributed mainly to maintain the conformation of rhBMP-2 and thus stimulate the synergistic action of CS and rhBMP-2 in osteogenic differentiation and osteoinductivity. Additionally, the incorporation of CS was also beneficial for the dissolution of the scaffold. Those results suggest that the CSPC has superior properties for incorporation of rhBMP-2 and our developed CSPC/rhBMP-2 scaffold have great potential for future use in bone tissue regeneration. PMID:24044997

Zhang, Jing; Zhou, Huanjun; Yang, Kai; Yuan, Yuan; Liu, Changsheng

2013-12-01

263

Degradable glycine-based photo-polymerizable polyphosphazenes for use as scaffolds for tissue regeneration.  

PubMed

Photo-polymerizable scaffolds are designed and prepared via short chain poly(organo)phosphazene building blocks bearing glycine allylester moieties. The polyphosphazene was combined with a trifunctional thiol and divinylester in various ratios, followed by thiol-ene photo-polymerization to obtain porous matrices. Degradation studies under aqueous conditions showed increasing rates in correlation with the polyphosphazene content. Preliminary cell studies show the non-cytotoxic nature of the polymers and their degradation products, as well as the cell adhesion and proliferation of adipose-derived stem cells. PMID:25355036

Rothemund, Sandra; Aigner, Tamara B; Iturmendi, Aitziber; Rigau, Maria; Husár, Branislav; Hildner, Florian; Oberbauer, Eleni; Prambauer, Martina; Olawale, Gbenga; Forstner, Reinhard; Liska, Robert; Schröder, Klaus R; Brüggemann, Oliver; Teasdale, Ian

2015-03-01

264

A Bi-Layered Elastomeric Scaffold for Tissue Engineering of Small-Diameter Vascular Grafts  

PubMed Central

A major barrier in the development of a clinically-useful small-diameter tissue engineered vascular graft (TEVG) is the scaffold component. Scaffold requirements include matching the mechanical and structural properties with those of native vessels and optimizing the microenvironment to foster cell integration, adhesion, and growth. We have developed a small-diameter, bi-layered, biodegradable, elastomeric scaffold based on a synthetic, biodegradable elastomer. The scaffold incorporates a highly porous inner layer, allowing cell integration and growth, and an external, fibrous reinforcing layer deposited by electrospinning. Scaffold morphology and mechanical properties were assessed, quantified, and compared to those of native vessels. Scaffolds were then seeded with adult stem cells via a rotational vacuum seeding device to obtain a TEVG, cultured in dynamic conditions for 7 days, and evaluated for cellularity. The scaffold showed a firm integration of the two polymeric layers with no delaminations. Mechanical properties were physiologically-consistent showing anisotropy, elastic modulus (1.4±0.4 MPa), and ultimate tensile stress (8.3±1.7 MPa) comparable with native vessels. Compliance and suture retention force were 4.6±0.5×10?4 mmHg?1 and 3.4±0.3 N, respectively. Seeding resulted in a rapid, uniform, bulk integration of cells, with a seeding efficiency of 92±1%. The scaffolds maintained a high level of cellular density throughout dynamic culture. This approach, combining artery-like mechanical properties and a rapid and efficient cellularization, might contribute to the future clinical translation of TEVGs. PMID:19540370

Soletti, Lorenzo; Hong, Yi; Guan, Jianjun; Stankus, John J.; El-Kurdi, Mohammed S.; Wagner, William R.; Vorp, David A.

2011-01-01

265

Evaluation of thresholding techniques for segmenting scaffold images in tissue engineering  

NASA Astrophysics Data System (ADS)

Tissue engineering attempts to address the ever widening gap between the demand and supply of organ and tissue transplants using natural and biomimetic scaffolds. The regeneration of specific tissues aided by synthetic materials is dependent on the structural and morphometric properties of the scaffold. These properties can be derived non-destructively using quantitative analysis of high resolution microCT scans of scaffolds. Thresholding of the scanned images into polymeric and porous phase is central to the outcome of the subsequent structural and morphometric analysis. Visual thresholding of scaffolds produced using stochastic processes is inaccurate. Depending on the algorithmic assumptions made, automatic thresholding might also be inaccurate. Hence there is a need to analyze the performance of different techniques and propose alternate ones, if needed. This paper provides a quantitative comparison of different thresholding techniques for segmenting scaffold images. The thresholding algorithms examined include those that exploit spatial information, locally adaptive characteristics, histogram entropy information, histogram shape information, and clustering of gray-level information. The performance of different techniques was evaluated using established criteria, including misclassification error, edge mismatch, relative foreground error, and region non-uniformity. Algorithms that exploit local image characteristics seem to perform much better than those using global information.

Rajagopalan, Srinivasan; Yaszemski, Michael J.; Robb, Richard A.

2004-05-01

266

Bone tissue engineering using polycaprolactone scaffolds fabricated via selective laser sintering  

Microsoft Academic Search

Polycaprolactone (PCL) is a bioresorbable polymer with potential applications for bone and cartilage repair. In this work, porous PCL scaffolds were computationally designed and then fabricated via selective laser sintering (SLS), a rapid prototyping technique. The microstructure and mechanical properties of the fabricated scaffolds were assessed and compared to the designed porous architectures and computationally predicted properties. Scaffolds were then

Jessica M. Williams; Adebisi Adewunmi; Rachel M. Schek; Colleen L. Flanagan; Paul H. Krebsbach; Stephen E. Feinberg; Scott J. Hollister; Suman Das

2005-01-01

267

Elastin-Coated Biodegradable Photopolymer Scaffolds for Tissue Engineering Applications  

PubMed Central

One of the main open issues in modern vascular surgery is the nonbiodegradability of implants used for stent interventions, which can lead to small caliber-related thrombosis and neointimal hyperplasia. Some new, resorbable polymeric materials have been proposed to substitute traditional stainless-steel stents, but so far they were affected by poor mechanical properties and low biocompatibility. In this respect, a new material, polypropylene fumarate (PPF), may be considered as a promising candidate to implement the development of next generation stents, due to its complete biodegradability, and excellent mechanical properties and the ease to be precisely patterned. Besides all these benefits, PPF has not been tested yet for vascular prosthesis, mainly because it proved to be almost inert, while the ability to elicit a specific biological function would be of paramount importance in such critical surgery applications. Here, we propose a biomimetic functionalization process, aimed at obtaining specific bioactivation and thus improved cell-polymer interaction. Porous PPF-based scaffolds produced by deep-UV photocuring were coated by elastin and the functionalized scaffolds were extensively characterized, revealing a stable bound between the protein and the polymer surface. Both 3T3 and HUVEC cell lines were used for in vitro tests displaying an enhancement of cells adhesion and proliferation on the functionalized scaffolds. PMID:25405204

Barenghi, Rossella; Beke, Szabolcs; Gavazzo, Paola; Farkas, Balázs; Scaglione, Silvia

2014-01-01

268

Investigation of Neovascularization in Three-Dimensional Porous Scaffolds In Vivo by a Combination of Multiscale Photoacoustic Microscopy and Optical Coherence Tomography  

PubMed Central

It is a grand challenge to visualize and assess in vivo neovascularization in a three-dimensional (3D) scaffold noninvasively, together with high spatial resolution and deep penetration depth. Here we used multiscale photoacoustic microscopy (PAM), including acoustic-resolution PAM (AR-PAM) and optical-resolution PAM (OR-PAM), to chronically monitor neovascularization in an inverse opal scaffold implanted in a mouse model up to 6 weeks by taking advantage of the optical absorption contrast intrinsic to hemoglobin molecules in red blood cells. By combining with optical coherence tomography (OCT) based on optical scattering contrast, we also demonstrated the capability to simultaneously image and analyze the vasculature and the scaffold in the same mouse. The hybrid system containing OR-PAM and OCT offered a fine lateral resolution of ?5??m and a penetration depth of ?1?mm into the scaffold/tissue construct. AR-PAM further extended the penetration depth up to ?3?mm at a lateral resolution of ?45??m. By quantifying the 3D PAM data, we further examined the effect of pore size (200 vs. 80??m) of a scaffold on neovascularization. The data collected from PAM were consistent with those obtained from traditional invasive, labor-intensive histologic analyses. PMID:22838500

Cai, Xin; Zhang, Yu; Li, Li; Choi, Sung-Wook; MacEwan, Matthew R.; Yao, Junjie; Kim, Chulhong

2013-01-01

269

Novel Scaffolds Fabricated Using Oleuropein for Bone Tissue Engineering  

PubMed Central

We investigated the feasibility of oleuropein as a cross-linking agent for fabricating three-dimensional (3D) porous composite scaffolds for bone tissue engineering. Human-like collagen (HLC) and nanohydroxyapatite (n-HAp) were used to fabricate the composite scaffold by way of cross-linking. The mechanical tests revealed superior properties for the cross-linked scaffolds compared to the uncross-linked scaffolds. The as-obtained composite scaffold had a 3D porous structure with pores ranging from 120 to 300??m and a porosity of 73.6 ± 2.3%. The cross-linked scaffolds were seeded with MC3T3-E1 Subclone 14 mouse osteoblasts. Fluorescence staining, the Cell Counting Kit-8 (CCK-8) assay, and scanning electron microscopy (SEM) indicated that the scaffolds enhanced cell adhesion and proliferation. Our results indicate the potential of these scaffolds for bone tissue engineering. PMID:24959582

Fan, Hui; Hui, Junfeng; Duan, Zhiguang; Fan, Daidi; Mi, Yu; Deng, Jianjun; Li, Hui

2014-01-01

270

Functionalized carbon nanotube reinforced scaffolds for bone regenerative engineering: fabrication, in vitro and in vivo evaluation.  

PubMed

Designing biodegradable scaffolds with bone-compatible mechanical properties has been a significant challenge in the field of bone tissue engineering and regenerative engineering. The objective of this work is to improve the polymeric scaffold's mechanical strength by compositing it with mechanically superior carbon nanotubes. Poly(lactide-co-glycolide) (PLGA) microsphere scaffolds exhibit mechanical properties in the range of human cancellous bone. On the other hand, carbon nanotubes have outstanding mechanical properties. The aim of this study is to improve further the mechanical strength of PLGA scaffolds such that they may be applicable for a wide range of load-bearing repair and regeneration applications. We have formed composite microspheres of PLGA containing pristine and modified (with hydroxyl (OH), carboxylic acid (COOH)) multi-walled carbon nanotubes (MWCNTs), and fabricated them into three-dimensional porous scaffolds. Results show that by adding only 3% MWCNTs, the compressive strength and modulus was significantly increased (35 MPa, 510.99 MPa) compared to pure PLGA scaffolds (19 MPa and 166.38 MPa). Scanning electron microscopy images showed excellent cell adhesion and proliferation. In vitro studies exhibited good cell viability, proliferation and mineralization. The in vivo study, however, indicated differences in inflammatory response throughout the 12 weeks of implantation, with OH-modified MWCNTs having the least response, followed by unmodified and COOH-modified exhibiting a more pronounced response. Overall, our results show that PLGA scaffolds containing water-dispersible MWCNTs are mechanically stronger and display good cellular and tissue compatibility, and hence are potential candidates for load-bearing bone tissue engineering. PMID:24687391

Mikael, Paiyz E; Amini, Ami R; Basu, Joysurya; Josefina Arellano-Jimenez, M; Laurencin, Cato T; Sanders, Mary M; Barry Carter, C; Nukavarapu, Syam P

2014-06-01

271

Lysis of gram-positive and gram-negative bacteria by antibacterial porous polymeric monolith formed in microfluidic biochips for sample preparation.  

PubMed

Bacterial cell lysis is demonstrated using polymeric microfluidic biochips operating via a hybrid mechanical shearing/contact killing mechanism. These biochips are fabricated from a cross-linked poly(methyl methacrylate) (X-PMMA) substrate by well-controlled, high-throughput laser micromachining. The unreacted double bonds at the surface of X-PMMA provide covalent bonding for the formation of a porous polymeric monolith (PPM), thus contributing to the mechanical stability of the biochip and eliminating the need for surface treatment. The lysis efficiency of these biochips was tested for gram-positive (Enterococcus saccharolyticus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli and Pseudomonas fluorescens) and confirmed by off-chip PCR without further purification. The influence of the flow rate when pumping the bacterial suspension through the PPM, and of the hydrophobic-hydrophilic balance on the cell lysis efficiency was investigated at a cell concentration of 10(5) CFU/mL. It was shown that the contribution of contact killing to cell lysis was more important than that of mechanical shearing in the PPM. The biochip showed better lysis efficiency than the off-chip chemical, mechanical, and thermal lysis techniques used in this work. The biochip also acts as a filter that isolates cell debris and allows PCR-amplifiable DNA to pass through. The system performs more efficient lysis for gram-negative than for gram-positive bacteria. The biochip does not require chemical/enzymatic reagents, power consumption, or complicated design and fabrication processes, which makes it an attractive on-chip lysis device that can be used in sample preparation for genetics and point-of-care diagnostics. The biochips were reused for 20 lysis cycles without any evidence of physical damage to the PPM, significant performance degradation, or DNA carryover when they were back-flushed between cycles. The biochips efficiently lysed both gram-positive and gram-negative bacteria in about 35 min per lysis and PPM regeneration cycle. PMID:25059724

Aly, Mohamed Aly Saad; Gauthier, Mario; Yeow, John

2014-09-01

272

Acrylic-acid-functionalized PolyHIPE scaffolds for use in 3D cell culture.  

PubMed

This study describes the development of a functional porous polymer for use as a scaffold to support 3D hepatocyte culture. A high internal phase emulsion (HIPE) is prepared containing the monomers styrene (STY), divinylbenzene (DVB), and 2-ethylhexyl acrylate (EHA) in the external oil phase and the monomer acrylic acid (Aa) in the internal aqueous phase. Upon thermal polymerization with azobisisobutyronitrile (AIBN), the resulting porous polymer (polyHIPE) is found to have an open-cell morphology and a porosity of 89%, both suitable characteristics for 3D cell scaffold applications. X-ray photo-electron spectroscopy reveals that the polyHIPE surface contained 7.5% carboxylic acid functionality, providing a useful substrate for subsequent surface modifications and bio-conjugations. Initial bio-compatibility assessments with human hepatocytes show that the acid functionality does not have any detrimental effect on cell adhesion. It is therefore believed that this material can be a useful precursor scaffold towards 3D substrates that offer tailored surface functionality for enhanced cell adhesion. PMID:24243821

Hayward, Adam S; Sano, Naoko; Przyborski, Stefan A; Cameron, Neil R

2013-12-01

273

Recent advances in bone tissue engineering scaffolds  

PubMed Central

Bone disorders are of significant concern due to increase in the median age of our population. Traditionally, bone grafts have been used to restore damaged bone. Synthetic biomaterials are now being used as bone graft substitutes. These biomaterials were initially selected for structural restoration based on their biomechanical properties. Later scaffolds were engineered to be bioactive or bioresorbable to enhance tissue growth. Now scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous, biodegradable materials that harbor different growth factors, drugs, genes or stem cells. In this review, we highlight recent advances in bone scaffolds and discuss aspects that still need to be improved. PMID:22939815

Bose, Susmita; Roy, Mangal; Bandyopadhyay, Amit

2012-01-01

274

Dexamethasone-releasing biodegradable polymer scaffolds fabricated by a gas-foaming\\/salt-leaching method  

Microsoft Academic Search

Dexamethasone, a steroidal anti-inflammatory drug, was incorporated into porous biodegradable polymer scaffolds for sustained release. The slowly released dexamethasone from the degrading scaffolds was hypothesized to locally modulate the proliferation and differentiation of various cells. Dexamethasone containing porous poly(d,l-lactic-co-glycolic acid) (PLGA) scaffolds were fabricated by a gas-foaming\\/salt-leaching method. Dexamethasone was loaded within the polymer phase of the PLGA scaffold in

Jun Jin Yoon; Jung Hoe Kim; Tae Gwan Park

2003-01-01

275

Method for making a bio-compatible scaffold  

DOEpatents

A method for forming a three-dimensional, biocompatible, porous scaffold structure using a solid freeform fabrication technique (referred to herein as robocasting) that can be used as a medical implant into a living organism, such as a human or other mammal. Imaging technology and analysis is first used to determine the three-dimensional design required for the medical implant, such as a bone implant or graft, fashioned as a three-dimensional, biocompatible scaffold structure. The robocasting technique is used to either directly produce the three-dimensional, porous scaffold structure or to produce an over-sized three-dimensional, porous scaffold lattice which can be machined to produce the designed three-dimensional, porous scaffold structure for implantation.

