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Sample records for artificial bone substitute

  1. Histologic Evaluation of Human Alveolar Sockets Treated With an Artificial Bone Substitute Material

    PubMed Central

    Wakimoto, Mari; Ueno, Takaaki; Hirata, Azumi; Iida, Seiji; Aghaloo, Tara; Moy, Peter K.

    2012-01-01

    This study involved a histologic, enzyme histologic, immunohistologic, and three-dimensional microstructure evaluating the extent of osteogenesis and repair in the human alveolar extraction socket achievable with an artificial bone substitute. After tooth extraction in 7 patients, extraction sockets were filled with Mastergraft (15% hydroxyapatite, 85% β-tricalcium phosphate complex). Radio-micrographs and histologic examinations were performed on samples obtained during dental implant placement procedure. On micro– computed tomography, new bone was observed in all collected samples, and osteogenesis was observed to have taken place around the artificial bone substitute. Histologically, active osteogenesis was found throughout the region observed. Addition of new bone around the Mastergraft was observed, and osteoblast-like cells were present. Cells that had partially invaded the artificial bone included tartrate-resistant acid phosphate–positive and CD34-positive cells. These findings indicate that the Mastergraft artificial bone induced osteogenesis in the jawbone and seemed effective for repairing bone defects. PMID:21415629

  2. The Role of Resorbable Plate and Artificial Bone Substitute in Reconstruction of Large Orbital Floor Defect

    PubMed Central

    Kwon, Ho; Kim, Ho Jun; Jeong, Yeon Jin; Jung, Sung-No

    2016-01-01

    It is essential to reduce and reconstruct bony defects adequately in large orbital floor fracture and defect. Among many reconstructive methods, alloplastic materials have attracted attention because of their safety and ease of use. We have used resorbable plates combined with artificial bone substitutes in large orbital floor defect reconstructions and have evaluated their long-term reliability compared with porous polyethylene plate. A total of 147 patients with traumatic orbital floor fracture were included in the study. Surgical results were evaluated by clinical evaluations, exophthalmometry, and computed tomography at least 12 months postoperatively. Both orbital floor height discrepancy and orbital volume change were calculated and compared with preoperative CT findings. The average volume discrepancy and vertical height discrepancies were not different between two groups. Also, exophthalmometric measurements were not significantly different between the two groups. No significant postoperative complication including permanent diplopia, proptosis, and enophthalmos was noted. Use of a resorbable plate with an artificial bone substitute to repair orbital floor defects larger than 2.5 cm2 in size yielded long-lasting, effective reconstruction without significant complications. We therefore propose our approach as an effective alternative method for large orbital floor reconstructions. PMID:27517041

  3. Bone grafts and their substitutes.

    PubMed

    Fillingham, Y; Jacobs, J

    2016-01-01

    The continual cycle of bone formation and resorption is carried out by osteoblasts, osteocytes, and osteoclasts under the direction of the bone-signaling pathway. In certain situations the host cycle of bone repair is insufficient and requires the assistance of bone grafts and their substitutes. The fundamental properties of a bone graft are osteoconduction, osteoinduction, osteogenesis, and structural support. Options for bone grafting include autogenous and allograft bone and the various isolated or combined substitutes of calcium sulphate, calcium phosphate, tricalcium phosphate, and coralline hydroxyapatite. Not all bone grafts will have the same properties. As a result, understanding the requirements of the clinical situation and specific properties of the various types of bone grafts is necessary to identify the ideal graft. We present a review of the bone repair process and properties of bone grafts and their substitutes to help guide the clinician in the decision making process. PMID:26733632

  4. Developing better artificial bones.

    PubMed

    Flinn, Edward D

    2003-01-01

    Researchers at the Center for Commercial Applications of Combustion in Space at the Colorado School of Mines are preparing the Space-DRUMS (Dynamically Responding Ultrasonic Matrix Systems) materials processing facility for transport to the International Space Station. The Space-DRUMS uses acoustic pressure beams to maintain the position of a suspended liquid or solid. Space-DRUMS will be used to extend experiments with tricalcium phosphate in the development of artificial bone material. PMID:12524712

  5. Bone grafts, bone substitutes and orthobiologics

    PubMed Central

    Roberts, Timothy T.; Rosenbaum, Andrew J.

    2012-01-01

    The biology of fracture healing is better understood than ever before, with advancements such as the locking screw leading to more predictable and less eventful osseous healing. However, at times one’s intrinsic biological response, and even concurrent surgical stabilization, is inadequate. In hopes of facilitating osseous union, bone grafts, bone substitutes and orthobiologics are being relied on more than ever before. The osteoinductive, osteoconductive and osteogenic properties of these substrates have been elucidated in the basic science literature and validated in clinical orthopaedic practice. Furthermore, an industry built around these items is more successful and in demand than ever before. This review provides a comprehensive overview of the basic science, clinical utility and economics of bone grafts, bone substitutes and orthobiologics. PMID:23247591

  6. Composite bone substitutes prepared by two methods

    NASA Astrophysics Data System (ADS)

    Lee, Hoe Y.

    A variety of ceramics and polymers exists that can be used as bone substitute materials with desirable properties such as biocompatibility and osteoconductivity. A key feature missing in these bone substitutes, or scaffolds, is the ability to bear loads. This work explored two methods for solving this problem. The first used cancellous bone taken from bovine femoral bone to create a natural scaffold through a heat treating process that eliminated the organic components and sintered the bone minerals, known as hydroxyapatite, together. The strength and Young's modulus of the natural scaffold were greatly improved after polymer infiltration with polymethylmethacrylate. Unfortunately, compression testing revealed that there was not a good interfacial bond between the mineral and polymer phases. The second method employed a freeze-casting technique to create synthetic hydroxyapatite scaffolds that have an aligned lamellar microstructure. By varying the amount of hydroxyapatite in the initial slurry mixture and the cooling rate, synthetic scaffolds with a range of porosities and strengths was produced. The highest solid loading and fastest cooling rate produced a scaffold with a strength and modulus approaching that of cortical bone. Further study is required to produce a two phase composite that is chemically bonded together for optimal performance. The synthetic scaffolds, with their tunable mechanical properties and ease of fabrication, make them a promising material for a load-bearing bone substitute.

  7. High-strength mineralized collagen artificial bone

    NASA Astrophysics Data System (ADS)

    Qiu, Zhi-Ye; Tao, Chun-Sheng; Cui, Helen; Wang, Chang-Ming; Cui, Fu-Zhai

    2014-03-01

    Mineralized collagen (MC) is a biomimetic material that mimics natural bone matrix in terms of both chemical composition and microstructure. The biomimetic MC possesses good biocompatibility and osteogenic activity, and is capable of guiding bone regeneration as being used for bone defect repair. However, mechanical strength of existing MC artificial bone is too low to provide effective support at human load-bearing sites, so it can only be used for the repair at non-load-bearing sites, such as bone defect filling, bone graft augmentation, and so on. In the present study, a high strength MC artificial bone material was developed by using collagen as the template for the biomimetic mineralization of the calcium phosphate, and then followed by a cold compression molding process with a certain pressure. The appearance and density of the dense MC were similar to those of natural cortical bone, and the phase composition was in conformity with that of animal's cortical bone demonstrated by XRD. Mechanical properties were tested and results showed that the compressive strength was comparable to human cortical bone, while the compressive modulus was as low as human cancellous bone. Such high strength was able to provide effective mechanical support for bone defect repair at human load-bearing sites, and the low compressive modulus can help avoid stress shielding in the application of bone regeneration. Both in vitro cell experiments and in vivo implantation assay demonstrated good biocompatibility of the material, and in vivo stability evaluation indicated that this high-strength MC artificial bone could provide long-term effective mechanical support at human load-bearing sites.

  8. Artificial Gravity: Effects on Bone Turnover

    NASA Technical Reports Server (NTRS)

    Heer, M.; Zwart, S /R.; Baecker, N.; Smith, S. M.

    2007-01-01

    The impact of microgravity on the human body is a significant concern for space travelers. Since mechanical loading is a main reason for bone loss, artificial gravity might be an effective countermeasure to the effects of microgravity. In a 21-day 6 head-down tilt bed rest (HDBR) pilot study carried out by NASA, USA, the utility of artificial gravity (AG) as a countermeasure to immobilization-induced bone loss was tested. Blood and urine were collected before, during, and after bed rest for bone marker determinations. Bone mineral density was determined by DXA and pQCT before and after bed rest. Urinary excretion of bone resorption markers (n-telopeptide and helical peptide) were increased from pre-bed rest, but there was no difference between the control and the AG group. The same was true for serum c-telopeptide measurements. Bone formation markers were affected by bed rest and artificial gravity. While bone-specific alkaline phosphatase tended to be lower in the AG group during bed rest (p = 0.08), PINP, another bone formation marker, was significantly lower in AG subjects than CN before and during bed rest. PINP was lower during bed rest in both groups. For comparison, artificial gravity combined with ergometric exercise was tested in a 14-day HDBR study carried out in Japan (Iwase et al. J Grav Physiol 2004). In that study, an exercise regime combined with AG was able to significantly mitigate the bed rest-induced increase in the bone resorption marker deoxypyridinoline. While further study is required to more clearly differentiate bone and muscle effects, these initial data demonstrate the potential effectiveness of short-radius, intermittent AG as a countermeasure to the bone deconditioning that occurs during bed rest and spaceflight. Future studies will need to optimize not only the AG prescription (intensity and duration), but will likely need to include the use of exercise or other combined treatments.

  9. Sensory substitution as an artificially acquired synaesthesia.

    PubMed

    Ward, Jamie; Wright, Thomas

    2014-04-01

    In this review we explore the relationship between synaesthesia and sensory substitution and argue that sensory substitution does indeed show properties of synaesthesia. Both are associated with atypical perceptual experiences elicited by the processing of a qualitatively different stimulus to that which normally gives rise to that experience. In the most common forms of sensory substitution, perceptual processing of an auditory or tactile signal (which has been converted from a visual signal) is experienced as visual-like in addition to retaining auditory/tactile characteristics. We consider different lines of evidence that support, to varying degrees, the assumption that sensory substitution is associated with visual-like experiences. We then go on to analyse the key similarities and differences between sensory substitution and synaesthesia. Lastly, we propose two testable predictions: firstly that, in an expert user of a sensory substitution device, the substituting modality should not be lost. Secondly that stimulation within the substituting modality, but by means other than a sensory substitution device, should still produce sensation in the normally substituted modality. PMID:22885223

  10. Bone graft substitutes for spine fusion: A brief review

    PubMed Central

    Gupta, Ashim; Kukkar, Nitin; Sharif, Kevin; Main, Benjamin J; Albers, Christine E; El-Amin III, Saadiq F

    2015-01-01

    Bone graft substitutes are widely used in the field of orthopedics and are extensively used to promote vertebral fusion. Fusion is the most common technique in spine surgery and is used to treat morbidities and relieve discomfort. Allograft and autograft bone substitutes are currently the most commonly used bone grafts to promote fusion. These approaches pose limitations and present complications to the patient. Numerous alternative bone graft substitutes are on the market or have been developed and proposed for application. These options have attempted to promote spine fusion by enhancing osteogenic properties. In this review, we reviewed biology of spine fusion and the current advances in biomedical materials and biological strategies for application in surgical spine fusion. Our findings illustrate that, while many bone graft substitutes perform well as bone graft extenders, only osteoinductive proteins (recombinant bone morphogenetic proteins-2 and osteogenic protein-1) provide evidence for use as both bone enhancers and bone substitutes for specific types of spinal fusion. Tissue engineered hydrogels, synthetic polymer composites and viral based gene therapy also holds the potential to be used for spine fusion in future, though warrants further investigation to be used in clinical practice. PMID:26191491

  11. Bone graft substitutes for spine fusion: A brief review.

    PubMed

    Gupta, Ashim; Kukkar, Nitin; Sharif, Kevin; Main, Benjamin J; Albers, Christine E; El-Amin Iii, Saadiq F

    2015-07-18

    Bone graft substitutes are widely used in the field of orthopedics and are extensively used to promote vertebral fusion. Fusion is the most common technique in spine surgery and is used to treat morbidities and relieve discomfort. Allograft and autograft bone substitutes are currently the most commonly used bone grafts to promote fusion. These approaches pose limitations and present complications to the patient. Numerous alternative bone graft substitutes are on the market or have been developed and proposed for application. These options have attempted to promote spine fusion by enhancing osteogenic properties. In this review, we reviewed biology of spine fusion and the current advances in biomedical materials and biological strategies for application in surgical spine fusion. Our findings illustrate that, while many bone graft substitutes perform well as bone graft extenders, only osteoinductive proteins (recombinant bone morphogenetic proteins-2 and osteogenic protein-1) provide evidence for use as both bone enhancers and bone substitutes for specific types of spinal fusion. Tissue engineered hydrogels, synthetic polymer composites and viral based gene therapy also holds the potential to be used for spine fusion in future, though warrants further investigation to be used in clinical practice. PMID:26191491

  12. The Use of Bone Graft Substitute in Hand Surgery

    PubMed Central

    Liodaki, Eirini; Kraemer, Robert; Mailaender, Peter; Stang, Felix

    2016-01-01

    Abstract Bone defects are a very common problem in hand surgery, occurring in bone tumor surgery, in complicated fractures, and in wrist surgery. Bone substitutes may be used instead of autologous bone graft to avoid donor site morbidity. In this article, we will review our experience with the use of Cerament bone void filler (Bonesupport, Lund, Sweden) in elective and trauma hand surgery. A prospective clinical study was conducted with 16 patients treated with this bone graft substitute in our department over a period of 3.5 years. Twelve patients (2 female, 10 male; with an average age of 42.42 years) with monostoic enchondroma of the phalanges were treated and 4 patients (1 female, 3 male; with an average age of 55.25 years) with complicated metacarpal fractures with bone defect. Data such as postoperative course with rating of pain, postoperative complications, functional outcome assessment at 1, 2, 3, 6 months, time to complete remodeling were registered. Postoperative redness and swelling after bone graft substitute use was noticed in 7 patients with enchondroma surgery due to the thin soft-tissue envelope of the fingers. Excellent total active motion of the involved digit was noticed in 10 of 12 enchondroma patients and in all 4 fracture patients at 2-month follow-up. In summary, satisfying results are described, making the use of injectable bone graft substitute in the surgical treatment of enchondromas, as well as in trauma hand surgery a good choice. PMID:27310946

  13. 3D Printing of Octacalcium Phosphate Bone Substitutes.

    PubMed

    Komlev, Vladimir S; Popov, Vladimir K; Mironov, Anton V; Fedotov, Alexander Yu; Teterina, Anastasia Yu; Smirnov, Igor V; Bozo, Ilya Y; Rybko, Vera A; Deev, Roman V

    2015-01-01

    Biocompatible calcium phosphate ceramic grafts are able of supporting new bone formation in appropriate environment. The major limitation of these materials usage for medical implants is the absence of accessible methods for their patient-specific fabrication. 3D printing methodology is an excellent approach to overcome the limitation supporting effective and fast fabrication of individual complex bone substitutes. Here, we proposed a relatively simple route for 3D printing of octacalcium phosphates (OCP) in complexly shaped structures by the combination of inkjet printing with post-treatment methodology. The printed OCP blocks were further implanted in the developed cranial bone defect followed by histological evaluation. The obtained result confirmed the potential of the developed OCP bone substitutes, which allowed 2.5-time reducing of defect's diameter at 6.5 months in a region where native bone repair is extremely inefficient. PMID:26106596

  14. 3D Printing of Octacalcium Phosphate Bone Substitutes

    PubMed Central

    Komlev, Vladimir S.; Popov, Vladimir K.; Mironov, Anton V.; Fedotov, Alexander Yu.; Teterina, Anastasia Yu.; Smirnov, Igor V.; Bozo, Ilya Y.; Rybko, Vera A.; Deev, Roman V.

    2015-01-01

    Biocompatible calcium phosphate ceramic grafts are able of supporting new bone formation in appropriate environment. The major limitation of these materials usage for medical implants is the absence of accessible methods for their patient-specific fabrication. 3D printing methodology is an excellent approach to overcome the limitation supporting effective and fast fabrication of individual complex bone substitutes. Here, we proposed a relatively simple route for 3D printing of octacalcium phosphates (OCP) in complexly shaped structures by the combination of inkjet printing with post-treatment methodology. The printed OCP blocks were further implanted in the developed cranial bone defect followed by histological evaluation. The obtained result confirmed the potential of the developed OCP bone substitutes, which allowed 2.5-time reducing of defect’s diameter at 6.5 months in a region where native bone repair is extremely inefficient. PMID:26106596

  15. Engineering bone tissue substitutes from human induced pluripotent stem cells

    PubMed Central

    de Peppo, Giuseppe Maria; Marcos-Campos, Iván; Kahler, David John; Alsalman, Dana; Shang, Linshan; Vunjak-Novakovic, Gordana; Marolt, Darja

    2013-01-01

    Congenital defects, trauma, and disease can compromise the integrity and functionality of the skeletal system to the extent requiring implantation of bone grafts. Engineering of viable bone substitutes that can be personalized to meet specific clinical needs represents a promising therapeutic alternative. The aim of our study was to evaluate the utility of human-induced pluripotent stem cells (hiPSCs) for bone tissue engineering. We first induced three hiPSC lines with different tissue and reprogramming backgrounds into the mesenchymal lineages and used a combination of differentiation assays, surface antigen profiling, and global gene expression analysis to identify the lines exhibiting strong osteogenic differentiation potential. We then engineered functional bone substitutes by culturing hiPSC-derived mesenchymal progenitors on osteoconductive scaffolds in perfusion bioreactors and confirmed their phenotype stability in a subcutaneous implantation model for 12 wk. Molecular analysis confirmed that the maturation of bone substitutes in perfusion bioreactors results in global repression of cell proliferation and an increased expression of lineage-specific genes. These results pave the way for growing patient-specific bone substitutes for reconstructive treatments of the skeletal system and for constructing qualified experimental models of development and disease. PMID:23653480

  16. Correction of alveolar cleft with calcium-based bone substitutes.

    PubMed

    Lazarou, Spiros A; Contodimos, George B; Gkegkes, Ioannis D

    2011-05-01

    The criterion standard of alveolar cleft repair is iliac crest bone graft before secondary canine eruption. Tooth eruption has never been shown to occur in synthetic bone substitute, and there is no ideal autologous bone graft for primary repair. This prospective study evaluated alveolar cleft grafting with a calcium substitute before primary canine eruption. Ten consecutive patients with complete cleft lip, palate, and unilateral alveolar cleft with reasonably aligned arches were grafted beginning in January 2003 to March 2007. Mean age at surgery was 10.4 months. Follow-up ranged from 3 to 7 years. Radiologic evaluation of alveolar ridge was performed at the age of 4.All 10 patients were operated on by the same surgeon using the same technique, that is, conservative elevation of nasal, oral, and anterior alveolar mucosal flaps around the cleft, closure of nasal and oral flaps, placement of 1 to 3 mL of calcium substitute paste or crystals in the pocket, and closure of the anterior alveolar mucosa. All 10 patients healed without complication. Clinical evaluation revealed a well-healed arch with primary canine growth in the area of the previous cleft. Adequate normal bone formation and often a descending secondary canine were radiologically confirmed. Calcium substitutes offer significant advantages over other biomaterials as well as autologous bone grafts particularly in the primary alveolar cleft reconstruction. Our study has shown for the first time that teeth can erupt through this material, which turns into a normal functioning bone in the alveolar ridge. PMID:21558929

  17. 3D artificial bones for bone repair prepared by computed tomography-guided fused deposition modeling for bone repair.

    PubMed

    Xu, Ning; Ye, Xiaojian; Wei, Daixu; Zhong, Jian; Chen, Yuyun; Xu, Guohua; He, Dannong

    2014-09-10

    The medical community has expressed significant interest in the development of new types of artificial bones that mimic natural bones. In this study, computed tomography (CT)-guided fused deposition modeling (FDM) was employed to fabricate polycaprolactone (PCL)/hydroxyapatite (HA) and PCL 3D artificial bones to mimic natural goat femurs. The in vitro mechanical properties, in vitro cell biocompatibility, and in vivo performance of the artificial bones in a long load-bearing goat femur bone segmental defect model were studied. All of the results indicate that CT-guided FDM is a simple, convenient, relatively low-cost method that is suitable for fabricating natural bonelike artificial bones. Moreover, PCL/HA 3D artificial bones prepared by CT-guided FDM have more close mechanics to natural bone, good in vitro cell biocompatibility, biodegradation ability, and appropriate in vivo new bone formation ability. Therefore, PCL/HA 3D artificial bones could be potentially be of use in the treatment of patients with clinical bone defects. PMID:25133309

  18. Mesenchymal stem cells combined with an artificial dermal substitute improve repair in full-thickness skin wounds.

    PubMed

    Leonardi, Dilmar; Oberdoerfer, Daniel; Fernandes, Marilda C; Meurer, Rosalva T; Pereira-Filho, Gustavo A; Cruz, Paloma; Vargas, Marcelo; Chem, Roberto C; Camassola, Melissa; Nardi, Nance B

    2012-12-01

    Autografts represent the gold standard for the treatment of full thickness burns. Factors such as lack of suitable donor sites and poor skin quality, however, have led to the development of artificial dermal substitutes. The investigation of mechanisms leading to enhanced functionality of these skin substitutes has been attracting great attention. This study aimed to investigate the effect of autologous stem cells on the integration and vascularization of a dermal substitute in full-thickness skin wounds, in a murine model. Two cell populations were compared, whole bone marrow cells and cultivated mesenchymal stem cells, isolated from mice transgenic for the enhanced green fluorescent protein, which allowed tracking of the transplanted cells. The number of cells colonizing the dermal substitute, as well as vascular density, were higher in mice receiving total bone marrow and particularly mesenchymal stem cells, than in control animals. The effect was more pronounced in animals treated with mesenchymal stem cells, which located primarily in the wound bed, suggesting a paracrine therapeutic mechanism. These results indicate that combining mesenchymal stem cells with artificial dermal substitutes may represent an important potential modality for treating full thickness burns, even in allogeneic combinations due to the immunoregulatory property of these cells. PMID:22998897

  19. Controlling Bone Graft Substitute Microstructure to Improve Bone Augmentation.

    PubMed

    Sheikh, Zeeshan; Drager, Justin; Zhang, Yu Ling; Abdallah, Mohamed-Nur; Tamimi, Faleh; Barralet, Jake

    2016-07-01

    Vertical bone augmentation procedures are frequently carried out to allow successful placement of dental implants in otherwise atrophic ridges and represent one of the most common bone grafting procedures currently performed. Onlay autografting is one of the most prevalent and predictable techniques to achieve this; however, there are several well documented complications and drawbacks associated with it and synthetic alternatives are being sought. Monetite is a bioresorbable dicalcium phosphate with osteoconductive and osteoinductive potential that has been previously investigated for onlay bone grafting and it is routinely made by autoclaving brushite to simultaneously sterilize and phase convert. In this study, monetite disc-shaped grafts are produced by both wet and dry heating methods which alter their physical properties such as porosity, surface area, and mechanical strength. Histological observations after 12 weeks of onlay grafting on rabbit calvaria reveal higher bone volume (38%) in autoclaved monetite grafts in comparison with the dry heated monetite grafts (26%). The vertical bone height gained is similar for both the types of monetite grafts (up to 3.2 mm). However, it is observed that the augmented bone height is greater in the lateral than the medial areas of both types of monetite grafts. It is also noted that the higher porosity of autoclaved monetite grafts increases the bioresorbability, whereas the dry heated monetite grafts having lower porosity but higher surface area resorb to a significantly lesser extent. This study provides information regarding two types of monetite onlay grafts prepared with different physical properties that can be further investigated for clinical vertical bone augmentation applications. PMID:27214877

  20. Physicochemical Characteristics of Bone Substitutes Used in Oral Surgery in Comparison to Autogenous Bone

    PubMed Central

    Berberi, Antoine; Samarani, Antoine; Nader, Nabih; Noujeim, Ziad; Dagher, Maroun; Kanj, Wasfi; Mearawi, Rita; Salemeh, Ziad; Badran, Bassam

    2014-01-01

    Bone substitutes used in oral surgery include allografts, xenografts, and synthetic materials that are frequently used to compensate bone loss or to reinforce repaired bone, but little is currently known about their physicochemical characteristics. The aim of this study was to evaluate a number of physical and chemical properties in a variety of granulated mineral-based biomaterials used in dentistry and to compare them with those of autogenous bone. Autogenous bone and eight commercial biomaterials of human, bovine, and synthetic origins were studied by high-resolution X-ray diffraction, atomic absorption spectrometry, and laser diffraction to determine their chemical composition, calcium release concentration, crystallinity, and granulation size. The highest calcium release concentration was 24. 94 mg/g for Puros and the lowest one was 2.83 mg/g for Ingenios β-TCP compared to 20.15 mg/g for natural bone. The range of particles sizes, in terms of median size D50, varied between 1.32 μm for BioOss and 902.41 μm for OsteoSponge, compared to 282.1 μm for natural bone. All samples displayed a similar hexagonal shape as bone, except Ingenios β-TCP, Macrobone, and OsteoSponge, which showed rhomboid and triclinic shapes, respectively. Commercial bone substitutes significantly differ in terms of calcium concentration, particle size, and crystallinity, which may affect their in vivo performance. PMID:25143936

  1. Exposed tibial bone after burns: Flap reconstruction versus dermal substitute.

    PubMed

    Verbelen, Jozef; Hoeksema, Henk; Pirayesh, Ali; Van Landuyt, Koenraad; Monstrey, Stan

    2016-03-01

    A 44 years old male patient had suffered extensive 3rd degree burns on both legs, undergoing thorough surgical debridement, resulting in both tibias being exposed. Approximately 5 months after the incident he was referred to the Department of Plastic and Reconstructive Surgery of the University Hospital Gent, Belgium, to undergo flap reconstruction. Free flap surgery was performed twice on both lower legs but failed on all four occasions. In between flap surgery, a dermal substitute (Integra(®)) was applied, attempting to cover the exposed tibias with a layer of soft tissue, but also without success. In order to promote the development of granulation tissue over the exposed bone, small holes were drilled in both tibias with removal of the outer layer of the anterior cortex causing the bone to bleed and subsequently negative pressure wound therapy (NPWT) was applied. The limited granulation tissue resulting from this procedure was then covered with a dermal substitute (Glyaderm(®)), consisting of acellular human dermis with an average thickness of 0.25mm. This dermal substitute was combined with a NPWT-dressing, and then served as an extracellular matrix (ECM), guiding the distribution of granulation tissue over the remaining areas of exposed tibial bone. Four days after initial application of Glyaderm(®) combined with NPWT both tibias were almost completely covered with a thin coating of soft tissue. In order to increase the thickness of this soft tissue cover two additional layers of Glyaderm(®) were applied at intervals of approximately 1 week. One week after the last Glyaderm(®) application both wounds were autografted. The combination of an acellular dermal substitute (Glyaderm(®)) with negative pressure wound therapy and skin grafting proved to be an efficient technique to cover a wider area of exposed tibial bone in a patient who was not a candidate for free flap surgery. An overview is also provided of newer and simpler techniques for coverage of

  2. Hydroxyapatite crystals as a bone graft substitute in benign lytic lesions of bone

    PubMed Central

    Gupta, Anil Kumar; Kumar, Praganesh; Keshav, Kumar; Singh, Anant

    2015-01-01

    Background: Bone grafts are required to fill a cavity created after curettage of benign lytic lesions of the bone. To avoid the problems associated at donor site with autologous bone graft, we require allograft or bone graft substitutes. We evaluated the healing of lytic lesions after hydroxyapatite (HA) grafting by serial radiographs. Materials and Methods: Forty cases of benign lytic lesions of bone were managed by simple curettage and grafting using HA blocks. Commercially available HA of bovine origin (Surgiwear Ltd., Shahjahanpur, India) was used for this purpose. Mean duration of followup was 34.8 months (range 12–84 months). Mean patient age was 19.05 years (range 3–55 years). Radiological staging of graft incorporation was done as per criteria of Irwin et al. 2001. Results: In our series, two cases were in stage I. A total of 11 cases were in stage II and 27 were in stage III. Graft incorporation was radiologically complete by 15 months. Clinical recovery was observed before radiological healing. The average time taken to return to preoperative function was 3 months. Recurrence was observed in giant cell tumor (n = 3) and chondromyxoid fibroma (n = 1). There was no incidence of graft rejection, collapse, growth plate disturbances or antigenic response. Conclusions: We conclude that calcium HA is biologically acceptable bone graft substitute in the management of benign lytic lesions of bone. PMID:26806973

  3. Rapid prototyped porous nickel-titanium scaffolds as bone substitutes.

    PubMed

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

    2014-01-01

    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

  4. Rapid prototyped porous nickel–titanium scaffolds as bone substitutes

    PubMed Central

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

    2014-01-01

    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

  5. The Influence of Hyperbaric Oxygen Treatment on the Healing of Experimental Defects Filled with Different Bone Graft Substitutes

    PubMed Central

    Sirin, Yigit; Olgac, Vakur; Dogru-Abbasoglu, Semra; Tapul, Leyla; Aktas, Samil; Soley, Sinan

    2011-01-01

    To assess potential effects of hyperbaric oxygen (HBOT) on artificial bone grafts, β - Tricalcium phosphate (β-TCP) and calcium phosphate coated bovine bone (CPCBB) substitutes were applied to standard bone defects in rat tibiae. The control defects were left empty. Half of the animals received 60 minutes of 2.4 atmosphere absolute (ATA) of HBOT. Rats were sacrificed at one, two and four weeks. Bone healing was assessed histologically and histomorphometrically using light microscopy. The periosteum over the bone defects was examined ultrastructurally. Cardiac blood was collected to determine the serum osteocalcin levels. The HBOT increased new bone formation in the unfilled controls and β-TCP groups and significantly decreased cartilage matrix and fibrous tissue formations in all groups. Active osteoblasts and highly organized collagen fibrils were prominent in the periosteum of β-TCP and control groups. Serum osteocalcin levels also increased with HBOT. The healing of defects filled with CPCBB was similar to the controls and it did not respond to HBOT. These findings suggested that the HBOT had beneficial effects on the healing of unfilled bone defects and those filled with β-TCP bone substitute but not with CPCBB, indicating a material-specific influence pattern of HBOT. PMID:21326954

  6. Gelatin-Modified Bone Substitute with Bioactive Molecules Enhance Cellular Interactions and Bone Regeneration.

    PubMed

    Teotia, Arun Kumar; Gupta, Ankur; Raina, Deepak Bushan; Lidgren, Lars; Kumar, Ashok

    2016-05-01

    In this work, we have synthesized injectable bone cement incorporated with gelatin to enhance cellular interaction. Human osteosarcoma Saos-2 cells derived bone morphogenetic proteins (BMP's) and a bisphosphonate (zoledronic acid (0.2 mM)) were also incorporated to cement. In vitro studies conducted using Saos-2 demonstrated enhanced cell proliferation on gelatin (0.2%w/v) cement. The differentiation of C2C12 mouse myoblast cells into bone forming cells showed 6-fold increase in ALP levels on gelatin cement. Polymerase chain reaction (PCR) for bone biomarkers showed osteoinductive potential of gelatin cement. We investigated efficacy for local delivery of these bioactive molecules in enhancing bone substitution qualities of bone cements by implanting in 3.5 mm critical size defect in tibial metaphysis of wistar rats. The rats were sacrificed after 12 weeks and 16 weeks post implantation. X-ray, micro-CT, histology, and histomorphometry analysis were performed to check bone healing. The cement materials slowly resorbed from the defect site leaving HAP creating porous matrix providing surface for bone formation. The materials showed high biocompatibility and initial bridging was observed in all the animals but maximum bone formation was observed in animals implanted with cement incorporated with zoledronic acid followed by cement with BMP's compared to other groups. PMID:27077816

  7. Biomechanical competence of six different bone screws for reconstructive surgery in three different transplants: Fibular, iliac crest, scapular and artificial bone.

    PubMed

    Pietsch, Arnold P; Raith, Stefan; Ode, Jan-Eric; Teichmann, Jan; Lethaus, Bernd; Möhlhenrich, Stephan C; Hölzle, Frank; Duda, Georg N; Steiner, Timm

    2016-06-01

    The goal of this study was to determine a combination of screw and transplantation type that offers optimal primary stability for reconstructive surgery. Fibular, iliac crest, and scapular transplants were tested along with artificial bone substrate. Six different kinds of bone screws (Medartis(©)) were compared, each type utilized with one of six specimens from human transplants (n = 6). Controlled screw-in-tests were performed and the required torque was protocolled. Subsequently, pull-out-tests were executed to determine the retention forces. The artificial bone substitute material showed significantly higher retention forces than real bone samples. The self-drilling screws achieved the significantly highest retention values in the synthetic bone substitute material. Cancellous screws achieved the highest retention in the fibular transplants, while self-drilling and cancellous screws demonstrated better retention than cortical screws in the iliac crest. In the scapular graft, no significant differences were found between the screw types. In comparison to the human transplant types, the cortical screws showed the significantly highest values in the fibula and the lowest values in the iliac crest. The best retention was found in the combination of cancellous screws with fibular graft (514.8 N + -252.3 N). For the flat bones (i.e., scapular and illiac crest) we recommend the cancellous screws. PMID:27107477

  8. Embroidered and surface modified polycaprolactone-co-lactide scaffolds as bone substitute: in vitro characterization.

    PubMed

    Rentsch, Barbe; Hofmann, Andre; Breier, Annette; Rentsch, Claudia; Scharnweber, Dieter

    2009-10-01

    The aim of this study was to evaluate an embroidered polycaprolactone-co-lactide (trade name PCL) scaffold for the application in bone tissue engineering. The surface of the PCL scaffolds was hydrolyzed with NaOH and coated with collagen I (coll I) and chondroitin sulfate (CS). It was investigated if a change of the surface properties and the application of coll I and CS could promote cell adhesion, proliferation, and osteogenic differentiation of human mesenchymal stem cells (hMSC). The porosity (80%) and pore size (0.2-1 mm) of the scaffold could be controlled by embroidery technique and should be suitable for bone ingrowth. The treatment with NaOH made the polymer surface more hydrophilic (water contact angle dropped to 25%), enhanced the coll I adsorption (up to 15%) and the cell attachment (two times). The coll I coated scaffold improved cell attachment and proliferation (three times). CS, as part of the artificial matrix, could induce the osteogenic differentiation of hMSC without other differentiation additives. The investigated scaffolds could act not just as temporary matrix for cell migration, proliferation, and differentiation in bone tissue engineering but also have a great potential as bioartificial bone substitute. PMID:19626441

  9. Radially and axially graded multizonal bone graft substitutes targeting critical-sized bone defects from polycaprolactone/hydroxyapatite/tricalcium phosphate.

    PubMed

    Ergun, Asli; Yu, Xiaojun; Valdevit, Antonio; Ritter, Arthur; Kalyon, Dilhan M

    2012-12-01

    Repair and regeneration of critical sized defects via the utilization of polymeric bone graft substitutes are challenges. Here, we introduce radially and axially graded multizonal bone graft substitutes fabricated from polycaprolactone (PCL), and PCL biocomposites with osteoconductive particles, that is, hydroxyapatite (HA), and β-tricalcium phosphate (TCP). The novel bone graft substitutes should provide a greater degree of freedom to the orthopedic surgeon especially for repair of critically sized bone defects. The modulus of the graft substitute could be tailored in the axial direction upon the systematic variation of the HA/TCP concentration, while in the radial direction the bone graft substitute consisted of an outer layer with high stiffness, encapsulating a softer core with greater porosity. The biocompatibility of the bone graft substitutes was investigated using in vitro culturing of human bone marrow-derived stromal cells followed by the analysis of cell proliferation and differentiation rates. The characterization of the tissue constructs included the enzymatic alkaline phosphates (ALP) activity, microcomputed tomography imaging, and polymerase chain reaction analysis involving the expressions of bone markers, that is, Runx2, ALP, collagen type I, osteopontin, and osteocalcin, overall demonstrating the differentiation of bone marrow derived stem cells (BMSCs) via osteogenic lineage and formation of mineralized bone tissue. PMID:22764839

  10. Radially and Axially Graded Multizonal Bone Graft Substitutes Targeting Critical-Sized Bone Defects from Polycaprolactone/Hydroxyapatite/Tricalcium Phosphate

    PubMed Central

    Ergun, Asli; Yu, Xiaojun; Valdevit, Antonio; Ritter, Arthur

    2012-01-01

    Repair and regeneration of critical sized defects via the utilization of polymeric bone graft substitutes are challenges. Here, we introduce radially and axially graded multizonal bone graft substitutes fabricated from polycaprolactone (PCL), and PCL biocomposites with osteoconductive particles, that is, hydroxyapatite (HA), and β-tricalcium phosphate (TCP). The novel bone graft substitutes should provide a greater degree of freedom to the orthopedic surgeon especially for repair of critically sized bone defects. The modulus of the graft substitute could be tailored in the axial direction upon the systematic variation of the HA/TCP concentration, while in the radial direction the bone graft substitute consisted of an outer layer with high stiffness, encapsulating a softer core with greater porosity. The biocompatibility of the bone graft substitutes was investigated using in vitro culturing of human bone marrow-derived stromal cells followed by the analysis of cell proliferation and differentiation rates. The characterization of the tissue constructs included the enzymatic alkaline phosphates (ALP) activity, microcomputed tomography imaging, and polymerase chain reaction analysis involving the expressions of bone markers, that is, Runx2, ALP, collagen type I, osteopontin, and osteocalcin, overall demonstrating the differentiation of bone marrow derived stem cells (BMSCs) via osteogenic lineage and formation of mineralized bone tissue. PMID:22764839

  11. PDGFBB promotes PDGFR{alpha}-positive cell migration into artificial bone in vivo

    SciTech Connect

    Yoshida, Shigeyuki; Iwasaki, Ryotaro; Kawana, Hiromasa; Miyauchi, Yoshiteru; Hoshi, Hiroko; Miyamoto, Hiroya; Mori, Tomoaki; Kanagawa, Hiroya; Katsuyama, Eri; Fujie, Atsuhiro; Hao, Wu; and others

    2012-05-18

    Highlights: Black-Right-Pointing-Pointer We examined effects of PDGFBB in PDGFR{alpha} positive cell migration in artificial bones. Black-Right-Pointing-Pointer PDGFBB was not expressed in osteoblastic cells but was expressed in peripheral blood cells. Black-Right-Pointing-Pointer PDGFBB promoted PDGFR{alpha} positive cell migration into artificial bones but not osteoblast proliferation. Black-Right-Pointing-Pointer PDGFBB did not inhibit osteoblastogenesis. -- Abstract: Bone defects caused by traumatic bone loss or tumor dissection are now treated with auto- or allo-bone graft, and also occasionally by artificial bone transplantation, particularly in the case of large bone defects. However, artificial bones often exhibit poor affinity to host bones followed by bony union failure. Thus therapies combining artificial bones with growth factors have been sought. Here we report that platelet derived growth factor bb (PDGFBB) promotes a significant increase in migration of PDGF receptor {alpha} (PDGFR{alpha})-positive mesenchymal stem cells/pre-osteoblastic cells into artificial bone in vivo. Growth factors such as transforming growth factor beta (TGF{beta}) and hepatocyte growth factor (HGF) reportedly inhibit osteoblast differentiation; however, PDGFBB did not exhibit such inhibitory effects and in fact stimulated osteoblast differentiation in vitro, suggesting that combining artificial bones with PDGFBB treatment could promote host cell migration into artificial bones without inhibiting osteoblastogenesis.

  12. Osteoinductive nanohydroxyapatite bone substitute prepared via in situ hydrothermal transformation of cuttlefish bone.

    PubMed

    Hongmin, Li; Wei, Zhou; Xingrong, Yan; Jing, Wei; Wenxin, Geng; Jihong, Cui; Xin, Xie; Fulin, Chen

    2015-05-01

    The capacity to induce a rapid and controlled healing of bone defects is critical for a bone substitute. Previous studies have reported hydrothermal transformation (HT) of aragonite from cuttlebone (CB) to cuttlebone hydroxyapatite (CBHA). However, the biocompatibility and in vivo characteristic of CBHA have not been fully investigated. We fabricated CBHA via the in situ HT of aragonite from CB. This CBHA exhibited a highly porous structure and nanoscaled surface morphology with a significantly higher protein adsorption rate than CB. Marrow mesenchymal stem cells (MSCs) were seeded and cultured on the CBHA and CB to evaluate their influence on cell proliferation and differentiation. According to scanning electronic microscopy observation and MTT assay, the MSCs adhered and proliferated well on both the CBHA and CB. Compared with the cells on the CB, the MSCs on CBHA exhibited enhanced alkaline phosphatase activity and osteocalcin levels after 13 days of culture. In vivo testing revealed that CBHA could induce ectopic bone formation after implantation, while no bone formation being observed in the CB. These findings demonstrated that a nanoscaled and osteoinductive bone substitute could be produced by hydrothermally transforming an aragonite of CB into a hydroxyapatite. PMID:25115654

  13. Development and mechanical characterization of porous titanium bone substitutes.

    PubMed

    Barbas, A; Bonnet, A-S; Lipinski, P; Pesci, R; Dubois, G

    2012-05-01

    Commercially Pure Porous Titanium (CPPTi) can be used for surgical implants to avoid the stress shielding effect due to the mismatch between the mechanical properties of titanium and bone. Most researchers in this area deal with randomly distributed pores or simple architectures in titanium alloys. The control of porosity, pore size and distribution is necessary to obtain implants with mechanical properties close to those of bone and to ensure their osseointegration. The aim of the present work was therefore to develop and characterize such a specific porous structure. First of all, the properties of titanium made by Selective Laser Melting (SLM) were characterized through experimental testing on bulk specimens. An elementary pattern of the porous structure was then designed to mimic the orthotropic properties of the human bone following several mechanical and geometrical criteria. Finite Element Analysis (FEA) was used to optimize the pattern. A porosity of 53% and pore sizes in the range of 860 to 1500 μm were finally adopted. Tensile tests on porous samples were then carried out to validate the properties obtained numerically and identify the failure modes of the samples. Finally, FE elastoplastic analyses were performed on the porous samples in order to propose a failure criterion for the design of porous substitutes. PMID:22498281

  14. Cellular bone matrices: viable stem cell-containing bone graft substitutes

    PubMed Central

    Skovrlj, Branko; Guzman, Javier Z.; Al Maaieh, Motasem; Cho, Samuel K.; Iatridis, James C.; Qureshi, Sheeraz A.

    2015-01-01

    BACKGROUND CONTEXT Advances in the field of stem cell technology have stimulated the development and increased use of allogenic bone grafts containing live mesenchymal stem cells (MSCs), also known as cellular bone matrices (CBMs). It is estimated that CBMs comprise greater than 17% of all bone grafts and bone graft substitutes used. PURPOSE To critically evaluate CBMs, specifically their technical specifications, existing published data supporting their use, US Food and Drug Administration (FDA) regulation, cost, potential pitfalls, and other aspects pertaining to their use. STUDY DESIGN Areview of literature. METHODS A series of Ovid, Medline, and Pubmed-National Library of Medicine/National Institutes of Health (www.ncbi.nlm.nih.gov) searches were performed. Only articles in English journals or published with English language translations were included. Level of evidence of the selected articles was assessed. Specific technical information on each CBM was obtained by direct communication from the companies marketing the individual products. RESULTS Five different CBMs are currently available for use in spinal fusion surgery. There is a wide variation between the products with regard to the average donor age at harvest, total cellular concentration, percentage of MSCs, shelf life, and cell viability after defrosting. Three retrospective studies evaluating CBMs and fusion have shown fusion rates ranging from 90.2% to 92.3%, and multiple industry-sponsored trials are underway. No independent studies evaluating spinal fusion rates with the use of CBMs exist. All the commercially available CBMs claim to meet the FDA criteria under Section 361, 21 CFR Part 1271, and are not undergoing FDA premarket review. The CBMs claim to provide viable MSCs and are offered at a premium cost. Numerous challenges exist in regard to MSCs’ survival, function, osteoblastic potential, and cytokine production once implanted into the intended host. CONCLUSIONS Cellular bone matrices may

  15. Artificial Gravity as a Bone Loss Countermeasure in Simulated Weightlessness

    NASA Technical Reports Server (NTRS)

    Smith, S. M.; Zwart, S. R.; Crawford, G. E.; Gillman, P. L.; LeBlanc, A.; Shackelford, L. C.; Heer, M. A.

    2007-01-01

    The impact of microgravity on the human body is a significant concern for space travelers. We report here initial results from a pilot study designed to explore the utility of artificial gravity (AG) as a countermeasure to the effects of microgravity, specifically to bone loss. After an initial phase of adaptation and testing, 15 male subjects underwent 21 days of 6 head-down bed rest to simulate the deconditioning associated with space flight. Eight of the subjects underwent 1 h of centrifugation (AG, 1 gz at the heart, 2.5 gz at the feet) each day for 21 days, while 7 of the subjects served as untreated controls (CN). Blood and urine were collected before, during, and after bed rest for bone marker determinations. At this point, preliminary data are available on the first 8 subjects (6 AG, and 2 CN). Comparing the last week of bed rest to before bed rest, urinary excretion of the bone resorption marker n-telopeptide increased 95 plus or minus 59% (mean plus or minus SD) in CN but only 32 plus or minus 26% in the AG group. Similar results were found for another resorption marker, helical peptide (increased 57 plus or minus 0% and 35 plus or minus 13% in CN and AG respectively). Bone-specific alkaline phosphatase, a bone formation marker, did not change during bed rest. At this point, sample analyses are continuing, including calcium tracer kinetic studies. These initial data demonstrate the potential effectiveness of short-radius, intermittent AG as a countermeasure to the bone deconditioning that occurs during bed rest.

  16. Bacterial biosynthesis of a calcium phosphate bone-substitute material.

    PubMed

    Thackray, Aniac C; Sammons, Rachel L; Macaskie, Lynne E; Yong, Ping; Lugg, Harriet; Marquis, Peter M

    2004-04-01

    A species of Serratia bacteria produces nano-crystalline hydroxyapatite (HA) crystals by use of a cell-bound phosphatase enzyme, located both periplasmically and within extracellular polymeric materials. The enzyme functions in resting cells by cleaving glycerol-2-phosphate (G-2-P) to liberate free phosphate ions which combine with calcium in solution to produce a cell-bound calcium phosphate material. Bacteria grown as a biofilm on polyurethane reticulated foam cubes were challenged with calcium and G-2-P in a bioreactor to produce a 3-D porous bone-substitute material. The scaffold has 1 mm macropores and 1 microm micropores. XRD showed the crystallites to be 25-28 nm in size, resembling HA before sintering and beta-tricalcium phosphate (beta-TCP, whitlockite) after. When biofilm was grown on titanium discs and challenged with calcium and G-2-P, a calcium phosphate layer formed on the discs. Biomineralisation is therefore a potential route to production of precursor nanophase HA, which has the potential to improve strength. The scaffold material produced by this method could be used as a bone-filler or as an alternative method for coating implants with a layer of HA. PMID:15332607

  17. Synthetic Bone Substitute Engineered with Amniotic Epithelial Cells Enhances Bone Regeneration after Maxillary Sinus Augmentation

    PubMed Central

    Barboni, Barbara; Mangano, Carlo; Valbonetti, Luca; Marruchella, Giuseppe; Berardinelli, Paolo; Martelli, Alessandra; Muttini, Aurelio; Mauro, Annunziata; Bedini, Rossella; Turriani, Maura; Pecci, Raffaella; Nardinocchi, Delia; Zizzari, Vincenzo Luca; Tetè, Stefano; Piattelli, Adriano; Mattioli, Mauro

    2013-01-01

    Background Evidence has been provided that a cell-based therapy combined with the use of bioactive materials may significantly improve bone regeneration prior to dental implant, although the identification of an ideal source of progenitor/stem cells remains to be determined. Aim In the present research, the bone regenerative property of an emerging source of progenitor cells, the amniotic epithelial cells (AEC), loaded on a calcium-phosphate synthetic bone substitute, made by direct rapid prototyping (rPT) technique, was evaluated in an animal study. Material And Methods Two blocks of synthetic bone substitute (∼0.14 cm3), alone or engineered with 1×106 ovine AEC (oAEC), were grafted bilaterally into maxillary sinuses of six adult sheep, an animal model chosen for its high translational value in dentistry. The sheep were then randomly divided into two groups and sacrificed at 45 and 90 days post implantation (p.i.). Tissue regeneration was evaluated in the sinus explants by micro-computer tomography (micro-CT), morphological, morphometric and biochemical analyses. Results And Conclusions The obtained data suggest that scaffold integration and bone deposition are positively influenced by allotransplantated oAEC. Sinus explants derived from sheep grafted with oAEC engineered scaffolds displayed a reduced fibrotic reaction, a limited inflammatory response and an accelerated process of angiogenesis. In addition, the presence of oAEC significantly stimulated osteogenesis either by enhancing bone deposition or making more extent the foci of bone nucleation. Besides the modulatory role played by oAEC in the crucial events successfully guiding tissue regeneration (angiogenesis, vascular endothelial growth factor expression and inflammation), data provided herein show that oAEC were also able to directly participate in the process of bone deposition, as suggested by the presence of oAEC entrapped within the newly deposited osteoid matrix and by their ability to switch

  18. Alveolar bone regeneration for immediate implant placement using an injectable bone substitute: an experimental study in dogs

    PubMed Central

    Boix, Damien; Gauthier, Olivier; Guicheux, Jérôme; Pilet, Paul; Weiss, Pierre; Grimandi, Gaël; Daculsi, Guy

    2004-01-01

    Background The aim of the present study was to assess the efficacy of a ready-to-use injectable bone substitute for bone regeneration around dental implants placed into fresh extraction sockets. Methods Third and fourth mandibular premolars were extracted from 3 Beagle dogs and the interradicular septa were surgically reduced to induce a mesial bone defect. Thereafter, immediate placements of titanium implants were performed. On the left side of the jaw, mesial bone defects were filled with an injectable bone substitute (IBS), obtained by combining a polymer and a biphasic calcium phosphate ceramic. As a control, the right defects were left unfilled. After 3 months of healing, specimens were prepared for histological and histomorphometric evaluations. Results No post surgical complication was observed during the healing period. In all experimental conditions, histological observations revealed a lamellar bone formation in contact with the implant. Histomorphometric analysis showed that IBS triggers a significant (p<0.05) increase in term of thread numbers in contact with bone (TN), bone-to-implant contact (BIC) and peri-implant bone density (PBD), of about 8.6%, 11.0% and 14.7%, respectively. In addition, no significant difference was observed when TN, BIC and PBD in filled defects were compared to no-defect sites. Conclusion It is concluded that an injectable bone substitute composed of a polymeric carrier and calcium phosphate significantly increase bone regeneration around immediate implants. PMID:15212348

  19. [The mechanical chemical attachment of artificial cartilage (PVA-hydrogel) to metal substrate (or underlying bone)].

    PubMed

    Gu, Z; Xiao, J; Lou, S

    2001-06-01

    The biocompatibility and tribological characteristics of PVA-hydrogel are excellent, but it is very difficult to make the artificial cartilage material (PVA-hydrogel) attach to the underlying bone. In this study, PVA-hydrogel is attached to the metal fibre mesh by means of micro-mechanical interlock methods at first, then the surface of metal fibre mesh is bonded to the underlying bone by the bone cement(PMMA). In this way, the artificial cartilage can be firmly attached to the underlying bone(or metal substrate). Microstructure analysis and mechanical tests show that the attachment between artificial cartilage and the metal substrate is firm. PMID:11450530

  20. Eggshell Derived Hydroxyapatite as Bone Graft Substitute in the Healing of Maxillary Cystic Bone Defects: A Preliminary Report

    PubMed Central

    Kattimani, Vivekanand S; Chakravarthi, P Srinivas; Kanumuru, Narasimha Reddy; Subbarao, Vummidisetti V; Sidharthan, A; Kumar, T S Sampath; Prasad, L Krishna

    2014-01-01

    Background: Since ancient times, use of graft materials to promote healing of defects of bone is wellknown. Traditionally, missing bone is replaced with material from either patient or donor. Multiple sources of bone grafts have been used to graft bone defects to stimulate bone healing. Hydroxyapatite is naturally occurring mineral component of bone, which is osteoconductive. This versatile biomaterial is derived from many sources. The aim of this study is to evaluate the efficacy of eggshell derived hydroxyapatite (EHA) in the bone regeneration of human maxillary cystic bone defects secondary to cystic removal/apicoectomy and compare the material properties of EHA in vitro. Materials and Methods: A total of eight maxillary bone defects were grafted after cystic enucleation and/or apicoectomy in the year 2008 and completed the study at 1 year. The patients were followed-up 2 weeks after surgery for signs and symptoms of infection or any other complications that may have been related to surgical procedure. Follow-up radiographs were obtained immediately after surgery followed by 1, 2, and 3 months to assess the efficacy of EHA in bone healing. Physicochemical characterization of the EHA was carried out in comparison with synthetic hydroxyapatite (SHA), also compared the biocompatibility of EHA using in vitro cytotoxicity test. Results: By the end of the 8th week, the defects grafted with EHA showed complete bone formation. However, bone formation in non-grafted sites was insignificant. The values of density measurements were equal or more than that of surrounding normal bone. These results indicate that the osseous regeneration of the bone defect filled with EHA is significant. EHA showed the superior material properties in comparison with SHA. Conclusion: EHA is a versatile novel bone graft substitute that yielded promising results. Because of its biocompatibility, lack of disease transfer risks, ease of use and unlimited availability, EHA remains a viable choice

  1. Bone graft substitutes and bone morphogenetic proteins for osteoporotic fractures: what is the evidence?

    PubMed

    Van Lieshout, Esther M M; Alt, Volker

    2016-01-01

    Despite improvements in implants and surgical techniques, osteoporotic fractures remain challenging to treat. Among other major risk factors, decreased expression of morphogenetic proteins has been identified for impaired fracture healing in osteoporosis. Bone grafts or bone graft substitutes are often used for stabilizing the implant and for providing a scaffold for ingrowth of new bone. Both synthetic and naturally occurring biomaterials are available. Products generally contain hydroxyapatite, tricalcium phosphate, dicalcium phosphate, calcium phosphate cement, calcium sulfate (plaster of Paris), or combinations of the above. Products have been used for the treatment of osteoporotic fractures of the proximal humerus, distal radius, vertebra, hip, and tibia plateau. Although there is generally consensus that screw augmentation increased the biomechanical properties and implant stability, the results of using these products for void filling are not unequivocal. In osteoporotic patients, Bone Morphogenetic Proteins (BMPs) have the potential impact to improve fracture healing by augmenting the impaired molecular and cellular mechanisms. However, the clinical evidence on the use of BMPs in patients with osteoporotic fractures is poor as there are no published clinical trials, case series or case studies. Even pre-clinical literature on in vitro and in vivo data is weak as most articles focus on the beneficial role for BMPs for restoration of the underlying pathophysiological factors of osteoporosis but do not look at the specific effects on osteoporotic fracture healing. Limited data on animal experiments suggest stimulation of fracture healing in ovariectomized rats by the use of BMPs. In conclusion, there is only limited data on the clinical relevance and optimal indications for the use of bone graft substitute materials and BMPs on the treatment of osteoporotic fractures despite the clinical benefits of these materials in other clinical indications. Given the

  2. Fabrication and development of artificial osteochondral constructs based on cancellous bone/hydrogel hybrid scaffold.

    PubMed

    Song, Kedong; Li, Liying; Yan, Xinyu; Zhang, Yu; Li, Ruipeng; Wang, Yiwei; Wang, Ling; Wang, Hong; Liu, Tianqing

    2016-06-01

    Using tissue engineering techniques, an artificial osteochondral construct was successfully fabricated to treat large osteochondral defects. In this study, porcine cancellous bones and chitosan/gelatin hydrogel scaffolds were used as substitutes to mimic bone and cartilage, respectively. The porosity and distribution of pore size in porcine bone was measured and the degradation ratio and swelling ratio for chitosan/gelatin hydrogel scaffolds was also determined in vitro. Surface morphology was analyzed with the scanning electron microscope (SEM). The physicochemical properties and the composition were tested by using an infrared instrument. A double layer composite scaffold was constructed via seeding adipose-derived stem cells (ADSCs) induced to chondrocytes and osteoblasts, followed by inoculation in cancellous bones and hydrogel scaffolds. Cell proliferation was assessed through Dead/Live staining and cellular activity was analyzed with IpWin5 software. Cell growth, adhesion and formation of extracellular matrix in composite scaffolds blank cancellous bones or hydrogel scaffolds were also analyzed. SEM analysis revealed a super porous internal structure of cancellous bone scaffolds and pore size was measured at an average of 410 ± 59 μm while porosity was recorded at 70.6 ± 1.7 %. In the hydrogel scaffold, the average pore size was measured at 117 ± 21 μm and the porosity and swelling rate were recorded at 83.4 ± 0.8 % and 362.0 ± 2.4 %, respectively. Furthermore, the remaining hydrogel weighed 80.76 ± 1.6 % of the original dry weight after hydration in PBS for 6 weeks. In summary, the cancellous bone and hydrogel composite scaffold is a promising biomaterial which shows an essential physical performance and strength with excellent osteochondral tissue interaction in situ. ADSCs are a suitable cell source for osteochondral composite reconstruction. Moreover, the bi-layered scaffold significantly enhanced cell proliferation compared to the cells seeded on

  3. Efficacy of novel synthetic bone substitutes in the reconstruction of large segmental bone defects in sheep tibiae.

    PubMed

    Li, Jiao Jiao; Roohani-Esfahani, Seyed-Iman; Dunstan, Colin R; Quach, Terrence; Steck, Roland; Saifzadeh, Siamak; Pivonka, Peter; Zreiqat, Hala

    2016-02-01

    The treatment of large bone defects, particularly those with segmental bone loss, remains a significant clinical challenge as current approaches involving surgery or bone grafting often do not yield satisfactory long-term outcomes. This study reports the evaluation of novel ceramic scaffolds applied as bone graft substitutes in a clinically relevant in vivo model. Baghdadite scaffolds, unmodified or modified with a polycaprolactone coating containing bioactive glass nanoparticles, were implanted into critical-sized segmental bone defects in sheep tibiae for 26 weeks. Radiographic, biomechanical, μ-CT and histological analyses showed that both unmodified and modified baghdadite scaffolds were able to withstand physiological loads at the defect site, and induced substantial bone formation in the absence of supplementation with cells or growth factors. Notably, all samples showed significant bridging of the critical-sized defect (average 80%) with evidence of bone infiltration and remodelling within the scaffold implant. The unmodified and modified baghdadite scaffolds achieved similar outcomes of defect repair, although the latter may have an initial mechanical advantage due to the nanocomposite coating. The baghdadite scaffolds evaluated in this study hold potential for use as purely synthetic bone graft substitutes in the treatment of large bone defects while circumventing the drawbacks of autografts and allografts. PMID:26894676

  4. Histological Features and Biocompatibility of Bone and Soft Tissue Substitutes in the Atrophic Alveolar Ridge Reconstruction.