Cesarano, III, Joseph (Albuquerque, NM); Stuecker, John N. (Albuquerque, NM); Dellinger, Jennifer G. (Champaigne, IL); Jamison, Russell D. (Urbana, IL)

2006-01-31

276

TGF-?1-Enhanced TCP-Coated Sensate Scaffolds Can Detect Bone Bonding  

PubMed Central

Porous polybutylene terephthalate (PBT) scaffold systems were tested as orthopedic implants to determine whether these scaffolds could be used to detect strain transfer following bone growth into the scaffold. Three types of scaffold systems were tested: porous PBT scaffolds, porous PBT scaffolds with a thin ?-tricalcium phosphate coating (LC-PBT), and porous PBT scaffolds with the TCP coating vacuum packed into the scaffold pores (VI-PBT). In addition, the effect of applying TGF-?1 to scaffolds as an enhancement was examined. The scaffolds were placed onto the femora of rats and left in vivo for 4 months. The amount of bone ingrowth and the strain transfer through various scaffolds was evaluated by using scanning electron microscopy, histology, histomorphometry, and cantilever bend testing. The VI-PBT scaffold showed the highest and most consistent degree of mechanical interaction between bone and scaffold, providing strain transfers of 68.5% (±20.6) and 79.2% (±8.7) of control scaffolds in tension and compression, respectively. The strain transfer through the VI-PBT scaffold decreased to 29.1% (±24.3) and 30.4% (±25.8) in tension and compression when used with TGF-?1. TGF-?1 enhancement increased the strain transfer through LC-PBT scaffolds in compression from 9.4% (±8.7) to 49.7% (±31.0). The significant changes in mechanical strain transfer through LC-PBT and VI-PBT scaffolds correlated with changes in bone ingrowth fraction, which was increased by 39.6% in LC-PBT scaffolds and was decreased 21.3% in VI-PBT scaffolds after TGF-?1 enhancement. Overall, the results indicate that strain transfer through TCP-coated PBT scaffolds correlate with bone ingrowth after implantation, making these instrumented scaffolds useful for monitoring bone growth by monitoring strain transfer. PMID:15682399

Szivek, J.A.; Margolis, D.S.; Garrison, B.K.; Nelson, E.; Vaidyanathan, R.K.; DeYoung, D.W.

2008-01-01

277

Resorbable glass-ceramic phosphate-based scaffolds for bone tissue engineering: synthesis, properties, and in vitro effects on human marrow stromal cells.  

PubMed

Highly porous bioresorbable glass-ceramic scaffolds were prepared via sponge replication method by using an open-cell polyurethane foam as a template and phosphate-based glass powders. The glass, belonging to the P2O5-SiO2-CaO-MgO-Na2O-K2O system, was synthesized by a melting-quenching route, ground, and sieved to obtain powders with a grain size of less than 30??m. A slurry containing glass powders, polyvinyl alcohol, and water was prepared to coat the polymeric template. The removal of the polymer and the sintering of the glass powders were performed by a thermal treatment, in order to obtain an inorganic replica of the template structure. The structure and properties of the scaffold were investigated from structural, morphological, and mechanical viewpoints by means of X-ray diffraction, scanning electron microscopy, density measurements, image analysis, and compressive tests. The scaffolds exhibited a trabecular architecture that closely mimics the structure of a natural spongy bone. The solubility of the porous structures was assessed by soaking the samples in acellular simulated body fluid (SBF) and Tris-HCl for different time frames and then by assessing the scaffold weight loss. As far as the test in SBF is concerned, the nucleation of hydroxyapatite on the scaffold trabeculae demonstrates the bioactivity of the material. Biological tests were carried out using human bone marrow stromal cells to test the osteoconductivity of the material. The cells adhered to the scaffold struts and were metabolically active; it was found that cell differentiation over proliferation occurred. Therefore, the produced scaffolds, being biocompatible, bioactive, resorbable, and structurally similar to a spongy bone, can be proposed as interesting candidates for bone grafting. PMID:20566654

Vitale-Brovarone, Chiara; Ciapetti, Gabriela; Leonardi, Elisa; Baldini, Nicola; Bretcanu, Oana; Verné, Enrica; Baino, Francesco

2011-11-01

278

Porous Chitosan Scaffolds with Embedded Hyaluronic Acid/Chitosan/Plasmid-DNA Nanoparticles Encoding TGF-?1 Induce DNA Controlled Release, Transfected Chondrocytes, and Promoted Cell Proliferation  

PubMed Central

Cartilage defects resulting from traumatic injury or degenerative diseases have very limited spontaneous healing ability. Recent progress in tissue engineering and local therapeutic gene delivery systems has led to promising new strategies for successful regeneration of hyaline cartilage. In the present study, tissue engineering and local therapeutic gene delivery systems are combined with the design of a novel gene-activated matrix (GAM) embedded with hybrid hyaluronic acid(HA)/chitosan(CS)/plasmid-DNA nanoparticles encoding transforming growth factor (TGF)-?1. A chitosan scaffold functioned as the three-dimensional carrier for the nanoparticles. Results demonstrated that scaffold-entrapped plasmid DNA was released in a sustained and steady manner over 120 days, and was effectively protected in the HA/CS/pDNA nanoparticles. Culture results demonstrated that chondrocytes grown in the novel GAM were highly proliferative and capable of filling scaffold micropores with cells and extracellular matrix. Confocal laser scanning microscopy indicated that chondrocytes seeded in the GAM expressed exogenous transgenes labeled with green fluorescent protein. ELISA results demonstrated detectable TGF-?1 expression in the supernatant of GAM cultures, which peaked at the sixth day of culture and afterwards showed a moderate decline. Histological results and biochemical assays confirmed promotion of chondrocyte proliferation. Cell culture indicated no affects on phenotypic expression of ECM molecules, such as GAG. The results of this study indicate the suitability of this novel GAM for enhanced in vitro cartilage tissue engineering. PMID:23894564

Dai, Yuhu; Wu, Gang; Zhao, Huiqing; Zhang, Fucheng

2013-01-01

279

The Crystallization Behavior of Porous PLA Prepared by Modified Solvent Casting/Particulate Leaching Technique for Potential Use of Tissue Engineering Scaffold  

E-print Network

The porous PLA foams potential for tissue engineering usage are prepared by a modified solvent casting/particulate leaching method with different crystallinity. Since in typical method the porogens are solved in the solution and flow with the polymers during the casting and the crystallinity behavior of PLA chains in the limited space cannot be tracked, in this work the processing is modified by diffusing the PLA solution into a steady salt stack. With a thermal treatment before leaching while maintaining the stable structure of the porogens stack, the crystallinity of porous foams is made possible to control. The characterizations indicate the crystallization of porous foams is in a manner of lower crystallibility than the bulk materials. Pores and caves of around 250{\\mu}m size are obtained in samples with different crystallinity. The macro-structures are not much impaired by the crystallization nevertheless the morphological effect of the heating process is still obvious.

Ran Huang; Xiaomin Zhu; Haiyan Tu; Ajun Wan

2014-04-14

280

Scaffolding and Metacognition  

ERIC Educational Resources Information Center

This paper proposes an expanded conception of scaffolding with four key elements: (1) scaffolding agency--expert, reciprocal, and self-scaffolding; (2) scaffolding domain--conceptual and heuristic scaffolding; (3) the identification of self-scaffolding with metacognition; and (4) the identification of six zones of scaffolding activity; each zone…

Holton, Derek; Clarke, David

2006-01-01

281

One-step fabrication and high photocatalytic activity of porous graphitic carbon nitride/graphene oxide hybrid by direct polymerization of cyanamide without templates  

NASA Astrophysics Data System (ADS)

Graphene oxide modified porous g-C3N4 (porous g-C3N4/GO) had been synthesized by means of one-step calcination of cyanamide for efficient photocatalysis under visible light irradiation (? > 400 nm). We expect that the photocatalytic activity of this hybrid photocatalyst could be enhanced by the efficient visible light absorption due to the porous structure and efficient photo generated charge separation at the heterojunction formed between porous g-C3N4 and GO. Scanning electron microscopy (SEM) images demonstrated that the as prepared photocatalyst is composed of GO and porous g-C3N4. The UV-vis diffuse reflectance spectrum shows that optical absorption of porous g-C3N4/GO is more intensive than for pristine g-C3N4. The enhanced generation of photocurrent under visible light irradiation (? > 400 nm) is observed for the porous g-C3N4/GO. The results of photocatalytic experiments reveal that the pseudofirst-order kinetic constant of photocatalytic degradation of methylene blue (MB) using the porous g-C3N4/GO is 6 times higher than that of pristine g-C3N4.

Yu, Qingbo; Guo, Shuai; Li, Xianhua; Zhang, Mingxu

2014-10-01

282

Effect of hydroxyapatite-containing microspheres embedded into three-dimensional magnesium phosphate scaffolds on the controlled release of lysozyme and in vitro biodegradation  

PubMed Central

The functionality of porous three-dimensional (3D) magnesium phosphate (MgP) scaffold was investigated for the development of a novel protein delivery system and biomimetic bone tissue engineering scaffold. This enhancement can be achieved by incorporation of hydroxyapatite (HA)-containing polymeric microspheres (MSs) into a bulk MgP matrix, and a paste-extruding deposition (PED) system. In this work, the amount of MS and HA was precisely controlled when manufacturing MS-embedded MgP (MS/MgP) composite scaffolds. The main influence was researched in terms of in vitro lysozyme-release, in vitro biodegradation, mechanical properties, and in vitro calcification. The controlled release of lysozyme was indicated, while showing graded release patterns according to HA content. The composite scaffolds degraded gradually with MS content and degradation time. Due to the effect of HA inclusion, the higher HA-containing MS/MgP scaffolds could, not only delay the biodegradation process but also, compensate for the possible loss of mechanical properties. In this regard, it is reasonable to confirm the inverse relationship between biodegradation and corresponding compressive properties. In order to encourage bioactivity and osteoconductivity, the MS/MgP composite scaffolds were subjected to simulated body fluid treatment. Calcium deposition was, in turn, improved with increasing MS and HA content over time. This quantitative result was also proved using morphological and elemental analysis. In summary, a significant transformation of a monolithic MgP scaffold was directed toward a multifunctional bone tissue engineering scaffold equipped with controlled protein delivery, biodegradability, and bioactivity. PMID:25214782

Lee, Jongman; Yun, Hui-suk

2014-01-01

283

Effect of hydroxyapatite-containing microspheres embedded into three-dimensional magnesium phosphate scaffolds on the controlled release of lysozyme and in vitro biodegradation.  

PubMed

The functionality of porous three-dimensional (3D) magnesium phosphate (MgP) scaffold was investigated for the development of a novel protein delivery system and biomimetic bone tissue engineering scaffold. This enhancement can be achieved by incorporation of hydroxyapatite (HA)-containing polymeric microspheres (MSs) into a bulk MgP matrix, and a paste-extruding deposition (PED) system. In this work, the amount of MS and HA was precisely controlled when manufacturing MS-embedded MgP (MS/MgP) composite scaffolds. The main influence was researched in terms of in vitro lysozyme-release, in vitro biodegradation, mechanical properties, and in vitro calcification. The controlled release of lysozyme was indicated, while showing graded release patterns according to HA content. The composite scaffolds degraded gradually with MS content and degradation time. Due to the effect of HA inclusion, the higher HA-containing MS/MgP scaffolds could, not only delay the biodegradation process but also, compensate for the possible loss of mechanical properties. In this regard, it is reasonable to confirm the inverse relationship between biodegradation and corresponding compressive properties. In order to encourage bioactivity and osteoconductivity, the MS/MgP composite scaffolds were subjected to simulated body fluid treatment. Calcium deposition was, in turn, improved with increasing MS and HA content over time. This quantitative result was also proved using morphological and elemental analysis. In summary, a significant transformation of a monolithic MgP scaffold was directed toward a multifunctional bone tissue engineering scaffold equipped with controlled protein delivery, biodegradability, and bioactivity. PMID:25214782

Lee, Jongman; Yun, Hui-Suk

2014-01-01

284

Synovex Plus implants coated with a polymeric, porous film improve performance of beef steers and heifers fed in confinement for up to 200 days.  

PubMed

Synovex Plus (SP) is a product that delivers 28 mg of estradiol benzoate (EB) and 200 mg of trenbolone acetate (TBA). We studied the impact of a polymeric, porous coating on SP implants (CSP) to prolong release of EB and TBA, and stimulate feedlot performance of feedlot cattle for an extended period. In an explant study, 30 steers were implanted with SP in one ear and CSP in the contralateral ear. Cattle (n = 6/d) were necropsied 40, 81, 120, 160, and 200 d after treatment, and remaining EB and TBA were quantified. Linear regression of EB and TBA remaining as a function of time for each treatment were computed. Rates of EB and TBA depletion from SP were -0.1980 (r(2) = 0.9994) and -1.7073 mg/d (r(2) = 0.9644), respectively, and for CSP rates of EB and TBA depletion were -0.1049 (r(2) = 0.9123) and -0.9466 mg/d (r(2) = 0.9297), respectively. The effect of treatment on depletion rates of each analyte were significant (P < 0.05). Data also showed EB and TBA were delivered from CSP at least 200 d but were delivered from SP about 120 d. Multisite trials with beef-type steers (4 sites) and heifers (4 sites) evaluated feedlot performance and carcass characteristics in response to a CSP implant or when sham implanted (SC). A randomized complete block design with 9 blocks and 2 treatments was used per site within animal gender. Across sites, steers (n = 342, BW = 297 kg) were fed finishing rations for 190 to 202 d (mean 198 d) and heifers (n = 342, BW = 289 kg) were fed finishing rations for 191 to 201 d (mean 198 d). Cattle were harvested and carcasses evaluated. Data were pooled across sites within gender for statistical analysis. Steers and heifers treated with CSP yielded greater (P ? 0.003) ADG, DMI, and G:F than SC steers and heifers. Mean BW differences between CSP and SC continued to increase throughout the study, indicating CSP stimulated growth of steers and heifers for 198 d. Mean carcass weights of CSP steers (P = 0.005) and heifers (P = 0.004) were greater than those of SP steers and heifers by 26.2 and 20.6 kg, respectively. The LM area was larger (P < 0.001) in CSP steers and heifers than SC cattle. Marbling decreased with CSP treatment (P ? 0.031), which caused reductions (P ? 0.006) in proportions of carcasses grading Prime or Choice. Evidence from these studies showed that a single administration of CSP increased feedlot cattle performance for at least 198 d, compared with SC, and may reduce the need to reimplant cattle. PMID:23100600

Cleale, R M; Bechtol, D T; Drouillard, J S; Edmonds, J D; Edmonds, M; Hunsaker, B D; Kraft, L A; Lawrence, T E; Brewbaker, S; Waite, A R

2012-12-01

285

Development and characterization of a family of shape memory, biocompatible, degradable, porous (co)-polyurethanes via sol-gel chemistry  

NASA Astrophysics Data System (ADS)

In support of the goal of a tissue engineering scaffold that is moldable, biodegradable and has shape-memory, this work explored the space of polyurethane sol-gel formulations and solvents to create a biocompatible, porous xerogel with potential to be such a porous scaffold. The work has resulted in both a process and a sol-gel formulation to effectively create a family of degradable, biocompatible, shape memory, porous, block copolyurethane xerogels from polycaprolactone and castor oil. Formulations of the sol-gel family of potential scaffolds were characterized for their biocompatibility, hydrolytic degradability, porosity, and shape memory. Of the scaffolds tested in this fashion, the most successful supported the attachment and growth of 3T3 fibroblast cells at 72% of the rate of attachment and growth in the standard tissue culture plastic Petri dishes. A method was developed and explained that selects the solvent for creation of a porous xerogel by controlling the phase separation of the polymerizing polyurethane from the reaction solution. This method uses standard polymer solvent swelling and extraction test data. Solvent solutions plotted in the 3-D space of Hansen solubility parameters were used to select solvents that produced porous xerogels from two different polyurethane sol-gel formulations. The process effectively combines a set of methods that search the sol-gel formulation spaces for both shape-memory and porosity. Easily produced dense xerogels from trial sol-gel formulations are sufficient for DSC and initial DMA shape-memory test data, as well as standard solvent swelling and extraction test data to support the search for shape memory and the computation of rankings to select solvent(s) that is most likely to produce a porous xerogel. Accelerated degradation tests on the dense xerogels also produced results useful to guide further testing of the sol-gel formulations. Standard shape-memory research testing only characterizes the free return to shape or the shape memory force with no return from a tensile test. Characterization of the scaffold's compressive shape memory (percent strain recovery under stress) offers a clinical user design data for interactions with body tissue. Standard tensile shape memory ratios were translated to the compressive stress, strain, and temperature cycles used to characterize the shape-memory abilities of the two sol-gel families tested. The advantage of a thermoset polymer's ability to achieve 100% shape memory repeatability is demonstrated. This scaffold's compressive shape memory actuation energy density was above 6.0 KJ/m 3 over a range of recovery strains from 5% to 12%.

Lippincott, Hugh Walker

286

Platelet lysate embedded scaffolds for skin regeneration.  