    PubMed

    Maiorana, Carlo; Beretta, Mario; Rancitelli, Davide; Grossi, Giovanni Battista; Cicciù, Marco; Herford, Alan Scott

    2016-01-01

    The reconstruction of the atrophic alveolar ridges for implant placement is today a common procedure in dentistry daily practice. The surgical reconstruction provides for the optimization of the supporting bone for the implants and a restoration of the amount of keratinized gingiva for esthetic and functional reasons. In the past, tissue regeneration has been performed with autogenous bone and free gingival or connective tissue grafts. Nowadays, bone substitutes and specific collagen matrix allow for a complete restoration of the atrophic ridge without invasive harvesting procedures. A maxillary reconstruction of an atrophic ridge by means of tissue substitutes and its histological features are then presented. PMID:27022489

  5. Histological Features and Biocompatibility of Bone and Soft Tissue Substitutes in the Atrophic Alveolar Ridge Reconstruction

    PubMed Central

    Rancitelli, Davide; Grossi, Giovanni Battista; Herford, Alan Scott

    2016-01-01

    The reconstruction of the atrophic alveolar ridges for implant placement is today a common procedure in dentistry daily practice. The surgical reconstruction provides for the optimization of the supporting bone for the implants and a restoration of the amount of keratinized gingiva for esthetic and functional reasons. In the past, tissue regeneration has been performed with autogenous bone and free gingival or connective tissue grafts. Nowadays, bone substitutes and specific collagen matrix allow for a complete restoration of the atrophic ridge without invasive harvesting procedures. A maxillary reconstruction of an atrophic ridge by means of tissue substitutes and its histological features are then presented. PMID:27022489

  6. Osseointegration of Titanium Implants in Onlay of Cerament™, a New Ceramic Bone Substitute

    PubMed Central

    Truedsson, Anna; Wang, Jian-Sheng; Lindberg, Pia; Warfvinge, Gunnar

    2016-01-01

    The purpose was to investigate whether a new biphasic and injectable ceramic bone substitute Cerament™ that rapidly remodels to bone, may contribute to the retention of titanium implant screws during the healing period, and to analyze the pattern of bone formation around titanium implants.Titanium screws were implanted in rat tibiae and embedded with or without Cerament™ on the cortical surface. Torsional resistance was measured after 1 day, and after 6 and 12 weeks. Implant areas without bone substitute were analyzed histologically for comparison. The torsional resistance increased over time as the screws were osseointegrated. There was no difference in resistance between screws embedded in the bone substitute and control screws. The bone apposition was more pronounced on the proximal side of the screw than on the distal side. Cerament™ is capable of conducting bone growth from a cortical bone surface. The newly formed bone in this application does not significantly add to the osseointegrative strength of the implant screw, as measured by torque resistance, during the first 12 weeks. PMID:26751485

  7. Traumatic Periprosthetic Acetabular Fracture Treated with One-Stage Exchange and Bone Reconstruction Using a Synthetic Bone Graft Substitute

    PubMed Central

    2016-01-01

    A case of a traumatic periprosthetic acetabular fracture in an elderly patient, which was treated by one-stage hip exchange with implantation of an antiprotrusio cage and reconstruction of the acetabular bone loss with an injectable calcium sulphate/hydroxyapatite bone graft substitute, is reported. The paste-like bone graft substitute was injected through the holes of the antiprotrusio cage. After a setting time of 15 minutes, a low-profile cup was cemented onto the cage using polymethylmethacrylate and a new stem was inserted. The patient was encouraged to ambulate three days postoperatively weight-bearing as tolerated. At the one-year follow-up visit the patient was ambulatory and full weight-bearing without any walking aids. The follow-up radiographs demonstrated stable position and articulation of the revision hip arthroplasty with no signs of loosening of the antiprotrusio cage. However, the most interesting finding was that the bone graft substitute had remodelled to a great extent into bone. This calcium sulphate/hydroxyapatite composite shows high osteoconductive potential and can be used to regenerate bone stock in revision arthroplasty. PMID:27446621

  8. Traumatic Periprosthetic Acetabular Fracture Treated with One-Stage Exchange and Bone Reconstruction Using a Synthetic Bone Graft Substitute.

    PubMed

    Svacina, Jan

    2016-01-01

    A case of a traumatic periprosthetic acetabular fracture in an elderly patient, which was treated by one-stage hip exchange with implantation of an antiprotrusio cage and reconstruction of the acetabular bone loss with an injectable calcium sulphate/hydroxyapatite bone graft substitute, is reported. The paste-like bone graft substitute was injected through the holes of the antiprotrusio cage. After a setting time of 15 minutes, a low-profile cup was cemented onto the cage using polymethylmethacrylate and a new stem was inserted. The patient was encouraged to ambulate three days postoperatively weight-bearing as tolerated. At the one-year follow-up visit the patient was ambulatory and full weight-bearing without any walking aids. The follow-up radiographs demonstrated stable position and articulation of the revision hip arthroplasty with no signs of loosening of the antiprotrusio cage. However, the most interesting finding was that the bone graft substitute had remodelled to a great extent into bone. This calcium sulphate/hydroxyapatite composite shows high osteoconductive potential and can be used to regenerate bone stock in revision arthroplasty. PMID:27446621

  9. A perfusion bioreactor system efficiently generates cell-loaded bone substitute materials for addressing critical size bone defects.

    PubMed

    Kleinhans, Claudia; Mohan, Ramkumar Ramani; Vacun, Gabriele; Schwarz, Thomas; Haller, Barbara; Sun, Yang; Kahlig, Alexander; Kluger, Petra; Finne-Wistrand, Anna; Walles, Heike; Hansmann, Jan

    2015-09-01

    Critical size bone defects and non-union fractions are still challenging to treat. Cell-loaded bone substitutes have shown improved bone ingrowth and bone formation. However, a lack of methods for homogenously colonizing scaffolds limits the maximum volume of bone grafts. Additionally, therapy robustness is impaired by heterogeneous cell populations after graft generation. Our aim was to establish a technology for generating grafts with a size of 10.5 mm in diameter and 25 mm of height, and thus for grafts suited for treatment of critical size bone defects. Therefore, a novel tailor-made bioreactor system was developed, allowing standardized flow conditions in a porous poly(L-lactide-co-caprolactone) material. Scaffolds were seeded with primary human mesenchymal stem cells derived from four different donors. In contrast to static experimental conditions, homogenous cell distributions were accomplished under dynamic culture. Additionally, culture in the bioreactor system allowed the induction of osteogenic lineage commitment after one week of culture without addition of soluble factors. This was demonstrated by quantitative analysis of calcification and gene expression markers related to osteogenic lineage. In conclusion, the novel bioreactor technology allows efficient and standardized conditions for generating bone substitutes that are suitable for the treatment of critical size defects in humans. PMID:26011163

  10. A perfusion bioreactor system efficiently generates cell‐loaded bone substitute materials for addressing critical size bone defects

    PubMed Central

    Kleinhans, Claudia; Mohan, Ramkumar Ramani; Vacun, Gabriele; Schwarz, Thomas; Haller, Barbara; Sun, Yang; Kahlig, Alexander; Kluger, Petra; Finne‐Wistrand, Anna; Walles, Heike

    2015-01-01

    Abstract Critical size bone defects and non‐union fractions are still challenging to treat. Cell‐loaded bone substitutes have shown improved bone ingrowth and bone formation. However, a lack of methods for homogenously colonizing scaffolds limits the maximum volume of bone grafts. Additionally, therapy robustness is impaired by heterogeneous cell populations after graft generation. Our aim was to establish a technology for generating grafts with a size of 10.5 mm in diameter and 25 mm of height, and thus for grafts suited for treatment of critical size bone defects. Therefore, a novel tailor‐made bioreactor system was developed, allowing standardized flow conditions in a porous poly(L‐lactide‐co‐caprolactone) material. Scaffolds were seeded with primary human mesenchymal stem cells derived from four different donors. In contrast to static experimental conditions, homogenous cell distributions were accomplished under dynamic culture. Additionally, culture in the bioreactor system allowed the induction of osteogenic lineage commitment after one week of culture without addition of soluble factors. This was demonstrated by quantitative analysis of calcification and gene expression markers related to osteogenic lineage. In conclusion, the novel bioreactor technology allows efficient and standardized conditions for generating bone substitutes that are suitable for the treatment of critical size defects in humans. PMID:26011163

  11. Preparation, degradation, and calcification of biodegradable polyurethane foams for bone graft substitutes.

    PubMed

    Gorna, Katarzyna; Gogolewski, Sylwester

    2003-12-01

    Autogenous cancellous bone graft is used to heal critical-size segmental long bone defects and defects in the maxillofacial skeleton. Harvesting of bone graft is traumatic, causes morbidity of the donor site, and often results in complications. Thus, there is a need for new biologically functional bone graft substitutes that, instead of autogenous bone graft, could be used to facilitate bone regeneration in critical-size defects. Porous biodegradable elastomeric polyurethane scaffolds combined with the patient's own bone marrow could potentially be such bone substitutes. The elastomeric bone substitute prevents shear forces at the interface between bone and rigid, e.g., ceramic bone substitutes and establishes an intimate contact with the native bone ends, thus facilitating the proliferation of osteogenic cells and bone regeneration. Crosslinked 3D biodegradable polyurethane scaffolds (foams) with controlled hydrophilicity for bone graft substitutes were synthesized from biocompatible reactants. The scaffolds had hydrophilic-to-hydrophobic content ratios of 70:30, 50:50, and 30:70. The reactants used were hexamethylene diisocyanate, poly(ethylene oxide) diol (MW = 600) (hydrophilic component), and poly(epsilon-caprolactone) diol (M(w) = 2000), amine-based polyol (M(w) = 515) or sucrose-based polyol (M(w) = 445) (hydrophobic component), water as the chain extender and foaming agent, and stannous octoate, dibutyltin dilaurate, ferric acetylacetonate, and zinc octoate as catalysts. Citric acid was used as a calcium complexing agent, calcium carbonate, glycerol phosphate calcium salt, and hydroxyapatite were used as inorganic fillers, and lecithin or solutions of vitamin D(3) were used as surfactants. The scaffolds had an open-pore structure with pores whose size and geometry depended on the material's chemical composition. The compressive strengths of the scaffolds were in the range of 4-340 kPa and the compressive moduli in the range of 9-1960 kPa, the values of

  12. Bone substitute material on the basis of natural components

    NASA Astrophysics Data System (ADS)

    Melnikova, S.; Zelichenko, E.; Zenin, B.; Guzeev, V.; Gurova, O.

    2014-10-01

    The creation of regenerative materials remains a problem for rehabilitation medicine, but the obtaining of initial substances that can cause bone tissue regeneration, possessing biological activity and creation on their basis of composite materials with specified physical and mechanical characteristics is an important scientific problem. This paper presents the investigation of physical-chemical and biological properties of bioresorbable composite material that can restore their own bone tissue of the body.

  13. Effect of the stiffness of bone substitutes on the biomechanical behaviour of femur for core decompression.

    PubMed

    Tran, T N; Kowalczyk, W; Hohn, H P; Jäger, M; Landgraeber, S

    2016-09-01

    Core decompression is the most common procedure for treatment of the early stages of osteonecrosis of the femoral head. The purpose of this study was to compare the biomechanical performance of four different bone graft substitutes combined with core decompression. Subject-specific finite element models generated from computed tomography (CT) scan data were used for a comprehensive analysis. Two different contact conditions were simulated representing states of osseointegration at the interface. Our results showed that the use of a low-stiffness bone substitute did not increase the risk of femoral fracture in the early postoperative phase, but resulted in less micromotion and interfacial stresses than high-stiffness bone substitutes. PMID:27282530

  14. Effects of liquid nitrogen cryotherapy and bone grafting on artificial bone defects in minipigs: a preliminary study.

    PubMed

    Pogrel, M A; Regezi, J A; Fong, B; Hakim-Faal, Z; Rohrer, M; Tran, C; Schiff, T

    2002-06-01

    Liquid nitrogen cryotherapy has been advocated as an adjunct in the enucleation and curettage of locally aggressive lesions of the jaws. Simultaneous autogenous bone grafting has also been advocated to accelerate bone formation and reduce morbidity. There is, however, relatively little scientific basis for either of these hypotheses. In this study, nine Yucatan minipigs had artificial defects created in the mandible, which were treated with liquid nitrogen spray. Half of the defects were grafted with autogenous bone from the chin and half were closed primarily. Two animals were sacrificed 3 days postoperatively to measure the width of necrosis and the rest were sacrificed at 3 months to assess healing and new bone formation. It was found that drilling the artificial defects alone caused bone necrosis for a mean depth of 0.09 mm. Liquid nitrogen cryospray caused a mean depth of bone necrosis of 0.82 mm (range 0.51-1.52 mm). The defects that were bone grafted healed well clinically. Defects not bone grafted showed a 50% rate of wound breakdown and sequestrum formation with delayed healing. Vital staining showed a non-significantly greater rate of bone formation in the grafted defects. Digitally superimposed radiography showed a non-significantly greater bone density in the non-grafted defects at 3 months postoperatively. It appears that liquid nitrogen cryospray does devitalize an area of bone around defects in the mandible. The width of necrosis is usually less than 1 mm and subsequent healing is enhanced by autogenous bone grafting. This has clinical implications. PMID:12190137

  15. Hydroxyapatite-calcium sulfate-hyaluronic acid composite encapsulated with collagenase as bone substitute for alveolar bone regeneration.

    PubMed

    Subramaniam, Sadhasivam; Fang, Yen-Hsin; Sivasubramanian, Savitha; Lin, Feng-Huei; Lin, Chun-pin

    2016-01-01

    Periodontitis is a very severe inflammatory condition of the periodontium that progressively damages the soft tissue and destroys the alveolar bone that supports the teeth. The bone loss is naturally irreversible because of limited reparability of the teeth. Advancement in tissue engineering provides an effective regeneration of osseous defects with suitable dental implants or tissue-engineered constructs. This study reports a hydroxyapatite, calcium sulfate hemihydrate and hyaluronic acid laden collagenase (HAP/CS/HA-Col) as a bone substitute for the alveolar bone regeneration. The composite material was mechanically tested and the biocompatibility was evaluated by WST-1 assay. The in vivo bone formation was assessed in rat with alveolar bone defects and the bone augmentation by the HAP/CS/HA-Col composite was confirmed by micro-CT images and histological examination. The mechanical strength of 6.69 MPa with excellent biocompatibility was obtained for the HAP/CS/HA-Col composite. The collagenase release profile had facilitated the acceleration of bone remodeling process and it was confirmed by the findings of micro-CT and H&E staining. The bone defects implanted with HAP/CS/HA composite containing 2 mg/mL type I collagenase have shown improved new bone formation with matured bone morphology in comparison with the HAP/CS/HA composite that lacks the collagenase and the porous hydroxyapatite (p-HAP) granules. The said findings demonstrated that the collagenase inclusion in HAP/CS/HA composite is a feasible approach for the alveolar bone regeneration and the same design can also be applied to other defective tissues. PMID:26454048

  16. Addition of blood to a phycogenic bone substitute leads to increased in vivo vascularization.

    PubMed

    Barbeck, Mike; Najman, Stevo; Stojanović, Sanja; Mitić, Žarko; Živković, Jelena M; Choukroun, Joseph; Kovačević, Predrag; Sader, Robert; Kirkpatrick, C James; Ghanaati, Shahram

    2015-09-01

    The present study aimed to analyze the effects of the addition of blood to the phycogenic bone substitute Algipore(®) on the severity of in vivo tissue reaction. Initially, Fourier-transform infrared spectroscopy (FTIR) of the bone substitute was conducted to analyze its chemical composition. The subcutaneous implantation model in Balb/c mice was then applied for up to 30 d to analyze the tissue reactions on the basis of specialized histochemical, immunohistochemical, and histomorphometrical methods. The data of the FTIR analysis showed that the phycogenic bone substitute material is mainly composed of hydroxyapatite with some carbonate content. The in vivo analyses revealed that the addition of blood to Algipore(®) had a major impact on both angiogenesis and vessel maturation. The higher vascularization seemed to be based on significantly higher numbers of multinucleated TRAP-positive cells. However, mostly macrophages and a relatively low number of multinucleated giant cells were involved in the tissue reaction to Algipore(®). The presented data show that the addition of blood to a bone substitute impacts the tissue reaction to it. In particular, the immune response and the vascularization were influenced, and these are believed to have a major impact on the regenerative potential of the process of bone tissue regeneration. PMID:26359820

  17. Nanoparticles of cobalt-substituted hydroxyapatite in regeneration of mandibular osteoporotic bones

    PubMed Central

    Ignjatović, Nenad; Ajduković, Zorica; Savić, Vojin; Najman, Stevo; Mihailović, Dragan; Vasiljević, Perica; Stojanović, Zoran; Uskoković, Vuk; Uskoković, Dragan

    2012-01-01

    Indications exist that paramagnetic calcium phosphates may be able to promote regeneration of bone faster than their regular, diamagnetic counterparts. In this study, analyzed was the influence of paramagnetic cobalt-substituted hydroxyapatite nanoparticles on osteoporotic alveolar bone regeneration in rats. Simultaneously, biocompatibility of the material was tested in vitro, on osteoblastic MC3T3-E1 and epithelial Caco-2 cells in culture. The material was shown to be biocompatible and nontoxic when added to epithelial monolayers in vitro, while it caused a substantial decrease in the cell viability as well as deformation of the cytoskeleton and cell morphology when incubated with the osteoblastic cells. In the course of six months after the implantation of the material containing different amounts of cobalt, ranging from 5 – 12 wt%, in the osteoporotic alveolar bone of the lower jaw, the following parameters were investigated: histopathological parameters, alkaline phosphatase and alveolar bone density. The best result in terms of osteoporotic bone tissue regeneration was observed for hydroxyapatite nanoparticles with the largest content of cobalt ions. The histological analysis showed a high level of reparatory ability of the nanoparticulate material implanted in the bone defect, paralleled by a corresponding increase in the alveolar bone density. The combined effect of growth factors from autologous plasma admixed to cobalt-substituted hydroxyapatite was furthermore shown to have a crucial effect on the augmented osteoporotic bone regeneration upon the implantation of the biomaterial investigated in this study. PMID:23090835

  18. Injectable bone substitute to preserve alveolar ridge resorption after tooth extraction: a study in dog

    PubMed Central

    Boix, Damien; Weiss, Pierre; Gauthier, Olivier; Guicheux, Jérôme; Bouler, Jean-Michel; Pilet, Paul; Daculsi, Guy; Grimandi, Gaël

    2006-01-01

    The aim of the present study was to assess the efficacy of a ready-to-use injectable bone substitute on the prevention of alveolar ridge resorption after tooth extraction. Maxillary and mandibular premolars were extracted from 3 Beagle dogs with preservation of alveolar bone. Thereafter, distal sockets were filled with an injectable bone substitute (IBS), obtained by combining a polymer solution and granules of a biphasic calcium phosphate (BCP) ceramic. As a control, the mesial sockets were left unfilled. After a 3 months healing period, specimens were removed and prepared for histomorphometric evaluation with image analysis. Histomorphometric study allowed to measure the mean and the maximal heights of alveolar crest modifications. Results always showed an alveolar bone resorption in unfilled sockets. Resorption in filled maxillary sites was significantly lower than in control sites. Interestingly, an alveolar ridge augmentation was measured in mandibular filled sockets including 30 % of newly-formed bone. It was concluded that an injectable bone substitute composed of a polymeric carrier and calcium phosphate can significantly increase alveolar ridge preservation after tooth extraction. PMID:17122930

  19. Mineralized polymer composites as biogenic bone substitute material

    NASA Astrophysics Data System (ADS)

    Shah, Rushita; Saha, Nabanita; Kitano, Takeshi; Saha, Petr

    2015-05-01

    Mineralized polymer composites (MPC) are recognized as potential fillers of bone defects. Though bioceramics exhibits quite a good bone-bonding and vascularization, it is considered to be too stiff and brittle for using alone. Thus, the use of polymer scaffold instead of bioceramics has several advantages including combining the osteoconductivity and bone-bonding potential of the inorganic phase with the porosity and interconnectivity of the three-dimensional construction. Aiming the advantages of ceramic-polymer composite scaffolds, the calcium carbonate (CaCO3) based biomineralized scaffold was prepared, where the PVP-CMC hydrogel was used as an extracellular matrix. This paper is reported about the morphology, swelling trend (in physiological solution) and viscoelastic behavior of (90 min mineralized) MPC. The dry MPC are off-white, coarse in texture, comparatively less flexible than the original PVP-CMC based hydrogel film, and the deposition of granular structures on the surface of the hydrogel film confirms about the development of biomineralized scaffold/polymer composites. Irrespective of thickness, the dry MPC shows higher values of swelling ratio within 30 min, which varies between 200-250 approximately. The dynamic viscoelastic nature of freshly prepared MPC was investigated applying 1% and 10% strain. At higher strain the viscoelastic moduli (G' and G") show significant change, and the nature of MPC turns from elastic to viscous. Based on the observed basic properties, the MPC (calcite based polymer composites) can be recommended for the treatment of adyanamic bone disorder.

  20. Synthetic Calcite as a Scaffold for Osteoinductive Bone Substitutes.

    PubMed

    Chróścicka, Anna; Jaegermann, Zbigniew; Wychowański, Piotr; Ratajska, Anna; Sadło, Jarosław; Hoser, Grażyna; Michałowski, Sławomir; Lewandowska-Szumiel, Malgorzata

    2016-07-01

    Although a wide variety of biomaterials have been already proposed for use in bone tissue engineering, there is still need for man-made materials, which would combine support for osteogenesis with simplicity desirable for upscaling and costs reduction. In this study we have shown that synthetic calcite may serve as a scaffold for human osteoblasts transplantation. A simple dynamic system allows uniform and effective cell distribution. Cell viability and osteogenic phenotype were confirmed by XTT assay, alkaline phosphatase activity and selected osteoblast-specific genes expression. Extracellular matrix deposited by cells improved elasticity and made the whole system similar to the flexible composite material rather than to the brittle ceramic implants. It was revealed in the compression tests and also by the improved samples handling. Subcutaneous implantation of the cell-seeded calcite scaffolds to immunodeficient mice resulted in mineralized bone formation, which was confirmed histologically and by EPR analysis. The latter we propose as a method supplementary to histological analysis, for bone regeneration investigations. It specifically confirms the presence of bone mineral with a unique sensitivity and using bulk samples, which eliminates the risk of missing the material in the preparation. Our study resulted in development of a new osteogenic tissue engineered product based on man-made calcite. PMID:26666226

  1. [Study on the preparation and application of individual artificial bone with carbon/carbon composites].

    PubMed

    Ni, Xinye; Qian, Nong; Zhou, Dong; Miao, Yunliang; Xiong, Xinbo; Lin, Tao; Chen, Da; Zhao, Gongyin; Zhong, Ping

    2013-12-01

    The present paper is aimed to study the preparation and application of individual artificial bone of carbon/carbon composites. Using computer tomography images (CT), we acquired a three-dimensional image. Firstly, we described bone contour line outlined with manual and automatic method by the binary volume data. Secondly, we created 3D object surface information by marching cubes. Finally, we converted this information to non-uniform rational B-spine (NURBS) by using geomagic software. Individual artificial bone with carbon/carbon composite was prepared through the CNC Machining Center. We replaced the humeral head of the tested rabbit, and then observed the effects of implantation in neuroimaging and pathological section. Using this method, we found that the bone shape processed and bone shape replaced was consistent. After implantation, the implant and the surrounding bone tissue bound closely, and bone tissue grew well on the surface of the implant. It has laid a sound foundation of the preparation using this method for individual artificial bone of carbon/carbon composite material. PMID:24645609

  2. Antimicrobial Formulations of Absorbable Bone Substitute Materials as Drug Carriers Based on Calcium Sulfate.

    PubMed

    Pförringer, D; Obermeier, A; Kiokekli, M; Büchner, H; Vogt, S; Stemberger, A; Burgkart, R; Lucke, M

    2016-07-01

    Substitution of bones is a well-established, necessary procedure to treat bone defects in trauma and orthopedic surgeries. For prevention or treatment of perioperative infection, the implantation of resorbable bone substitute materials carrying antibiotics is a necessary treatment. In this study, we investigated the newly formulated calcium-based resorbable bone substitute materials containing either gentamicin (CaSO4-G [Herafill-G]), vancomycin (CaSO4-V), or tobramycin (Osteoset). We characterized the released antibiotic concentration per unit. Bone substitute materials were implanted in bones of rabbits via a standardized surgical procedure. Clinical parameters and levels of the antibiotic-releasing materials in serum were determined. Local concentrations of antibiotics were measured using antimicrobial tests of bone tissue. Aminoglycoside release kinetics in vitro per square millimeter of bead surface showed the most prolonged release for gentamicin, followed by vancomycin and, with the fastest release, tobramycin. In vivo level in serum detected over 28 days was highest for gentamicin at 0.42 μg/ml, followed by vancomycin at 0.11 μg/ml and tobramycin at 0.04 μg/ml. The clinical parameters indicated high biocompatibility for materials used. None of the rabbits subjected to the procedure showed any adverse reaction. The highest availability of antibiotics at 14.8 μg/g on day 1 in the cortical tibia ex vivo was demonstrated for gentamicin, decreasing within 14 days. In the medulla, vancomycin showed a high level at 444 μg/g on day 1, decreasing continuously over 14 days, whereas gentamicin decreased faster within the initial 3 days. The compared antibiotic formulations varied significantly in release kinetics in serum as well as locally in medulla and cortex. PMID:27067337

  3. Supercritical carbon dioxide-processed resorbable polymer nanocomposites for bone graft substitute applications

    NASA Astrophysics Data System (ADS)

    Baker, Kevin C.

    Numerous clinical situations necessitate the use of bone graft materials to enhance bone formation. While autologous and allogenic materials are considered the gold standards in the setting of fracture healing and spine fusion, their disadvantages, which include donor site morbidity and finite supply have stimulated research and development of novel bone graft substitute materials. Among the most promising candidate materials are resorbable polymers, composed of lactic and/or glycolic acid. While the characteristics of these materials, such as predictable degradation kinetics and biocompatibility, make them an excellent choice for bone graft substitute applications, they lack mechanical strength when synthesized with the requisite porous morphology. As such, porous resorbable polymers are often reinforced with filler materials. In the presented work, we describe the use of supercritical carbon dioxide (scCO2) processing to create porous resorbable polymeric constructs reinforced by nanostructured, organically modified Montmorillonite clay (nanoclay). scCO2 processing simultaneously disperses the nanoclay throughout the polymeric matrix, while imparting a porous morphology to the construct conducive to facilitating cellular infiltration and neoangiogenesis, which are necessary components of bone growth. With the addition of as little as 2.5wt% of nanoclay, the compressive strength of the constructs nearly doubles putting them on par with human cortico-cancellous bone. Rheological measurements indicate that the dominant mode of reinforcement of the nanocomposite constructs is the restriction of polymer chain mobility. This restriction is a function of the positive interaction between polymer chains and the nanoclay. In vivo inflammation studies indicate biocompatibility of the constructs. Ectopic osteogenesis assays have determined that the scCO2-processed nanocomposites are capable of supporting growth-factor induced bone formation. scCO 2-processed resorbable

  4. Automating the Processing Steps for Obtaining Bone Tissue-Engineered Substitutes: From Imaging Tools to Bioreactors

    PubMed Central

    Costa, Pedro F.; Martins, Albino; Neves, Nuno M.; Gomes, Manuela E.

    2014-01-01

    Bone diseases and injuries are highly incapacitating and result in a high demand for tissue substitutes with specific biomechanical and structural features. Tissue engineering has already proven to be effective in regenerating bone tissue, but has not yet been able to become an economically viable solution due to the complexity of the tissue, which is very difficult to be replicated, eventually requiring the utilization of highly labor-intensive processes. Process automation is seen as the solution for mass production of cellularized bone tissue substitutes at an affordable cost by being able to reduce human intervention as well as reducing product variability. The combination of tools such as medical imaging, computer-aided fabrication, and bioreactor technologies, which are currently used in tissue engineering, shows the potential to generate automated production ecosystems, which will, in turn, enable the generation of commercially available products with widespread clinical application. PMID:24673688

  5. New Bismuth-Substituted Hydroxyapatite Nanoparticles for Bone Tissue Engineering

    NASA Astrophysics Data System (ADS)

    Ciobanu, Gabriela; Bargan, Ana Maria; Luca, Constantin

    2015-11-01

    New bismuth-substituted hydroxyapatite [Ca10- x Bi x (PO4)6(OH)2 where x = 0-2.5] nanoparticles were synthesized by the co-precipitation method from aqueous solutions. The structural properties of the samples were analyzed by scanning electron microscopy coupled with x-ray analysis, x-ray powder diffraction, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller surface area analysis. The results confirm that bismuth ions have been incorporated into the hydroxyapatite lattice. The prepared nanocrystalline powders consisted of hydroxyapatite as single phase with hexagonal structure, crystal sizes smaller than 60 nm and (Bi + Ca)/P atomic ratio of around 1.67. The hydroxyapatite samples doped with Bi have mesoporous textures with pores size of around 2 nm and specific surface area in the range of 12-25 m2/g. The Bi-substituted hydroxyapatite powders are more effective against Gram-negative Escherichia coli bacteria than Gram-positive Staphylococcus aureus bacteria.

  6. Directly auto-transplanted mesenchymal stem cells induce bone formation in a ceramic bone substitute in an ectopic sheep model

    PubMed Central

    Boos, Anja M; Loew, Johanna S; Deschler, Gloria; Arkudas, Andreas; Bleiziffer, Oliver; Gulle, Heinz; Dragu, Adrian; Kneser, Ulrich; Horch, Raymund E; Beier, Justus P

    2011-01-01

    Abstract Bone tissue engineering approaches increasingly focus on the use of mesenchymal stem cells (MSC). In most animal transplantation models MSC are isolated and expanded before auto cell transplantation which might be critical for clinical application in the future. Hence this study compares the potential of directly auto-transplanted versus in vitro expanded MSC with or without bone morphogenetic protein-2 (BMP-2) to induce bone formation in a large volume ceramic bone substitute in the sheep model. MSC were isolated from bone marrow aspirates and directly auto-transplanted or expanded in vitro and characterized using fluorescence activated cell sorting (FACS) and RT-PCR analysis before subcutaneous implantation in combination with BMP-2 and β-tricalcium phosphate/hydroxyapatite (β-TCP/HA) granules. Constructs were explanted after 1 to 12 weeks followed by histological and RT-PCR evaluation. Sheep MSC were CD29+, CD44+ and CD166+ after selection by Ficoll gradient centrifugation, while directly auto-transplanted MSC-populations expressed CD29 and CD166 at lower levels. Both, directly auto-transplanted and expanded MSC, were constantly proliferating and had a decreasing apoptosis over time in vivo. Directly auto-transplanted MSC led to de novo bone formation in a heterotopic sheep model using a β-TCP/HA matrix comparable to the application of 60 μg/ml BMP-2 only or implantation of expanded MSC. Bone matrix proteins were up-regulated in constructs following direct auto-transplantation and in expanded MSC as well as in BMP-2 constructs. Up-regulation was detected using immunohistology methods and RT-PCR. Dense vascularization was demonstrated by CD31 immunohistology staining in all three groups. Ectopic bone could be generated using directly auto-transplanted or expanded MSC with β-TCP/HA granules alone. Hence BMP-2 stimulation might become dispensable in the future, thus providing an attractive, clinically feasible approach to bone tissue engineering. PMID

  7. On the properties of artificial neural network filters for bone-suppressed digital radiography

    NASA Astrophysics Data System (ADS)

    Park, Eunpyeong; Park, Junbeom; Kim, Daecheon; Youn, Hanbean; Jeon, Hosang; Kim, Jin Sung; Kang, Dong-Joong; Kim, Ho Kyung

    2016-04-01

    Dual-energy imaging can enhance lesion conspicuity. However, the conventional (fast kilovoltage switching) dual-shot dual-energy imaging is vulnerable to patient motion. The single-shot method requires a special design of detector system. Alternatively, single-shot bone-suppressed imaging is possible using post-image processing combined with a filter obtained from training an artificial neural network. In this study, the authors investigate the general properties of artificial neural network filters for bone-suppressed digital radiography. The filter properties are characterized in terms of various parameters such as the size of input vector, the number of hidden units, the learning rate, and so on. The preliminary result shows that the bone-suppressed image obtained from the filter, which is designed with 5,000 teaching images from a single radiograph, results in about 95% similarity with a commercial bone-enhanced image.

  8. In vivo study of porous strontium-doped calcium polyphosphate scaffolds for bone substitute applications.

    PubMed

    Tian, Meng; Chen, Feng; Song, Wei; Song, Yancheng; Chen, Yuanwei; Wan, Changxiu; Yu, Xixun; Zhang, Xiaohua

    2009-07-01

    The purpose of this study was to investigate in vivo biocompatibility and osteogenesis as well as degradability of the porous strontium-doped calcium polyphosphate (SCPP) scaffolds as a biomaterial for bone substitute applications. The evaluation was performed on a rabbit model over a period of 16 weeks by histology combined with image analysis, X-ray microradiography and immunohistochemistry methods. The histological and X-ray microradiographic results showed that the SCPP scaffold exhibited good biocompatibility and extensive osteoconductivity with host bone. Moreover, a significant more bone formation was observed in the SCPP group compared with that in the CPP group, especially at the initial stage after implantation. New bone volumes (NBVs) of the SCPP group determined at week 4, 8 and 16 were 14, 27 and 45%, respectively. Accordingly, NBVs of the CPP group were 10, 19 and 40%. Immunohistochemical results revealed that both the expression of collagen type I and bone morphogenetic proteins in the SCPP group were higher than that in the CPP group, which might be associated with the release of strontium ions during the implantation. In addition, during 16 weeks implantation the SCPP scaffold exhibited similar degradability with the CPP scaffold in vivo. Both scaffolds showed the greatest degradation rate for the first 4 weeks, and then the degradation rate gradually decreased. The results presented in this study demonstrated that SCPP scaffold can be considered as a biocompatible material, making it attractive for bone substitute application purposes. PMID:19267259

  9. Evaluation of suitable porosity for sintered porous {beta}-tricalcium phosphate as a bone substitute

    SciTech Connect

    Park, Jin-Hong; Bae, Ji-Yong; Shim, Jaebum; Jeon, Insu

    2012-09-15

    Structural and mechanical characterization is performed for sintered porous beta tricalcium phosphate ({beta}-TCP) to determine the appropriate porosity for use as a bone substitute. Four different types of porous {beta}-TCP specimen with different porosities are fabricated through a sintering process. For structural characterization, scanning electron microscopy and a Microfocus X-ray computed tomography system are used to investigate the pore openings on the specimen's surface, pore size, pore distribution, and pore interconnections. Compression tests of the specimens are performed, and mechanical properties such as the elastic modulus and compressive strength are obtained. Also, the geometric shape and volume of the {beta}-TCP around the contact region of two pores, which need to be initially resolved after implantation in order to increase the size of the pore openings, are evaluated through simple calculations. The results show that porous {beta}-TCP with 42.1% porosity may be a suitable bone substitute candidate in terms of sustaining external loads, and inducing and cultivating bone cells. - Highlights: Black-Right-Pointing-Pointer Structural and mechanical characterization was performed for sintered porous {beta}-TCP specimens. Black-Right-Pointing-Pointer For structural characterization, SEM and Microfocus X-ray CT system were used. Black-Right-Pointing-Pointer For mechanical characterization, compression tests were performed. Black-Right-Pointing-Pointer Porous {beta}-TCP with 42.1% porosity may be a suitable bone substitute.

  10. A novel alkali metals/strontium co-substituted calcium polyphosphate scaffolds in bone tissue engineering.

    PubMed

    Song, Wei; Wang, Qiguang; Wan, Changxiu; Shi, Tong; Markel, David; Blaiser, Ralph; Ren, Weiping

    2011-08-01

    Our purpose of this study is to develop potassium or sodium/strontium co-substituted calcium polyphosphate (K/Sr-CPP or Na/Sr-CPP) bioceramics in application of bone repairing scaffold. The incorporation of K, Na, and Sr into CPP substrate via a calcining-sintering process was confirmed by X-ray diffractometry and inductively coupled plasma atomic emission spectroscopy. In vitro degradation study of co-substituted CPP indicated the incorporation of alkali metal elements promoted the degradability of CPP, and the scanning electron microscope showed the apatite-like minerals were precipitated on the surface of co-substituted CPP. The compress resistant strength of co-substituted CPP was elevated by dopants. The MTT assay and confocal laser-scanning microscope on osteoblasts culturing with co-substituted CPP showed no cytotoxicity. The cell proliferation on co-substituted CPP was even better than others. Thus, this co-substituted CPP bioceramics might have potential of applications in orthopedic field. PMID:21732528

  11. Dual mode antibacterial activity of ion substituted calcium phosphate nanocarriers for bone infections.

    PubMed

    Sampath Kumar, T S; Madhumathi, K; Rubaiya, Y; Doble, Mukesh

    2015-01-01

    Nanotechnology has tremendous potential for the management of infectious diseases caused by multi-drug resistant bacteria, through the development of newer antibacterial materials and efficient modes of antibiotic delivery. Calcium phosphate (CaP) bioceramics are commonly used as bone substitutes due to their similarity to bone mineral and are widely researched upon for the treatment of bone infections associated with bone loss. CaPs can be used as local antibiotic delivery agents for bone infections and can be substituted with antibacterial ions in their crystal structure to have a wide spectrum, sustained antibacterial activity even against drug resistant bacteria. In the present work, a dual mode antibiotic delivery system with antibacterial ion substituted calcium deficient hydroxyapatite (CDHA) nanoparticles has been developed. Antibacterial ions such as zinc, silver, and strontium have been incorporated into CDHA at concentrations of 6, 0.25-0.75, and 2.5-7.5 at. %, respectively. The samples were found to be phase pure, acicular nanoparticles of length 40-50 nm and width 5-6 nm approximately. The loading and release profile of doxycycline, a commonly used antibiotic, was studied from the nanocarriers. The drug release was studied for 5 days and the release profile was influenced by the ion concentrations. The release of antibacterial ions was studied over a period of 21 days. The ion substituted CDHA samples were tested for antibacterial efficacy on Staphylococcus aureus and Escherichia coli by MIC/MBC studies and time-kill assay. AgCDHA and ZnCDHA showed high antibacterial activity against both bacteria, while SrCDHA was weakly active against S. aureus. Present study shows that the antibiotic release can provide the initial high antibacterial activity, and the sustained ion release can provide a long-term antibacterial activity. Such dual mode antibiotic and antibacterial ion release offers an efficient and potent way to treat an incumbent drug

  12. Computational Analysis of Artificial Gravity as a Possible Countermeasure to Spaceflight Induced Bone Loss

    NASA Technical Reports Server (NTRS)

    Mulugeta, L.; Werner, C. R.; Pennline, J. A.

    2015-01-01

    During exploration class missions, such as to asteroids and Mars, astronauts will be exposed to reduced gravity for extended periods. Data has shown that astronauts lose bone mass at a rate of 1% to 2% a month in microgravity, particularly in lower extremities such as the proximal femur. Exercise countermeasures have not completely eliminated bone loss from long duration spaceflight missions, which leaves astronauts susceptible to early onset osteoporosis and greater risk of fracture. Introduction of the Advanced Resistive Exercise Device and other large exercise devices on the International Space Station (ISS), coupled with improved nutrition, has further minimized bone loss. However, unlike the ISS, exploration vehicles will have very limited volume and power available to accommodate such capabilities. Therefore, novel concepts like artificial gravity systems are being explored as a means to provide sufficient load stimulus to the musculoskeletal system to mitigate bone changes that may lead to early onset osteoporosis and increased risk of fracture. Currently, there is minimal data available to drive further research and development efforts to appropriately explore such options. Computational modeling can be leveraged to gain insight on the level of osteoprotection that may be achieved using artificial gravity produced by a spinning spacecraft or centrifuge. With this in mind, NASA's Digital Astronaut Project (DAP) has developed a bone remodeling model that has been validated for predicting volumetric bone mineral density (vBMD) changes of trabecular and cortical bone both for gravitational unloading condition and the equivalent of 1g daily load stimulus. Using this model, it is possible to simulate vBMD changes in trabecular and cortical bone under different gravity conditions. In this presentation, we will discuss our preliminary findings regarding if and how artificial gravity may be used to mitigate spaceflight induced bone loss.

  13. The necessity of selenium substitution in total parenteral nutrition and artificial alimentation.

    PubMed

    Gramm, H J; Kopf, A; Brätter, P

    1995-03-01

    For the trace element selenium, in contrast to zinc, iron, copper, chromium, manganese and iodine, there is still no clear official recommendation with regard to routine substitution in artificial nutrition. An overview of the manifestations of selenium deficiency in humans during the period 1979-1995 shows that nutritive deficiencies are exclusively TPN-induced or the result of severe malnutrition. The pathology of TPN-induced selenium deficiency and the analytic assessment of selenium status are described. Patients undergoing long-term parenteral nutrition or suffering from an increased loss of intestinal secretions have to be characterized as being especially at risk for clinical selenium deficiency. The relationship of the serum selenium kinetics in pediatric and adult patients to the depletion of body compartments during the course of short-term and prolonged TPN is discussed. Because of the importance of the selenoproteins, the regularly occurring depletion during selenium-free TPN and the borderline supply of selenium in Germany the routine substitution of selenium in TPN is strongly recommended. The pharmaceutical industry should be encouraged to develop a trace element solution that includes selenium, so that the nutritive requirement of patients on TPN can be satisfied. Adequate intravenous dosage recommendations are based on maintenance of glutathione peroxidase homeostasis. The routine supplementation dosage may not meet the selenium requirements of intensive care patients under conditions of increased metabolic demands on their anti-oxidative system. PMID:8846151

  14. Artificial Gravity: Will it Preserve Bone Health on Long-Duration Missions?

    NASA Technical Reports Server (NTRS)

    Davis-Street, Janis; Paloski, William H.

    2005-01-01

    Prolonged microgravity exposure disrupts bone, muscle, and cardiovascular homeostasis, sensory-motor coordination, immune function, and behavioral performance. Bone loss, in particular, remains a serious impediment to the success of exploration-class missions by increasing the risks of bone fracture and renal stone formation for crew members. Current countermeasures, consisting primarily of resistive and aerobic exercise, have not yet proven fully successful for preventing bone loss during long-duration spaceflight. While other bone-specific countermeasures, such as pharmacological therapy and dietary modifications, are under consideration, countermeasure approaches that simultaneously address multiple physiologic systems may be more desirable for exploration-class missions, particularly if they can provide effective protection at reduced mission resource requirements (up-mass, power, crew time, etc). The most robust of the multi-system approaches under consideration, artificial gravity (AG), could prevent all of the microgravity-related physiological changes from occurring. The potential methods for realizing an artificial gravity countermeasure are reviewed, as well as selected animal and human studies evaluating the effects of artificial gravity on bone function. Future plans for the study of the multi-system effects of artificial gravity include a joint, cooperative international effort that will systematically seek an optimal prescription for intermittent AG to preserve bone, muscle, and cardiovascular function in human subjects deconditioned by 6 degree head-down-tilt-bed rest. It is concluded that AG has great promise as a multi-system countermeasure, but that further research is required to determine the appropriate parameters for implementation of such a countermeasure for exploration-class missions.

  15. The evaluation of a synthetic long bone structure as a substitute for human tissue in gunshot experiments.

    PubMed

    Kneubuehl, B P; Thali, M J

    2003-12-17

    Our goal was to compare experimental gunshot wounds in our non-biological bone model with similarly created wounds in swine bones, and evaluate the results. The design of the synthetic (polyurethane) bone was patterned after human bone structure, with a compact outer layer covering a porous inner layer. Ordnance gelatin, as substitute bone marrow, was injected into the bone's hollow core. To simulate the periostium, the bone was covered with a layer of latex. Then the bone was embedded in gelatin used to simulate surrounding soft tissue. For comparison, fresh swine bones were also embedded in gelatin, and fired upon under the same guidelines. All gunshots were high-speed filmed. In our experimental study, gunshot wounds to swine bones, and to our synthetic, non-biological bones were compared. The results (the comparison between the biological swine bones and the non-biological model bones) in regard to the following points are absolutely equal: the loss of velocity and energy after striking bone, bone fragmentation, bullet deformation, and the penetrating wound channel. Continuing studies with our synthetic bone model will bring about an even greater understanding of the mechanisms of "bullet-bone interaction". For this reason, we have extended our variety of bone models to include other skeletal structures such as skull, spine, pelvis and flat bones for further gunshot experiments. PMID:14642718

  16. [Substitution of antelope horn in Danqi Piantan capsule with artificial bezoar in vitro].

    PubMed

    Wang, Jin-bo; Li, Zheng; Chen, Tao; Zhang, Yan-jun; Cui, Wei-li; Li, Jin

    2015-11-01

    The in vitro cell culture experiment was conducted to study the effect of Danqi Piantan capsule (DPC) and DPC dislodge the antelope horn with artificial bezoar double (DPCBD) on nerve regeneration and blood vessel regeneration and preliminarily investigate the possibility of substituting antelope horn in DPC with artificial bezoar. In this experiment, rats were randomly divided into 5 groups: the blank serum control group, the model group, DPC groups (0.306 g x kg(-1) x d(-1), the same below), DPC remove of antelope horn (DPCRA) groups and DPCBD groups. Brain microvascular endothelial cells cultured in vitro (BMEC), astrocytes and neural stem cells (NSC) were co-cultured to simulate neurovascular unit, label neurons with microtubule associated protein III (β-tubulin III) antibody and lable astrocytes with glial fibrillary acidicprotein (GFAP). ELISA was used for the detection of the content of BMEC lactate dehydrogenase instrument method (LDH), the inverted phase contrastmicroscope was adopted to observe the formation of BMEC tube like structure, the number of leukocytes and leukocytes adherent to BMEC were counted under the microscope, the expression levels of β-tubulin III and the ratio of GFAP positive cells was detected with inimmunofluorescence, and RT-PCR method was used to detect NGF, BDNF, VEGF and VEGFr-2 mRNA. According to the result, compared with the model group, both DPC and DPCBD can reduce LDH leakage, promote the formation of BMEC tube like structure, inhibit leukocytes and their adhesion to BMEC, increase the β-tubulin III positive cell differentiation proportion (P < 0. 01), reduce the proportion of GFAP positive cells (P < 0.01), increase the expressions of co-cultured NGF, VEGF, BDNF and VEGFr-2 mRNA to a certain extent, with the most significant difference on NGF and VEGF mRNA expressions (P < 0.05) and the same efficacy in both groups. DPCRA groups showed less impact on all indexes than that of DPCBD and DPC groups. The same efficacy of

  17. [Preliminary study on substitution of Antelope Horn in Danqi Piantan capsule with artificial bezoar].

    PubMed

    Wang, Jin-bo; Chen, Tao; Li, Zheng; Zhang, Yan-jun; Cui, Wei-li; Li, Jin

    2015-09-01

    To study the protective effect of Danqi Piantan capsule ( DPC) and its antelope horn substitution (DPCAS) on the cerebral ischemia, in order to preliminary study the possibility of replacing antelope horn with artificial bezoar. In this study, the left middle cerebral artery occlusion (MCAO) was adopted. Totally 150 SD rats were randomly divided into 5 groups: the sham operation group, the model group, the Danqi Piantan capsule (DPC) group (0.246 g x kg(-1) x d(-1)), the Danqi Piantan capsule without antelope horn (DPCRA) group (0.246 g x kg(-1) x d(-1)), the Danqi Piantan capsule without antelope horn and with double artificial bezoar (DPCDB) group (0.246 g x kg(-1) x d(-1)). The MCAO model was prepared 1 h later after the administration on the 5th day. At 24 h after the operation, the inner canthus blood was collected to determine the serum superoxide dismutase (SOD) activity and the endothelin (ET) content. At 72 h after the operation, the cerebral infarct size and the cerebral index were determined by TTC-staining. The fluorescent quantitative PCR method was used to detect brain Bcl-2, Caspase-3, IL-1β, P-selectin, E-selectin, ICAM-1 mRNA expressions. The mmunohistochemical method was used to detect ICAM-1, IL-1β, TNF-α, IL-6 expressions in ischemic penumbra. According to the results, compared with the model group, DPCDB and DPC groups showed almost consistent results, indicating both of the two group can significantly improved cerebral infarction index and cerebral index (P < 0.05), increase the serum SOD activity (P < 0.05), decrease the serum ET level and Caspase-3 expression, IL-1β, P-selectin, E-selectin, ICAM-1 mRNA expressions in brain tissues (P < 0.05) and expressions of ICAM-1, IL-1,6, TNF-α, IL-6 positive cells in ischemic penumbra (P < 0.05) and increase the Bcl-2 expression (P < 0.05). The DPCRA group showed much lower impacts on indexes than DPCDB and DPC groups. This suggests that DPCDB and DPC reveal similar efficacies and antelope horn in

  18. Fabrication of porous hydroxyapatite scaffolds as artificial bone preform and its biocompatibility evaluation.

    PubMed

    Jang, Dong-Woo; Franco, Rose Ann; Sarkar, Swapan Kumar; Lee, Byong-Taek

    2014-01-01

    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

  19. Effect of sintered silicate-substituted hydroxyapatite on remodelling processes at the bone-implant interface.

    PubMed

    Porter, Alexandra E; Patel, Nelesh; Skepper, Jeremy N; Best, Serena M; Bonfield, William

    2004-07-01

    Phase pure, sintered granules of hydroxyapatite (HA) and silicon-substituted hydroxyapatite (Si-HA) were implanted for 6 and 12 weeks in an ovine model. Samples containing the bone-implant interface were prepared for ultramicrotomy and transmission electron microscopy (TEM) using an anhydrous sample preparation procedure. The results demonstrate that the morphology of apatite deposits and the sequence of events at the interfaces of bone with pure HA and with Si-HA implants, were different. Organised collagen fibrils were first found at the bone/Si-HA interface after 6 weeks, whereas they were found only after 12 weeks around the pure HA implant. Many more nodular aggregates comprised of plate-like apatite crystallites were observed in the vicinity of Si-HA than around the pure HA after 12 weeks in vivo. These findings suggest that the incorporation of silicate ions into HA promotes processes of bone remodelling at the bone/HA interface. TEM observations suggested that the trabecular bone weaves over the Si-HA and that the collagen fibrils form a mechanical interlock with the Si-HA ceramic implants. High-resolution lattice imaging illustrated apatite crystallites contiguous with the Si-HA ceramic and revealed a direct relationship between the bone mineral and the Si-HA ceramic. PMID:14980425

  20. 3D image analysis and artificial intelligence for bone disease classification.

    PubMed

    Akgundogdu, Abdurrahim; Jennane, Rachid; Aufort, Gabriel; Benhamou, Claude Laurent; Ucan, Osman Nuri

    2010-10-01

    In order to prevent bone fractures due to disease and ageing of the population, and to detect problems while still in their early stages, 3D bone micro architecture needs to be investigated and characterized. Here, we have developed various image processing and simulation techniques to investigate bone micro architecture and its mechanical stiffness. We have evaluated morphological, topological and mechanical bone features using artificial intelligence methods. A clinical study is carried out on two populations of arthritic and osteoporotic bone samples. The performances of Adaptive Neuro Fuzzy Inference System (ANFIS), Support Vector Machines (SVM) and Genetic Algorithm (GA) in classifying the different samples have been compared. Results show that the best separation success (100 %) is achieved with Genetic Algorithm. PMID:20703627

  1. Biodegradable and semi-biodegradable composite hydrogels as bone substitutes: morphology and mechanical characterization.

    PubMed

    Sanginario, V; Ginebra, M P; Tanner, K E; Planell, J A; Ambrosio, L

    2006-05-01

    Biodegradable and semi-biodegradable composite hydrogels are proposed as bone substitutes. They consist of an hydrophilic biodegradable polymer (HYAFF 11) as matrix and two ceramic powders (alpha-TCP and HA) as reinforcement. Both components of these composites have been of great interest in biomedical applications due to their excellent biocompatibility and tissue interactions, however they have never been investigated as bone substitute composites. Morphological and mechanical analysis have shown that the two fillers behave in a very different way. In the HYAFF 11/alpha-TCP composite, alpha-TCP is able to hydrolyze in contact with water while in the HYAFF 11 matrix. As a result, the composite sets and hardens, and entangled CDHA crystals are formed in the hydrogel phase and increases in the mechanical properties are obtained. In the HYAFF11/HA composite the ceramic reinforcement acts as inert phase leading to lower mechanical properties. Both mechanical properties and microstructure analysis have demonstrated the possibility to design hydrophilic biodegradable composite structures for bone tissue substitution applications. PMID:16688585

  2. A Modified Rabbit Ulna Defect Model for Evaluating Periosteal Substitutes in Bone Engineering: A Pilot Study

    PubMed Central

    El Backly, Rania M.; Chiapale, Danilo; Muraglia, Anita; Tromba, Giuliana; Ottonello, Chiara; Santolini, Federico; Cancedda, Ranieri; Mastrogiacomo, Maddalena

    2014-01-01

    The present work defines a modified critical size rabbit ulna defect model for bone regeneration in which a non-resorbable barrier membrane was used to separate the radius from the ulna to create a valid model for evaluation of tissue-engineered periosteal substitutes. Eight rabbits divided into two groups were used. Critical defects (15 mm) were made in the ulna completely eliminating periosteum. For group I, defects were filled with a nanohydroxyapatite poly(ester urethane) scaffold soaked in PBS and left as such (group Ia) or wrapped with a tissue-engineered periosteal substitute (group Ib). For group II, an expanded-polytetrafluoroethylene (e-PTFE) (GORE-TEX®) membrane was inserted around the radius then the defects received either scaffold alone (group IIa) or scaffold wrapped with periosteal substitute (group IIb). Animals were euthanized after 12–16 weeks, and bone regeneration was evaluated by radiography, computed microtomography (μCT), and histology. In the first group, we observed formation of radio-ulnar synostosis irrespective of the treatment. This was completely eliminated upon placement of the e-PTFE (GORE-TEX®) membrane in the second group of animals. In conclusion, modification of the model using a non-resorbable e-PTFE membrane to isolate the ulna from the radius was a valuable addition allowing for objective evaluation of the tissue-engineered periosteal substitute. PMID:25610828

  3. A modified rabbit ulna defect model for evaluating periosteal substitutes in bone engineering: a pilot study.

    PubMed

    El Backly, Rania M; Chiapale, Danilo; Muraglia, Anita; Tromba, Giuliana; Ottonello, Chiara; Santolini, Federico; Cancedda, Ranieri; Mastrogiacomo, Maddalena

    2014-01-01

    The present work defines a modified critical size rabbit ulna defect model for bone regeneration in which a non-resorbable barrier membrane was used to separate the radius from the ulna to create a valid model for evaluation of tissue-engineered periosteal substitutes. Eight rabbits divided into two groups were used. Critical defects (15 mm) were made in the ulna completely eliminating periosteum. For group I, defects were filled with a nanohydroxyapatite poly(ester urethane) scaffold soaked in PBS and left as such (group Ia) or wrapped with a tissue-engineered periosteal substitute (group Ib). For group II, an expanded-polytetrafluoroethylene (e-PTFE) (GORE-TEX(®)) membrane was inserted around the radius then the defects received either scaffold alone (group IIa) or scaffold wrapped with periosteal substitute (group IIb). Animals were euthanized after 12-16 weeks, and bone regeneration was evaluated by radiography, computed microtomography (μCT), and histology. In the first group, we observed formation of radio-ulnar synostosis irrespective of the treatment. This was completely eliminated upon placement of the e-PTFE (GORE-TEX(®)) membrane in the second group of animals. In conclusion, modification of the model using a non-resorbable e-PTFE membrane to isolate the ulna from the radius was a valuable addition allowing for objective evaluation of the tissue-engineered periosteal substitute. PMID:25610828

  4. Three-Dimensional Assessment of Volumetric Changes in Sinuses Augmented with Two Different Bone Substitutes

    PubMed Central

    Karabuda, Z. Cuneyt

    2016-01-01

    Introduction. The bone volume of the posterior maxilla may not be appropriate for implant placement, due to factors such as pneumatized maxillary sinus. The purpose of this study was to evaluate the percentage of graft volume reduction following sinus floor elevation (SFE), with either slow resorbable bone substitute only or a composite of slow and fast resorbable bone substitutes, using cone beam computed tomography (CBCT). Materials and Methods. In this retrospective study, CBCT scans of SFE procedures were evaluated to determine the volume of grafted sinus with either deproteinized bovine bone (DBB) or a 2 : 1 mixture of biphasic calcium sulfate (CS) and DBB, as a composite. The volumetric changes of sinus augmentations were measured 2 weeks (V-I) and 6 months (V-II) after operation. Results. Thirty-three patients were included in this study. The average percentage volume reduction was 9.39 ± 3.01% and 17.65 ± 4.15% for DBB and composite grafts, respectively. A significant graft volume reduction was observed between V-I and V-II for both groups (p < 0.01). The DBB group exhibited significantly less volume reduction than the composite group (p < 0.01). Conclusions. Augmented sinus volume may change before implant placement. DBB offers greater volume stability during healing than composite grafts. PMID:27517044

  5. Interfacial and biological properties of the gradient coating on polyamide substrate for bone substitute.

    PubMed

    Huang, Di; Niu, Lulu; Wei, Yan; Guo, Meiqing; Zuo, Yi; Zou, Qin; Hu, Yinchun; Chen, Weiyi; Li, Yubao

    2014-10-01

    Fabrication of bioactive and mechanical matched bone substitutes is crucial for clinical application in bone defects repair. In this study, nano-hydroxyapatite/polyamide (nHA/PA) composite was coated on injection-moulded PA by a chemical corrosion and phase-inversion technique. The shear strength, gradient composition and pore structure of the bioactive coating were characterized. Osteoblast-like MG63 cells were cultured on pure PA and composite-coated PA samples. The cells' adhesion, spread and proliferation were determined using MTT assay and microscopy. The results confirm that the samples with the nHA/PA composite coating have better cytocompatibility and have no negative effects on cells. To investigate the in vivo biocompatibility, both pure PA and composite-coated PA cylinders were implanted in the trochlea of rabbit femurs and studied histologically, and the bonding ability with bone were determined using push-out tests. The results show that composite-coated implants exhibit better biocompatibility and the shear strength of the composite-coated implants with host bone at 12 weeks can reach 3.49±0.42 MPa, which is significantly higher than that of pure PA implants. These results indicate that composite-coated PA implants have excellent biocompatibility and bonding abilities with host bone and they have the potential to be applied in repair of bone defects. PMID:25121648

  6. Interfacial and biological properties of the gradient coating on polyamide substrate for bone substitute

    PubMed Central

    Huang, Di; Niu, Lulu; Wei, Yan; Guo, Meiqing; Zuo, Yi; Zou, Qin; Hu, Yinchun; Chen, Weiyi; Li, Yubao

    2014-01-01

    Fabrication of bioactive and mechanical matched bone substitutes is crucial for clinical application in bone defects repair. In this study, nano-hydroxyapatite/polyamide (nHA/PA) composite was coated on injection-moulded PA by a chemical corrosion and phase-inversion technique. The shear strength, gradient composition and pore structure of the bioactive coating were characterized. Osteoblast-like MG63 cells were cultured on pure PA and composite-coated PA samples. The cells' adhesion, spread and proliferation were determined using MTT assay and microscopy. The results confirm that the samples with the nHA/PA composite coating have better cytocompatibility and have no negative effects on cells. To investigate the in vivo biocompatibility, both pure PA and composite-coated PA cylinders were implanted in the trochlea of rabbit femurs and studied histologically, and the bonding ability with bone were determined using push-out tests. The results show that composite-coated implants exhibit better biocompatibility and the shear strength of the composite-coated implants with host bone at 12 weeks can reach 3.49 ± 0.42 MPa, which is significantly higher than that of pure PA implants. These results indicate that composite-coated PA implants have excellent biocompatibility and bonding abilities with host bone and they have the potential to be applied in repair of bone defects. PMID:25121648

  7. Histological evaluation of an impacted bone graft substitute composed of a combination of mineralized and demineralized allograft in a sheep vertebral bone defect.