PubMed

Introduction: The work presents the development of acellular scaffolds extemporaneously embedded with platelet lysate (PL), as an innovative approach in the field of tissue regeneration/reparation. PL embedded scaffolds should have a tridimensional architecture to support cell migration and growth, in order to restore skin integrity. For this reason, chondroitin sulfate (CS) was associated with sodium alginate (SA) to prepare highly porous systems. Methods: The developed scaffolds were characterized for chemical stability to ?-radiation, morphology, hydration and mechanical properties. Moreover, the capability of fibroblasts and endothelial cells to populate the scaffold was evaluated by means of proliferation test 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and confocal laser scanning microscopy study. The scaffolds, not altered by sterilization, were characterized by limited swelling and high flexibility, by foam-like structure with bubbles that formed a high surface area and irregular texture suitable for cell adhesion. Results: Cell growth and scaffold population were evident on the bubble surface, where the cells appeared anchored to the scaffold structure. Conclusion: Scaffold network based on CS and SA demonstrated to be an effective support to enhance and to allow fibroblasts and endothelial cells (human umbilical vein endothelial cells, HUVEC) adhesion and proliferation. In particular, it could be hypothesized that cell adhesion was facilitated by the synergic effect of PL and CS. Although further in vivo evaluation is needed, on the basis of in vitro results, PL embedded scaffolds seem promising systems for skin wound healing. PMID:25297510

Sandri, Giuseppina; Bonferoni, Maria Cristina; Rossi, Silvia; Ferrari, Franca; Mori, Michela; Cervio, Marila; Riva, Federica; Liakos, Ioannis; Athanassiou, Athanassia; Saporito, Francesca; Marini, Lara; Caramella, Carla

2014-10-01

287

Nanofibrous Scaffolds for Dental and Craniofacial Applications  

PubMed Central

Tissue-engineering solutions often harness biomimetic materials to support cells for functional tissue regeneration. Three-dimensional scaffolds can create a multi-scale environment capable of facilitating cell adhesion, proliferation, and differentiation. One such multi-scale scaffold incorporates nanofibrous features to mimic the extracellular matrix along with a porous network for the regeneration of a variety of tissues. This review will discuss nanofibrous scaffold synthesis/fabrication, biological effects of nanofibers, their tissue- engineering applications in bone, cartilage, enamel, dentin, and periodontium, patient-specific scaffolds, and incorporated growth factor delivery systems. Nanofibrous scaffolds cannot only further the field of craniofacial regeneration but also advance technology for tissue-engineered replacements in many physiological systems. PMID:21828356

Gupte, M.J.; Ma, P.X.

2012-01-01

288

Structural and fluid transport characterization of bio-scaffolds based on 3D imaging data  

Microsoft Academic Search

Bio-scaffolds which are most commonly open celled porous structures are increasingly used for tissue engineering and regenerative medicine. Numerical studies exploring the influence of architecture on structural and flow characteristics of porous media have been carried out but these studies almost exclusively assume an idealized repeating unit cell approach. However, most of the traditional techniques employed to manufacture bio-scaffolds do

B. Notarberardino; P. G. Young; G. R. Tabor; L. Hao; I. G. Turner; A. Harkara

2009-01-01

289

Mathematically defined tissue engineering scaffold architectures prepared by stereolithography  

E-print Network

and freedom of design. Porous scaffolds are designed with computer software and built with either a poly(D,L-lactide)-based resin or a poly(D,L-lactide-co-e-cap- rolactone)-based resin. Characterisation of the scaffolds by micro

290

Tissue growth into three-dimensional composite scaffolds with controlled micro-features and nanotopographical surfaces.  

PubMed

Controlling topographic features at all length scales is of great importance for the interaction of cells with tissue regenerative materials. We utilized an indirect three-dimensional printing method to fabricate polymeric scaffolds with pre-defined and controlled external and internal architecture that had an interconnected structure with macro- (400-500 ?m) and micro- (?25 ?m) porosity. Polycaprolactone (PCL) was used as model system to study the kinetics of tissue growth within porous scaffolds. The surface of the scaffolds was decorated with TiO2 and bioactive glass (BG) nanoparticles to the better match to nanoarchitecture of extracellular matrix (ECM). Micrometric BG particles were also used to reveal the effect of particle size on the cell behavior. Observation of tissue growth and enzyme activity on two-dimensional (2D) films and three-dimensional (3D) scaffolds showed effects of nanoparticle inclusion and of surface curvature on the cellular adhesion, proliferation, and kinetics of preosteoblastic cells (MC3T3-E1) tissue growth into the pore channels. It was found that the presence of nanoparticles in the substrate impaired cellular adhesion and proliferation in 3D structures. Evaluation of alkaline phosphate activity showed that the presence of the hard particles affects differentiation of the cells on 2D films. Notwithstanding, the effect of particles on cell differentiation was not as strong as that seen by the curvature of the substrate. We observed different effects of nanofeatures on 2D structures with those of 3D scaffolds, which influence the cell proliferation and differentiation for non-load-bearing applications in bone regenerative medicine. PMID:23463703

Tamjid, Elnaz; Simchi, Arash; Dunlop, John W C; Fratzl, Peter; Bagheri, Reza; Vossoughi, Manouchehr

2013-10-01

291

Micro-computed tomography based computational fluid dynamics for the determination of shear stresses in scaffolds within a perfusion bioreactor.  

PubMed

Perfusion bioreactors are known to exert shear stresses on cultured cells, leading to cell differentiation and enhanced extracellular matrix deposition on scaffolds. The influence of the scaffold's porous microstructure is investigated for a polycaprolactone (PCL) scaffold with a regular microarchitecture and a silk fibroin (SF) scaffold with an irregular network of interconnected pores. Their complex 3D geometries are imaged by micro-computed tomography and used in direct pore-level simulations of the entire scaffold-bioreactor system to numerically solve the governing mass and momentum conservation equations for fluid flow through porous media. The velocity field and wall shear stress distribution are determined for both scaffolds. The PCL scaffold exhibited an asymmetric distribution with peak and plateau, while the SF scaffold exhibited a homogenous distribution and conditioned the flow more efficiently than the PCL scaffold. The methodology guides the design and optimization of the scaffold geometry. PMID:24492950

Zermatten, Emilie; Vetsch, Jolanda Rita; Ruffoni, Davide; Hofmann, Sandra; Müller, Ralph; Steinfeld, Aldo

2014-05-01

292

ECM Inspired Coating of Embroidered 3D Scaffolds Enhances Calvaria Bone Regeneration  

PubMed Central

Resorbable polymeric implants and surface coatings are an emerging technology to treat bone defects and increase bone formation. This approach is of special interest in anatomical regions like the calvaria since adults lose the capacity to heal large calvarial defects. The present study assesses the potential of extracellular matrix inspired, embroidered polycaprolactone-co-lactide (PCL) scaffolds for the treatment of 13?mm full thickness calvarial bone defects in rabbits. Moreover the influence of a collagen/chondroitin sulfate (coll I/cs) coating of PCL scaffolds was evaluated. Defect areas filled with autologous bone and empty defects served as reference. The healing process was monitored over 6 months by combining a novel ultrasonographic method, radiographic imaging, biomechanical testing, and histology. The PCL coll I/cs treated group reached 68% new bone volume compared to the autologous group (100%) and the biomechanical stability of the defect area was similar to that of the gold standard. Histological investigations revealed a significantly more homogenous bone distribution over the whole defect area in the PCL coll I/cs group compared to the noncoated group. The bioactive, coll I/cs coated, highly porous, 3-dimensional PCL scaffold acted as a guide rail for new skull bone formation along and into the implant. PMID:25013767

Rentsch, C.; Rentsch, B.; Heinemann, S.; Bernhardt, R.; Bischoff, B.; Förster, Y.; Scharnweber, D.; Rammelt, S.

2014-01-01

293

Cell infiltration and growth in a low density, uncompressed three-dimensional electrospun nanofibrous scaffold.  

PubMed

A limiting factor of traditional electrospinning is that the electrospun scaffolds consist entirely of tightly packed nanofiber layers that only provide a superficial porous structure due to the sheet-like assembly process. This unavoidable characteristic hinders cell infiltration and growth throughout the nanofibrous scaffolds. Numerous strategies have been tried to overcome this challenge, including the incorporation of nanoparticles, using larger microfibers, or removing embedded salt or water-soluble fibers to increase porosity. However, these methods still produce sheet-like nanofibrous scaffolds, failing to create a porous three-dimensional scaffold with good structural integrity. Thus, we have developed a three-dimensional cotton ball-like electrospun scaffold that consists of an accumulation of nanofibers in a low density and uncompressed manner. Instead of a traditional flat-plate collector, a grounded spherical dish and an array of needle-like probes were used to create a Focused, Low density, Uncompressed nanoFiber (FLUF) mesh scaffold. Scanning electron microscopy showed that the cotton ball-like scaffold consisted of electrospun nanofibers with a similar diameter but larger pores and less-dense structure compared to the traditional electrospun scaffolds. In addition, laser confocal microscopy demonstrated an open porosity and loosely packed structure throughout the depth of the cotton ball-like scaffold, contrasting the superficially porous and tightly packed structure of the traditional electrospun scaffold. Cells seeded on the cotton ball-like scaffold infiltrated into the scaffold after 7 days of growth, compared to no penetrating growth for the traditional electrospun scaffold. Quantitative analysis showed approximately a 40% higher growth rate for cells on the cotton ball-like scaffold over a 7 day period, possibly due to the increased space for in-growth within the three-dimensional scaffolds. Overall, this method assembles a nanofibrous scaffold that is more advantageous for highly porous interconnectivity and demonstrates great potential for tackling current challenges of electrospun scaffolds. PMID:21112625

Blakeney, Bryan A; Tambralli, Ajay; Anderson, Joel M; Andukuri, Adinarayana; Lim, Dong-Jin; Dean, Derrick R; Jun, Ho-Wook

2011-02-01

294

Cell Infiltration and Growth in a Low Density, Uncompressed Three-Dimensional Electrospun Nanofibrous Scaffold  

PubMed Central

A limiting factor of traditional electrospinning is that the electrospun scaffolds consist entirely of tightly packed nanofiber layers that only provide a superficial porous structure due to the sheet-like assembly process. This unavoidable characteristic hinders cell infiltration and growth throughout the nanofibrous scaffolds. Numerous strategies have been tried to overcome this challenge, including the incorporation of nanoparticles, using larger microfibers, or removing embedded salt or water-soluble fibers to increase porosity. However, these methods still produce sheet-like nanofibrous scaffolds, failing to create a porous three-dimensional scaffold with good structural integrity. Thus, we have developed a three-dimensional cotton ball-like electrospun scaffold that consists of an accumulation of nanofibers in a low density and uncompressed manner. Instead of a traditional flat-plate collector, a grounded spherical dish and an array of needle-like probes were used to create a Focused, Low density, Uncompressed nanoFiber (FLUF) mesh scaffold. Scanning electron microscopy showed that the cotton ball-like scaffold consisted of electrospun nanofibers with a similar diameter but larger pores and less dense structure compared to the traditional electrospun scaffolds. In addition, laser confocal microscopy demonstrated an open porosity and loosely packed structure throughout the depth of the cotton ball-like scaffold, contrasting the superficially porous and tightly packed structure of the traditional electrospun scaffold. Cells seeded on the cotton ball-like scaffold infiltrated into the scaffold after 7 days of growth, compared to no penetrating growth for the traditional electrospun scaffold. Quantitative analysis showed approximately a 40% higher growth rate for cells on the cotton ball-like scaffold over a 7 day period, possibly due to the increased space for in-growth within the three-dimensional scaffolds. Overall, this method assembles a nanofibrous scaffold that is more advantageous for highly porous interconnectivity and demonstrates great potential for tackling current challenges of electrospun scaffolds. PMID:21112625

Blakeney, Bryan A.; Tambralli, Ajay; Anderson, Joel M.; Andukuri, Adinarayana; Lim, Dong-Jin; Dean, Derrick R.; Jun, Ho-Wook

2010-01-01

295

Porous Materials Porous Materials  

E-print Network

1 Porous Materials x Porous Materials · Physical properties * Characteristic impedance p = p 0 e -jk xa- = vej[ ] p x - j ; Zc= p ve = c ka 0k = c 1-j #12;2 Porous Materials · Specific acoustic impedance Porous Materials · Finite thickness ­ blocked p e + -jk (x-d)a p e - jk (x-d)a d x #12

Berlin,Technische Universität

296

Platelet-Rich Plasma Favors Proliferation of Canine Adipose-Derived Mesenchymal Stem Cells in Methacrylate-Endcapped Caprolactone Porous Scaffold Niches  

PubMed Central

Osteoarticular pathologies very often require an implementation therapy to favor regeneration processes of bone, cartilage and/or tendons. Clinical approaches performed on osteoarticular complications in dogs constitute an ideal model for human clinical translational applications. The adipose-derived mesenchymal stem cells (ASCs) have already been used to accelerate and facilitate the regenerative process. ASCs can be maintained in vitro and they can be differentiated to osteocytes or chondrocytes offering a good tool for cell replacement therapies in human and veterinary medicine. Although ACSs can be easily obtained from adipose tissue, the amplification process is usually performed by a time consuming process of successive passages. In this work, we use canine ASCs obtained by using a Bioreactor device under GMP cell culture conditions that produces a minimum of 30 million cells within 2 weeks. This method provides a rapid and aseptic method for production of sufficient stem cells with potential further use in clinical applications. We show that plasma rich in growth factors (PRGF) treatment positively contributes to viability and proliferation of canine ASCs into caprolactone 2-(methacryloyloxy) ethyl ester (CLMA) scaffolds. This biomaterial does not need additional modifications for cASCs attachment and proliferation. Here we propose a framework based on a combination of approaches that may contribute to increase the therapeutical capability of stem cells by the use of PRGF and compatible biomaterials for bone and connective tissue regeneration. PMID:24955632

Rodríguez-Jiménez, Francisco Javier; Valdes-Sánchez, Teresa; Carrillo, José M.; Rubio, Mónica; Monleon-Prades, Manuel; García-Cruz, Dunia Mercedes; García, Montserrat; Cugat, Ramón; Moreno-Manzano, Victoria

2012-01-01

297

Porous polymer monoliths for small molecule separations: advancements and limitations.  

PubMed

Porous polymer monoliths are considered to be one of the major breakthroughs in separation science. These materials are well known to be best suited for the separation of large molecules, specifically proteins, an observation most often explained by convective mass transfer and the absence of small pores in the polymer scaffold. However, this conception is not sufficient to explain the performance of small molecules. This review focuses in particular on the preparation of (macro)porous polymer monoliths by simple free-radical processes and the key events in their formation. There is special focus on the fluid transport properties in the heterogeneous macropore space (flow dispersion) and on the transport of small molecules in the swollen, and sometimes permanently porous, globule-scale polymer matrix. For small molecule applications in liquid chromatography, it is consistently found in the literature that the major limit for the application of macroporous polymer monoliths lies not in the optimization of surface area and/or modification of the material and microscopic morphological properties only, but in the improvement of mass transfer properties. In this review we discuss the effect of resistance to mass transfer arising from the nanoscale gel porosity. Gel porosity induces stagnant mass transfer zones in chromatographic processes, which hamper mass transfer efficiency and have a detrimental effect on macroscopic chromatographic dispersion under equilibrium (isocratic) elution conditions. The inherent inhomogeneity of polymer networks derived from free-radical cross-linking polymerization, and hence the absence of a rigid (meso)porous pore space, represents a major challenge for the preparation of efficient polymeric materials for the separation of small molecules. PMID:21190103

Nischang, Ivo; Teasdale, Ian; Brüggemann, Oliver

2011-06-01

298

Supercritical fluid technologies and tissue engineering scaffolds  

Microsoft Academic Search

Supercritical fluid (SCF) processing methods possess advantages over standard processing methods for the production of scaffolds for use in tissue engineering. Advantages include the absence of organic solvents, the ability to incorporate delicate biologicals without loss of activity, and control over the morphology of an internal porous architecture. This review describes SCF processing methods of relevance to tissue engineering and

Robin A. Quirk; Richard M. France; Kevin M. Shakesheff; Steven M. Howdle

2004-01-01

299

Jellyfish collagen scaffolds for cartilage tissue engineering.  

PubMed

Porous scaffolds were engineered from refibrillized collagen of the jellyfish Rhopilema esculentum for potential application in cartilage regeneration. The influence of collagen concentration, salinity and temperature on fibril formation was evaluated by turbidity measurements and quantification of fibrillized collagen. The formation of collagen fibrils with a typical banding pattern was confirmed by atomic force microscopy and transmission electron microscopy analysis. Porous scaffolds from jellyfish collagen, refibrillized under optimized conditions, were fabricated by freeze-drying and subsequent chemical cross-linking. Scaffolds possessed an open porosity of 98.2%. The samples were stable under cyclic compression and displayed an elastic behavior. Cytotoxicity tests with human mesenchymal stem cells (hMSCs) did not reveal any cytotoxic effects of the material. Chondrogenic markers SOX9, collagen II and aggrecan were upregulated in direct cultures of hMSCs upon chondrogenic stimulation. The formation of typical extracellular matrix components was further confirmed by quantification of sulfated glycosaminoglycans. PMID:24184178

Hoyer, Birgit; Bernhardt, Anne; Lode, Anja; Heinemann, Sascha; Sewing, Judith; Klinger, Matthias; Notbohm, Holger; Gelinsky, Michael

2014-02-01

300

Peripheral nerve morphogenesis induced by scaffold micropatterning  

PubMed Central

Several bioengineering approaches have been proposed for peripheral nervous system repair, with limited results and still open questions about the underlying molecular mechanisms. We assessed the biological processes that occur after the implantation of collagen scaffold with a peculiar porous microstructure of the wall in a rat sciatic nerve transection model compared to commercial collagen conduits and nerve crush injury using functional, histological and genome wide analyses. We demonstrated that within 60 days, our conduit had been completely substituted by a normal nerve. Gene expression analysis documented a precise sequential regulation of known genes involved in angiogenesis, Schwann cells/axons interactions and myelination, together with a selective modulation of key biological pathways for nerve morphogenesis induced by porous matrices. These data suggest that the scaffold’s microstructure profoundly influences cell behaviors and creates an instructive micro-environment to enhance nerve morphogenesis that can be exploited to improve recovery and understand the molecular differences between repair and regeneration. PMID:24559639

Memon, Danish; Boneschi, Filippo Martinelli; Madaghiele, Marta; Brambilla, Paola; Del Carro, Ubaldo; Taveggia, Carla; Riva, Nilo; Trimarco, Amelia; Lopez, Ignazio D.; Comi, Giancarlo; Pluchino, Stefano; Martino, Gianvito; Sannino, Alessandro; Quattrini, Angelo

2014-01-01

301

Highly porous chemically modified carbon cryogels and their coherent nanocomposites for energy applications  

E-print Network

the pores, porous media for natural gas (methane) storage at reduced pressure, and scaffolds for hydride the pores, porous media for natural gas (m intimately associated with current energy and environmental issues. Modern society is built upon cars

Cao, Guozhong

302

Macroscopic architecture of charge transfer-induced molecular recognition from electron-rich polymer interpenetrated porous frameworks.  