    PubMed

    Fujishiro, Takaaki; Bauer, Thomas W; Kobayashi, Naomi; Kobayashi, Hideo; Sunwoo, Moon Hae; Seim, Howard B; Turner, A Simon

    2007-09-01

    Demineralized bone matrix (DBMs) preparations are a potential alternative or supplement to autogenous bone graft, but many DBMs have not been adequately tested in clinically relevant animal models. The aim of current study was to compare the efficacy of a new bone graft substitute composed of a combination of mineralized and demineralized allograft, along with hyaluronic acid (AFT Bone Void Filler) with several other bone graft materials in a sheep vertebral bone void model. A drilled defect in the sheep vertebral body was filled with either the new DBM preparation, calcium sulfate (OsteoSet), autologous bone graft, or left empty. The sheep were euthanized after 6 or 12 weeks, and the defects were examined by histology and quantitative histomorphometry. The morphometry data were analyzed by one-way analysis of variance with the post hoc Tukey-Kramer test or the Student's t-test. All of the bone defects in the AFT DBM preparation group showed good new bone formation with variable amounts of residual DBM and mineralized bone graft. The DBM preparation group at 12 weeks contained significantly more new bone than the defects treated with calcium sulfate or left empty (respectively, p < 0.05, p < 0.01). There was no significant difference between the DBM and autograft groups. No adverse inflammatory reactions were associated with any of the three graft materials. The AFT preparation of a mixture of mineralized and demineralized allograft appears to be an effective autograft substitute as tested in this sheep vertebral bone void model. PMID:17309059

  8. Role of platelet-rich plasma in combination with alloplastic bone substitute in regeneration of osseous defects

    PubMed Central

    Singh, Indrajeet; Gupta, Hemant; Pradhan, R; Sinha, VP; Gupta, Sumit

    2012-01-01

    Introduction Bone grafts are frequently used for the treatment of bone defects, but can cause postoperative complications, and sometimes a sufficient quantity of bone is not available. Hence, synthetic biomaterials have been used as an alternative to autogenous bone grafts. Recent clinical reports suggest that application of autologous blood plasma enriched with platelets can enhance the formation of new bone. There are very few in vitro or in vivo studies published on the efficiency of platelet-rich plasma (PRP). The objective of this study was to evaluate the alloplastic bone substitute for its osteogenic potential with or without PRP. Materials and Methods Twenty-three patients with periapical bony defects were selected for this study. Clinical parameters such as pain visual analog scale (VAS), swelling, infection, graft migration, rejection, radiographical interpretations at regular interval and scintigraphic evaluation were done to evaluate osteogenic potential of alloplastic bone substitute with or without PRP. Results The highest acceleration in bone formation was observed in groups where alloplastic bone substitute was used with PRP. There were no statistically significant differences between the two groups regarding other outcome variables throughout the postoperative period. Conclusion Addition of PRP significantly accelerates vascularization of the graft, improves soft tissue healing, reduces postoperative morbidity and enhances bone regeneration. PMID:25756013

  9. Development of hydroxyapatite scaffolds for artificial bone grafts

    NASA Astrophysics Data System (ADS)

    Ajaal, Tawfik Taher

    The Taguchi method of experimental design is very well suited to improving the production process of the synthetic bone grafts for several reasons. First, it is very efficient and easy to apply, so that it does not require large amounts of time or resources to conduct a given set of experiments. This makes it possible to conduct a series of experiments that result in continuous process improvement. Second, the effect of many different process variables can be examined simultaneously, which ensures that beneficial factor combinations are not overlooked. Finally, using a Taguchi signal-to-noise ratio leads to concurrent optimization of the process and reduction of process variability. The application of Taguchi method was successful in optimizing the production process of the synthetic bone grafts. The compressive strength was doubled while maintaining the appropriate porosity level and microstructure for the bioactivity process. The mean value of the compression strength obtained was 5.8 MPa with density of 0.515 gm/cm3 for samples prepared from 45 pores per inch (PPI) foam reticulate, and 3.2 MPa with 0.422 gm/cm 3 for samples prepared from 30 PPI foam reticulate. Three levels of porosity were identified namely, macro, meso, and micro-porosity. The pore sizes were (350--400) mum, (100--120) mum and (2--6) mum respectively based on the used substrate. Using the Taguchi method in conjunction with a statistical experimental design, the various steps of the scaffold production process such as slurry preparation, coating process, drying, calcining and sintering processes were optimized. The final optimized process gave highly reproducible results.

  10. Bone tissue reactions to biomimetic ion-substituted apatite surfaces on titanium implants

    PubMed Central

    Ballo, Ahmed M.; Xia, Wei; Palmquist, Anders; Lindahl, Carl; Emanuelsson, Lena; Lausmaa, Jukka; Engqvist, Håkan; Thomsen, Peter

    2012-01-01

    The aim of this study was to evaluate the bone tissue response to strontium- and silicon-substituted apatite (Sr-HA and Si-HA) modified titanium (Ti) implants. Sr-HA, Si-HA and HA were grown on thermally oxidized Ti implants by a biomimetic process. Oxidized implants were used as controls. Surface properties, i.e. chemical composition, surface thickness, morphology/pore characteristics, crystal structure and roughness, were characterized with various analytical techniques. The implants were inserted in rat tibiae and block biopsies were prepared for histology, histomorphometry and scanning electron microscopy analysis. Histologically, new bone formed on all implant surfaces. The bone was deposited directly onto the Sr-HA and Si-HA implants without any intervening soft tissue. The statistical analysis showed significant higher amount of bone–implant contact (BIC) for the Si-doped HA modification (P = 0.030), whereas significant higher bone area (BA) for the Sr-doped HA modification (P = 0.034), when compared with the non-doped HA modification. The differences were most pronounced at the early time point. The healing time had a significant impact for both BA and BIC (P < 0.001). The present results show that biomimetically prepared Si-HA and Sr-HA on Ti implants provided bioactivity and promoted early bone formation. PMID:22279159

  11. Immunohistochemical characterization of wound healing at two different bone graft substitutes.

    PubMed

    Sager, M; Ferrari, D; Wieland, M; Dard, M; Becker, J; Schwarz, F

    2012-05-01

    The immunohistochemical characteristics of wound healing following application of a biphasic calcium phosphate or a collagen coated natural bone combined with a native collagen membrane in a dog model was assessed. Standardized buccal dehiscence-type defects were surgically created following implant bed preparation in 6 dogs. Following implant placement, defects were randomly filled with a collagen coated natural bone mineral (GBO), or a biphasic hydroxyapatite/beta tricalcium phosphate (SBC), and covered with a native collagen membrane. After 1, 4, and 9 weeks' submerged healing, dissected blocks were processed for immunohistochemical (collagen type I (CI), osteocalcin (OC), angiogenesis (TG)) analysis. At 1 week, GBO and SBC granules were homogeneously surrounded by a well vascularized, non-mineralized tissue (NMT). CI and OC antigen reactivity was commonly observed adjacent to both bone graft substitutes. At 4 and 9 weeks, SBC and GBO granules were completely integrated into a secondly formed network of spongiosa. At 9 weeks, dissolution of some granules was observed in the SBC group. Adjacent to these granules, NMT was significantly increased and revealed a pronounced CI, OC and TG antigen reactivity. The initial pattern of bone regeneration and graft integration was comparable in both groups; bone remodelling was more pronounced with SBC. PMID:22169169

  12. Dual Mode Antibacterial Activity of Ion Substituted Calcium Phosphate Nanocarriers for Bone Infections

    PubMed Central

    Sampath Kumar, T. S.; Madhumathi, K.; Rubaiya, Y.; Doble, Mukesh

    2015-01-01

    Nanotechnology has tremendous potential for the management of infectious diseases caused by multi-drug resistant bacteria, through the development of newer antibacterial materials and efficient modes of antibiotic delivery. Calcium phosphate (CaP) bioceramics are commonly used as bone substitutes due to their similarity to bone mineral and are widely researched upon for the treatment of bone infections associated with bone loss. CaPs can be used as local antibiotic delivery agents for bone infections and can be substituted with antibacterial ions in their crystal structure to have a wide spectrum, sustained antibacterial activity even against drug resistant bacteria. In the present work, a dual mode antibiotic delivery system with antibacterial ion substituted calcium deficient hydroxyapatite (CDHA) nanoparticles has been developed. Antibacterial ions such as zinc, silver, and strontium have been incorporated into CDHA at concentrations of 6, 0.25–0.75, and 2.5–7.5 at. %, respectively. The samples were found to be phase pure, acicular nanoparticles of length 40–50 nm and width 5–6 nm approximately. The loading and release profile of doxycycline, a commonly used antibiotic, was studied from the nanocarriers. The drug release was studied for 5 days and the release profile was influenced by the ion concentrations. The release of antibacterial ions was studied over a period of 21 days. The ion substituted CDHA samples were tested for antibacterial efficacy on Staphylococcus aureus and Escherichia coli by MIC/MBC studies and time-kill assay. AgCDHA and ZnCDHA showed high antibacterial activity against both bacteria, while SrCDHA was weakly active against S. aureus. Present study shows that the antibiotic release can provide the initial high antibacterial activity, and the sustained ion release can provide a long-term antibacterial activity. Such dual mode antibiotic and antibacterial ion release offers an efficient and potent way to treat an incumbent

  13. Osteofibrous Dysplasia managed with Extraperiosteal excision, Autologous free fibular graft and bone graft substitute

    PubMed Central

    Abraham, Vineet T; Marimuthu, Chandrasekaran; Subbaraj, Ravichandran; Rengarajan, Nandakumar

    2015-01-01

    Introduction: Osteofibrous Dysplasia is a rare benign self-limiting fibro-osseous lesion most commonly seen in the diaphysis of the tibia. Its incidence is reported to be 0.2% of all primary bone tumors. It occurs in the first two decades of life with a slight male preponderance. Surgical options include extra periosteal resection, autologous graft, limb lengthening procedures etc. There are no case reports mentioning the use of synthetic bone graft to fill the defect following extraperiosteal excision. Case Report: A 13 year old girl presented with pain and swelling of the (R) leg since 2 months following a trivial injury at school. Examination revealed a 5×3cm tender swelling on the anteromedial aspect of the middle third tibia. Radiographs and MRI, revealed an eccentric expansile lytic lesion, which was multilocular and was present at the junction of the metaphysis and diaphysis on the antero -medial aspect of tibia. The cortex had ballooned out and there was a possibility of an impending fracture. Biopsy was done which revealed osteofibrous dysplasia. We did an extraperiosteal excision of the lesion. To fill the cavity we harvested 10 cm of the contralateral fibula and since there was still space in the cavity, we packed bone graft substitute (hydroxyapatite crystals) into the defect. The surgical management of osteofibrous dysplasia is controversial. Various methods of treatment of such cases have been described in literature. The use of synthetic graft is an option in these patients as it reduces morbidity; and in our case we had good graft incorporation with this method. Conclusion: Extraperiosteal Excision of Osteofibrous dysplasia combined with autologous free fibular graft and bone graft substitute is a good surgical option to prevent recurrence and mange bone defects in this rare lesion. PMID:27299018

  14. Fantastic plastic? Experimental evaluation of polyurethane bone substitutes as proxies for human bone in trauma simulations.

    PubMed

    Smith, Martin J; James, Stephen; Pover, Tim; Ball, Nina; Barnetson, Victoria; Foster, Bethany; Guy, Carl; Rickman, John; Walton, Virginia

    2015-09-01

    Recent years have seen steady improvements in the recognition and interpretation of violence related injuries in human skeletal remains. Such work has at times benefited from the involvement of biological anthropologists in forensic casework and has often relied upon comparison of documented examples with trauma observed in skeletal remains. In cases where no such example exists investigators must turn to experimentation. The selection of experimental samples is problematic as animal proxies may be too dissimilar to humans and human cadavers may be undesirable for a raft of reasons. The current article examines a third alternative in the form of polyurethane plates and spheres marketed as viable proxies for human bone in ballistic experiments. Through subjecting these samples to a range of impacts from both modern and archaic missile weapons it was established that such material generally responds similarly to bone on a broad, macroscopic scale but when examined in closer detail exhibits a range of dissimilarities that call for caution in extrapolating such results to real bone. PMID:26130519

  15. Melt-electrospun polycaprolactone-strontium substituted bioactive glass scaffolds for bone regeneration.

    PubMed

    Ren, Jiongyu; Blackwood, Keith A; Doustgani, Amir; Poh, Patrina P; Steck, Roland; Stevens, Molly M; Woodruff, Maria A

    2013-10-01

    Polycaprolactone (PCL) is a resorbable polymer used extensively in bone tissue engineering owing to good structural properties and processability. Strontium substituted bioactive glass (SrBG) has the ability to promote osteogenesis and may be incorporated into scaffolds intended for bone repair. Here we describe for the first time, the development of a PCL-SrBG composite scaffold incorporating 10% (weight) of SrBG particles into PCL bulk, produced by the technique of melt-electrospinning. We show that we are able to reproducibly manufacture composite scaffolds with an interconnected porous structure and, furthermore, these scaffolds were demonstrated to be non-cytotoxic in vitro. Ions present in the SrBG component were shown to dissolve into cell culture media and promoted precipitation of a calcium phosphate layer on the scaffold surface which in turn led to noticeably enhanced alkaline phosphatase activity in MC3T3-E1 cells compared to PLC-only scaffolds. These results suggest that melt-electrospun PCL-SrBG composite scaffolds show potential to become effective bone graft substitutes. PMID:24123950

  16. Melt-electrospun polycaprolactone strontium-substituted bioactive glass scaffolds for bone regeneration.

    PubMed

    Ren, Jiongyu; Blackwood, Keith A; Doustgani, Amir; Poh, Patrina P; Steck, Roland; Stevens, Molly M; Woodruff, Maria A

    2014-09-01

    Polycaprolactone (PCL) is a resorbable polymer used extensively in bone tissue engineering owing to good structural properties and processability. Strontium-substituted bioactive glass (SrBG) has the ability to promote osteogenesis and may be incorporated into scaffolds intended for bone repair. Here, we describe for the first time, the development of a PCL-SrBG composite scaffold incorporating 10% (weight) of SrBG particles into PCL bulk, produced by the technique of melt electrospinning. We show that we are able to reproducibly manufacture composite scaffolds with an interconnected porous structure and, furthermore, these scaffolds were demonstrated to be noncytotoxic in vitro. Ions present in the SrBG component were shown to dissolve into cell culture media and promoted precipitation of a calcium phosphate layer on the scaffold surface which in turn led to noticeably enhanced alkaline phosphatase activity in MC3T3-E1 cells compared to PLC-only scaffolds. These results suggest that melt-electrospun PCL-SrBG composite scaffolds show potential to become effective bone graft substitutes. PMID:24133006

  17. Collagen immobilization of multi-layered BCP-ZrO2 bone substitutes to enhance bone formation

    NASA Astrophysics Data System (ADS)

    Linh, Nguyen Thuy Ba; Jang, Dong-Woo; Lee, Byong-Taek

    2015-08-01

    A porous microstructure of multi-layered BCP-ZrO2 bone substitutes was fabricated using the sponge replica method in which the highly interconnected structure was immobilized with collagen via ethyl(dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide crosslinking. Their struts are combined with a three-layered BCP/BCP-ZrO2/ZrO2 microstructure. Collagen fibers were firmly attached to the strut surface of the BCP-ZrO2 scaffolds. With control of the three-layered microstructure and collagen immobilization, the compressive strength of the scaffolds increased significantly to 6.8 MPa compared to that of the monolithic BCP scaffolds (1.3 MPa). An in vitro study using MTT, confocal observation, and real-time polymer chain reaction analysis demonstrated that the proliferation and differentiation of the pre-osteoblast-like MC3T3-E1 cells was improved due to the collagen incorporation. Remarkable enhancement of bone regeneration was observed without any immunological reaction in the femurs of rabbits during 1 and 5 months of implantation. Furthermore, the interfaces between new bone and the scaffold struts bonded directly without any gaps.

  18. The creation of the artificial RING finger from the cross-brace zinc finger by {alpha}-helical region substitution

    SciTech Connect

    Miyamoto, Kazuhide; Togiya, Kayo

    2010-04-16

    The creation of the artificial RING finger as ubiquitin-ligating enzyme (E3) has been demonstrated. In this study, by the {alpha}-helical region substitution between the EL5 RING finger and the Williams-Beuren syndrome transcription factor (WSTF) PHD finger, the artificial E3 (WSTF PHD{sub R}ING finger) was newly created. The experiments of the chemical modification of residues Cys and the circular dichroism spectra revealed that the WSTF PHD{sub R}ING finger binds two zinc atoms and adopts the zinc-dependent ordered-structure. In the substrate-independent ubiquitination assay, the WSTF PHD{sub R}ING finger functions as E3 and was poly- or mono-ubiquitinated. The present strategy is very simple and convenient, and consequently it might be widely applicable to the creation of various artificial E3 RING fingers with the specific ubiquitin-conjugating enzyme (E2)-binding capability.

  19. Tof-Sims Application for Evaluating the Atomic Structure of New Bone Substitute Material

    NASA Astrophysics Data System (ADS)

    Oteri, G.; Pisanom, M.; Cicciù, M.

    2016-05-01

    The aim of this experimental study is to evaluate, in vitro, the chemical composition and the micromorphological structure of a bone substitute material surface. This material is based on calcium triphosphate and hydroxyapatite microgranules. Some results of a preliminary surface study of the above mentioned bioceramic materials are reported. The study has been carried out by means of time-of-flight secondary ion mass spectrometry (TOF-SIMS), complemented by X-ray photoelectron spectrometry (XPS) measurements. Whereas XPS data supplies the average surface composition of the system, TOF-SIMS supplies laterally and depth resolved information on the sample. This preliminary study confirms the properties of osteoconduction and scaffold features of the material. Moreover, a possible osteoinductive capability could be due to the presence of surface micropores, which could help in the attraction of bone morphogenetic protein (BMP), thus promoting the osteogenesis.

  20. Biocompatibility of artificial bone based on vancomycin loaded mesoporous silica nanoparticles and calcium sulfate composites.

    PubMed

    Gu, Jisheng; Wang, Teng; Fan, Guoxin; Ma, Junhua; Hu, Wei; Cai, Xiaobing

    2016-04-01

    The aim of this study was to evaluate the in vitro and in vivo biocompatibility of artificial bone based on vancomycin loaded mesoporous silica nanoparticles and calcium sulfate composites. In vitro cytotoxicity tests by cholecystokinin octapeptide (CCK-8) assay showed that the 5 %Van-MSN-CaSO4 and Van-CaSO4 bone cements were cytocompatible for mouse osteoblastic cell line MC3T3-E1. The microscopic observation confirmed that MC3T3-E1cells incubated with Van-CaSO4 group and 5 %Van-MSN-CaSO4 group exhibited clear spindle-shaped changes, volume increase and maturation, showing that these cements supported adhesion of osteoblastic cells on their surfaces. In addition, the measurement of alkaline phosphatase activity revealed the osteoconductive property of these biomaterials. In order to assess in vivo biocompatibility, synthesized cements were implanted into the distal femur of twelve adult male and female New Zealand rabbits. After implantation in artificial defects of the distal femur, 5 %Van-MSN-CaSO4 and Van-CaSO4 bone cements did not damage the function of main organs of rabbits. In addition, the Van-MSN-CaSO4 composite allowed complete repair of bone defects with new bone formation 3 months after implantation. These results show potential application of Van-MSN-CaSO4 composites as bone graft materials for the treatment of open fracture in human due to its mechanical, osteoconductive and potential sustained drug release characteristics and the absence of adverse effects on the body. PMID:26883948

  1. Vacuum-sintered body of a novel apatite for artificial bone

    NASA Astrophysics Data System (ADS)

    Tamura, Kenichi; Fujita, Tatsushi; Morisaki, Yuriko

    2013-12-01

    We produced regenerative artificial bone material and bone parts using vacuum-sintered bodies of a novel apatite called "Titanium medical apatite (TMA®)" for biomedical applications. TMA was formed by chemically connecting a Ti oxide molecule with the reactive [Ca10(PO4)6] group of Hydroxyapatite (HAp). The TMA powders were kneaded with distilled water, and solid cylinders of compacted TMA were made by compression molding at 10 MPa using a stainless-steel vessel. The TMA compacts were dried and then sintered in vacuum (about 10-3 Pa) or in air using a resistance heating furnace in the temperature range 1073-1773 K. TMA compacts were sintered at temperatures greater than 1073 K, thus resulting in recrystallization. The TMA compact bodies sintered in the range 1273-1773 K were converted into mixtures composed of three crystalline materials: α-TCP (tricalcium phosphate), β-TCP, and Perovskite-CaTiO3. The Perovskite crystals were stable and hard. In vacuum-sintering, the Perovskite crystals were transformed into fibers (approximately 1 µm in diameter × 8 µm in length), and the fiber distribution was uniform in various directions. We refer to the TMA vacuum-sintered bodies as a "reinforced composite material with Perovskite crystal fibers." However, in atmospheric sintering, the Perovskite crystals were of various sizes and were irregularly distributed as a result of the effect of oxygen. After sintering temperature at 1573 K, the following results were obtained: the obtained TMA vacuum-sintered bodies (1) were white, (2) had a density of approximately 2300 kg/m3 (corresponding to that of a compact bone or a tooth), and had a thermal conductivity of approximately 31.3 W/(m·K) (corresponding to those of metal or ceramic implants). Further, it was possible to cut the TMA bodies into various forms with a cutting machine. An implant made of TMA and inserted into a rabbit jaw bone was covered by new bone tissues after just one month because of the high

  2. High-solid-content hydroxyapatite slurry for the production of bone substitute scaffolds.

    PubMed

    Cunningham, E; Dunne, N; Walker, G; Buchanan, F

    2009-08-01

    Key to various bone substitute scaffold production techniques is the development of free-flowing ceramic slurry with optimum theological properties. The aim is to achieve a colloidal suspension with as high a solid content as possible while maintaining a low viscosity which easily penetrates the pores of relevant sacrificial templates. The following investigation describes the optimization of a hydroxyapatite slip and demonstrates its potential application in scaffold production. Using predominantly spherical particles of hydroxyapatite of between 0.82 microm and 16.2 microm, coupled with a 2 wt % addition of the anionic polyelectrolyte, ammonium polyacrylate, an 80 wt % (55.9 vol%) hydroxyapatite solid loaded slip with a viscosity of approximately 126mPas has been developed. Its ability to infiltrate and replicate porous preforms has been shown using polyurethane foam. The enhanced particle packing achieved has allowed for the production of scaffolds with highly dense and uniform grain structures. The results represent a significant improvement in current slurry production techniques and can be utilized to develop high-density ceramic bone substitute scaffolds. PMID:19743638

  3. Fabrication of gelatin-strontium substituted calcium phosphate scaffolds with unidirectional pores for bone tissue engineering.

    PubMed

    Wu, Yu-Chun; Lin, Wei-Yu; Yang, Chyun-Yu; Lee, Tzer-Min

    2015-03-01

    This study fabricated homogeneous gelatin-strontium substituted calcium phosphate composites via coprecipitation in a gelatin solution. Unidirectional porous scaffolds with an oriented microtubular structure were then manufactured using freeze-drying technology. The resulting structure and pore alignment were determined using scanning electron microscopy. The pore size were in the range of 200-400 μm, which is considered ideal for the engineering of bone tissue. The scaffolds were further characterized using energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. Hydroxyapatite was the main calcium phosphate compound in the scaffolds, with strontium incorporated into the crystal structure. The porosity of the scaffolds decreased with increasing concentration of calcium-phosphate. The compressive strength in the longitudinal direction was two to threefold higher than that observed in the transverse direction. Our results demonstrate that the composite scaffolds degraded by approximately 20 % after 5 weeks. Additionally, in vitro results reveal that the addition of strontium significantly increased human osteoblastic cells proliferation. Scaffolds containing strontium with a Sr-CaP/(gelatin + Sr-CaP) ratio of 50 % provided the most suitable environment for cell proliferation, particularly under dynamic culture conditions. This study demonstrates the considerable potential of composite scaffolds composed of gelatin-strontium-substituted calcium phosphate for applications in bone tissue engineering. PMID:25773230

  4. Bioactive glass incorporation in calcium phosphate cement-based injectable bone substitute for improved in vitro biocompatibility and in vivo bone regeneration.

    PubMed

    Sadiasa, Alexander; Sarkar, Swapan Kumar; Franco, Rose Ann; Min, Young Ki; Lee, Byong Taek

    2014-01-01

    In this work, we fabricated injectable bone substitutes modified with the addition of bioactive glass powders synthesized via ultrasonic energy-assisted hydrothermal method to the calcium phosphate-based bone cement to improve its biocompatibility. The injectable bone substitutes was initially composed of a powder component (tetracalcium phosphate, dicalcium phosphate dihydrate and calcium sulfate dehydrate) and a liquid component (citric acid, chitosan and hydroxyl-propyl-methyl-cellulose) upon which various concentrations of bioactive glass were added: 0%, 10%, 20% and 30%. Setting time and compressive strength of the injectable bone substitutes were evaluated and observed to improve with the increase of bioactive glass content. Surface morphologies were observed via scanning electron microscope before and after submersion of the samples to simulated body fluid and increase in apatite formation was detected using x-ray diffraction machine. In vitro biocompatibility of the injectable bone substitutes was observed to improve with the addition of bioactive glass as the proliferation/adhesion behavior of cells on the material increased. Human gene markers were successfully expressed using real time-polymerase chain reaction and the samples were found to promote cell viability and be more biocompatible as the concentration of bioactive glass increases. In vivo biocompatibility of the samples containing 0% and 30% bioactive glass were evaluated using Micro-CT and histological staining after 3 months of implantation in male rabbits' femurs. No inflammatory reaction was observed and significant bone formation was promoted by the addition of bioactive glass to the injectable bone substitute system. PMID:23470354

  5. Evaluation of a new biochemical index for the estimation of bone demineralization using artificial intelligence.

    PubMed

    Barnhill, S D; Zhang, Z; Madyastha, K R

    1995-04-01

    The use of artificial neural networks (ANN) for the identification of a positive correlation between the QuiOs quotient, a single-valued indicator of bone mineral density, and multisite dual energy x-ray absorptiometry (DEXA) measurements is described. The measurements were obtained using the Hologic QDRR-2000 x-ray bone densitometer in a multicenter clinical trial including 374 female patients. The QuiOs quotient estimates bone mineral density and determines the severity of bone density loss. This quotient is calculated by using a proprietary software program to perform a multivariate analysis of the results of testing of serum levels of calcium, phosphate, total alkaline phosphate, two alkaline phosphatase isoenzymes (liver and intestine), estradiol, and progesterone. The results show that given the four DEXA measurements obtained from the bone densitometer, the trained neural network can predict whether the corresponding QuiOs score of the same patient will be below the cutoff score of 0.690. The findings in this study indicate a positive correlation between DEXA measurements and the QuiOs quotient obtained from two different sources. PMID:10150355

  6. Enhanced bioactivity of a poly(propylene fumarate) bone graft substitute by augmentation with nano-hydroxyapatite.

    PubMed

    Lewandrowski, Kai-Uwe; Bondre, Shrikar P; Wise, Donald L; Trantolo, Debra J

    2003-01-01

    The bioactivity of a nano-hydroxyapatite-augmented, bioresorbable bone graft substitute made from the unsaturated polyester, poly(propylene fumarate), was analyzed by evaluating biocompatibility and osteointegration of implants placed into a rat tibial defect. Three groups of eight animals each were evaluated by grouting bone graft substitutes into 3-mm holes that were made into the anteromedial tibial metaphysis of rats. Thus, a total of 24 animals was included in this study. Two different formulations varying as to the type of hydroxyapatite were used: Group 1 - nano-hydroxyapatite, Group 2 - micron-hydroxyapatite, with a Group 3 control defect remaining unfilled. Animals of each of the three groups were sacrificed in groups of eight at postoperative week three. Histologic analysis revealed best superior biocompatibility and osteointegration of bone graft substitutes when nanohydroxyapatite was employed. At three weeks, there was more reactive new bone formation in this group when compared to the micron-hydroxyapatite group. The control group showed incomplete closure of the defect. This study suggested that nano-hydroxyapatite may improve upon the bioactivity of bone implant and repair materials. The model scaffold used in this study, poly(propylene fumarate), appeared to provide an osteoconductive pathway by which bone will grow in faster. Clinical implications of the use potential advantages of nano-hydroxyapatite on bone repair and orthopaedic implant design are discussed. PMID:12775902

  7. Small-sized granules of biphasic bone substitutes support fast implant bed vascularization

    PubMed Central

    Barbeck, M; Dard, M; Kokkinopoulou, M; Markl, J; Booms, P; Sader, RA; Kirkpatrick, CJ; Ghanaati, S

    2015-01-01

    The present study investigated the influence of granule size of 2 biphasic bone substitutes (BoneCeramic® 400–700 μm and 500–1000 μm) on the induction of multinucleated giant cells (MNGCs) and implant bed vascularization in a subcutaneous implantation model in rats. Furthermore, degradation mechanisms and particle phagocytosis of both materials were examined by transmission electron microscopy (TEM). Both granule types induced tissue reactions involving primarily mononuclear cells and only small numbers of MNGCs. Higher numbers of MNGCs were detected in the group with small granules starting on day 30, while higher vascularization was observed only at day 10 in this group. TEM analysis revealed that both mono- and multinucleated cells were involved in the phagocytosis of the materials. Additionally, the results allowed recognition of the MNGCs as the foreign body giant cell phenotype. Histomorphometrical analysis of the size of phagocytosed particles showed no differences between the 2 granule types. The results indicate that granule size seems to have impact on early implant bed vascularization and also on the induction of MNGCs in the late phase of the tissue reaction. Furthermore, the results revealed that a synthetic bone substitute material can induce tissue reactions similar to those of some xenogeneic materials, thus pointing to a need to elucidate their “ideal” physical characteristics. The results also show that granule size in the range studied did not alter phagocytosis by mononuclear cells. Finally, the investigation substantiates the differentiation of material-induced MNGCs, which are of the foreign body giant cell type. PMID:26083163

  8. Effects of artificial gravity during bed rest on bone metabolism in humans

    PubMed Central

    Smith, S. M.; Zwart, S. R.; Heer, M. A.; Baecker, N.; Evans, H. J.; Feiveson, A. H.; Shackelford, L. C.; LeBlanc, A. D.

    2009-01-01

    We report results from a study designed to explore the utility of artificial gravity (AG) as a countermeasure to bone loss induced by microgravity simulation. After baseline testing, 15 male subjects underwent 21 days of 6° head-down bed rest to simulate the deconditioning associated with spaceflight. Eight of the subjects underwent 1 h of centrifugation (AG; 1 Gz at the heart, 2.5 Gz at the feet) each day for 21 days, whereas seven of the subjects served as untreated controls (Con). Blood and urine were collected before, during, and after bed rest for bone marker determinations. Bone mineral density (BMD) and bone mineral content (BMC) were determined by dual-energy X-ray absorptiometry and peripheral quantitative computerized tomography before and after bed rest. Urinary excretion of bone resorption markers increased during bed rest, but the AG and Con groups did not differ significantly. The same was true for serum C-telopeptide. During bed rest, bone alkaline phosphatase (ALP) and total ALP tended to be lower in the AG group (P = 0.08, P = 0.09). Neither BMC nor BMD changed significantly from the pre-bed rest period in AG or Con groups, and the two groups were not significantly different. However, when AG and Con data were combined, there was a significant (P < 0.05) effect of time for whole body total BMC and total hip and trochanter BMD. These data failed to demonstrate efficacy of this AG prescription to prevent the changes in bone metabolism observed during 3 wk of bed rest. PMID:19074572

  9. Effects of zinc-substituted nano-hydroxyapatite coatings on bone integration with implant surfaces*

    PubMed Central

    Zhao, Shi-fang; Dong, Wen-jing; Jiang, Qiao-hong; He, Fu-ming; Wang, Xiao-xiang; Yang, Guo-li

    2013-01-01

    Objective: The purpose of this study was to investigate the effects of a zinc-substituted nano-hydroxyapatite (Zn-HA) coating, applied by an electrochemical process, on implant osseointegraton in a rabbit model. Methods: A Zn-HA coating or an HA coating was deposited using an electrochemical process. Surface morphology was examined using field-emission scanning electron microscopy. The crystal structure and chemical composition of the coatings were examined using an X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). A total of 78 implants were inserted into femurs and tibias of rabbits. After two, four, and eight weeks, femurs and tibias were retrieved and prepared for histomorphometric evaluation and removal torque (RTQ) tests. Results: Rod-like HA crystals appeared on both implant surfaces. The dimensions of the Zn-HA crystals seemed to be smaller than those of HA. XRD patterns showed that the peaks of both coatings matched well with standard HA patterns. FTIR spectra showed that both coatings consisted of HA crystals. The Zn-HA coating significantly improved the bone area within all threads after four and eight weeks (P<0.05), the bone to implant contact (BIC) at four weeks (P<0.05), and RTQ values after four and eight weeks (P<0.05). Conclusions: The study showed that an electrochemically deposited Zn-HA coating has potential for improving bone integration with an implant surface. PMID:23733429

  10. In Vitro Elution Characteristics of Gentamicin and Vancomycin from Synthetic Bone Graft Substitutes

    PubMed Central

    Maier, Gerrit Steffen; Roth, Klaus Edgar; Andereya, Stefan; Birnbaum, Klaus; Niedhart, Christopher; Lühmann, Markus; Ohnsorge, Jörg; Maus, Uwe

    2013-01-01

    Objects: Beta tricalciumphosphate pellets loaded with individualized antibiotics may represent novel options in the treatment of osteomyelitis and infectious bone disease. Here, the in vitro antibiotic elution of vancomycin and gentamicin from the synthetic bone graft substitutes Cerasorb® and Cerasorb M® was tested. Methods: Antibiotic elution and concentration of gentamcin and vancomycin were measured using photometrically-based measurement and homogeneous particle-enhanced turbidimetric inhibition immunoassays (PETINIA). Results: Initially both materials showed a high release of the loaded antibiotics, with Cerasorb M® showing lower release levels for gentamicin and vancomycin than Cerasorb®. Gentamicin concentrations of Cerasorb M granules and Cerasorb were below the minimum detectiontreshold until day four and six of the experiment respectively. The vancomycin release-level followed a similar pattern, although the vancomycin concentration eluted by Cerasorb M® granules stayed above the detection threshold during the experimental time. Conclusions: Cerasorb® and Cersorb M® may represent a new treatment option in osteomyelitis and infectious bone disease. PMID:24285988

  11. Design and optimization of a tissue-engineered bone graft substitute

    NASA Astrophysics Data System (ADS)

    Shimko, Daniel Andrew

    2004-12-01

    formulation, and scaffold material from all preceding studies were combined and a tissue-engineered bone graft was fabricated. The graft was exposed to long-term in vitro culture, and then mechanically evaluated to determine its clinical potential. The studies contained herein constitute the first steps in the conception and development of a viable tissue-engineered bone graft substitute and establish a solid scientific foundation for future in vivo experimentation utilizing this design.

  12. Design, synthesis, and initial evaluation of D-glyceraldehyde crosslinked gelatin-hydroxyapatite as a potential bone graft substitute material

    NASA Astrophysics Data System (ADS)

    Florschutz, Anthony Vatroslav

    Utilization of bone grafts for the treatment of skeletal pathology is a common practice in orthopaedic, craniomaxillofacial, dental, and plastic surgery. Autogenous bone graft is the established archetype but has disadvantages including donor site morbidity, limited supply, and prolonging operative time. In order to avoid these and other issues, bone graft substitute materials are becoming increasingly prevalent among surgeons for reconstructing skeletal defects and arthrodesis applications. Bone graft substitutes are biomaterials, biologics, and guided tissue/bone regenerative devices that can be used alone or in combinations as supplements or alternatives to autogenous bone graft. There is a growing interest and trend to specialize graft substitutes for specific indications and although there is good rationale for this indication-specific approach, the development and utility of a more universal bone graft substitute may provide a better answer for patients and surgeons. The aim of the present research focuses on the design, synthesis, and initial evaluation of D-glyceraldehyde crosslinked gelatin-hydroxyapatite composites for potential use as a bone graft substitutes. After initial establishment of rational material design, gelatinhydroxyapatite scaffolds were fabricated with different gelatin:hydroxyapatite ratios and crosslinking concentrations. The synthesized scaffolds were subsequently evaluated on the basis of their swelling behavior, porosity, density, percent composition, mechanical properties, and morphology and further assessed with respect to cell-biomaterial interaction and biomineralization in vitro. Although none of the materials achieved mechanical properties suitable for structural graft applications, a reproducible material design and synthesis was achieved with properties recognized to facilitate bone formation. Select scaffold formulations as well as a subset of scaffolds loaded with recombinant human bone morphogenetic protein-2 were

  13. Healing patterns of critical size bony defects in rats after grafting with bone substitutes soaked in recombinant human bone morphogenetic protein-2: histological and histometric evaluation.

    PubMed

    Mokbel, N; Naaman, N; Nohra, J; Badawi, N

    2013-09-01

    The aim of the study was to evaluate the effect of different bone substitutes soaked in recombinant human bone morphogenetic protein-2 (rhBMP-2) on the healing of critical size defects in calvarial bone. Defects were created in 24 Sprague Dawley rats. The rhBMP-2 was diluted to obtain a final concentration of 0.2mg/ml. Rats were divided into four groups and treated as follows: in the first group the defect was filled with anorganic bovine bone mineral (ABBM) and rhBMP-2, the second group was treated with freeze-dried bone allograft (FDBA) and rhBMP-2, and the third group was treated with autogenous bone (AUTO). In the control group the defects were left untreated. Animals were killed after 8weeks and calcified histological sections prepared. Histometric measurements showed that mean (SD) bone formation was 4.00 (1.69)mm(2) in the ABBM group, 2.56 (1.06)mm(2) in the FDBA group, and 2.30 (0.34)mm(2) in the AUTO group. The difference between the ABBM group and the other 3 groups was significant (p<0.0001) with a mean bone formation of 0.82 (0.25)mm(2) in the control group. There was no significant difference between the FDBA and the AUTO groups (p=0.96). Within the limits of this study we concluded that the addition of rhBMP-2 to bone substitutes was efficacious in regenerating bone in critical size bone defects in calveria in rats. PMID:22939894

  14. Development of porous polyurethane/strontium-substituted hydroxyapatite composites for bone regeneration.

    PubMed

    Sariibrahimoglu, Kemal; Yang, Wanxun; Leeuwenburgh, Sander C G; Yang, Fang; Wolke, Joop G C; Zuo, Yi; Li, Yubao; Jansen, John A

    2015-06-01

    Polyurethane (PU) has been widely used for the biomedical applications but its potential for bone regeneration is limited due to its lack of osteoconductive properties. Strontium substituted hydroxyapatite (SrHA) particles, on the other hand, are known to exhibit a positive effect on bone formation. Therefore, the aim of this study was to (i) develop porous polyurethane scaffolds containing strontium SrHA nanoparticles (PU/SrHA) and (ii) compare their in vitro biological performance for applications in bone regeneration to PU scaffolds. SrHA and HA was synthesized using a conventional wet-chemical neutralization reaction at temperatures of 25, 50, and 80°C. Chemical analysis was performed by inductively coupled plasma-optical emission spectrometry. Synthesizing temperatures at 25 and at 50°C were selected for the composite preparation (abbreviated as HA-25, SrHA-25, HA-50, and SrHA-50, respectively). PU was synthesized from isophorone diisocyanate, polytetramethylene ether glycol, and 1,4-butanediol. Composite scaffolds were prepared by addition of HA or SrHA nanoparticles into PU scaffolds during polymer preparation. The results showed that the Sr content in HA nanoparticles increased with increasing synthesis temperature. The addition of nanoparticles decreased the elongation-at-break and tensile strength, but significantly increased the surface wettability of the PU scaffolds. In vitro degradation tests demonstrated that release of cations was significantly higher from PU/SrHA-50 composite scaffolds. Cell culture tests indicated that PU composites containing either HA or SrHA nanoparticles increased proliferation of bone marrow stem cells as compared to plain PU scaffolds, whereas osteogenic differentiation was not affected by the incorporation of HA nanoparticles irrespective of the incorporation of Sr. PMID:25203691

  15. Tailoring the degradation and biological response of a magnesium-strontium alloy for potential bone substitute application.

    PubMed

    Han, Junjie; Wan, Peng; Ge, Ye; Fan, Xinmin; Tan, Lili; Li, Jianjun; Yang, Ke

    2016-01-01

    Bone defects are very challenging in orthopedic practice. There are many practical and clinical shortcomings in the repair of the defect by using autografts, allografts or xenografts, which continue to motivate the search for better alternatives. The ideal bone grafts should provide mechanical support, fill osseous voids and enhance the bone healing. Biodegradable magnesium-strontium (Mg-Sr) alloys demonstrate good biocompatibility and osteoconductive properties, which are promising biomaterials for bone substitutes. The aim of this study was to evaluate and pair the degradation of Mg-Sr alloys for grafting with their clinical demands. The microstructure and performance of Mg-Sr alloys, in vitro degradation and biological properties including in vitro cytocompatibility and in vivo implantation were investigated. The results showed that the as-cast Mg-Sr alloy exhibited a rapid degradation rate compared with the as-extruded alloy due to the intergranular distribution of the second phase and micro-galvanic corrosion. However, the initial degradation could be tailored by the coating protection, which was proved to be cytocompatible and also suitable for bone repair observed by in vivo implantation. The integrated fracture calluses were formed and bridged the fracture gap without gas bubble accumulation, meanwhile the substitutes simultaneously degraded. In conclusion, the as-cast Mg-Sr alloy with coating is potential to be used for bone substitute alternative. PMID:26478374

  16. A biomechanical study on fixation stability with twin hook or lag screw in artificial cancellous bone.

    PubMed

    Olsson, O; Tanner, K E; Ceder, L; Ryd, L

    2002-01-01

    The twin hook has been developed as an alternative to the conventional lag screw to be combined with a barrelled side-plate in the treatment of trochanteric hip fractures. With two oppositely directed apical hooks introduced into the subchondral bone of the femoral head, the twin hook provides different stabilising properties to the lag screw. The femoral head purchase of the twin hook and the lag screw were compared in a biomechanical study using artificial cancellous bone, and responses to axial and torsional loading was determined. A distinct yield point in load and torque was noted for the lag screw, representing failure of the laminas supporting the threads. For the twin hook, gradual increase of load and torque occurred during impaction of the bone supporting the hooks. The peak loads and torques were higher for the lag screw, but were similar for both devices after 8 mm deformation. The stiffness was higher for the lag screw, but in counter-clockwise rotation the stiffness for the lag screw was negligible. The twin hook appeared to provide fixation stability comparable to that offered by the lag screw, but with conceivable advantages in terms of a deformation response involving bone impaction and gradually increasing stability. PMID:12466867

  17. The effect of a biphasic injectable bone substitute on the interface strength in a rabbit knee prosthesis model

    PubMed Central

    2013-01-01

    Background In joint prosthetic surgery, various methods are used to provide implant stability. We used an injectable bone substitute, composed of calcium sulfate/hydroxyapatite, as bone defect filler to stabilize a tibia prosthesis in an experimental rabbit model. The aim of the study was to investigate and compare the stability of prosthetic fixation with and without the use of an injectable bone substitute. Methods Sixteen rabbits were used and the tibia prostheses were implanted bilaterally, one side with the prosthesis alone and the other side with the prosthesis and calcium sulfate/hydroxyapatite (Cerament™). The rabbits were randomly divided into two groups and euthanized after 6 and 12 weeks, respectively. The prosthesis was extracted measuring the pull-out force in an Instron tester, and the bone surrounding the former prosthesis site was analyzed by histology, histomorphometry, and micro-computed tomography. Results At 6 weeks no difference in maximum pull-out force was found between the prostheses fixed with or without Cerament™. At 12 weeks the maximum pull-out force for the prostheses with Cerament™ was significantly higher than that for the prostheses without Cerament™ (p = 0.04). The maximum pull-out force at 12 weeks was significantly higher than that at 6 weeks for the prostheses fixed with Cerament™ (p = 0.03) but not for the prostheses without. Conclusion We conclude that early prosthesis-bone interface strength is not influenced by a bone substitute. However, during remodeling, the bone substitute might provide improved mechanical support for the prosthesis. The results support further studies of the use of injectable calcium sulfate/hydroxyapatite in fixation of prosthetic joint implants. PMID:23899023

  18. In vitro cytotoxicity of a novel injectable and biodegradable alveolar bone substitute.

    PubMed

    Zhang, Zhixing; Feng, Xiangli; Mao, Jing; Xiao, Jianzhong; Liu, Chenmei; Qiu, Jinjun

    2009-02-01

    The unsaturated polyphosphoester (UPPE) polymer is being investigated as an injectable and biodegradable system for alveolar bone repair in the treatment of periodontal diseases. The incorporation of beta-tricalcium phosphate (beta-TCP) particles into the UPPE polymer was previously shown to significantly increase the material's mechanical properties. Moreover, in vitro experiments demonstrated that the UPPE/beta-TCP composite was capable of zero-order release of tetracycline for over 2 weeks. In this study, we investigated the in vitro cytotoxicity of each individual component, the resulting cross-linked network and the degradation products of the UPPE/beta-TCP composite using an AlamarBlue viability assay. We confirmed that each individual component except beta-TCP and the in vitro degradation products of the composite displayed a dose-dependent cytotoxic response. Once cross-linked, however, the composite did not demonstrate an adverse response. Our results suggest that the UPPE/beta-TCP composite holds great promise for use as an injectable and biodegradable alveolar bone substitute. PMID:19116137

  19. Preparation and characterization of calcium phosphate ceramics and composites as bone substitutes

    NASA Astrophysics Data System (ADS)

    Zhang, Xing

    Marine CaCO3 skeletons have tailored architectures created by nature, which give them structural support and other functions. For example, seashells have dense lamellar structures, while coral, cuttlebone and sea urchin spines have interconnected porous structures. In our experiments, seashells, coral and cuttlebone were hydrothermally converted to hydroxyapatite (HAP), and sea urchin spines were converted to Mg-substituted tricalcium phosphate (beta-TCMP), while maintaining their original structures. Partially converted shell samples have mechanical strength, which is close to that of compact human bone. After implantation of converted shell and spine samples in rat femoral defects for 6 weeks, there was newly formed bone growth up to and around the implants. Some new bone was found to migrate through the pores of converted spine samples and grow inward. These results show good bioactivity and osteoconductivity of the implants, indicating the converted shell and spine samples can be used as bone defect fillers. Calcium phosphate powders were prepared through different synthesis methods. Micro-size HAP rods were synthesized by hydrothermal method through a nucleation-growth mechanism. On the other hand, HAP particles, which have good crystallinity, were prepared by wet precipitation with further hydrothermal treatment. beta-TCP or beta-TCMP powders were prepared by a two-step process: wet precipitation of apatitic tricalcium phosphate ('precursor') and calcination of the precursor at 800°C for 3 hours. beta-TCMP or beta-TCP powders were also prepared by solid-state reactions from CaHPO4 and CaCO 3 with/without MgO. Biphasic calcium phosphate, which is mixture of HAP and beta-TCP, can be prepared though mechanical mixing of HAP and beta-TCP powders synthesized as above. Dense beta-TCP and beta-TCMP ceramics can be produced by pressing green bodies at 100MPa and further sintering above 1100°C for 2 hours. beta-TCMP ceramics ˜99.4% relative dense were prepared by

  20. Analysis of Impingement between Patella Bone and Bearing Post in Cruciate-Substituting High-Flexion Total Knee Arthroplasty

    PubMed Central

    Chon, Jegyun; Shin, Sangyeop; Jang, Gunil; Jeon, Taehyeon

    2016-01-01

    Background We investigated the causes of impingement between the patella bone and the bearing post during high flexion in cruciate-substituting total knee arthroplasty and proposed a treatment strategy. Methods This prospective cohort study included 218 cases that had undergone cruciate-substituting total knee arthroplasty from February 2014 to January 2015; a single surgeon performed the operation using the same method without patellar resurfacing in all patients. Results In these patients, the occurrence of impingement was determined by performing more than 120° high knee flexion after inserting a bearing perioperatively. The incidence of impingement was significantly associated with bearing design, femoral implant size, patella bone length, and patella inferior pole angle (p < 0.05). The impingement was resolved by resection of the lower articular side of the patella bone. Conclusions In the cruciate-substituting high-flexion total knee arthroplasty, impingement between the patella bone and bearing post was more common in patients with mobile bearing, small-size femoral component, and a long patella or a large inferior pole angle. In cases of intraoperative impingement between the patella bone and the bearing post, resection in the lower portion of the patella prevented impingement of the bearing with soft tissue or the patella by widening the space between the patella and the bearing post, which in turn prevented postoperative reduction in range of motion. PMID:27247740

  1. Fibrin gel-immobilized primary osteoblasts in calcium phosphate bone cement: in vivo evaluation with regard to application as injectable biological bone substitute.

    PubMed

    Kneser, U; Voogd, A; Ohnolz, J; Buettner, O; Stangenberg, L; Zhang, Y H; Stark, G B; Schaefer, D J

    2005-01-01

    Osteogenic injectable bone substitutes may be useful for many applications. We developed a novel injectable bone substitute based on osteoblast-fibrin glue suspension and calcium phosphate bone cement (BC). Human osteoblasts were isolated from trabecular bone samples and cultured under standard conditions. Osteoblasts were suspended in fibrinogen solution (FS). BC was cured with thrombin solution. 8 x 4 mm injectable bone discs were prepared using silicon molds and a custom-made applicator device. Discs containing BC, BC/FS, or BC/FS/osteoblasts were implanted subcutaneously into athymic nude mice. After 3, 9 and 24 weeks, specimens were explanted and subjected to morphologic and biomechanical evaluation. In vitro fibrin gel-embedded osteoblasts displayed a differentiated phenotype as evidenced by alkaline phosphatase, collagen type 1 and von Kossa stains. A proportion of osteoblasts appeared morphologically intact over a 3-day in vitro period following application into the BC. BC/FS and BC/FS/osteoblast discs were sparsely infiltrated with vascularized connective tissue. There was no bone formation in implants from all groups. However, positive von Kossa staining only in BC/FS/osteoblast groups suggests engraftment of at least some of the transplanted cells. Biomechanical evaluation demonstrated initial stability of the composites. Young's modulus and maximal load did not differ significantly in the BC/FS and BC/FS/osteoblast groups. The practicability of osteoblast-containing injectable bone could be demonstrated. The dense microstructure and the suboptimal initial vascularization of the composites may explain the lack of bone formation. Modifications with regard to enhanced osteoblast survival are mandatory for a possible application as injectable osteogenic bone replacement system. PMID:16046862

  2. Evaluation of an injectable bone substitute (betaTCP/hydroxyapatite/hydroxy-propyl-methyl-cellulose) in severely osteopenic and aged rats.

    PubMed

    Blouin, S; Moreau, M F; Weiss, P; Daculsi, G; Baslé, M F; Chappard, D

    2006-09-01

    The use of injectable biomaterials is of interest in osteoporotic patients to locally restore bone mass in sites at risk of fracture. An injectable bone substitute (IBS1 made of betaTCP/hydroxyapatite as a calcium phosphate substitute and hydroxy-propyl-methyl-cellulose as a polymer carrier) was used in a severely osteopenic rat model obtained by combining orchidectomy (ORX) and disuse (paralysis induced by botulinum toxin - BTX). Fifty-six aged male rats were randomized into three groups: 18 were SHAM operated; 38 were ORX and BTX injected in the right hindlimb; they constituted the OP (osteoporotic) group. One month after ORX-BTX surgery, 20 of these OP rats received a IBS1 injection in the right femur (OP-IBS1 rats). Animals were studied at the time of IBS1 injection 1 month post ORX-BTX (M1), 1 month (M2) and 2 months (M3) after IBS1 injection. Bone mass (BV/TV) and microarchitectural parameters were measured by microCT. BV/TV was decreased after ORX-BTX; ORX and BTX had cumulative effects on bone loss (differences maximized on the right femur). BV/TV (combining the volume of both bone and material in OP-IBS1 rats) was elevated at M1 but decreased at M2. Marked bone formation was found onto the biomaterial granules but bone had a woven texture. A marked increase in the number of nonosteoclastic TRAcP+ cells was found in the implanted area. IBS1 induced new bone formation shortly after implantation but both IBS1 and woven bone were resorbed without inducing lamellar bone. Biomaterial trials must be conducted with long-term implantation periods, in aged osteoporotic animals. PMID:16739169

  3. Minimally Invasive Alveolar Ridge Preservation Utilizing an In Situ Hardening β-Tricalcium Phosphate Bone Substitute: A Multicenter Case Series

    PubMed Central

    Leventis, Minas D.; Fairbairn, Peter; Kakar, Ashish; Leventis, Angelos D.; Margaritis, Vasileios; Lückerath, Walter; Horowitz, Robert A.; Rao, Bappanadu H.; Lindner, Annette; Nagursky, Heiner

    2016-01-01

    Ridge preservation measures, which include the filling of extraction sockets with bone substitutes, have been shown to reduce ridge resorption, while methods that do not require primary soft tissue closure minimize patient morbidity and decrease surgical time and cost. In a case series of 10 patients requiring single extraction, in situ hardening beta-tricalcium phosphate (β-TCP) granules coated with poly(lactic-co-glycolic acid) (PLGA) were utilized as a grafting material that does not necessitate primary wound closure. After 4 months, clinical observations revealed excellent soft tissue healing without loss of attached gingiva in all cases. At reentry for implant placement, bone core biopsies were obtained and primary implant stability was measured by final seating torque and resonance frequency analysis. Histological and histomorphometrical analysis revealed pronounced bone regeneration (24.4 ± 7.9% new bone) in parallel to the resorption of the grafting material (12.9 ± 7.7% graft material) while high levels of primary implant stability were recorded. Within the limits of this case series, the results suggest that β-TCP coated with polylactide can support new bone formation at postextraction sockets, while the properties of the material improve the handling and produce a stable and porous bone substitute scaffold in situ, facilitating the application of noninvasive surgical techniques. PMID:27190516

  4. Minimally Invasive Alveolar Ridge Preservation Utilizing an In Situ Hardening β-Tricalcium Phosphate Bone Substitute: A Multicenter Case Series.

    PubMed

    Leventis, Minas D; Fairbairn, Peter; Kakar, Ashish; Leventis, Angelos D; Margaritis, Vasileios; Lückerath, Walter; Horowitz, Robert A; Rao, Bappanadu H; Lindner, Annette; Nagursky, Heiner

    2016-01-01

    Ridge preservation measures, which include the filling of extraction sockets with bone substitutes, have been shown to reduce ridge resorption, while methods that do not require primary soft tissue closure minimize patient morbidity and decrease surgical time and cost. In a case series of 10 patients requiring single extraction, in situ hardening beta-tricalcium phosphate (β-TCP) granules coated with poly(lactic-co-glycolic acid) (PLGA) were utilized as a grafting material that does not necessitate primary wound closure. After 4 months, clinical observations revealed excellent soft tissue healing without loss of attached gingiva in all cases. At reentry for implant placement, bone core biopsies were obtained and primary implant stability was measured by final seating torque and resonance frequency analysis. Histological and histomorphometrical analysis revealed pronounced bone regeneration (24.4 ± 7.9% new bone) in parallel to the resorption of the grafting material (12.9 ± 7.7% graft material) while high levels of primary implant stability were recorded. Within the limits of this case series, the results suggest that β-TCP coated with polylactide can support new bone formation at postextraction sockets, while the properties of the material improve the handling and produce a stable and porous bone substitute scaffold in situ, facilitating the application of noninvasive surgical techniques. PMID:27190516

  5. Artificial Bone and Teeth through Controlled Ice Growth in Colloidal Suspensions

    SciTech Connect

    Tomsia, Antoni P.; Saiz, Eduardo; Deville, Sylvain

    2007-06-14

    The formation of regular patterns is a common feature of many solidification processes involving cast materials. We describe here how regular patterns can be obtained in porous alumina and hydroxyapatite (HAP) by controlling the freezing of ceramic slurries followed by subsequent ice sublimation and sintering, leading to multilayered porous ceramic structures with homogeneous and well-defined architecture. These porous materials can be infiltrated with a second phase of choice to yield biomimetic nacre-like composites with improved mechanical properties, which could be used for artificial bone and teeth applications. Proper control of the solidification patterns provides powerful means of control over the final functional properties. We discuss the relationships between the experimental results, ice growth fundamentals, the physics of ice and the interaction between inert particles and the solidification front during directional freezing.

  6. Artificial Bone and Teeth through Controlled Ice Growth in Colloidal Suspensions

    NASA Astrophysics Data System (ADS)

    Tomsia, Antoni P.; Saiz, Eduardo; Deville, Sylvain

    2007-06-01

    The formation of regular patterns is a common feature of many solidification processes involving cast materials. We describe here how regular patterns can be obtained in porous alumina and hydroxyapatite (HAP) by controlling the freezing of ceramic slurries followed by subsequent ice sublimation and sintering, leading to multilayered porous ceramic structures with homogeneous and well-defined architecture. These porous materials can be infiltrated with a second phase of choice to yield biomimetic nacre-like composites with improved mechanical properties, which could be used for artificial bone and teeth applications. Proper control of the solidification patterns provides powerful means of control over the final functional properties. We discuss the relationships between the experimental results, ice growth fundamentals, the physics of ice and the interaction between inert particles and the solidification front during directional freezing.

  7. Synthesis and biological screening by novel hybrid fluorocarbon hydrocarbon compounds for use as artificial blood substitutes

    NASA Technical Reports Server (NTRS)

    Moacanin, J.; Scherer, K.; Toronto, A.; Lawson, D.; Terranova, T.; Yavrouian, A.; Astle, L.; Harvey, S.; Kaaelble, D. H.

    1979-01-01

    A series of hybrid fluorochemicals of general structure R(1)R(2)R(3)CR(4) was prepared where the R(i)'s (i=1,2,3) is a saturated fluoroalkyl group of formula C sub N F sub 2n+1, and R(4) is an alkyl group C sub n H sub 2n+1 or a related moiety containing amino, ether, or ester functions but no CF bonds. Compounds of this class containing approximately eight to twenty carbons total have physical properties suitable for use as the oxygen carrying phase of fluorochemical emulsion artificial blood. The chemical synthesis, and physical and biological testing of pure single isomers of the proposed artificial blood candidate compounds are included. Significant results are given.

  8. Novel approach to the fabrication of an artificial small bone using a combination of sponge replica and electrospinning methods

    NASA Astrophysics Data System (ADS)

    Kim, Yang-Hee; Lee, Byong-Taek

    2011-06-01

    In this study, a novel artificial small bone consisting of ZrO2-biphasic calcium phosphate/polymethylmethacrylate-polycaprolactone-hydroxyapatite (ZrO2-BCP/PMMA-PCL-HAp) was fabricated using a combination of sponge replica and electrospinning methods. To mimic the cancellous bone, the ZrO2/BCP scaffold was composed of three layers, ZrO2, ZrO2/BCP and BCP, fabricated by the sponge replica method. The PMMA-PCL fibers loaded with HAp powder were wrapped around the ZrO2/BCP scaffold using the electrospinning process. To imitate the Haversian canal region of the bone, HAp-loaded PMMA-PCL fibers were wrapped around a steel wire of 0.3 mm diameter. As a result, the bundles of fiber wrapped around the wires imitated the osteon structure of the cortical bone. Finally, the ZrO2/BCP scaffold was surrounded by HAp-loaded PMMA-PCL composite bundles. After removal of the steel wires, the ZrO2/BCP scaffold and bundles of HAp-loaded PMMA-PCL formed an interconnected structure resembling the human bone. Its diameter, compressive strength and porosity were approximately 12 mm, 5 MPa and 70%, respectively, and the viability of MG-63 osteoblast-like cells was determined to be over 90% by the MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. This artificial bone shows excellent cytocompatibility and is a promising bone regeneration material.