PubMed

Fluorescent and electron-rich polymer threaded into porous framework provides a scaffold for sensing acceptor molecules through noncovalent interactions. Herein, poly(9-vinylcarbazole) (PVK) threaded MIL-101 with confined nanospace was synthesized by vinyl-monomer impregnation, in situ polymerization, and interpenetration. The pore size of the resulted hybrid could be controlled by varying the time of polymerization and interpenetration. The interaction of PVK-threaded MIL-101 with guest molecules showed a charge-transfer progress with an obvious red shift in the optical spectra. Depending on the degree of the interaction, the solution color changed from blue to green or to yellow. In particular, electron-rich PVK-threaded MIL-101 could effectively probe electron-poor nitro compounds, especially 1,3,5-trinitrobenzene (TNP), a highly explosive material. This sensing approach is a colorimetric methodology, which is very simple and convenient for practical analysis and operation. PMID:25707851

Bai, Linyi; Wang, Peng; Bose, Purnandhu; Li, Peizhou; Zou, Ruqiang; Zhao, Yanli

2015-03-11

303

Mechanical and biological properties of hydroxyapatite\\/tricalcium phosphate scaffolds coated with poly(lactic-co-glycolic acid)  

Microsoft Academic Search

Regeneration of bone, cartilage and osteochondral tissues by tissue engineering has attracted intense attention due to its potential advantages over the traditional replacement of tissues with synthetic implants. Nevertheless, there is still a dearth of ideal or suitable scaffolds based on porous biomaterials, and the present study was undertaken to develop and evaluate a useful porous composite scaffold system. Here,

Xigeng Miao; Dawn Meifang Tan; Jian Li; Yin Xiao; Ross Crawford

2008-01-01

304

Development of porous PLGA/PEI1.8k biodegradable microspheres for the delivery of mesenchymal stem cells (MSCs).  

PubMed

Multipotent mesenchymal stem cells (MSCs) promise a therapeutic alternative for many debilitating and incurable diseases. However, one of the major limitations for the therapeutic application of human MSC (hMSC) is the lengthy ex vivo expansion time for preparing a sufficient amount of cells due to the low engraftment rate after transplantation. To solve this conundrum, a porous biodegradable polymeric microsphere was investigated as a potential scaffold for the delivery of MSCs. The modified water/oil/water (W1/O/W2) double emulsion solvent evaporation method was used for the construction of porous microspheres. PEI1.8k was blended with poly(lactic-co-glycolic acid) (PLGA) to enhance electrostatic cellular attachment to the microspheres. The porous PLGA/PEI1.8k (PPP) particles demonstrated an average particle size of 290?m and an average pore size of 14.3?m, providing a micro-carrier for the MSC delivery. PPP particles allowed for better attachment of rMSCs than non-porous PLGA/PEI1.8k (NPP) particles and non-porous (NP) and porous PLGA (PP) microspheres. rMSC successfully grew on the PPP particles for 2weeks in vitro. Next, PPP particles loaded with 3 different amounts of hMSC showed increased in vivo engraftment rates and maintained the stemness characteristics of hMSC compared with hMSCs-alone group in rats 2weeks after intramyocardial administration. These customized PPP particles for MSC delivery are a biodegradable and injectable scaffold that can be used for clinical applications. PMID:25575866

Lee, Young Sook; Lim, Kwang Suk; Oh, Jung-Eun; Yoon, A-Rum; Joo, Wan Seok; Kim, Hyun Soo; Yun, Chae-Ok; Kim, Sung Wan

2015-05-10

305

Seamless vascularized large-diameter tubular collagen scaffolds reinforced with polymer knittings for esophageal regenerative medicine.  

PubMed

A clinical demand exists for alternatives to repair the esophagus in case of congenital defects, cancer, or trauma. A seamless biocompatible off-the-shelf large-diameter tubular scaffold, which is accessible for vascularization, could set the stage for regenerative medicine of the esophagus. The use of seamless scaffolds eliminates the error-prone tubularization step, which is necessary when emanating from flat scaffolds. In this study, we developed and characterized three different types of seamless tubular scaffolds, and evaluated in vivo tissue compatibility, including vascularization by omental wrapping. Scaffolds (luminal Ø ? 1.5 cm) were constructed using freezing, lyophilizing, and cross-linking techniques and included (1) single-layered porous collagen scaffold, (2) dual-layered (porous+dense) collagen scaffold, and (3) hybrid scaffold (collagen+incorporated polycaprolacton knitting). The latter had an ultimate tensile strength comparable to a porcine esophagus. To induce rapid vascularization, scaffolds were implanted in the omentum of sheep using a wrapping technique. After 6 weeks of biocompatibility, vascularization, calcification, and hypoxia were evaluated using immunohistochemistry. Scaffolds were biocompatible, and cellular influx and ingrowth of blood vessels were observed throughout the whole scaffold. No calcification was observed, and slight hypoxic conditions were detected only in the direct vicinity of the polymer knitting. It is concluded that seamless large-diameter tubular collagen-based scaffolds can be constructed and vascularized in vivo. Such scaffolds provide novel tools for esophageal reconstruction. PMID:24099067

Hoogenkamp, Henk R; Koens, Martin J W; Geutjes, Paul J; Ainoedhofer, Herwig; Wanten, Geert; Tiemessen, Dorien M; Hilborn, Jöns; Gupta, Bhuvanesh; Feitz, Wouter F J; Daamen, Willeke F; Saxena, Amulya K; Oosterwijk, Egbert; van Kuppevelt, Toin H

2014-05-01

306

Reinforced nanohydroxyapatite/polyamide66 scaffolds by chitosan coating for bone tissue engineering.  

PubMed

High porosity of scaffold is always accompanied by poor mechanical property; the aim of this study was to enhance the strength and modulus of the highly porous scaffold of nanohydroxyapatite/polyamide66 (n-HA/PA66) by coating chitosan (CS) and to investigate the effect of CS content on the scaffold physical properties and cytological properties. The results show that CS coating can reinforce the scaffold effectively. The compress modulus and strength of the CS coated n-HA/PA66 scaffolds are improved to 32.71 and 2.38 MPa, respectively, being about six times and five times of those of the uncoated scaffolds. Meanwhile, the scaffolds still exhibit a highly interconnected porous structure and the porosity is approximate about 78%, slightly lower than the value (84%) of uncoated scaffold. The cytological properties of scaffolds were also studied in vitro by cocultured with osteoblast-like MG63 cells. The cytological experiments demonstrate that the reinforced scaffolds display favorable cytocompatibility and have no significant difference with the uncoated n-HA/PA66 scaffolds. The CS reinforced n-HA/PA66 scaffolds can meet the basic mechanical requirement of bone tissue engineering scaffold, presenting a potential for biomedical application in bone reconstruction and repair. PMID:21953937

Huang, Di; Zuo, Yi; Zou, Qin; Wang, Yanying; Gao, Shibo; Wang, Xiaoyan; Liu, Haohuai; Li, Yubao

2012-01-01

307

Polymeric microspheres  

DOEpatents

The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

2004-04-13

308

Porosity and Cell Preseeding Influence Electrospun Scaffold Maturation and Meniscus Integration In Vitro  

PubMed Central

Electrospinning generates fibrous scaffolds ideal for engineering soft orthopedic tissues. By modifying the electrospinning process, scaffolds with different structural organization and content can be generated. For example, fibers can be aligned in a single direction, or the porosity of the scaffold can be modified through the use of multi-jet electrospinning and the removal of sacrificial fibers. In this work, we investigated the role of fiber alignment and scaffold porosity on construct maturation and integration within in vitro meniscus defects. Further, we explored the effect of preseeding expanded meniscus fibrochondrocytes (MFCs) onto the scaffold at a high density before in vitro repair. Our results demonstrate that highly porous electropun scaffolds integrate better with a native tissue and mature to a greater extent than low-porosity scaffolds, while scaffold alignment does not influence integration or maturation. The addition of expanded MFCs to scaffolds before in vitro repair improved integration with the native tissue, but did not influence maturation. In contrast, preculture of these same scaffolds for 1 month before repair decreased integration with the native tissue, but resulted in a more mature scaffold compared to implantation of cellular scaffolds or acellular scaffolds. This work will inform scaffold selection in future in vivo studies by identifying the ideal scaffold and seeding methods for meniscus tissue engineering. PMID:22994398

Ionescu, Lara C.

2013-01-01

309

Characterization of scaffold architecture by optical coherence tomography  

NASA Astrophysics Data System (ADS)

Cells, scaffold and culture environment are the three essential elements in engineering tissue constructs. Among these elements, the scaffold plays a critical role in converting cells into tissue since it provides a template and space for cells to grow and produce the desired matrix. Scaffolds are usually fabricated into three-dimensional blocks from biodegradable polymers with different internal architectures, for instance they are with fibrous or porous structures. The mechanical properties and nutrient diffusion ability of scaffolds are highly dependent on their internal structure. The biodegradable feature of scaffolds leads to a dramatic change in their microstructure during in vitro culture or after implantation. In this study, we explore optical coherence tomography (OCT) as a potential tool to characterize architecture of scaffolds including porosity, pore distribution and interconnectivity. This instrument is a fibre based time domain OCT equipped with a 1300 nm superluminescent diode, with a bandwidth of 52 nm and a free space resolution of 16x16x14 μm. Two model scaffold systems have been investigated. One was porous poly(lactide) scaffold fabricated by solvent-evaporation and salt leaching technique with dual poregens. Another was fibrous chitosan scaffold produced by wet spinning. Variations of scaffolds architecture, in term of porosity and interconnectivity, with different fabrication conditions could be quantified with the help of a commercial software (Volocity, Improvision). This study demonstrated that OCT can be used as a tool to guide scaffold fabrication and optimise their internal structure. Moreover, it can be used as on-line monitoring for scaffold degradation in various culture conditions.

Yang, Ying; Bagnaninchi, Pierre O.; Cunha-Reis, Cassilda; Aydin, Halil M.; Piskin, Erhan; El Haj, Alicia

2007-02-01

310

A micro-scale surface-structured PCL scaffold fabricated by a 3D plotter and a chemical blowing agent.  

PubMed

To study cell responses, polymeric scaffolds with a controllable pore size and porosity have been fabricated using rapid-prototyping methods. However, the scaffolds fabricated by rapid prototyping have very smooth surfaces, which tend to discourage initial cell attachment. Initial cell attachment, migration, differentiation and proliferation are strongly dependent on the chemical and physical characteristics of the scaffold surface. In this study, we propose a three-dimensional (3D) plotting method supplemented with a chemical blowing agent to produce a surface-modified 3D scaffold in which the surface is inscribed with nano- and micro-sized pores. The chemically-blown 3D polymeric scaffold exhibited positive qualities, including the compressive modulus, hydrophilicity and initial cell adhesion. Cell cultures on the scaffolds demonstrated that chondrocytes interacted better with the surface-modified scaffold than with a normal 3D scaffold. PMID:20092682

Yoon, Hyeon; Kim, Geun Hyung; Koh, Young Ho

2010-01-01

311

Calcium phosphate scaffolds for bone repair  

NASA Astrophysics Data System (ADS)

Calcium phosphates, with their chemical similarity to bone mineral, show biocompatibility with hard and soft tissues and offer massive potential for bone repair, both as scaffolds to be implanted directly into the defect and as structures for cell transplantation or to guide new bone growth in tissue engineering. This paper reviews the requirements and motivation for synthetic bone graft alternatives and the production routes for, particularly, hydroxyapatite porous scaffolds. It also considers the important role of substitution of ions such as silicate into calcium phosphates so as to more closely mirror the chemistry of bone mineral and to elicit specific biological responses.

Shepherd, J. H.; Best, S. M.

2011-04-01

312

Soy Protein Scaffold Biomaterials for Tissue Engineering and Regenerative Medicine  

NASA Astrophysics Data System (ADS)

Developing functional biomaterials using highly processable materials with tailorable physical and bioactive properties is an ongoing challenge in tissue engineering. Soy protein is an abundant, natural resource with potential use for regenerative medicine applications. Preliminary studies show that soy protein can be physically modified and fabricated into various biocompatible constructs. However, optimized soy protein structures for tissue regeneration (i.e. 3D porous scaffolds) have not yet been designed. Furthermore, little work has established the in vivo biocompatibility of implanted soy protein and the benefit of using soy over other proteins including FDA-approved bovine collagen. In this work, freeze-drying and 3D printing fabrication processes were developed using commercially available soy protein to create porous scaffolds that improve cell growth and infiltration compared to other soy biomaterials previously reported. Characterization of scaffold structure, porosity, and mechanical/degradation properties was performed. In addition, the behavior of human mesenchymal stem cells seeded on various designed soy scaffolds was analyzed. Biological characterization of the cell-seeded scaffolds was performed to assess feasibility for use in liver tissue regeneration. The acute and humoral response of soy scaffolds implanted in an in vivo mouse subcutaneous model was also investigated. All fabricated soy scaffolds were modified using thermal, chemical, and enzymatic crosslinking to change properties and cell growth behavior. 3D printing allowed for control of scaffold pore size and geometry. Scaffold structure, porosity, and degradation rate significantly altered the in vivo response. Freeze-dried soy scaffolds had similar biocompatibility as freeze-dried collagen scaffolds of the same protein content. However, the soy scaffolds degraded at a much faster rate, minimizing immunogenicity. Interestingly, subcutaneously implanted soy scaffolds affected blood glucose and insulin sensitivity levels. Furthermore, soy scaffolds implanted in the intraperitoneal cavity attached to adjacent liver tissue with no abnormalities. In vitro, soy scaffolds supported hMSC viability and transdifferentiation into hepatocyte-like cells. These results support the use of soy scaffolds for liver tissue engineering and for treating metabolic diseases. Based on achievable structural and mechanical properties, as well as systemic effects of ingested and degraded soy proteins, soy protein scaffolds may serve as new multifunctional biomaterials for tissue engineering and regenerative medicine.

Chien, Karen B.

313

Study of gelatin-containing artificial skin V: fabrication of gelatin scaffolds using a salt-leaching method  

Microsoft Academic Search

Porous gelatin scaffolds were prepared using a salt-leaching method and these were compared to scaffolds fabricated using a freeze-drying method. The salt-leached gelatin scaffolds were easily formed into desired shapes with a uniformly distributed and interconnected pore structure with an average pore size of around 350?m. The mechanical strength and the biodegradation rate of the scaffolds increased with the porosity,

Sang Bong Lee; Yong Han Kim; Moo Sang Chong; Seung Hwa Hong; Young Moo Lee

2005-01-01

314

Three-dimensional chitosan-nanohydroxyapatite composite scaffolds for bone tissue engineering  

NASA Astrophysics Data System (ADS)

We describe the structure of biodegradable chitosan-nanohydroxyapatite (nHA) composites scaffolds and their interaction with pre-osteoblasts for bone tissue engineering. The scaffolds were fabricated via freezing and lyophilization. The nanocomposite scaffolds were characterized by a highly porous structure and pore size of ˜50-125 ?m, irrespective of nHA content. The observed significant enhancement in the biological response of pre-osteoblast on nanocomposite scaffolds expressed in terms of cell attachment, proliferation, and widespread morphology in relation to pure chitosan points toward their potential use as scaffold material for bone regeneration.

Thein-Han, W. W.; Misra, R. D. K.

2009-09-01

315

Design, construction and mechanical testing of digital 3D anatomical data-based PCL-HA bone tissue engineering scaffold.  