  9. Engineering interaction between bone marrow derived endothelial cells and electrospun surfaces for artificial vascular graft applications.

    PubMed

    Ahmed, Furqan; Dutta, Naba K; Zannettino, Andrew; Vandyke, Kate; Choudhury, Namita Roy

    2014-04-14

    The aim of this investigation was to understand and engineer the interactions between endothelial cells and the electrospun (ES) polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) nanofiber surfaces and evaluate their potential for endothelialization. Elastomeric PVDF-HFP samples were electrospun to evaluate their potential use as small diameter artificial vascular graft scaffold (SDAVG) and compared with solvent cast (SC) PVDF-HFP films. We examined the consequences of fibrinogen adsorption onto the ES and SC samples for endothelialisation. Bone marrow derived endothelial cells (BMEC) of human origin were incubated with the test and control samples and their attachment, proliferation, and viability were examined. The nature of interaction of fibrinogen with SC and ES samples was investigated in detail using ELISA, XPS, and FTIR techniques. The pristine SC and ES PVDF-HFP samples displayed hydrophobic and ultrahydrophobic behavior and accordingly, exhibited minimal BMEC growth. Fibrinogen adsorbed SC samples did not significantly enhance endothelial cell binding or proliferation. In contrast, the fibrinogen adsorbed electrospun surfaces showed a clear ability to modulate endothelial cell behavior. This system also represents an ideal model system that enables us to understand the natural interaction between cells and their extracellular environment. The research reported shows potential of ES surfaces for artificial vascular graft applications. PMID:24564790

  10. Ability of bone graft substitutes to support the osteoprogenitor cells: An in-vitro study

    PubMed Central

    Dahabreh, Ziad; Panteli, Michalis; Pountos, Ippokratis; Howard, Mark; Campbell, Peter; Giannoudis, Peter V

    2014-01-01

    AIM: To compare seven commercially available bone graft substitutes (BGS) in terms of these properties and without using any additional biological growth factors. METHODS: Porcine osteoprogenitor cells were loaded on seven commercially available BGS and allowed to proliferate for one week followed by osteogenic induction. Staining for live/dead cells as well as scanning electron microscopy (SEM) was carried out to determine viability and cellular binding. Further outcome measures included alkaline phosphatase (ALP) assays with normalisation for DNA content to quantify osteogenic potential. Negative and positive control experiments were carried out in parallel to validate the results. RESULTS: Live/dead and SEM imaging showed higher viability and attachment with β-tricalcium phosphate (β-TCP) than with other BGS (P < 0.05). The average ALP activity in nmol/mL (normalised value for DNA content in nmol/μg DNA) per sample was 657.58 (132.03) for β-TCP, 36.22 (unable to normalise) for calcium sulphate, 19.93 (11.39) for the Hydroxyapatite/Tricalcium Phosphate composite, 14.79 (18.53) for polygraft, 13.98 (8.15) for the highly porous β-Tricalcium Phosphate, 5.56 (10.0) for polymers, and 3.82 (3.8) for Hydroxyapatite. CONCLUSION: Under the above experimental conditions, β-TCP was able to maintain better the viability of osteoprogenitor cells and allow proliferation and differentiation (P < 0.05). PMID:25258672

  11. Histological assessment of augmented jaw bone utilizing a new collagen barrier membrane compared to a standard barrier membrane to protect a granular bone substitute material.

    PubMed

    Friedmann, Anton; Strietzel, Frank Peter; Maretzki, Burghard; Pitaru, Sandu; Bernimoulin, Jean-Pierre

    2002-12-01

    Successful bone augmentation requires predictable space maintenance and adequate exclusion of those cells that lack osteogenetic potential from the defect area. Natural bone mineral is considered to be osteoconductive and is used as space maker in combination with membrane barrier techniques. The aim of this study was to compare qualitative histological results achieved by using deproteinized bovine bone mineral (DBBM) as a space maintainer and a new collagen barrier (Ossix, test group) vs. the same bone substitute and the standard e-PTFE membrane (Gore-Tex), control group). Twenty-eight patients were randomly assigned to the test or the control group. Seven months after augmentation procedures, biopsies were obtained at reentry and were analysed histomorphometrically. In all, 14 specimens of group I (test group, Ossix) and 13 specimens of group II (controls, PTFE-membranes) showed close qualitative similarity of their histologies. Histomorphometrically, total mineralized bone area was 42% +/- 18% in group I vs. 39% +/- 15% in group II. The unmineralized tissue area was 44% +/- 15% vs. 46% +/- 12% and the area of DBBM remnants 14% +/- 9% and 15% +/- 12%, respectively. The differences were statistically nonsignificant (Mann-Whitney test). The occurrence of barrier exposure did not interfere with the histological outcome either in the test or in the control group. The new collagen barrier combined with the DBBM provided qualitative bone regeneration comparable to the standard e-PTFE material combined with the same mineral. PMID:12519332

  12. Alveolar ridge preservation with the socket-plug technique utilizing an alloplastic putty bone substitute or a particulate xenograft: a histological pilot study.

    PubMed

    Mahesh, Lanka; Venkataraman, Narayan; Shukla, Sagrika; Prasad, Hari; Kotsakis, Georgios A

    2015-04-01

    Following tooth extraction, ridge preservation procedures are employed to regenerate bone in the extraction socket, limit consequent ridge resorption, and provide a stable base for implant placement. The purpose of this study is to histologically evaluate and compare bone regeneration in extraction sockets grafted with either a putty alloplastic bone substitute or particulate anorganic bovine xenograft utilizing the socket-plug technique. Nineteen patients underwent 20 tooth extractions and ridge preservation following a standardized protocol. Ten sites were grafted with calcium phosphosilicate putty (CPS group) and the remaining 10 with anorganic bovine bone substitute (BO group). Patients were recalled after 4-6 months to evaluate the bone regeneration and to proceed with implant placement. A bone core was obtained during the implant procedure from each site and was used for histologic analysis. Histomorphometry revealed that residual graft values were significantly higher in the BO group (25.60% ± 5.89%) compared to the CPS group (17.40% ± 9.39%) (P < .05). The amount of new bone regenerated was also statistically significant higher in the alloplast group (47.15% ± 8.5%) as compared to the xenograft group (22.2% ± 3.5%) (P < .05). Results suggest that ridge preservation using a putty calcium phosphosilicate alloplastic bone substitute demonstrates more timely graft substitution and increased bone regeneration when compared to an anorganic bovine bone xenograft. PMID:23772806

  13. IN VIVO PERFORMANCE OF THE EXPERIMENTAL CHITOSAN BASED BONE SUBSTITUTE--ADVANCED THERAPY MEDICINAL PRODUCT. A STUDY IN SHEEP.

    PubMed

    Bojar, Witold; Kucharska, Martyna; Ciach, Tomasz; Paśnik, Iwona; Korobowicz, Elzbieta; Patkowski, Krzysztof; Gruszecki, Tomasz; Szymanowski, Marek; Rzodkiewicz, Przemysław

    2016-01-01

    When evaluating a novel bone substitute material, advanced in vivo testing is an important step in development and safety affirmation. Sheep seems to be a valuable model for human bone turnover and remodeling activity. The experimental material composed with the stem cells is an advanced therapy medicinal product (acc. to EC Regulation 1394/2007). Our research focuses on histological differences in bone formation (guided bone regeneration--GBR) in sheep maxillas after implantation of the new chitosan/tricalcium phosphate/alginate (CH/TCP/Alg) biomaterial in comparison to the commercially available xenogenic bone graft and a/m enhanced with the stem cells isolated from the adipose tissue. Twelve adult female sheep of BCP synthetic line, weighing 60-70 kg were used for the study. The 11 mm diameter defects in maxilla bone were prepared with a trephine bur under general anesthesia and then filled with the bone substitute materials: CH/TCP/Alg, BioOss Collagen, Geistlich AG (BO), CH/TCP/Alg composed with the stem cells (CH/S) or left just with the blood clot (BC). Inbreeding cycle of the animals terminated at 4 months after surgery. Dissected specimens of the maxilla were evaluated histologically and preliminary under microtomography. Histological evaluation showed early new bone formation observed around the experimental biomaterial and commercially available BO. There were no features of purulent inflammation and necrosis, or granulomatous inflammation. Microscopic examination after 4 months following the surgery revealed trabecular bone formation around chitosan based bone graft and xenogenic material with no significant inflammatory response. Different results--no bone recreation were observed for the negative control (BC). In conclusion, the tested materials (CH/TCP/Alg and BO) showed a high degree of biocompatibility and some osteoconductivity in comparison with the control group. Although the handiness, granules size and setting time of CHffCP/Alg may be refined

  14. Investigation on artificial blood or substitute blood replace the natural blood.

    PubMed

    Keyhanian, Sh; Ebrahimifard, M; Zandi, M

    2014-01-01

    Blood is a liquid tissue in which dissolved with abundant chemical factors and millions of different cells The reduction of unwanted side effects, especially diseases that emerge through blood such as HIV and hepatitis, has a significant role for modern medicine of transfusion and transplantation. The issues and costs of human blood collection and storage, direct this procedure towards the use of alternatives blood. Two important research fields of this area were oxygen carriers based on hemoglobin and perfluoro chemicals. While they do not have the same quality as the blood cell products, the oxygen carrier solutions have potential clinical and non-clinical applications. The result showed that these products can reach to the body tissues easier than normal red blood cells, and can control the oxygen directly. The final aim of transfusion is to establish a transfusion system with no side effects, and the fact that oxygen carrier artificial blood has this property. The article attempts to step towards solving some problems of blood transfusion through describing the properties of artificial blood alternatives. PMID:25002929

  15. Synthesis of Cholesterol-Substituted Glycopeptides for Tailor-Made Glycocalyxification of Artificial Membrane Systems.

    PubMed

    Stuhr-Hansen, Nicolai; Madl, Josef; Villringer, Sarah; Aili, Ulrika; Römer, Winfried; Blixt, Ola

    2016-08-01

    Synthetic minimal membrane systems are extremely useful for better understanding of complex cellular structures and cell surface processes. We have developed a facile method for synthesis of cholesterylated peptides, each bearing a carbohydrate moiety and a fluorescent tag. The position of the cholesterol moiety on the peptide can be controlled by using a new Fmoc-protected cholesterol-triazole-lysine group, which we constructed by means of solid-phase peptide synthesis. We succeeded in integrating the glyco modules into giant unilamellar vesicles by electroformation or infusion in buffer solution. The glyco-decorated liposomes were recognized by a lectin and had unique topological membrane features. In conclusion, this work is a proof of principle for the functionalization of artificial membranes with a primitive synthetic glycocalyx useful for studying carbohydrate-protein interactions on a simplified cell-like membrane surface. PMID:27168414

  16. The Effect of Hyaluronate-Carboxymethyl Cellulose on Bone Graft Substitute Healing in a Rat Spinal Fusion Model

    PubMed Central

    Lee, Jung Hee

    2011-01-01

    Objective The aim of this study was to evaluate the impact of sodium hyaluronate-sodium carboxymethyl cellulose (HA-CMC), an anti-adhesive material for spinal surgery, on bone fusion by applying it to rat spinal models after lumbar posterolateral fusion. Methods Lumbar posterolateral fusion was performed at L4-5 using bone graft substitutes in 30 rats. HA-CMC was injected in 15 rats at a dose of 0.2 cc (HA-CMC group) and a saline solution of 0.2 cc in the other 15 rats (control group). Simple radiographs were taken until postoperative 9 weeks with an interval of one week. At postoperative 4 and 9 weeks, three dimensional computed tomography (3D CT) scanning was performed to observe the process of bone fusion. At 9 weeks, bone fusion was confirmed by gross examination and manual palpation. Results There were no statistically significant differences in bone fusion between the two groups. 3D CT scanning did not reveal significant differences between the groups. The gross examination and manual palpation after autopsy performed at 9 weeks confirmed bone union in 93.3% of both groups. Conclusion The anti-adhesive material used for spinal surgery did not have adverse effects on spinal fusion in rats. PMID:22259686

  17. Use of mineralized collagen bone graft substitutes and dorsal locking plate in treatment of elder metaphyseal comminuted distal radius fracture

    NASA Astrophysics Data System (ADS)

    Liu, Ke-Bin; Huang, Kui; Teng, Yu; Qu, Yan-Zheng; Cui, Wei; Huang, Zhen-Fei; Sun, Ting-Fang; Guo, Xiao-Dong

    2014-03-01

    Bone graft may be needed to fill bone defect in elderly patients with a metaphyseal comminuted distal radius fracture. In this retrospective, nonrandomized, single-surgeon study, we evaluated the clinical and radiologic outcomes of using both dorsal locking plates with or without augmentation with mineralized collagen (MC) bone graft for elderly patients with dorsally metaphyseal comminuted radius fractures. Patients in group 1 ( n = 12) were treated with dorsal locking plates with MC bone graft application into the metaphyseal bone defect, and those in group 2 ( n = 12) only with dorsal locking plates. Clinical and radiologic parameters were determined at three and 12 months after surgery. At final follow-up, no significant difference was noted between the 2 groups in terms of palmar tilt and radial inclination ( p = 0.80); however, ulnar variance increased significantly in the group 2 treated with dorsal locking plates without augmentation ( p < 0.05). Functionally, there was no significant difference between the groups. Our preliminary study suggests that combination of MC as bone-graft substitutes and dorsal locking plates may be a usefully alternative for elderly patients with metaphyseal comminuted distal radius fracture.

  18. Crystal polymer interaction with new injectable bone substitute; SEM and Hr TEM study.

    PubMed

    Daculsi, G; Rohanizadeh, R; Weiss, P; Bouler, J M

    2000-04-01

    A composite constituted of calcium phosphate (CaP) granules and a hydrophilic polymer as a carrier (hydroxy-propyl-methyl cellulose, HPMC) was developed to be an injectable bone substitute (IBS, CNRS patent). IBS is a composite and not an ionic cement. The composite obtained is ready to use and sterile. Chemical interactions between organic and inorganic components appeared during the association of the two. The interactions of the CaP and the polymer have been studied using scanning electron microscopy (SEM), electron microprobe (EDX), and high-resolution transmission electron microscopy (HrTEM) SEM revealed a degradation of the granules into smaller particles while EDX was unable to show significant changes in the Ca/P ratio during aging of the composite. With Hr TEM, however, we observed hydrolysis (process of dissolution and precipitation) from the surface to about 13 nm into the HA crystals and occasional dissolution with precipitation of beta-TCP crystals. In HA, the first zone of interaction consisted of a single layer of small globular crystals of 2 to 3 nm in diameter. Numerous lattice patterns in all three axes could be observed. Under the globular crystals zone, the inter-reticular distances of the single crystals appeared enlarged by 1.2% (from 0.817 to 0.827 nm). The enlargement seems to correspond to diffusion of HPO(4) into the crystal lattice. In beta-TCP crystals, dissolution was observed to be several nanometers deep, but globular surface precipitation rarely was observed. With time or after steam sterilization, no changes were observed. These data demonstrate the strong interactions of the hydrophylic polymer with calcium phosphate, but only in the first several nanometers of thickness. PMID:10644956

  19. Injectable Bone Substitute Based on β-TCP Combined With a Hyaluronan-Containing Hydrogel Contributes to Regeneration of a Critical Bone Size Defect Towards Restitutio ad Integrum.

    PubMed

    Barbeck, Mike; Hoffmann, Christiane; Sader, Robert; Peters, Fabian; Hübner, Wolf-Dietrich; Kirkpatrick, Charles James; Ghanaati, Shahram

    2016-04-01

    In the present in vivo study, the regenerative potential of a new injectable bone substitute (IBS) composed of beta-tricalcium phosphate (β-TCP) and hyaluronan was tested in a rabbit distal femoral condyle model. To achieve this, 2 defects of 6 mm in diameter and 10 mm in length were drilled into each femur condyle in a total of 12 animals. For each animal, 1 hole was filled with the substitute material, and the other was left empty to serve as the control. After 1, 3, and 6 months, the regenerative process was analyzed by radiography as well as by histological and histomorphometrical analysis. The results revealed that bone tissue formation took place through osteoconductive processes over time, starting from the defect borders to the center. Both the β-TCP content and the hydrogel support bone tissue growth. The histomorphometrical measurements showed that the amount of bone formation in the experimental group was significantly higher compared with that found in the control group after 3 months (19.51 ± 5.08% vs. 1.96 ± 0.77%, P < .05) and 6 months (4.57 ± 1.56% vs. 0.23 ± 0.21%, P < .05). The application of the IBS gave a restitutio ad integrum result after 6 months and was associated with its nearly complete degradation, in contrast to the results found in the control group. In conclusion, the results of the present study demonstrate that the IBS contributes to sufficient bone regeneration by serving as a scaffold-like structure, combined with its degradation within 6 months. PMID:26301338

  20. Bacterial cellulose membranes used as artificial substitutes for dural defection in rabbits.

    PubMed

    Xu, Chen; Ma, Xia; Chen, Shiwen; Tao, Meifeng; Yuan, Lutao; Jing, Yao

    2014-01-01

    To improve the efficacy and safety of dural repair in neurosurgical procedures, a new dural material derived from bacterial cellulose (BC) was evaluated in a rabbit model with dural defects. We prepared artificial dura mater using bacterial cellulose which was incubated and fermented from Acetobacter xylinum. The dural defects of the rabbit model were repaired with BC membranes. All surgeries were performed under sodium pentobarbital anesthesia, and all efforts were made to minimize suffering. All animals were humanely euthanized by intravenous injection of phenobarbitone, at each time point, after the operation. Then, the histocompatibility and inflammatory effects of BC were examined by histological examination, real-time fluorescent quantitative polymerase chain reaction (PCR) and Western Blot. BC membranes evenly covered the surface of brain without adhesion. There were seldom inflammatory cells surrounding the membrane during the early postoperative period. The expression of inflammatory cytokines IL-1β, IL-6 and TNF-α as well as iNOS and COX-2 were lower in the BC group compared to the control group at 7, 14 and 21 days after implantation. BC can repair dural defects in rabbit and has a decreased inflammatory response compared to traditional materials. However, the long-term effects need to be validated in larger animals. PMID:24937688

  1. Bacterial Cellulose Membranes Used as Artificial Substitutes for Dural Defection in Rabbits

    PubMed Central

    Xu, Chen; Ma, Xia; Chen, Shiwen; Tao, Meifeng; Yuan, Lutao; Jing, Yao

    2014-01-01

    To improve the efficacy and safety of dural repair in neurosurgical procedures, a new dural material derived from bacterial cellulose (BC) was evaluated in a rabbit model with dural defects. We prepared artificial dura mater using bacterial cellulose which was incubated and fermented from Acetobacter xylinum. The dural defects of the rabbit model were repaired with BC membranes. All surgeries were performed under sodium pentobarbital anesthesia, and all efforts were made to minimize suffering. All animals were humanely euthanized by intravenous injection of phenobarbitone, at each time point, after the operation. Then, the histocompatibility and inflammatory effects of BC were examined by histological examination, real-time fluorescent quantitative polymerase chain reaction (PCR) and Western Blot. BC membranes evenly covered the surface of brain without adhesion. There were seldom inflammatory cells surrounding the membrane during the early postoperative period. The expression of inflammatory cytokines IL-1β, IL-6 and TNF-α as well as iNOS and COX-2 were lower in the BC group compared to the control group at 7, 14 and 21 days after implantation. BC can repair dural defects in rabbit and has a decreased inflammatory response compared to traditional materials. However, the long-term effects need to be validated in larger animals. PMID:24937688

  2. Autologous serum improves bone formation in a primary stable silica-embedded nanohydroxyapatite bone substitute in combination with mesenchymal stem cells and rhBMP-2 in the sheep model

    PubMed Central

    Boos, Anja M; Weigand, Annika; Deschler, Gloria; Gerber, Thomas; Arkudas, Andreas; Kneser, Ulrich; Horch, Raymund E; Beier, Justus P

    2014-01-01

    New therapeutic strategies are required for critical size bone defects, because the gold standard of transplanting autologous bone from an unharmed area of the body often leads to several severe side effects and disadvantages for the patient. For years, tissue engineering approaches have been seeking a stable, axially vascularized transplantable bone replacement suitable for transplantation into the recipient bed with pre-existing insufficient conditions. For this reason, the arteriovenous loop model was developed and various bone substitutes have been vascularized. However, it has not been possible thus far to engineer a primary stable and axially vascularized transplantable bone substitute. For that purpose, a primary stable silica-embedded nanohydroxyapatite (HA) bone substitute in combination with blood, bone marrow, expanded, or directly retransplanted mesenchymal stem cells, recombinant human bone morphogenetic protein 2 (rhBMP-2), and different carrier materials (fibrin, cell culture medium, autologous serum) was tested subcutaneously for 4 or 12 weeks in the sheep model. Autologous serum lead to an early matrix change during degradation of the bone substitute and formation of new bone tissue. The best results were achieved in the group combining mesenchymal stem cells expanded with 60 μg/mL rhBMP-2 in autologous serum. Better ingrowth of fibrovascular tissue could be detected in the autologous serum group compared with the control (fibrin). Osteoclastic activity indicating an active bone remodeling process was observed after 4 weeks, particularly in the group with autologous serum and after 12 weeks in every experimental group. This study clearly demonstrates the positive effects of autologous serum in combination with mesenchymal stem cells and rhBMP-2 on bone formation in a primary stable silica-embedded nano-HA bone grafting material in the sheep model. In further experiments, the results will be transferred to the sheep arteriovenous loop model in

  3. Hard tissue regeneration using bone substitutes: an update on innovations in materials

    PubMed Central

    Sarkar, Swapan Kumar

    2015-01-01

    Bone is a unique organ composed of mineralized hard tissue, unlike any other body part. The unique manner in which bone can constantly undergo self-remodeling has created interesting clinical approaches to the healing of damaged bone. Healing of large bone defects is achieved using implant materials that gradually integrate with the body after healing is completed. Such strategies require a multidisciplinary approach by material scientists, biological scientists, and clinicians. Development of materials for bone healing and exploration of the interactions thereof with the body are active research areas. In this review, we explore ongoing developments in the creation of materials for regenerating hard tissues. PMID:25995658

  4. Hard tissue regeneration using bone substitutes: an update on innovations in materials.

    PubMed

    Sarkar, Swapan Kumar; Lee, Byong Taek

    2015-05-01

    Bone is a unique organ composed of mineralized hard tissue, unlike any other body part. The unique manner in which bone can constantly undergo self-remodeling has created interesting clinical approaches to the healing of damaged bone. Healing of large bone defects is achieved using implant materials that gradually integrate with the body after healing is completed. Such strategies require a multidisciplinary approach by material scientists, biological scientists, and clinicians. Development of materials for bone healing and exploration of the interactions thereof with the body are active research areas. In this review, we explore ongoing developments in the creation of materials for regenerating hard tissues. PMID:25995658

  5. Bioresorbable bone graft substitutes of different osteoconductivities: a histologic evaluation of osteointegration of poly(propylene glycol-co-fumaric acid)-based cement implants in rats.

    PubMed

    Lewandrowski, K U; Gresser, J D; Wise, D L; Trantol, D J

    2000-04-01

    Bioresorbable bone graft substitutes may significantly reduce the disadvantages associated with autografts, allografts and other synthetic materials currently used in bone graft procedures. We investigated the biocompatibility and osteointegration of a bioresorbable bone graft substitute made from the unsaturated polyester poly(propylene-glycol-co-fumaric acid), or simply poly(propylene fumarate), PPF, which is crosslinked in the presence of soluble and insoluble calcium filler salts. Four sets of animals each having three groups of 8 were evaluated by grouting bone graft substitutes of varying compositions into 3-mm holes that were made into the anteromedial tibial metaphysis of rats. Four different formulations varying as to the type of soluble salt filler employed were used: set 1--calcium acetate, set 2--calcium gluconate, set 3--calcium propionate, and set 4--control with hydroxapatite, HA, only. Animals of each of the three sets were sacrificed in groups of 8 at postoperative week 1, 3, and 7. Histologic analysis revealed that in vivo biocompatibility and osteointegration of bone graft substitutes was optimal when calcium acetate was employed as a soluble salt filler. Other formulations demonstrated implant surface erosion and disintegration which was ultimately accompanied by an inflammatory response. This study suggested that PPF-based bone graft substitutes can be designed to provide an osteoconductive pathway by which bone will grow in faster because of its capacity to develop controlled porosities in vivo. Immediate applicability of this bone graft substitute, the porosity of which can be tailored for the reconstruction of defects of varying size and quality of the recipient bed, is to defects caused by surgical debridement of infections, previous surgery, tumor removal, trauma, implant revisions and joint fusion. Clinical implications of the relation between developing porosity, resulting osteoconduction, and bone repair in vivo are discussed. PMID

  6. Facilitated receptor-recognition and enhanced bioactivity of bone morphogenetic protein-2 on magnesium-substituted hydroxyapatite surface

    NASA Astrophysics Data System (ADS)

    Huang, Baolin; Yuan, Yuan; Li, Tong; Ding, Sai; Zhang, Wenjing; Gu, Yuantong; Liu, Changsheng

    2016-04-01

    Biomaterial surface functionalized with bone morphogenetic protein-2 (BMP-2) is a promising approach to fabricating successful orthopedic implants/scaffolds. However, the bioactivity of BMP-2 on material surfaces is still far from satisfactory and the mechanism of related protein-surface interaction remains elusive. Based on the most widely used bone-implants/scaffolds material, hydroxyapatite (HAP), we developed a matrix of magnesium-substituted HAP (Mg-HAP, 2.2 at% substitution) to address these issues. Further, we investigated the adsorption dynamics, BMPRs-recruitment, and bioactivity of recombinant human BMP-2 (rhBMP-2) on the HAP and Mg-HAP surfaces. To elucidate the mechanism, molecular dynamic simulations were performed to calculate the preferred orientations, conformation changes, and cysteine-knot stabilities of adsorbed BMP-2 molecules. The results showed that rhBMP-2 on the Mg-HAP surface exhibited greater bioactivity, evidenced by more facilitated BMPRs-recognition and higher ALP activity than on the HAP surface. Moreover, molecular simulations indicated that BMP-2 favoured distinct side-on orientations on the HAP and Mg-HAP surfaces. Intriguingly, BMP-2 on the Mg-HAP surface largely preserved the active protein structure evidenced by more stable cysteine-knots than on the HAP surface. These findings explicitly clarify the mechanism of BMP-2-HAP/Mg-HAP interactions and highlight the promising application of Mg-HAP/BMP-2 matrixes in bone regeneration implants/scaffolds.

  7. Facilitated receptor-recognition and enhanced bioactivity of bone morphogenetic protein-2 on magnesium-substituted hydroxyapatite surface

    PubMed Central

    Huang, Baolin; Yuan, Yuan; Li, Tong; Ding, Sai; Zhang, Wenjing; Gu, Yuantong; Liu, Changsheng

    2016-01-01

    Biomaterial surface functionalized with bone morphogenetic protein-2 (BMP-2) is a promising approach to fabricating successful orthopedic implants/scaffolds. However, the bioactivity of BMP-2 on material surfaces is still far from satisfactory and the mechanism of related protein-surface interaction remains elusive. Based on the most widely used bone-implants/scaffolds material, hydroxyapatite (HAP), we developed a matrix of magnesium-substituted HAP (Mg-HAP, 2.2 at% substitution) to address these issues. Further, we investigated the adsorption dynamics, BMPRs-recruitment, and bioactivity of recombinant human BMP-2 (rhBMP-2) on the HAP and Mg-HAP surfaces. To elucidate the mechanism, molecular dynamic simulations were performed to calculate the preferred orientations, conformation changes, and cysteine-knot stabilities of adsorbed BMP-2 molecules. The results showed that rhBMP-2 on the Mg-HAP surface exhibited greater bioactivity, evidenced by more facilitated BMPRs-recognition and higher ALP activity than on the HAP surface. Moreover, molecular simulations indicated that BMP-2 favoured distinct side-on orientations on the HAP and Mg-HAP surfaces. Intriguingly, BMP-2 on the Mg-HAP surface largely preserved the active protein structure evidenced by more stable cysteine-knots than on the HAP surface. These findings explicitly clarify the mechanism of BMP-2-HAP/Mg-HAP interactions and highlight the promising application of Mg-HAP/BMP-2 matrixes in bone regeneration implants/scaffolds. PMID:27075233

  8. Exercise does not enhance aged bone's impaired response to artificial loading in C57Bl/6 mice.

    PubMed

    Meakin, Lee B; Udeh, Chinedu; Galea, Gabriel L; Lanyon, Lance E; Price, Joanna S

    2015-12-01

    Bones adapt their structure to their loading environment and so ensure that they become, and are maintained, sufficiently strong to withstand the loads to which they are habituated. The effectiveness of this process declines with age and bones become fragile fracturing with less force. This effect in humans also occurs in mice which experience age-related bone loss and reduced adaptation to loading. Exercise engenders many systemic and local muscular physiological responses as well as engendering local bone strain. To investigate whether these physiological responses influence bones' adaptive responses to mechanical strain we examined whether a period of treadmill exercise influenced the adaptive response to an associated period of artificial loading in young adult (17-week) and old (19-month) mice. After treadmill acclimatization, mice were exercised for 30 min three times per week for two weeks. Three hours after each exercise period, right tibiae were subjected to 40 cycles of non-invasive axial loading engendering peak strain of 2250 με. In both young and aged mice exercise increased cross-sectional muscle area and serum sclerostin concentration. In young mice it also increased serum IGF1. Exercise did not affect bone's adaptation to loading in any measured parameter in young or aged bone. These data demonstrate that a level of exercise sufficient to cause systemic changes in serum, and adaptive changes in local musculature, has no effect on bone's response to loading 3h later. This study provides no support for the beneficial effects of exercise on bone in the elderly being mediated by systemic or local muscle-derived effects rather than local adaptation to altered mechanical strain. PMID:26142929

  9. Short-term effects of mineral particle sizes on cellular degradation activity after implantation of injectable calcium phosphate biomaterials and the consequences for bone substitution.