PubMed

The study aims to investigate the techniques of design and construction of CT 3D reconstructional data-based polycaprolactone (PCL)-hydroxyapatite (HA) scaffold. Femoral and lumbar spinal specimens of eight male New Zealand white rabbits were performed CT and laser scanning data-based 3D printing scaffold processing using PCL-HA powder. Each group was performed eight scaffolds. The CAD-based 3D printed porous cylindrical stents were 16 piece × 3 groups, including the orthogonal scaffold, the Pozi-hole scaffold and the triangular hole scaffold. The gross forms, fiber scaffold diameters and porosities of the scaffolds were measured, and the mechanical testing was performed towards eight pieces of the three kinds of cylindrical scaffolds, respectively. The loading force, deformation, maximum-affordable pressure and deformation value were recorded. The pore-connection rate of each scaffold was 100 % within each group, there was no significant difference in the gross parameters and micro-structural parameters of each scaffold when compared with the design values (P > 0.05). There was no significant difference in the loading force, deformation and deformation value under the maximum-affordable pressure of the three different cylinder scaffolds when the load was above 320 N. The combination of CT and CAD reverse technology could accomplish the design and manufacturing of complex bone tissue engineering scaffolds, with no significant difference in the impacts of the microstructures towards the physical properties of different porous scaffolds under large load. PMID:25596860

Yao, Qingqiang; Wei, Bo; Guo, Yang; Jin, Chengzhe; Du, Xiaotao; Yan, Chao; Yan, Junwei; Hu, Wenhao; Xu, Yan; Zhou, Zhi; Wang, Yijin; Wang, Liming

2015-01-01

316

Investigation of potential injectable polymeric biomaterials for bone regeneration  

PubMed Central

This article reviews the potential injectable polymeric biomaterial scaffolds currently being investigated for application in bone tissue regeneration. Two types of injectable biomaterial scaffolds are focused in this review, including injectable microspheres and injectable gels. The injectable microspheres section covers several polymeric materials, including poly(l-lactide-co-glycolide)-PLGA, poly (propylene fumarate), and chitosan. The injectable gel section covers alginate gels, hyaluronan hydrogels, poly(ethylene-glycol)-PEG hydrogels, and PEG-PLGA copolymer hydrogels. This review focuses on the effect of cellular behaviorin vitro andin vivo in terms of material properties of polymers, such as biodegradation, biocompatibility, porosity, microsphere size, and cross-linking nature. Injectable polymeric biomaterials offer a major advantage for orthopedic applications by allowing the ability to use noninvasive or minimally invasive treatment methods. Therefore, combining injectable polymeric biomaterial scaffolds with cells have a significant potential to treat orthopedic bone defects, including spine fusion, and craniofacial and periodontal defects. PMID:23401336

Dreifke, Michael B.; Ebraheim, Nabil A.; Jayasuriya, Ambalangodage C.

2014-01-01

317

Micro-CT-based screening of biomechanical and structural properties of bone tissue engineering scaffolds.  

PubMed

The development of successful scaffolds for bone tissue engineering requires a concurrent engineering approach that combines different research fields. In order to limit in vivo experiments and reduce trial and error research, a scaffold screening technique has been developed. In this protocol seven structural and three biomechanical properties of potential scaffold materials are quantified and compared to the desired values. The property assessment is done on computer models of the scaffolds, and these models are based on micro-CT images. As a proof of principle, three porous scaffolds were evaluated with this protocol: stainless steel, hydroxyapatite, and titanium. These examples demonstrate that the modelling technique is able to quantify important scaffold properties. Thus, a powerful technique for automated screening of bone tissue engineering scaffolds has been developed that in a later stage may be used to tailor the scaffold properties to specific requirements. PMID:16937187

Van Cleynenbreugel, Tim; Schrooten, Jan; Van Oosterwyck, Hans; Vander Sloten, Jos

2006-07-01

318

Composite scaffolds of mesoporous bioactive glass and polyamide for bone repair  

PubMed Central

A bone-implanted porous scaffold of mesoporous bioglass/polyamide composite (m-BPC) was fabricated, and its biological properties were investigated. The results indicate that the m-BPC scaffold contained open and interconnected macropores ranging 400–500 ?m, and exhibited a porosity of 76%. The attachment ratio of MG-63 cells on m-BPC was higher than polyamide scaffolds at 4 hours, and the cells with normal phenotype extended well when cultured with m-BPC and polyamide scaffolds. When the m-BPC scaffolds were implanted into bone defects of rabbit thighbone, histological evaluation confirmed that the m-BPC scaffolds exhibited excellent biocompatibility and osteoconductivity, and more effective osteogenesis than the polyamide scaffolds in vivo. The results indicate that the m-BPC scaffolds improved the efficiency of new bone regeneration and, thus, have clinical potential for bone repair. PMID:22679367

Su, Jiacan; Cao, Liehu; Yu, Baoqing; Song, Shaojun; Liu, Xinwei; Wang, Zhiwei; Li, Ming

2012-01-01

319

Optimizing Degradable Scaffolds for Cranium Tissue Repair  

Microsoft Academic Search

INTRODUCTION: The issue of repairing deformities in the craniofacial area continues to be a challenging one for reconstructive surgeons. To date many methods and materials have been used to obtain a waterproof seal of bone defects in the cranium (1). Various methods have been used for the preparation of porous polymeric structures for biomedical applications (2). The aim of this

H M Aydin; Y Yang; E Piskin; A El Haj

320

3-D scaffolds a new tool to fight cancer  

Cancer.gov

Porous polymer scaffolds fabricated to support the growth of biological tissue for implantation may hold the potential to greatly accelerate the development of cancer therapeutics. Researchers at Rice University, the University of Texas MD Anderson Cancer Center in Houston, and Mount Sinai Medical Center in New York reported this week that three-dimensional scaffolds used to culture Ewing’s sarcoma cells were effective at mimicking the environment in which such tumors develop.

321

The morphology of anisotropic 3D-printed hydroxyapatite scaffolds  

Microsoft Academic Search

Three-dimensional (3D) scaffolds with tailored pores ranging from the nanometer to millimeter scale can support the reconstruction of centimeter-sized osseous defects. Three-dimensional-printing processes permit the voxel-wise fabrication of scaffolds. The present study rests upon 3D-printing with nano-porous hydroxyapatite granulates. The cylindrical design refers to a hollow bone with higher density at the periphery. The millimeter-wide central channel follows the symmetry

Fabienne C. Fierz; Felix Beckmann; Marius Huser; Stephan H. Irsen; Barbara Leukers; Frank Witte; Özer Degistirici; Adrian Andronache; Michael Thie; Bert Müller

2008-01-01

322

Simulation of Cell Growth and Diffusion in Tissue Engineering Scaffolds  

Microsoft Academic Search

With the development in recent years, tissue engineering is becoming one of the therapeutic strategies that have the potential\\u000a for repairing the damaged or malfunctioned human tissues. The proposed scheme of tissue engineering generally contains seeding\\u000a cells onto a porous scaffold. The cell-scaffold construct is then cultured in vitro for a period of time and transplanted\\u000a into the patient afterward.

Szu-Ying Ho; Ming-Han Yu; C. A. Chung

323

Porous polymer media  

DOEpatents

Highly crosslinked monolithic porous polymer materials for chromatographic applications. By using solvent compositions that provide not only for polymerization of acrylate monomers in such a fashion that a porous polymer network is formed prior to phase separation but also for exchanging the polymerization solvent for a running buffer using electroosmotic flow, the need for high pressure purging is eliminated. The polymer materials have been shown to be an effective capillary electrochromatographic separations medium at lower field strengths than conventional polymer media. Further, because of their highly crosslinked nature these polymer materials are structurally stable in a wide range of organic and aqueous solvents and over a pH range of 2-12.

Shepodd, Timothy J. (Livermore, CA)

2002-01-01

324

Neural stem cell differentiation in collagen scaffolds for retinal tissue engineering  

E-print Network

Rat neural stem cells (NSCs) were cultured in monolayer or in porous collagen scaffolds and exposed to neurogenic or non-neurogenic medium to determine the effects on neural differentiation and neurite growth. Nestin, ...

Ueda, Erica (Erica Ann)

2008-01-01

325

Three-Dimensional Scaffolds Offer New Tool to Study Cancer | Physical Sciences in Oncology  

Cancer.gov

Porous polymer scaffolds fabricated to support the growth of biological tissue for implantation may hold the potential to greatly accelerate the development of cancer therapeutics, according to research published in the Proceedings of the National Academy of Sciences.

326

Bioinspired porous membranes containing polymer nanoparticles for wound healing.  

PubMed

Skin damages covering a surface larger than 4 cm(2) require a regenerative strategy based on the use of appropriate wound dressing supports to facilitate the rapid tissue replacement and efficient self-healing of the lost or damaged tissue. In the present work, A novel biomimetic approach is proposed for the design of a therapeutic porous construct made of poly(L-lactic acid) (PLLA) fabricated by thermally induced phase separation (TIPS). Biomimicry of ECM was achieved by immobilization of type I collagen through a two-step plasma treatment for wound healing. Anti-inflammatory (indomethacin)-containing polymeric nanoparticles (nps) were loaded within the porous membranes in order to minimize undesired cell response caused by post-operative inflammation. The biological response to the scaffold was analyzed by using human keratinocytes cell cultures. In this work, a promising biomimetic construct for wound healing and soft tissue regeneration with drug-release properties was fabricated since it shows (i) proper porosity, pore size, and mechanical properties, (ii) biomimicry of ECM, and (iii) therapeutic potential. PMID:24522948

Ferreira, Ana M; Mattu, Clara; Ranzato, Elia; Ciardelli, Gianluca

2014-12-01

327

Gene delivery by surface immobilization of plasmid to tissue-engineering scaffolds  

Microsoft Academic Search

Biomaterial scaffolds that serve as vehicles for gene delivery to promote expression of inductive factors have numerous regenerative medicine applications. In this report, we investigate plasmid delivery from biomaterial scaffolds using a surface immobilization strategy. Porous scaffolds were fabricated from poly(D,L-lactide-co-glycolide) (PLG), and plasmids were immobilized by drying. In vitro plasmid release indicated that the majority (>70%) of adsorbed plasmids

D M Salvay; M Zelivyanskaya; L D Shea

2010-01-01

328

Scaffold development using 3D printing with a starch-based polymer  

Microsoft Academic Search

Rapid prototyping (RP) techniques have been utilised by tissue engineers to produce three-dimensional (3D) porous scaffolds. RP technologies allow the design and fabrication of complex scaffold geometries with a fully interconnected pore network. Three-dimensional printing (3DP) technique was used to fabricate scaffolds with a novel micro- and macro-architecture. In this study, a unique blend of starch-based polymer powders (cornstarch, dextran

C. X. F Lam; X. M Mo; S. H Teoh; D. W Hutmacher

2002-01-01

329

Structural evaluation of scaffolds prototypes produced by three-dimensional printing  

Microsoft Academic Search

The fabrication of porous scaffolds with complex architectures represents a challenge in tissue engineering. Recent studies\\u000a have shown that it is possible to construct tissue-engineered bone repair scaffolds with tight pore size distributions and\\u000a controlled geometries using 3D printing techniques. In this context, this work aims to evaluate the 3D printing process in\\u000a order to study its potential for scaffold

Miguel Castilho; Ines Pires; Barbara Gouveia; Jorge Rodrigues

330

Electrically Conductive Chitosan/Carbon Scaffolds for Cardiac Tissue Engineering  

PubMed Central

In this work, carbon nanofibers were used as doping material to develop a highly conductive chitosan-based composite. Scaffolds based on chitosan only and chitosan/carbon composites were prepared by precipitation. Carbon nanofibers were homogeneously dispersed throughout the chitosan matrix, and the composite scaffold was highly porous with fully interconnected pores. Chitosan/carbon scaffolds had an elastic modulus of 28.1 ± 3.3 KPa, similar to that measured for rat myocardium, and excellent electrical properties, with a conductivity of 0.25 ± 0.09 S/m. The scaffolds were seeded with neonatal rat heart cells and cultured for up to 14 days, without electrical stimulation. After 14 days of culture, the scaffold pores throughout the construct volume were filled with cells. The metabolic activity of cells in chitosan/carbon constructs was significantly higher as compared to cells in chitosan scaffolds. The incorporation of carbon nanofibers also led to increased expression of cardiac-specific genes involved in muscle contraction and electrical coupling. This study demonstrates that the incorporation of carbon nanofibers into porous chitosan scaffolds improved the properties of cardiac tissue constructs, presumably through enhanced transmission of electrical signals between the cells. PMID:24417502

2015-01-01

331

Characterization and cytocompatibility of biphasic calcium phosphate/polyamide 6 scaffolds for bone regeneration.  

PubMed

Porous scaffolds of biphasic calcium phosphate (BCP)/polyamide 6 (PA6) with weight ratios of 30/70, 45/55, and 55/45 have been fabricated through a modified thermally induced phase separation technique. The chemical structure properties, macrostructure, and mechanical strength of the scaffolds were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and mechanical testing. The results indicated that the BCP/PA6 scaffolds had an interconnected porous structure with a pore size mainly ranging from 100 to 900 ?m and many micropores on the rough pore walls. The mechanical property of the scaffold was significantly enhanced by the addition of BCP inorganic fillers. The 55/45 BCP/PA6 composite scaffold with 76.5% ± 2.1% porosity attained a compressive strength of 1.86 ± 0.14 MPa. Moreover, the BCP/PA6 porous scaffold was cultured with rat calvarial osteoblasts to investigate the cell proliferation, viability, and differentiation function (alkaline phosphatase). The type I collagen expression was also used to characterize the differentiation of rat calvarial osteoblasts on BCP/PA6 composite scaffold by immunocytochemistry. The in vitro cytocompatibility evaluation demonstrated that the BCP/PA6 scaffold acted as a good template for the cells adhesion, spreading, growth, and differentiation. These results suggest that the BCP/PA6 porous composite could be a candidate as an excellent substitute for damaged or defect bone. PMID:20878919

Shen, Juan; Li, Yubao; Zuo, Yi; Zou, Qin; Cheng, Lin; Zhang, Li; Gong, Mei; Gao, Shibo

2010-11-01

332

Scaffold design and fabrication technologies for engineering tissues — state of the art and future perspectives  

Microsoft Academic Search

Today, tissue engineers are attempting to engineer virtually every human tissue. Potential tissue-engineered products include cartilage, bone, heart valves, nerves, muscle, bladder, liver, etc. Tissue engineering techniques generally require the use of a porous scaffold, which serves as a threedimensional template for initial cell attachment and subsequent tissue formation both in vitro and in vivo. The scaffold provides the necessary

Dietmar W. Hutmacher

2001-01-01

333

Three-dimensional polycaprolactone scaffold via needleless electrospinning promotes cell proliferation and infiltration.  

PubMed

Electrospinning has been widely used in fabrication of tissue engineering scaffolds. Currently, most of the electrospun nanofibers performed like a conventional two-dimensional (2D) membrane, which hindered their further applications. Moreover, the low production rate of the traditional needle-electrospinning (NE) also limited the commercialization. In this article, disc-electrospinning (DE) was utilized to fabricate a three-dimensional (3D) scaffold consisting of porous macro/nanoscale fibers. The morphology of the porous structure was investigated by scanning electron microscopy images, which showed irregular pores of nanoscale spreading on the surface of DE polycaprolactone (PCL) fibers. Protein adsorption assessment illustrated the porous structure could significantly enhance proteins pickup, which was 55% higher than that of solid fiber scaffolds. Fibroblasts were cultured on the scaffold. The results demonstrated that DE fiber scaffold could enhance initial cell attachment. In the 7 days of culture, fibroblasts grew faster on DE fiber scaffold in comparison with solid fiber, solvent cast (SC) film and TCP. Fibroblasts on DE fibers showed a stretched shape and integrated with the porous surface tightly. Cells were also found to migrate into the DE scaffold up to 800?m. Results supported the use of DE PCL fibers as a 3D tissue engineering scaffold in soft tissue regeneration. PMID:24996758

Li, Dawei; Wu, Tong; He, Nanfei; Wang, Jing; Chen, Weiming; He, Liping; Huang, Chen; Ei-Hamshary, Hany A; Al-Deyab, Salem S; Ke, Qinfei; Mo, Xiumei

2014-09-01

334

Anterior cruciate ligament regeneration using mesenchymal stem cells and silk scaffold in large animal model  

Microsoft Academic Search

Although in vivo studies in small animal model show the ligament regeneration by implanting mesenchymal stem cells (MSCs) and silk scaffold, large animal studies are still needed to evaluate the silk scaffold before starting a clinical trial. The aim of this study is to regenerate anterior cruciate ligament (ACL) in pig model. The micro-porous silk mesh was fabricated by incorporating

Hongbin Fan; Haifeng Liu; Siew L. Toh; James C. H. Goh

2009-01-01

335

Synthesis and characterization of nanocomposite scaffolds based on triblock copolymer of L-lactide, ?-caprolactone and nano-hydroxyapatite for bone tissue engineering.  

PubMed

The employment of biodegradable polymer scaffolds is one of the main approaches for achieving a tissue engineered construct to reproduce bone tissues, which provide a three dimensional template to regenerate desirable tissues for different applications. The main goal of this study is to design a novel triblock scaffold reinforced with nano-hydroxyapatite (nHA) for hard tissue engineering using gas foaming/salt leaching method with minimum solvent usage. With this end in view, the biodegradable triblock copolymers of l-lactide and ?-caprolactone with different mol% were synthesized by ring-opening polymerization method in the presence of Sn(Oct)2 catalyst as initiator and ethylene glycol as co-initiator. The chemical compositions of biodegradable copolymers were characterized by means of FTIR and NMR. The thermal and crystallization behaviors of copolymers were characterized using TGA and DSC thermograms. Moreover, nano-hydroxyapatite was synthesized by the chemical precipitation process and was thoroughly characterized by FTIR, XRD and TEM. Additionally, the nanocomposites with different contents of nHA were prepared by mixing triblock copolymer with nHA. Mechanical properties of the prepared nanocomposites were evaluated by stress-strain measurements. It was found that the nanocomposite with 30% of nHA showed the optimum result. Therefore, nanocomposite scaffolds with 30% nHA were fabricated by gas foaming/salt leaching method and SEM images were used to observe the microstructure and morphology of nanocomposites and nanocomposite scaffolds before and after cell culture. The in-vitro and cell culture tests were also carried out to further evaluate the biological properties. The results revealed that the porous scaffolds were biocompatible to the osteoblast cells because the cells spread and grew well. The resultant nanocomposites could be considered as good candidates for use in bone tissue engineering. PMID:25063111

Torabinejad, Bahman; Mohammadi-Rovshandeh, Jamshid; Davachi, Seyed Mohammad; Zamanian, Ali

2014-09-01

336

EFFECT OF SCAFFOLD MICROARCHITECTURE ON OSTEOGENIC DIFFERENTIATION OF HUMAN MESENCHYMAL STEM CELLS  

PubMed Central

Design of macroporous synthetic grafts that can promote infiltration of cells, their differentiation, and synthesis of bone-specific extracellular matrix is a key determinant for in vivo bone tissue regeneration and repair. In this study, we investigated the effect of the microarchitecture of the scaffold on osteogenic differentiation of human mesenchymal stem cells (hMSCs). Poly(ethylene glycol) diacrylate-co-N-acryloyl 6-aminocaproic acid cryogels were fabricated to have either a pore network consisting of cellular, randomly oriented pores (termed ‘spongy’) or a pore network consisting of lamellar columns (termed ‘columnar’), with both cryogel types showing a similar porosity. Both spongy and columnar cryogels supported comparable levels of cell viability and proliferation of hMSCs in vitro. However, spongy cryogels promoted osteogenic differentiation to a greater extent than their columnar counterparts, as evidenced by increased alkaline phosphatase activity and osteoblastic gene expression over 21 days post culture. Leveraging upon our previous work, we further evaluated the ability of these synthetic scaffolds in conjunction with mineralisation to promote ectopic bone formation upon subcutaneous implantation in nude rats. Mineralised spongy and columnar cryogels, both in the presence and absence of exogenous hMSCs, promoted ectopic bone formation in vivo. No such bone formation was observed in acellular cryogels devoid of mineralisation, with extensive host cell infiltration and vascularisation in columnar cryogels, and negligible infiltration into spongy cryogels. Our results thus present a novel method to tune the microarchitecture of porous polymeric scaffolds, in addition to suggesting their efficacy as synthetic bone grafts. PMID:23329467

Kim, Su Hee; Kim, Soo Hyun; Yamaguchi, Tomonori; Masuda, Koichi; Varghese, Shyni

2015-01-01

337

Effects of designed PLLA and 50:50 PLGA scaffold architectures on bone formation in vivo.  

PubMed

Biodegradable porous scaffolds have been investigated as an alternative approach to current metal, ceramic, and polymer bone graft substitutes for lost or damaged bone tissues. Although there have been many studies investigating the effects of scaffold architecture on bone formation, many of these scaffolds were fabricated using conventional methods such as salt leaching and phase separation, and were constructed without designed architecture. To study the effects of both designed architecture and material on bone formation, this study designed and fabricated three types of porous scaffold architecture from two biodegradable materials, poly (L-lactic acid) (PLLA) and 50:50 Poly(lactic-co-glycolic acid) (PLGA), using image based design and indirect solid freeform fabrication techniques, seeded them with bone morphogenetic protein-7 transduced human gingival fibroblasts, and implanted them subcutaneously into mice for 4 and 8?weeks. Micro-computed tomography data confirmed that the fabricated porous scaffolds replicated the designed architectures. Histological analysis revealed that the 50:50 PLGA scaffolds degraded but did not maintain their architecture after 4?weeks implantation. However, PLLA scaffolds maintained their architecture at both time points and showed improved bone ingrowth, which followed the internal architecture of the scaffolds. Mechanical properties of both PLLA and 50:50 PLGA scaffolds decreased but PLLA scaffolds maintained greater mechanical properties than 50:50 PLGA after implantation. The increase of mineralized tissue helped support the mechanical properties of bone tissue and scaffold constructs between 4-8?weeks. The results indicate the importance of choice of scaffold materials and computationally designed scaffolds to control tissue formation and mechanical properties for desired bone tissue regeneration. PMID:22162220

Saito, Eiji; Liao, Elly E; Hu, Wei-Wen; Krebsbach, Paul H; Hollister, Scott J

2013-02-01

338

Effects of designed PLLA and 50:50PLGA scaffold architectures on bone formation in vivo  

PubMed Central

Biodegradable porous scaffolds have been investigated as an alternative approach to current metal, ceramic, and polymer bone graft substitutes for lost or damaged bone tissues. Although there have been many studies investigating the effects of scaffold architecture on bone formation, many of these scaffolds were fabricated using conventional methods, such as salt leaching and phase separation, and were constructed without designed architecture. To study the effects of both designed architecture and material on bone formation, we designed and fabricated three types of porous scaffold architecture from two biodegradable materials, poly (L-lactic acid) (PLLA) and 50:50Poly (lactic-co-glycolic acid) (PLGA) using image based design and indirect solid freeform fabrication techniques, seeded them with bone morphogenic protein-7 transduced human gingival fibroblasts and implanted them subcutaneously into mice for 4 and 8 weeks. Micro-computed tomography data confirmed that the fabricated porous scaffolds replicated the designed architectures. Histological analysis revealed that the 50:50PLGA scaffolds degraded and did not maintain their architecture after 4 weeks. The PLLA scaffolds maintained their architecture at both time points and showed improved bone ingrowth which followed the internal architecture of the scaffolds. Mechanical properties of both PLLA and 50:50PLGA scaffolds decreased, but PLLA scaffolds maintained greater mechanical properties than 50:50PLGA after implantation. The increase of mineralized tissue helped to support mechanical properties of bone tissue and scaffold constructs from 4 to 8 weeks. The results indicated the importance of choice of scaffold materials and computationally designed scaffolds to control tissue formation and mechanical properties for desired bone tissue regeneration. PMID:22162220

Saito, Eiji; Liao, Elly E.; Hu, Wei-Wen; Krebsbach, Paul H.; Hollister, Scott J.

2015-01-01

339

Osteoblast attachment to hydroxyapatite micro-tube scaffolds.  

PubMed

Tissue engineering offers a novel route for repairing damaged or diseased tissue by incorporating the patient's own healthy cells or donated cells into temporary scaffolds that act as a matrix for cell cultivation. Tissue scaffolds that are biocompatible and are porous with interconnected porous channels for cell ingrowth with a suitable degradation rate would be advantageous. In this study hydroxyapatite micro-tubes produced using the biomimetic coating technique will be pressed into a tissue scaffold. A compaction and sintering study will be done to observe appropriate pressure and heat treatment to produce a mechanically stable scaffold material. The ideal pressure was found to be 2.5 MPa where the tube-like structure was maintained, high porosity was achieved and suitable strength was possible. Sintering between 1,000 and 1,100 °C was found to produce good results. The average porosity for the chosen pressure of 2.5 MPa was 68%. The scaffold was observed with SEM, micro tomography (micro-CT), chemical analysis and degradation testing. Porous channels were established using micro-CT where the porous channels were roughly 100 µm. Chemical analysis showed constant release of calcium and phosphorous, and far below toxic levels of heavy metals from the die. Degradation testing showed high degradation compared to tested commercially available materials. Cell culturing was done on the scaffold to characterise the biological performance of the scaffolds. Cell culturing was done in a 7 and 24 day cell culture to examine cell morphology and cell ingrowth. The results showed cell ingrowth into a micro-tube and cell orientation in a longitudinal direction. SEM, confocal microscopy and histology were employed as characterisation tools for observing cell ingrowth. PMID:24728743

Kolos, E C; Ruys, A J

2014-07-01

340

In-situ polymerization PLOT columns I: divinylbenzene  

NASA Technical Reports Server (NTRS)

A novel method for preparation of porous-layer open-tubular (PLOT) columns is described. The method involves a simple and reproducible, straight-forward in-situ polymerization of monomer directly on the metal tube.

Shen, T. C.

1992-01-01

341

In-situ polymerization PLOT columns I: divinylbenzene.  

PubMed

A novel method for preparation of porous-layer open-tubular (PLOT) columns is described. The method involves a simple and reproducible, straight-forward in-situ polymerization of monomer directly on the metal tube. PMID:11540239

Shen, T C

1992-06-01

342

Two Photon Polymerization of Ormosils  

NASA Astrophysics Data System (ADS)

In this work, 3D structures of hybrid polymers—ORMOSILS (organically modified silicates) were produced via Two Photon Polymerization (2PP) of hybrid methacrylates based on silane derivates. Synthetic routes have been used to obtain series of hybrid monomers, their structure and purity being checked by NMR Spectroscopy and Fourier Transform Infrared Spectroscopy. Two photon polymerization method (a relatively new technology which allows fast micro and nano processing of three-dimensional structures with application in medical devices, tissue scaffolds, photonic crystals etc) was used for monomers processing. As laser a Ti: Sapphire laser was used, with 200 fs pulse duration and 2 kHz repetition rate, emitting at 775 nm. A parametric study on the influence of the processing parameters (laser fluence, laser scanning velocity, photo initiator) on the written structures was carried out. The as prepared polymeric scaffolds were tested in mesenchymal stem cells and fibroblasts cell cultures, with the aim of further obtaining bone and dermal grafts. Cells morphology, proliferation, adhesion and alignment were analyzed for different experimental conditions.

Matei, A.; Zamfirescu, M.; Jipa, F.; Luculescu, C.; Dinescu, M.; Buruiana, E. C.; Buruiana, T.; Sima, L. E.; Petrescu, S. M.

2010-10-01

343

Biologically inspired growth of hydroxyapatite crystals on bio-organics-defined scaffolds  

SciTech Connect

Graphical abstract: Petal-like crystals were observed to form on the surface of the BG/COL/ChS scaffolds. Highlights: ? Porous scaffolds were prepared using bioglass, collagen and chondroitin sulfate. ? Highly oriented HA crystals were grown on scaffolds using simulated body fluids ? The microstructure and orientation of HA were explained by molecular configuration. - Abstract: Several bio-organics-defined composite scaffolds were prepared using 58s-bioglass (BG), collagen (Col) and chondroitin sulfate (ChS). These scaffolds possess highly porous structure. X-ray diffraction of these scaffolds strongly indicated that hydroxyapatite (HA) crystals formed on their surfaces in simulated body fluids within 3 d, and similar formation process of crystals could be obtained on BG/Col and BG/Col/ChS scaffolds. The morphology and structure of the crystals were further examined by scanning electron microscopy. The results obtained indicate that an apatite with petal-like structure similar to that found on BG/Col scaffolds can be produced on BG/Col/ChS scaffolds through biomimetic synthesis, while that on BG/ChS scaffolds took place differently. The differences could be explained by self-assembly processes and the different macromolecular configurations of the Col and ChS fibrils which self-assemble spontaneously into their fibers. On the other hand, the bio-organics-defined composites have good cell biocompability. The results may be applicable to develop tailored biomaterials for peculiar bone substitute.

Yang, Chunrong, E-mail: milkhoney3@163.com [Department of Materials Science and Engineering, Fujian University of Technology, Fuzhou 350108 (China); Li, Yuli; Nan, Kaihui [Eye Hospital, Wenzhou Medical College, Wenzhou 325027 (China)

2013-03-15

344

Biomimetic magnetic silk scaffolds.  

PubMed

Magnetic silk fibroin protein (SFP) scaffolds integrating magnetic materials and featuring magnetic gradients were prepared for potential utility in magnetic-field assisted tissue engineering. Magnetic nanoparticles (MNPs) were introduced into SFP scaffolds via dip-coating methods, resulting in magnetic SFP scaffolds with different strengths of magnetization. Magnetic SFP scaffolds showed excellent hyperthermia properties achieving temperature increases up to 8 °C in about 100 s. The scaffolds were not toxic to osteogenic cells and improved cell adhesion and proliferation. These findings suggest that tailored magnetized silk-based biomaterials can be engineered with interesting features for biomaterials and tissue-engineering applications. PMID:25734962

Samal, Sangram K; Dash, Mamoni; Shelyakova, Tatiana; Declercq, Heidi A; Uhlarz, Marc; Bañobre-López, Manuel; Dubruel, Peter; Cornelissen, Maria; Herrmannsdörfer, Thomas; Rivas, Jose; Padeletti, Giuseppina; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L; Dediu, V Alek

2015-03-25

345

Versatile modular scaffolds  

NASA Technical Reports Server (NTRS)

Movable and fixed modular scaffolds can be tailored to most scaffolding needs by interconnecting only 4 basic structural elements: platforms, rails, vertical-support angles, and stiffener. Standard nuts and bolts are used to join elements, simplifying construction, and reducing costs. Scaffolds are rigid and can be made any length. They are stable on unlevel ground and can extend to well over 50 feet in height. Scaffolds allow for internal elevators and for wheels and air mounts so that same elements can be used for standing or movable scaffold.

Kerley, J.

1981-01-01

346

Hydrophilic PCU scaffolds prepared by grafting PEGMA and immobilizing gelatin to enhance cell adhesion and proliferation.  

PubMed

Gelatin contains many functional motifs which can modulate cell specific adhesion, so we modified polycarbonate urethane (PCU) scaffold surface by immobilization of gelatin. PCU-g-gelatin scaffolds were prepared by direct immobilizing gelatins onto the surface of aminated PCU scaffolds. To increase the immobilization amount of gelatin, poly(ethylene glycol) methacrylate (PEGMA) was grafted onto PCU scaffolds by surface initiated atom transfer radical polymerization. Then, following amination and immobilization, PCU-g-PEGMA-g-gelatin scaffolds were obtained. Both modified scaffolds were characterized by chemical and biological methods. After immobilization of gelatin, the microfiber surface became rough, but the original morphology of scaffolds was maintained successfully. PCU-g-PEGMA-g-gelatin scaffolds were more hydrophilic than PCU-g-gelatin scaffolds. Because hydrophilic PEGMA and gelatin were grafted and immobilized onto the surface, the PCU-g-PEGMA-g-gelatin scaffolds showed low platelet adhesion, perfect anti-hemolytic activity and excellent cell growth and proliferation capacity. It could be envisioned that PCU-g-PEGMA-g-gelatin scaffolds might have potential applications in tissue engineering artificial scaffolds. PMID:25746263

Shi, Changcan; Yuan, Wenjie; Khan, Musammir; Li, Qian; Feng, Yakai; Yao, Fanglian; Zhang, Wencheng

2015-05-01

347

Tissue regeneration in vivo within recombinant spidroin 1 scaffolds.  

PubMed

One of the major tasks of tissue engineering is to produce tissue grafts for the replacement or regeneration of damaged tissue, and natural and recombinant silk-based polymer scaffolds are promising candidates for such grafts. Here, we compared two porous scaffolds made from different silk proteins, fibroin of Bombyx mori and a recombinant analog of Nephila clavipes spidroin 1 known as rS1/9, and their biocompatibility and degradation behavior in vitro and in vivo. The vascularization and intergrowth of the connective tissue, which was penetrated with nerve fibers, at 8 weeks after subcutaneous implantation in Balb/c mice was more profound using the rS1/9 scaffolds. Implantation of both scaffolds into bone defects in Wistar rats accelerated repair compared to controls with no implanted scaffold at 4 weeks. Based on the number of macrophages and multinuclear giant cells in the subcutaneous area and the number of osteoclasts in the bone, regeneration was determined to be more effective after the rS1/9 scaffolds were implanted. Microscopic examination of the morphology of the matrices revealed differences in their internal microstructures. In contrast to fibroin-based scaffolds, the walls of the rS1/9 scaffolds were visibly thicker and contained specific micropores. We suggest that the porous inner structure of the rS1/9 scaffolds provided a better micro-environment for the regenerating tissue, which makes the matrices derived from the recombinant rS1/9 protein favorable candidates for future in vivo applications. PMID:22364702

Moisenovich, Mikhail M; Pustovalova, Olga; Shackelford, Julia; Vasiljeva, Tamara V; Druzhinina, Tatiana V; Kamenchuk, Yana A; Guzeev, Vitaly V; Sokolova, Olga S; Bogush, Vladimir G; Debabov, Vladimir G; Kirpichnikov, Mikhail P; Agapov, Igor I

2012-05-01

348

Cell Population Kinetics of Collagen Scaffolds in Ex Vivo Oral Wound Repair  

PubMed Central

Biodegradable collagen scaffolds are used clinically for oral soft tissue augmentation to support wound healing. This study sought to provide a novel ex vivo model for analyzing healing kinetics and gene expression of primary human gingival fibroblasts (hGF) within collagen scaffolds. Sponge type and gel type scaffolds with and without platelet-derived growth factor-BB (PDGF) were assessed in an hGF containing matrix. Morphology was evaluated with scanning electron microscopy, and hGF metabolic activity using MTT. We quantitated the population kinetics within the scaffolds based on cell density and distance from the scaffold border of DiI-labled hGFs over a two-week observation period. Gene expression was evaluated with gene array and qPCR. The sponge type scaffolds showed a porous morphology. Absolute cell number and distance was higher in sponge type scaffolds when compared to gel type scaffolds, in particular during the first week of observation. PDGF incorporated scaffolds increased cell numbers, distance, and formazan formation in the MTT assay. Gene expression dynamics revealed the induction of key genes associated with the generation of oral tissue. DKK1, CYR61, CTGF, TGFBR1 levels were increased and integrin ITGA2 levels were decreased in the sponge type scaffolds compared to the gel type scaffold. The results suggest that this novel model of oral wound healing provides insights into population kinetics and gene expression dynamics of biodegradable scaffolds. PMID:25397671

Agis, Hermann; Collins, Amy; Taut, Andrei D.; Jin, Qiming; Kruger, Laura; Görlach, Christoph; Giannobile, William V.

2014-01-01

349

Polyurethane scaffold formation via a combination of salt leaching and thermally induced phase separation  

Microsoft Academic Search

Porous scaffolds have been made from two polyurethanes based on thermally induced phase separation of polymer dissolved in a DMSO\\/water mixture in combination with salt leaching. It is possible to obtain very porous foams with a very high interconnectivity. A major advantage of this method is that variables like porosity, pore size, and interconnectivity can be independently adjusted with the

R. G. J. C. Heijkants; R. V. van Calck; T. G. van Tienen; J. H. de Groot; A. J. Pennings; P. Buma; R. P. H. Veth; A. J. Schouten

2008-01-01

350

Three-dimensional, bioactive, biodegradable, polymerbioactive glass composite scaffolds with  

E-print Network

- teointegrative potential compared to degradable polymers of poly(lactic acid-glycolic acid) alone. Future workThree-dimensional, bioactive, biodegradable, polymer­bioactive glass composite scaffolds a degradable, porous, polymer bioactive glass com- posite possessing improved mechanical properties and os

Lu, Helen H.

351

Fabrication and characterization of hydrophilic poly(lactic- co-glycolic acid)\\/poly(vinyl alcohol) blend cell scaffolds by melt-molding particulate-leaching method  

Microsoft Academic Search

Porous PLGA\\/PVA scaffolds were fabricated by blending poly(lactic-co-glycolic acid) (PLGA) with polyvinyl alcohol (PVA) to improve the hydrophilicity and cell compatibility of the scaffolds for tissue engineering applications. PLGA\\/PVA blend scaffolds with different PVA compositions up to 20wt% were fabricated by a melt-molding particulate-leaching method (non-solvent method). The prepared scaffolds were investigated by scanning electron microscopy (SEM), mercury intrusion porosimetry,

Se Heang Oh; Soung Gon Kang; Eun Seok Kim; Sang Ho Cho; Jin Ho Lee

2003-01-01

352

Enhancement of neurite outgrowth in neuron cancer stem cells by growth on 3-D collagen scaffolds  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Neuron cancer stem cells (NCSCs) behave high multiply of growth on collagen scaffold. Black-Right-Pointing-Pointer Enhancement of NCSCs neurite outgrowth on porous collagen scaffold. Black-Right-Pointing-Pointer 3-D collagen culture of NCSCs shows an advance differentiation than 2-D culture. -- Abstract: Collagen is one component of the extracellular matrix that has been widely used for constructive remodeling to facilitate cell growth and differentiation. The 3-D distribution and growth of cells within the porous scaffold suggest a clinical significance for nerve tissue engineering. In the current study, we investigated proliferation and differentiation of neuron cancer stem cells (NCSCs) on a 3-D porous collagen scaffold that mimics the natural extracellular matrix. We first generated green fluorescence protein (GFP) expressing NCSCs using a lentiviral system to instantly monitor the transitions of morphological changes during growth on the 3-D scaffold. We found that proliferation of GFP-NCSCs increased, and a single cell mass rapidly grew with unrestricted expansion between days 3 and 9 in culture. Moreover, immunostaining with neuronal nuclei (NeuN) revealed that NCSCs grown on the 3-D collagen scaffold significantly enhanced neurite outgrowth. Our findings confirmed that the 80 {mu}m porous collagen scaffold could enhance attachment, viability and differentiation of the cancer neural stem cells. This result could provide a new application for nerve tissue engineering and nerve regeneration.

Chen, Chih-Hao [Department of Electrical Engineering, I-Shou University, Taiwan, ROC (China) [Department of Electrical Engineering, I-Shou University, Taiwan, ROC (China); Neurosurgery, Department of Surgery, Kaohsiung Veterans General Hospital, Taiwan, ROC (China); Department of Biomedical Engineering, I-Shou University, Taiwan, ROC (China); Kuo, Shyh Ming [Department of Biomedical Engineering, I-Shou University, Taiwan, ROC (China)] [Department of Biomedical Engineering, I-Shou University, Taiwan, ROC (China); Liu, Guei-Sheung [Centre for Eye Research Australia, University of Melbourne (Australia)] [Centre for Eye Research Australia, University of Melbourne (Australia); Chen, Wan-Nan U. [Department of Biological Science and Technology, I-Shou University, Taiwan, ROC (China)] [Department of Biological Science and Technology, I-Shou University, Taiwan, ROC (China); Chuang, Chin-Wen [Department of Electrical Engineering, I-Shou University, Taiwan, ROC (China)] [Department of Electrical Engineering, I-Shou University, Taiwan, ROC (China); Liu, Li-Feng, E-mail: liulf@isu.edu.tw [Department of Biological Science and Technology, I-Shou University, Taiwan, ROC (China)] [Department of Biological Science and Technology, I-Shou University, Taiwan, ROC (China)

2012-11-09

353

Multimodal ultrasound-photoacoustic imaging of tissue engineering scaffolds and blood oxygen saturation in and around the scaffolds.  

PubMed

Preclinical, noninvasive imaging of tissue engineering polymeric scaffold structure and/or the physiological processes such as blood oxygenation remains a challenge. In vitro or ex vivo, the widely used scaffold characterization modalities such as porosimetry, electron or optical microscopy, and X-ray microcomputed tomography have limitations or disadvantages-some are invasive or destructive, others have limited tissue penetration (few hundred micrometers) and/or show poor contrast under physiological conditions. Postmortem histological analysis, the most robust technique for the evaluation of neovascularization is obviously not appropriate for acquiring physiological or longitudinal data. In this study, we have explored the potential of ultrasound (US)-coregistered photoacoustic (PA) imaging as a noninvasive multimodal imaging modality to overcome some of the above challenges and/or provide complementary information. US-PA imaging was employed to characterize poly(lactic-co-glycolic acid) (PLGA) polymer scaffolds or single-walled carbon nanotube (SWCNT)-incorporated PLGA (SWCNT-PLGA) polymer scaffolds as well as blood oxygen saturation within and around the scaffolds. Ex vivo, PLGA and SWCNT-PLGA scaffolds were placed at 0.5, 2, and 6 mm depths in chicken breast tissues. PLGA scaffolds could be localized with US imaging, but generate no PA signal (excitation wavelengths 680 and 780 nm). SWCNT-PLGA scaffolds generated strong PA signals at both wavelengths due to the presence of the SWCNTs and could be localized with both US and PA imaging depths between 0.5-6 mm (lateral resolution = 90 ?m, axial resolution = 40 ?m). In vivo, PLGA and SWCNT-PLGA scaffolds were implanted in subcutaneous pockets at 2 mm depth in rats, and imaged at 7 and 14 days postsurgery. The anatomical position of both the scaffolds could be determined from the US images. Only SWCNT-PLGA scaffolds could be easily detected in the US-PA images. SWCNT-PLGA scaffolds had significant four times higher PA signal intensity compared with the surrounding tissue and PLGA scaffolds. In vivo blood oxygen saturation maps around and within the PLGA scaffolds could be obtained by PA imaging. There was no significant difference in oxygen saturation for the PLGA scaffolds at the two time points. The blood oxygen saturation maps complemented the histological analysis of neovascularization of the PLGA scaffolds. PMID:24107069

Talukdar, Yahfi; Avti, Pramod; Sun, John; Sitharaman, Balaji

2014-05-01

354

Bio-mimetic hollow scaffolds for long bone replacement  

NASA Astrophysics Data System (ADS)

The tissue engineering focuses on synthesis or regeneration of tissues and organs. The hierarchical structure of nearly all porous scaffolds on the macro, micro- and nanometer scales resembles that of engineering foams dedicated for technical applications, but differ from the complex architecture of long bone. A major obstacle of scaffold architecture in tissue regeneration is the limited cell infiltration as the result of the engineering approaches. The biological cells seeded on the three-dimensional constructs are finally only located on the scaffold's periphery. This paper reports on the successful realization of calcium phosphate scaffolds with an anatomical architecture similar to long bones. Two base materials, namely nano-porous spray-dried hydroxyapatite hollow spheres and tri-calcium phosphate powder, were used to manufacture cylindrically shaped, 3D-printed scaffolds with micro-passages and one central macro-canal following the general architecture of long bones. The macro-canal is built for the surgical placement of nerves or larger blood vessels. The micro-passages allow for cell migration and capillary formation through the entire scaffold. Finally, the nanoporosity is essential for the molecule transport crucial for signaling, any cell nutrition and waste removal.

Müller, Bert; Deyhle, Hans; Fierz, Fabienne C.; Irsen, Stephan H.; Yoon, Jin Y.; Mushkolaj, Shpend; Boss, Oliver; Vorndran, Elke; Gburek, Uwe; Degistirici, Özer; Thie, Michael; Leukers, Barbara; Beckmann, Felix; Witte, Frank

2009-08-01

355

Neovascularization in Biodegradable Inverse Opal Scaffolds with Uniform and Precisely Controlled Pore Sizes**  

PubMed Central

The formation of a stable vascular network in a scaffold is one of the most challenging tasks in tissue engineering and regenerative medicine. Despite the common use of porous scaffolds in these applications, little is known about the effect of pore size on the neovascularization in these scaffolds. Here we fabricated poly(D, L-lactide-co-glycolide) inverse opal scaffolds with uniform pore sizes of 79, 147, 224, and 312 ?m in diameter and then used them to systematically study neovascularization in vivo. Histology analyses revealed that scaffolds with small pores (<200 ?m) favored the formation of vascular networks with small vessels at high densities and poor penetration depth. By contrast, scaffolds with large pores (>200 ?m) favored the formation of vascular networks with large blood vessels at low densities and deep penetration depth. Based on the different patterns of vessel ingrowth as regulated by the pore size, we proposed a model to describe vascularization in a three-dimensional porous scaffold, which can potentially serve as a guideline for future design of porous scaffolds. PMID:23184495

Choi, Sung-Wook; Zhang, Yu; MacEwan, Matthew R.; Xia, Younan

2012-01-01

356

Mesenchymal stem cell proliferation and differentiation on load-bearing trabecular Nitinol scaffolds.  

PubMed

Bone tissue regeneration in load-bearing regions of the body requires high-strength porous scaffolds capable of supporting angiogenesis and osteogenesis. 70% porous Nitinol (NiTi) scaffolds with a regular 3-D architecture resembling trabecular bone were produced from Ni foams using an original reactive vapor infiltration technique. The "trabecular Nitinol" scaffolds possessed a high compressive strength of 79 MPa and high permeability of 6.9×10(-6) cm2. The scaffolds were further modified to produce a near Ni-free surface layer and evaluated in terms of Ni ion release and human mesenchymal stem cell (hMSC) proliferation (AlamarBlue), differentiation (alkaline phosphatase activity, ALP) and mineralization (Alizarin Red S staining). Scanning electron microscopy was employed to qualitatively corroborate the results. hMSCs were able to adhere and proliferate on both as-produced and surface-modified trabecular NiTi scaffolds, to acquire an osteoblastic phenotype and produce a mineralized extracellular matrix. Both ALP activity and mineralization were increased on porous scaffolds compared to control polystyrene plates. Experiments in a model coculture system of microvascular endothelial cells and hMSCs demonstrated the formation of prevascular structures in trabecular NiTi scaffolds. These data suggest that load-bearing trabecular Nitinol scaffolds could be effective in regenerating damaged or lost bone tissue. PMID:23747323

Gotman, Irena; Ben-David, Dror; Unger, Ronald E; Böse, Thomas; Gutmanas, Elazar Y; Kirkpatrick, C James

2013-09-01

357

The mechanically enhanced phase separation of sprayed polyurethane scaffolds and their effect on the alignment of fibroblasts.  

PubMed

This paper reports a method to fabricate anisotropic scaffolds of tunable porosity and mechanical properties. Scaffolds were fabricated using a computer controlled sprayed phase separation technique. Following fabrication, the sheets were elongated 0, 35 or 70% of their original length to induce varying degrees of scaffold alignment and anisotropy. The nonsolvent used in the phase separation was shown to affect porosity and the elastic modulus. Mouse embryo NIH-3T3 fibroblasts were cultured on the scaffolds to investigate cell response to the anisotropy of the scaffold. A 2D FFT method was used to quantify cellular alignment. Cells were shown to align themselves with the scaffold. This sheet-like scaffold material can be used in single plys or can be laminated to form porous 3D composite scaffolds. PMID:19878993

Kennedy, James P; McCandless, Sean P; Lasher, Richard A; Hitchcock, Robert W

2010-02-01

358

Scaffold characterization using NLO multimodal microscopy in metrology for regenerative medicine  

NASA Astrophysics Data System (ADS)

Metrology in regenerative medicine aims to develop traceable measurement technologies for characterizing cellular and macromolecule behaviour in regenerative medicine products and processes. One key component in regenerative medicine is using three-dimensional porous scaffolds to guide cells during the regeneration process. The regeneration of specific tissues guided by tissue analogous substrates is dependent on diverse scaffold architectural properties that can be derived quantitatively from scaffolds images. This paper discuss the results obtained with the multimodal NLO microscope recently realized in our laboratory in characterizing 3D tissue engineered (TE) scaffolds colonized from human Mesenchimal stem cells (hMSC), focusing on the study of the three-dimensional metrological parameters.

Mortati, Leonardo; Divieto, Carla; Boffitto, Monica; Sartori, Susanna; Ciardelli, Gianluca; Sassi, Maria Paola

2013-09-01

359

Polymeric nanoparticles  

PubMed Central

Nanocarriers with various compositions and biological properties have been extensively applied for in vitro/in vivo drug and gene delivery. The family of nanocarriers includes polymeric nanoparticles, lipid-based carriers (liposomes/micelles), dendrimers, carbon nanotubes, and gold nanoparticles (nanoshells/nanocages). Among different delivery systems, polymeric carriers have several properties such as: easy to synthesize, inexpensive, biocompatible, biodegradable, non-immunogenic, non-toxic, and water soluble. In addition, cationic polymers seem to produce more stable complexes led to a more protection during cellular trafficking than cationic lipids. Nanoparticles often show significant adjuvant effects in vaccine delivery since they may be easily taken up by antigen presenting cells (APCs). Natural polymers such as polysaccharides and synthetic polymers have demonstrated great potential to form vaccine nanoparticles. The development of new adjuvants or delivery systems for DNA and protein immunization is an expanding research field. This review describes polymeric carriers especially PLGA, chitosan, and PEI as vaccine delivery systems. PMID:24128651

Bolhassani, Azam; Javanzad, Shabnam; Saleh, Tayebeh; Hashemi, Mehrdad; Aghasadeghi, Mohammad Reza; Sadat, Seyed Mehdi

2014-01-01

360

Micropatterning electrospun scaffolds to create intrinsic vascular networks.  

PubMed

Sufficient vascularization is critical to sustaining viable tissue-engineered (TE) constructs after implantation. Despite significant progress, current approaches lack suturability, porosity, and biodegradability, which hinders rapid perfusion and remodeling in vivo. Consequently, TE vascular networks capable of direct anastomosis to host vasculature and immediate perfusion upon implantation still remain elusive. Here, a hybrid fabrication method is presented for micropatterning fibrous scaffolds that are suturable, porous, and biodegradable. Fused deposition modeling offers an inexpensive and automated approach to creating sacrificial templates with vascular-like branching. By electrospinning around these poly(vinyl alcohol) templates and dissolving them in water, microvascular patterns were transferred to fibrous scaffolds. Results indicated that these scaffolds have sufficient suture retention strength to permit direct anastomosis in future studies. Vascularization of these scaffolds is demonstrated by in vitro endothelialization and perfusion. PMID:25142314

Jeffries, Eric M; Nakamura, Shintaro; Lee, Kee-Won; Clampffer, Jimmy; Ijima, Hiroyuki; Wang, Yadong

2014-11-01

361

Scaffold Sheet Design Strategy for Soft Tissue Engineering †  

PubMed Central

Creating heterogeneous tissue constructs with an even cell distribution and robust mechanical strength remain important challenges to the success of in vivo tissue engineering. To address these issues, we are developing a scaffold sheet tissue engineering strategy consisting of thin (?200 ?m), strong, elastic, and porous crosslinked urethane-doped polyester (CUPE) scaffold sheets that are bonded together chemically or through cell culture. Suture retention of the tissue constructs (four sheets) fabricated by the scaffold sheet tissue engineering strategy is close to the surgical requirement (1.8 N) rendering their potential for immediate implantation without a need for long cell culture times. Cell culture results using 3T3 fibroblasts show that the scaffold sheets are bonded into a tissue construct via the extracellular matrix produced by the cells after 2 weeks of in vitro cell culture. PMID:21113339

Tran, Richard T.; Thevenot, Paul; Zhang, Yi; Gyawali, Dipendra; Tang, Liping; Yang, Jian

2010-01-01

362

Synthesis and characterization of nanocrystalline forsterite coated poly(l-lactide-co-?-malic acid) scaffolds for bone tissue engineering applications.  

PubMed

In this research, after synthesizing poly(l-lactide-co-?-malic acid) (PLMA) copolymer, hybrid particles of ice and nanocrystalline forsterite (NF) as coating carriers were used to prepare NF-coated PLMA scaffolds. The porous NF-coated scaffolds were directly fabricated by a combined technique using porogen leaching and freeze-drying methods. The obtained results indicate that the scaffolds were structurally porous with NF particles on their surfaces. When compared to the uncoated scaffolds, the NF coating improved both mechanical properties as well as enhanced bioactivity of the scaffolds. In addition, in vitro biological response of the rat bone marrow stromal cells indicated that NF significantly increased the biocompatibility of NF-coated scaffolds compared with PLMA. PMID:25746252

Mozafari, M; Gholipourmalekabadi, M; Chauhan, N P S; Jalali, N; Asgari, S; Caicedoa, J C; Hamlekhan, A; Urbanska, A M

2015-05-01

363

PCL-coated hydroxyapatite scaffold derived from cuttlefish bone: in vitro cell culture studies.  

PubMed

In the present study, we examined the potential of using highly porous poly(?-caprolactone) (PCL)-coated hydroxyapatite (HAp) scaffold derived from cuttlefish bone for bone tissue engineering applications. The cell culture studies were performed in vitro with preosteoblastic MC3T3-E1 cells in static culture conditions. Comparisons were made with uncoated HAp scaffold. The attachment and spreading of preosteoblasts on scaffolds were observed by Live/Dead staining Kit. The cells grown on the HAp/PCL composite scaffold exhibited greater spreading than cells grown on the HAp scaffold. DNA quantification and scanning electron microscopy (SEM) confirmed a good proliferation of cells on the scaffolds. DNA content on the HAp/PCL scaffold was significantly higher compared to porous HAp scaffolds. The amount of collagen synthesis was determined using a hydroxyproline assay. The osteoblastic differentiation of the cells was evaluated by determining alkaline phosphatase (ALP) activity and collagen type I secretion. Furthermore, cell spreading and cell proliferation within scaffolds were observed using a fluorescence microscope. PMID:25063118

Milovac, Dajana; Gamboa-Martínez, Tatiana C; Ivankovic, Marica; Gallego Ferrer, Gloria; Ivankovic, Hrvoje

2014-09-01

364

Characterization of tissue scaffolds using optics and ultrasound  

NASA Astrophysics Data System (ADS)

Tissue scaffolds are an integral part of the tissue engineering process, assisting in the culturing of cells in three dimensions. It is important to understand both the properties of the scaffold and the growth of cells within the scaffold. This paper describes a system to characterise scaffolds using acoustic techniques alone and the development of an ultrasound modulated optical tomography system to study the growth of cells within the scaffolds. Our interest is in characterising the properties of gel-based and polymer foam-based scaffolds. Results from a purely acoustic system have been used to investigate the properties of foam scaffolds manufactured from synthetic polyesters poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) via a supercritical fluid process. As these are porous materials, they are particularly challenging acoustically as the pores scatter sound significantly. However, it is demonstrated that acoustic signals are detectable through a 6mm thick scaffold. Although acoustics alone can be used to characterize many properties of the scaffolds, useful information can also be obtained from optical techniques e.g. monitoring the growth of cells within the scaffold via optical absorption or fluorescence techniques. Light scattering is of course a significant problem for relatively thick engineered tissue (~5mm). The acoustic approach has been extended to include laser illumination and detection of the ultrasound modulated optical pulse. Images of optically-absorbing materials embedded in gel-based tissue phantoms will be presented demonstrating that a lateral resolution of 250?m and an axial resolution of ~90?m can be achieved in scattering samples.

Huynh, N. T.; Parker, N. G.; He, D.; Ruan, H.; Hayes-Gill, B. R.; Mather, M. L.; Crowe, J. A.; Rose, F. R. A. J.; Povey, M. J. W.; Morgan, S. P.

2011-03-01

365

In vitro evaluation of alginate/halloysite nanotube composite scaffolds for tissue engineering.  

PubMed

In this study, a series of alginate/halloysite nanotube (HNTs) composite scaffolds were prepared by solution-mixing and freeze-drying method. HNTs are incorporated into alginate to improve both the mechanical and cell-attachment properties of the scaffolds. The interfacial interactions between alginate and HNTs were confirmed by the atomic force microscope (AFM), transmission electron microscope (TEM) and FTIR spectroscopy. The mechanical, morphological, and physico-chemical properties of the composite scaffolds were investigated. The composite scaffolds exhibit significant enhancement in compressive strength and compressive modulus compared with pure alginate scaffold both in dry and wet states. A well-interconnected porous structure with size in the range of 100-200?m and over 96% porosity is found in the composite scaffolds. X-ray diffraction (XRD) result shows that HNTs are uniformly dispersed and partly oriented in the composite scaffolds. The incorporation of HNTs leads to increase in the scaffold density and decrease in the water swelling ratio of alginate. HNTs improve the stability of alginate scaffolds against enzymatic degradation in PBS solution. Thermogravimetrica analysis (TGA) shows that HNTs can improve the thermal stability of the alginate. The mouse fibroblast cells display better attachment to the alginate/HNT composite than those to the pure alginate, suggesting the good cytocompatibility of the composite scaffolds. Alginate/HNT composite scaffolds exhibit great potential for applications in tissue engineering. PMID:25686999

Liu, Mingxian; Dai, Libing; Shi, Huizhe; Xiong, Sheng; Zhou, Changren

2015-04-01

366

In vitro evaluation of chitosan\\/poly(lactic acid-glycolic acid) sintered microsphere scaffolds for bone tissue engineering  

Microsoft Academic Search

A three-dimensional (3-D) scaffold is one of the major components in many tissue engineering approaches. We developed novel 3-D chitosan\\/poly(lactic acid-glycolic acid) (PLAGA) composite porous scaffolds by sintering together composite chitosan\\/PLAGA microspheres for bone tissue engineering applications. Pore sizes, pore volume, and mechanical properties of the scaffolds can be manipulated by controlling fabrication parameters, including sintering temperature and sintering time.

Tao Jiang; Wafa I. Abdel-Fattah; Cato T. Laurencin

2006-01-01

367

Degradable amorphous scaffolds with enhanced mechanical properties and homogeneous cell distribution produced by a three-dimensional fiber deposition method  

Microsoft Academic Search

The mechanical properties of amorphous, degradable, and highly porous poly(lactide-co-caprolactone) structures have been improved by using a 3D fiber deposition (3DF) method. Two designs of 3DF scaffolds, with 45° and 90° layer rotation, were printed and compared with scaffolds produced by a salt-leaching method. The scaffolds had a porosity range from 64% to 82% and a high interconnectivity, measured by

Yang Sun; Anna Finne-Wistrand; Christine Albertsson; Zhe Xing; Kamal Mustafa; Wim J. Hendrikson; Dirk W. Grijpma; Lorenzo Moroni

2012-01-01

368

Tissue engineering scaffolds electrospun from cotton cellulose.  

PubMed

Nonwovens of cellulose nanofibers were fabricated by electrospinning of cotton cellulose in its LiCl/DMAc solution. The key factors associated with the electrospinning process, including the intrinsic properties of cellulose solutions, the rotating speed of collector and the applied voltage, were systematically investigated. XRD data indicated the electrospun nanofibers were almost amorphous. When increasing the rotating speed of the collector, preferential alignment of fibers along the drawing direction and improved molecular orientation were revealed by scanning electron microscope and polarized FTIR, respectively. Tensile tests indicated the strength of the nonwovens along the orientation direction could be largely improved when collected at a higher speed. In light of the excellent biocompatibility and biodegradability as well as their unique porous structure, the nonwovens were further assessed as potential tissue engineering scaffolds. Cell culture experiments demonstrated human dental follicle cells could proliferate rapidly not only on the surface but also in the entire scaffold. PMID:25439923

He, Xu; Cheng, Long; Zhang, Ximu; Xiao, Qiang; Zhang, Wei; Lu, Canhui

2015-01-22

369

Crosslinked, porous, polyacrylate beads  

NASA Technical Reports Server (NTRS)

Uniformly-shaped, porous, round beads are prepared by the co-polymerization of an acrylic monomer and a cross-linking agent in the presence of 0.05 to 5% by weight of an aqueous soluble polymer such as polyethylene oxide. Cross-linking proceeds at high temperature above about 50.degree. C or at a lower temperature with irradiation. Beads of even shape and even size distribution of less than 2 micron diameter are formed. The beads will find use as adsorbents in chromatography and as markers for studies of cell surface receptors.

Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Dreyer, William J. (Inventor)

1977-01-01

370

Crosslinked, porous, polyacrylate beads  

NASA Technical Reports Server (NTRS)

Uniformly-shaped, porous, round beads are prepared by the co-polymerization of an acrylic monomer and a cross-linking agent in the presence of 0.05 to 5% by weight of an aqueous soluble polymer such as polyethylene oxide. Cross-linking proceeds at high temperature above about 50.degree.C or at a lower temperature with irradiation. Beads of even shape and even size distribution of less than 2 micron diameter are formed. The beads will find use as adsorbents in chromatography and as markers for studies of cell surface receptors.

Rembaum, Alan (Inventor); Yen, Shiao-Ping Siao (Inventor); Dreyer, William J. (Inventor)

1976-01-01

371

Small, porous polyacrylate beads  

NASA Technical Reports Server (NTRS)

Uniformly-shaped, porous, round beads are prepared by the co-polymerization of an acrylic monomer and a cross-linking agent in the presence of 0.05 to 5% by weight of an aqueous soluble polymer such as polyethylene oxide. Cross-linking proceeds at high temperature above about 50.degree.C or at a lower temperature with irradiation. Beads of even shape and even size distribution of less than 2 micron diameter are formed. The beads will find use as adsorbents in chromatography and as markers for studies of cell surface receptors.

Rembaum, Alan (Inventor); Yen, Shiao-Ping Siao (Inventor); Dreyer, William J. (Inventor)

1976-01-01

372

A biomimetic three-dimensional woven composite scaffold for functional tissue engineering of cartilage  

NASA Astrophysics Data System (ADS)

Tissue engineering seeks to repair or regenerate tissues through combinations of implanted cells, biomaterial scaffolds and biologically active molecules. The rapid restoration of tissue biomechanical function remains an important challenge, emphasizing the need to replicate structural and mechanical properties using novel scaffold designs. Here we present a microscale 3D weaving technique to generate anisotropic 3D woven structures as the basis for novel composite scaffolds that are consolidated with a chondrocyte-hydrogel mixture into cartilage tissue constructs. Composite scaffolds show mechanical properties of the same order of magnitude as values for native articular cartilage, as measured by compressive, tensile and shear testing. Moreover, our findings showed that porous composite scaffolds could be engineered with initial properties that reproduce the anisotropy, viscoelasticity and tension-compression nonlinearity of native articular cartilage. Such scaffolds uniquely combine the potential for load-bearing immediately after implantation in vivo with biological support for cell-based tissue regeneration without requiring cultivation in vitro.

Moutos, Franklin T.; Freed, Lisa E.; Guilak, Farshid

2007-02-01

373

Hierarchical Scaffolding With Bambus  

PubMed Central

The output of a genome assembler generally comprises a collection of contiguous DNA sequences (contigs) whose relative placement along the genome is not defined. A procedure called scaffolding is commonly used to order and orient these contigs using paired read information. This ordering of contigs is an essential step when finishing and analyzing the data from a whole-genome shotgun project. Most recent assemblers include a scaffolding module; however, users have little control over the scaffolding algorithm or the information produced. We thus developed a general-purpose scaffolder, called Bambus, which affords users significant flexibility in controlling the scaffolding parameters. Bambus was used recently to scaffold the low-coverage draft dog genome data. Most significantly, Bambus enables the use of linking data other than that inferred from mate-pair information. For example, the sequence of a completed genome can be used to guide the scaffolding of a related organism. We present several applications of Bambus: support for finishing, comparative genomics, analysis of the haplotype structure of genomes, and scaffolding of a mammalian genome at low coverage. Bambus is available as an open-source package from our Web site. PMID:14707177

Pop, Mihai; Kosack, Daniel S.; Salzberg, Steven L.

2004-01-01

374

Spray-assisted layer-by-layer assembly on hyaluronic acid scaffolds for skin tissue engineering.  

PubMed

Tissue engineering approaches for the development of a single epidermal-dermal scaffold to treat full-thickness skin defects have been limited by difficulties in the fabrication of a bilayer scaffold combining the specific properties of the epidermis and the dermis. Here we present an innovative approach to developing a scaffold that holds promise for skin tissue engineering. We utilize the spray-assisted layer-by-layer assembly technique to deposit a polyelectrolyte multilayer film composed of hyaluronic acid and poly-L-lysine (the epidermal component) on a porous hyaluronic acid scaffold (the dermal component), in a rapid and controlled manner. The multilayer film promotes cell adhesion, contributing to regeneration of the epidermal barrier functions of skin. While human keratinocytes attached and proliferated on the coated porous scaffolds, they did not invade the porous dermal component, thus leaving room for seeding of relevant fibroblast cell types in this scaffold. This scaffold therefore holds promise for co-culture of different cells, which may be useful for treatment of full-thickness skin defects as well as other tissue engineering applications. PMID:24659574

Monteiro, Isa P; Shukla, Anita; Marques, Alexandra P; Reis, Rui L; Hammond, Paula T

2015-01-01

375

Imaging studies of peripheral nerve regeneration induced by porous collagen biomaterials  

E-print Network

There is urgent need to develop treatments for inducing regeneration in injured organs. Porous collagen-based scaffolds have been utilized clinically to induce regeneration in skin and peripheral nerves, however still there ...

Tzeranis, Dimitrios Spyridon

2013-01-01

376

Biomimetic materials and scaffolds for myocardial tissue regeneration.  

PubMed

One of the main challenges in tissue engineering/regenerative medicine (TERM) is the repair of damaged heart tissue, avoiding or minimizing ventricular remodeling which leads to ventricular dilatation and hypertrophy, sphericity increase, and functionality loss. Several approaches have been described to restore or enhance the contractility of the failing heart. One of them is based on the fabrication of 3D substrates that can be implanted in the infarcted area to provide an efficient support to the regenerative process. This review focuses on the strategies adopted to design and realize polymeric scaffolds for heart TERM. The implementation of different polymers and the design of scaffold architecture are described. PMID:23836778

Silvestri, Antonella; Boffito, Monica; Sartori, Susanna; Ciardelli, Gianluca

2013-08-01

377

Filling Porous Microspheres With Magnetic Material  

NASA Technical Reports Server (NTRS)

New process produces magnetic microspheres with controllable sizes, compositions, and properties for use in medical diagnostic tests, biological research, and chemical processes. Paramagnetic microspheres also made with process. Porous plastic microspheres prepared by polymerization of monomer in diluent by cross-linking agent. When diluent removed, it leaves tiny pores throughout polymerized spheres. Size and distribution of pores determined by amount and type of diluent and cross-linking agent.

Chang, Manchium; Colvin, Michael S.

1990-01-01

378

Bioactive scaffold for bone tissue engineering: An in vivo study  

NASA Astrophysics Data System (ADS)

Massive bone loss of the proximal femur is a common problem in revision cases of total hip implants. Allograft is typically used to reconstruct the site for insertion of the new prosthesis. However, for long term fixation and function, it is desirable that the allograft becomes fully replaced by bone tissue and aids in the regeneration of bone to that site. However, allograft use is typically associated with delayed incorporation and poor remodeling. Due to these profound limitations, alternative approaches are needed. Tissue engineering is an attractive approach to designing improved graft materials. By combining osteogenic activity with a resorbable scaffold, bone formation can be stimulated while providing structure and stability to the limb during incorporation and remodeling of the scaffold. Porous, surface modified bioactive ceramic scaffolds (pSMC) have been developed which stimulate the expression of the osteoblastic phenotype and production of bone-like tissue in vitro. The scaffold and two tissue-engineered constructs, osteoprogenitor cells seeded onto scaffolds or cells expanded in culture to form bone tissue on the scaffolds prior to implantation, were investigated in a long bone defect model. The rate of incorporation was assessed. Both tissue-engineered constructs stimulated bone formation and comparable repair at 2 weeks. In a rat femoral window defect model, bone formation increased over time for all groups in concert with scaffold resorption, leading to a 40% increase in bone and 40% reduction of the scaffold in the defect by 12 weeks. Both tissue-engineered constructs enhanced the rate of mechanical repair of long bones due to better bony union with the host cortex. Long bones treated with tissue engineered constructs demonstrated a return in normal torsional properties by 4 weeks as compared to 12 weeks for long bones treated with pSMC. Culture expansion of cells to produce bone tissue in vitro did not accelerate incorporation over the treatment with cells seeded at the time of surgery. Porous, surface modified bioactive ceramic is a promising scaffold material for tissue-engineered bone repair. Bone formation and scaffold resorption act in concert for maintenance and improvement of the structural properties of the long bones over time. As determined histomorphometrically and mechanically, the rate of incorporation of the scaffold was enhanced with the tissue-engineered constructs.

Livingston, Treena Lynne