    PubMed

    Gauthier, O; Bouler, J M; Weiss, P; Bosco, J; Aguado, E; Daculsi, G

    1999-08-01

    This in vivo study investigated the influence of two calcium phosphate particle sizes (40-80 microm and 200-500 microm) on the cellular degradation activity associated with the bone substitution process of two injectable bone substitutes (IBS). The tested biomaterials were obtained by associating a biphasic calcium phosphate (BCP) ceramic mineral phase and a 3% aqueous solution of a cellulosic polymer (hydroxypropylmethylcellulose). Both were injected into osseous defects at the distal end of rabbit femurs for 2- and 3-week periods. Quantitative results for tartrate-resistant acid phosphatase (TRAP) cellular activity, new bone formation, and ceramic resorption were studied for statistical purposes. Positive TRAP-stained degradation cells were significantly more numerous for IBS 40-80 than IBS 200-500, regardless of implantation time. BCP degradation was quite marked during the first 2 weeks for IBS 40-80, and bone colonization occurred more extensively for IBS 40-80 than for IBS 200-500. The resorption-bone substitution process occurred earlier and faster for IBS 40-80 than IBS 200-500. Both tested IBS displayed similar biological efficiency, with conserved in vivo bioactivity and bone-filling ability. Differences in calcium phosphate particle sizes influenced cellular degradation activity and ceramic resorption but were compatible with efficient bone substitution. PMID:10458280

  10. In Vitro characterization of low modulus linoleic acid coated strontium-substituted hydroxyapatite containing PMMA bone cement.

    PubMed

    Lam, W M; Pan, H B; Fong, M K; Cheung, W S; Wong, K L; Li, Z Y; Luk, K D K; Chan, W K; Wong, C T; Yang, C; Lu, W W

    2011-01-01

    Poly (methyl methacrylate) (PMMA) bone cement is widely used in vertebral body augmentation procedures such as vertebroplasty and balloon kyphoplasty. Filling high modulus PMMA increases the modulus of filled verterbra, increasing the risk of fracture in the adjacent vertebra. On the other hand, in porous PMMA bone cements, wear particle generation and deterioration of mechanical performance are the major drawbacks. This study adopts a new approach by utilizing linoleic acid coated strontium substituted hydroxyapatite nanoparticle (Sr-5 HA) and linoleic acid as plasticizer reducing bone cement's modulus with minimal impact on its strength. We determined the compressive strength (UCS) and modulus (Ec), hydrophobicity, injectability, in vitro bioactivity and biocompatibility of this bone cement at different filler and linoleic acid loading. At 20 wt % Sr5-HA incorporation, UCS and Ec were reduced from 63 ± 2 MPa, 2142 ± 129 MPa to 58 ± 2 MPa, 1785 ± 64 MPa, respectively. UCS and Ec were further reduced to 49 ± 2 MPa and 774 ± 70 MPa respectively when 15 v/v of linoleic acid was incorporated. After 7 days of incubation, pre-osteoblast cells (MC3T3-E1) attached on 20 wt % Sr5-HA and 20 wt % Sr5-HA with 15 v/v of linoleic acid group were higher (3.73 ± 0.01 x 10⁴, 2.27 ± 0.02 x 10⁴) than their PMMA counterpart (1.83 ± 0.04 x 10⁴). Incorporation of Sr5-HA with linoleic acid in monomer phase is more effective in reducing the bone cement's stiffness than Sr5-HA alone. Combination of low stiffness and high mechanical strength gives the novel bone cement the potential for use in vertebroplasty cement applications. PMID:21053263

  11. 175Yb-TTHMP as a good candidate for bone pain palliation and substitute of other radiopharmaceuticals

    PubMed Central

    Safarzadeh, Laleh

    2014-01-01

    Bone metastasis is one of the most frequent causes of pain in cancer patients. Different radioisotopes such as P-32, Sm-153, Ho-166, Lu-177, and Re-186 with several chemical ligands as ethylenediaminetetramethylene phosphonic acid (EDTMP), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid (DOTMP), and propylenediaminetetramethylene phosphonate (PDTMP) are recommended for bone pain palliation. In this work, 175Yb-triethylenetetraminehexamethylene phosphonic acid (TTHMP) was produced as a proper alternative to other radiopharmaceuticals. Relatively long half-life (T1/2 = 4.18 days), maximum energy beta particle Eβ =470 keV (86.5%), low abundance gamma emission 396 keV (6.4%), 286 keV (3.01%), 113.8 keV (1.88%) and low cost are considered advantageous of Yb-175 are to wider usage of this isotope; in addition, TTHMP is an ideal carrier moiety for bone metastases. Production, quality control, and biodistribution studies of 175Yb-TTHMP were targeted. Yb-175 chloride was obtained by thermal neutron bombardment of a natural Yb2O3 sample at Tehran Research Reactor (TRR), radiolabeling was completed in 1 h by the addition of TTHMP at the room temperature and pH was 7.5-8, radiochemical purity was higher than 95%. Biodistribution studies in normal rats were carried out. The results showed favorable biodistribution features of 175Yb-TTHMP, indicating significant accumulation in bone tissues compared with clinically used bone-seeking radiopharmaceuticals. This research presents 175Yb-TTHMP can be a good candidate for bone pain palliation and substitute of other radiopharmaceuticals, however, further biological studies in other mammals are still needed. PMID:25210277

  12. [Transitory bone loss during substitution treatment for hypothyroidism. Results of a two year prospective study].

    PubMed

    Trémollières, F; Pouillès, J M; Louvet, J P; Ribot, C

    1991-12-01

    The authors report the results of a prospective study designed to assess changes in vertebral and femoral bone density during the first two years of replacement therapy in 10 patients with hypothyroidism (4 men, 6 women). During the first year, bone density measured by dual photon absorptiometry fell significantly in the lumbar vertebrae (-5.4%), neck of the femur (-7%) and the trochanteric region (-7.3%). This bone loss was accompanied by an early increase in serum osteocalcin levels, urinary calcium/urinary creatinine ratio and in Sex Hormone Binding Globulin. During the second year, there was complete recovery of values of vertebral and trochanteric bone density, while density of the neck of the femur remained significantly lower than initial values. None of the patients showed any evidence of overdose during the period of monitoring of clinical and laboratory (free T4, total and free T3, ultra-sensitive TSH) parameters. This transitory bone loss could be indicative of a state of tissue hyperthyroidism and/or "hypersensitivity" of hypothyroid bone to the action of thyroid hormones. Its influence on the subsequent risk of fracture remains unclear. In the current state of knowledge, measurement of vertebral and femoral bone density appears to be indicated in patients given long term treatment which suppresses TSH, or requiring replacement therapy for severe hypothyroidism. Any demineralisation prior to treatment could justify the temporary prescription of an antiosteoclastic agent. PMID:1780668

  13. Effect of amputation level on the stress transferred to the femur by an artificial limb directly attached to the bone.

    PubMed

    Newcombe, L; Dewar, M; Blunn, G W; Fromme, P

    2013-12-01

    Attachment of an artificial limb directly to the skeleton has a number of potential benefits and the technique has been implemented for several amputation sites. In this paper the transfer of stress from an external, transfemoral prosthesis to the femur during normal walking activity is investigated. The stress distribution in the femur and at the implant-bone interface is calculated using finite element analysis for the 3D geometry and inhomogeneous, anisotropic material properties obtained from a CT scan of a healthy femur. Attachment of the prosthetic leg at three different levels of amputation is considered. Stress concentrations are found at the distal end of the bone and adjacent to the implant tip and stress shielding is observed adjacent to the implant. It is found that the stress distribution in the femur distal to the epiphysis, where the femur geometry is close to cylindrical, can be predicted from a cylindrical finite element model, using the correct choice of bone diameter as measured from a radiograph. Proximal to the lesser trochanter the stress decreases as the femur geometry diverges significantly from a cylinder. The stress concentration at the distal, resected end of the bone is removed when a collared implant is employed. These findings form the basis for appropriate settings of an external fail-safe device to protect the bone from excessive stress in the event of an undue load. PMID:23953406

  14. Novel bone substitute composed of chitosan and strontium-doped α-calcium sulfate hemihydrate: Fabrication, characterisation and evaluation of biocompatibility.

    PubMed

    Chen, Yirong; Zhou, Yilin; Yang, Shenyu; Li, Jiao Jiao; Li, Xue; Ma, Yunfei; Hou, Yilong; Jiang, Nan; Xu, Changpeng; Zhang, Sheng; Zeng, Rong; Tu, Mei; Yu, Bin

    2016-09-01

    Calcium sulfate is in routine clinical use as a bone substitute, offering the benefits of biodegradability, biocompatibility and a long history of use in bone repair. The osteoconductive properties of calcium sulfate may be further improved by doping with strontium ions. Nevertheless, the high degradation rate of calcium sulfate may impede bone healing as substantial material degradation may occur before the healing process is complete. The purpose of this study is to develop a novel composite bone substitute composed of chitosan and strontium-doped α-calcium sulfate hemihydrate in the form of microcapsules, which can promote osteogenesis while matching the natural rate of bone healing. The developed microcapsules exhibited controlled degradation that facilitated the sustained release of strontium ions. In vitro testing showed that the microcapsules had minimal cytotoxicity and ability to inhibit bacterial growth. In vivo testing in a mouse model showed the absence of genetic toxicity and low inflammatory potential of the microcapsules. The novel microcapsules developed in this study demonstrated suitable degradation characteristics for bone repair as well as favourable in vitro and in vivo behaviour, and hold promise for use as an alternative bone substitute in orthopaedic surgery. PMID:27207041

  15. Toward the definition of criteria for the recognition of artificial bone alterations*1

    NASA Astrophysics Data System (ADS)

    Morlan, Richard E.

    1984-09-01

    Cutting, fracturing, flaking, and polishing of bones and other osseous materials may in some instances be interpreted as evidence of former human activity. Such interpretations must avoid confusion with the wide variety of natural processes that alter bones. Reliable criteria are prerequisite to sound inferences based on bone, regardless of whether they have been redeposited or recovered from primary assemblages. Criteria must be defined by means of actualistic studies (neotaphonomy) and experiments that demonstrate causal relationships between patterns of alteration and the processes that produce them. The criteria can be empoyed in the interpretation of fossil bones (paleotaphonomy) on the basis of uniformitarian principles. At the present time, such relationships are relatively well understood in the case of cut marks on bones, and modest progress has been made in investigating fractured and flaked bones. Polished bones are little understood and difficult to interpret.

  16. Behavior of plaster of Paris-calcium carbonate composite as bone substitute. A study in rats.

    PubMed

    Dewi, Anne Handrini; Ana, Ika Dewi; Wolke, Joop; Jansen, John

    2013-08-01

    Calcium sulfate, also known as plaster of Paris (POP), is probably the oldest biomaterial used for bone grafting and considered to be a fast degradable material that allows complete resorption before the bone defect area is completely filled by new bone. The aim of this study was to investigate the possibility to combine POP with calcium carbonate in order to increase the the osteoconductivity of this material. Twenty four male Sprague Dawley rats, 5-months-old and weighing 300-350 g, were used in the study. Various treatment groups were created by the implantation of cylindrical samples of POP-100, POP-075 and POP-050 into the femoral condyles. After 1 and 4 weeks of implantation, rats were sacrificed and the implanted areas and the surrounding tissue were retrieved for histological analysis. The study was completed by an in vitro experiment, which included the soaking of the experimental materials into simulated body fluid. The results indicated that the composites were appropriate to be used as bone grafting material. The incorporation of CaCO3 into POP did decrease the degradation rate of the cements and induced faster bone formation, thus provides promising properties to this material. PMID:23239628

  17. Biological responses of brushite-forming Zn- and ZnSr- substituted beta-tricalcium phosphate bone cements.

    PubMed

    Pina, S; Vieira, S I; Rego, P; Torres, P M C; da Cruz e Silva, O A B; da Cruz e Silva, E F; Ferreira, J M F

    2010-01-01

    The core aim of this study was to investigate zinc (Zn)- and zinc and strontium (ZnSr)-containing brushite-forming beta-tricalcium phosphate (TCP) cements for their effects on proliferation and differentiation of osteoblastic-like cells (MC3T3-E1 cell line) as well as for their in vivo behaviour in trabecular bone cylindrical defects in a pilot study. In vitro proliferation and maturation responses of MC3T3-E1 osteoblastic-like cells to bone cements were studied at the cellular and molecular levels. The Zn- and Sr-containing brushite cements were found to stimulate pre-osteoblastic proliferation and osteoblastic maturation. Indeed, MC3T3-E1 cells exposed to the powdered cements had increased proliferative rates and higher adhesiveness capacity, in comparison to control cells. Furthermore, they exhibited higher alkaline phosphatase (ALP) activity and increased Type-I collagen secretion and fibre deposition into the extracellular matrix. Proliferative and collagen deposition properties were more evident for cells grown in cements doped with Sr. The in vivo osteoconductive propertiesof the ZnCPC and ZnSrCPC cements were also pursued. Histological and histomorphometric analyses were performed at 1 and 2 months after implantation, using carbonated apatite cement (Norian SRS) as control. There was no evidence of cement-induced adverse foreign body reactions, and furthermore ZnCPC and ZnSrCPC cements revealed better in vivo performance in comparison to the control apatite cement. Additionally, the presence of both zinc and strontium resulted in the highest rate of new bone formation. These novel results indicate that the investigated ZnCPC and ZnSrCPC cements are both biocompatible and osteoconductive, being good candidate materials to use as bone substitutes. PMID:20821372

  18. Evaluation of bone substitutes for treatment of peri-implant bone defects: biomechanical, histological, and immunohistochemical analyses in the rabbit tibia

    PubMed Central

    2016-01-01

    Purpose We sought to evaluate the effectiveness of bone substitutes in circumferential peri-implant defects created in the rabbit tibia. Methods Thirty rabbits received 45 implants in their left and right tibia. A circumferential bone defect (6.1 mm in diameter/4 mm depth) was created in each rabbit tibia using a trephine bur. A dental implant (4.1 mm × 8.5 mm) was installed after the creation of the defect, providing a 2-mm gap. The bone defect gaps between the implant and the bone were randomly filled according to the following groups: blood clot (CO), particulate Bio-Oss® (BI), and Bio-Oss® Collagen (BC). Ten animals were euthanized after periods of 15, 30, and 60 days. Biomechanical analysis by means of the removal torque of the implants, as well as histologic and immunohistochemical analyses for protein expression of osteocalcin (OC), Runx2, OPG, RANKL, and TRAP were evaluated. Results For biomechanics, BC showed a better biological response (61.00±15.28 Ncm) than CO (31.60±14.38 Ncm) at 30 days. Immunohistochemical analysis showed significantly different OC expression in CO and BC at 15 days, and also between the CO and BI groups, and between the CO and BC groups at 60 days. After 15 days, Runx2 expression was significantly different in the BI group compared to the CO and BC groups. RANKL expression was significantly different in the BI and CO groups and between the BI and BC groups at 15 days, and also between the BI and CO groups at 60 days. OPG expression was significantly higher at 60 days postoperatively in the BI group than the CO group. Conclusions Collectively, our data indicate that, compared to CO and BI, BC offered better bone healing, which was characterized by greater RUNX2, OC, and OPG immunolabeling, and required greater reversal torque for implant removal. Indeed, along with BI, BC presents promising biomechanical and biological properties supporting its possible use in osteoconductive grafts for filling peri-implant gaps. PMID:27382506

  19. The in vitro elution characteristics of antifungal-loaded PMMA bone cement and calcium sulfate bone substitute.

    PubMed

    Grimsrud, Christopher; Raven, Raymond; Fothergill, A W; Kim, Hubert T

    2011-08-01

    The use of antimicrobial-loaded delivery vehicles, most often as antibiotic beads, is common practice for the treatment of deep musculoskeletal infections. The elution of antibacterial drugs from various bone cements has been extensively studied. However, much less is known about the elution of other antimicrobials from these materials. In particular, the use of this approach for fungal infections has not been well studied despite growing concern about these difficult-to-treat organisms. Voriconazole is a broad-spectrum and highly effective antifungal that has been used in the treatment of resistant fungal pathogens. We examined the in vitro elution characteristics of voriconazole from nonabsorbable polymethylmethacrylate (PMMA) beads and from absorbable calcium sulfate beads. Voricanazole-containing beads were immersed in a 5-mL bath of phosphate-buffered saline at room temperature and placed on an orbital shaker. Eluent samples were collected over the course of 2 weeks. Concentrations of the antifungal drug in solution were measured using high-performance liquid chromatography. To verify biologic activity of the eluted antifungal, collected samples were also tested against control yeasts. We found that samples collected out to 2 weeks contained relatively high voriconazole concentrations and enough active antifungal activity to inhibit growth of the control yeasts. These data demonstrate that voriconazole retains its antifungal activity when mixed into either PMMA or calcium sulfate beads, and elutes out of beads at biologically effective concentrations over a time period of at least 2 weeks. Therefore, incorporation of voriconazole into either absorbable or nonabsorbable beads appears to be a reasonable strategy for the local delivery of a potent, broad-spectrum antifungal agent to an infected wound bed. PMID:21815580

  20. Histomorphometric evaluation of strontium-containing nanostructured hydroxyapatite as bone substitute in sheep.

    PubMed

    Machado, Callinca Paolla Gomes; Sartoretto, Suelen Cristina; Alves, Adriana Terezinha Neves Novellino; Lima, Inayá Barbosa Correa; Rossi, Alexandre Malta; Granjeiro, José Mauro; Calasans-Maia, Mônica Diuana

    2016-01-01

    The aim of this study is to evaluate the biocompatibility and osteoconductivity in surgical defects of sheep tibias filled with 1% strontium-containing nanostructured hydroxyapatite microspheres (SrHA), stoichiometric hydroxyapatite without strontium microspheres (HA), or blood clots. Santa Ines sheep were subjected to three perforations on the medial side of the left tibia. The biomaterials were characterized by X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) before implantation and by X-Ray Microfluorescence (µFRX) and Scanning Electron Microscopy (SEM) after sheep tibias implantation. Surgical defects were filled with blood clots (control), SrHA (Group 1) or HA (Group 2). After 30 days, 5-µm bone blocks were obtained for histological evaluation, and the blocks obtained from 1 animal were embedded in methylmethacrylate for undecalcified sections. Mononuclear inflammatory infiltrate remained mild in all experimental groups. Giant cells were observed surrounding biomaterials particles of both groups and areas of bone formation were detected in close contact with biomaterials. All groups showed newly formed bone from the periphery to the center of the defects, which the control, HA and SrHA presented 36.4% (± 21.8), 31.2% (± 14.7) and 26.2% (± 12.9) of newly formed bone density, respectively, not presenting statistical differences. In addition, the connective tissue density did not show any significant between groups. The SrHA showing a higher volume density of biomaterial (51.2 ± 14.1) present in the defect compared to HA (32.6 ± 8.5) after 30 days (p = 0.03). Microspheres containing 1% SrHA or HA can be considered biocompatible, have osteoconductive properties and may be useful biomaterials for clinical applications. PMID:27191738

  1. Evaluation of strontium introduced apatite cement as the injectable bone substitute developments.

    PubMed

    Sekine, Kazumitsu; Sakama, Minoru; Hamada, Kenichi

    2013-01-01

    We have developed bone cement introducing Strontium (Sr) to promote early bone regeneration. To prolong the release duration of Sr, we applied inorganic Sr filler for containing into the cement powder. The purpose of this study is to evaluate the mechanical properties, crystallinic properties, and ion release activities, especially Sr anion, of this cement. Alpha-TCP powder was mixed with Sr filler, with 0.1wt%, 0.5wt%, 1.0wt%, and 5.0wt%. These were mixed with mixing liquid and formed for each test. They were incubated and crystalized in 95% moisture for 1 week. The mechanical properties were studied by the compression, the diametral tensile strength and 4-point vending. Tested specimens were evaluated by X-ray diffraction(XRD) and scanning electron microscopic(SEM) imaging. The ion release behaviors were measured by inductively coupled plasma mass spectrometry(ICP-MS). The mechanical properties were increased in consistency of filler, but decreased in some samples because of declining the apatite matrix. And the Sr release showed interesting results as the sequential resource of Sr. By adjusting the mixing ratio or considering the application of these Sr releasable cements, this material would show good performance by its strength and longer Sr release for bone regeneration. PMID:24109823

  2. Mineralization of Synthetic Polymer Scaffolds: A Bottom-upApproach for the Development of Artificial Bone

    SciTech Connect

    Song, Jie; Viengkham, Malathong; Bertozzi, Carolyn R.

    2004-09-27

    The controlled integration of organic and inorganic components confers natural bone with superior mechanical properties. Bone biogenesis is thought to occur by templated mineralization of hard apatite crystals by an elastic protein scaffold, a process we sought to emulate with synthetic biomimetic hydrogel polymers. Crosslinked polymethacrylamide and polymethacrylate hydrogels were functionalized with mineral-binding ligands and used to template the formation of hydroxyapatite. Strong adhesion between the organic and inorganic materials was achieved for hydrogels functionalized with either carboxylate or hydroxy ligands. The mineral-nucleating potential of hydroxyl groups identified here broadens the design parameters for synthetic bone-like composites and suggests a potential role for hydroxylated collagen proteins in bone mineralization.

  3. SU-C-213-01: 3D Printed Patient Specific Phantom Composed of Bone and Soft Tissue Substitute Plastics for Radiation Therapy

    SciTech Connect

    Ehler, E; Sterling, D; Higgins, P

    2015-06-15

    Purpose: 3D printed phantoms constructed of multiple tissue approximating materials could be useful in both clinical and research aspects of radiotherapy. This work describes a 3D printed phantom constructed with tissue substitute plastics for both bone and soft tissue; air cavities were included as well. Methods: 3D models of an anonymized nasopharynx patient were generated for air cavities, soft tissues, and bone, which were segmented by Hounsfield Unit (HU) thresholds. HU thresholds were chosen to define air-to-soft tissue boundaries of 0.65 g/cc and soft tissue-to-bone boundaries of 1.18 g/cc based on clinical HU to density tables. After evaluation of several composite plastics, a bone tissue substitute was identified as an acceptable material for typical radiotherapy x-ray energies, composed of iron and PLA plastic. PET plastic was determined to be an acceptable soft tissue substitute. 3D printing was performed on a consumer grade dual extrusion fused deposition model 3D printer. Results: MVCT scans of the 3D printed heterogeneous phantom were acquired. Rigid image registration of the patient and the 3D printed phantom scans was performed. The average physical density of the soft tissue and bone regions was 1.02 ± 0.08 g/cc and 1.39 ± 0.14 g/cc, respectively, for the patient kVCT scan. In the 3D printed phantom MVCT scan, the average density of the soft tissue and bone was 1.01 ± 0.09 g/cc and 1.44 ± 0.12 g/cc, respectively. Conclusion: A patient specific phantom, constructed of heterogeneous tissue substitute materials was constructed by 3D printing. MVCT of the 3D printed phantom showed realistic tissue densities were recreated by the 3D printing materials. Funding provided by intra-department grant by University of Minnesota Department of Radiation Oncology.

  4. Posterolateral spinal fusion in a rabbit model using a collagen–mineral composite bone graft substitute

    PubMed Central

    Vizesi, F.; Cornwall, G. B.; Bell, D.; Oliver, R.; Yu, Y.

    2009-01-01

    Choosing the appropriate graft material to participate in the healing process in posterolateral spinal fusion continues to be a challenge. Combining synthetic graft materials with bone marrow aspirate (BMA) and autograft is a reasonable treatment option for surgeons to potentially reduce or replace the need for autograft. FormaGraft, a bone graft material comprising 12% bovine-derived collagen and 88% ceramic in the form of hydroxyapatite (HAp) and beta tricalcium phosphate (β-TCP) was evaluated in three possible treatment modalities for posterior spinal fusion in a standard rabbit model. These three treatment groups were FormaGraft alone, FormaGraft soaked in autogenous BMA, and FormaGraft with BMA and iliac crest autograft. No statistically demonstrable benefits or adverse effects of the addition of BMA were found in the current study based on macroscopic, radiology or mechanical data. This may reflect, in part, the good to excellent results of the collagen HA/TCP composite material alone in a well healing bony bed. Histology did, however, reveal a benefit with the use of BMA. Combining FormaGraft with autograft and BMA achieved results equivalent to autograft alone. The mineral and organic nature of the material provided a material that facilitated fusion between the transverse processes in a standard preclinical posterolateral fusion model. PMID:19475437

  5. Bioactive calcium sulfate/magnesium phosphate cement for bone substitute applications.

    PubMed

    Yang, Guangyong; Liu, Jianli; Li, Fan; Pan, Zongyou; Ni, Xiao; Shen, Yue; Xu, Huazi; Huang, Qing

    2014-02-01

    A novel calcium sulfate/magnesium phosphate cement (CSMPC) composite was prepared and studied in the present work. The physical properties including the phases, the microstructures, the setting properties and the compressive strengths of the CSMPCs were studied. The bio-performances of the CSMPCs were comprehensively evaluated using in vitro simulated body fluid (SBF) method and in vitro cell culture. The dependence of the physical and chemical properties of the CSMPC on its composition and microstructure was studied in detail. It is found that the CSMPC composites exhibited mediate setting times (6-12 min) compared to the calcium sulfate (CS) and the magnesium phosphate cement (MPC). They showed an encapsulation structure in which the unconverted hexagonal prism CSH particles were embedded in the xerogel-like MPC matrix. The phase compositions and the mechanical properties of the CSMPCs were closely related to the content of MPC and the hardening process. The CSMPCs exhibited excellent bioactivity and good biocompatibility to support the cells to attach and proliferate on the surface. The CSMPC composite has the potential to serve as bone grafts for the bone regeneration. PMID:24411353

  6. Tissue reactions to particles of bone-substitute materials in intraosseous and heterotopic sites in rats: discrimination of osteoinduction, osteocompatibility, and inflammation.

    PubMed

    Eid, K; Zelicof, S; Perona, B P; Sledge, C B; Glowacki, J

    2001-09-01

    Two rat models were used to characterize tissue-specific reactions to particles of bone-substitute materials: one for osteocompatibility in a healing tibial wound and the other in a heterotopic, subcutaneous site. Small, unicortical tibial wounds in rats healed spontaneously, beginning with the rapid proliferation of intramedullary woven bone. That temporary bone was resorbed by osteoclasts and finally, the cortical wound was healed with lamellar bone and the medullary space was repopulated with marrow. When various particulate materials were implanted into fresh wounds, three types of reactions were observed. (1) Demineralized bone powder (DBP) and non-resorbable calcium phosphate (nrCP) were incorporated into the reactive medullary and cortical bone. (2) Polymethylmetlhacrylate (PMMA) particles were surrounded with a fibrous layer, but did not impair bone healing. (3) Polyethylene (PE) shards and resorbable calcium phosphates (rCPs) were inflammatory and inhibited osseous repair. Subcutaneous sites showed osteoinductive, fibrotic, or inflammatory responses to these materials. Only DBP induced endochondral osteogenesis subcutaneously. The nrCP evoked a fibrous reaction. In contrast, rCPs, PMMA, and PE shards generated inflammatory reactions with each particle being surrounded by fibrous tissue and large multinucleated giant cells. In conclusion, only DBP showed osteoinductive as well as osteocompatible properties. The nrCP was osteocompatible. The rCPs stimulated various degrees of inflammatory responses. PMMA was osteocompatible and did not interfere with the bone healing process. PE was not osteocompatible and generated foreign body reactions in both sites. Use of the two sites distinguishes osteoinductive, osteocompatible, and inflammatory properties of particles of bone-substitute materials. PMID:11562148

  7. Comparison of three calcium phosphate bone graft substitutes from biomechanical, histological, and crystallographic perspectives using a rat posterolateral lumbar fusion model.

    PubMed

    Hu, Ming-Hsien; Lee, Pei-Yuan; Chen, Wen-Cheng; Hu, Jin-Jia

    2014-12-01

    This study evaluated the effectiveness of three calcium phosphate bone graft substitutes with different chemical compositions on spinal fusion using a rat posterolateral lumbar fusion model. Specifically, two recently developed non-dispersive tetracalcium phosphate/dicalcium phosphate anhydrous-based calcium phosphate cements (CPCs), namely a CPC consisting of equimolar amounts of the two compounds (nd-CPC) and a CPC consisting of a two-fold greater amount of dicalcium phosphate anhydrous (DCP-rich CPC), were compared with a commercial calcium phosphate bone graft (c-CPG) consisting of hydroxyapatite (60%) and β-tricalcium phosphate (40%). Single-level posterolateral lumbar fusion was performed at the L4-L5 vertebrae in fifteen adult rats (n=5 for each group). Spinal fusion was evaluated with radiographs, manual palpation, mechanical testing, micro-CT, and histology 8 weeks post-surgery. In particular, the crystallographic phases in the three substitutes were identified before and 8 weeks after their implantation. Manual palpation revealed stable constructs in nearly all of the spine specimens. The stiffness and bending load of fused spines in the two CPC groups were comparable to those in the c-CPG group. The radiographs specifically revealed implant resorption and bone remodeling in the DCP-rich CPC group. Analysis of 3D micro-CT images revealed that the bone volume ratio in the DCP-rich CPC group was significantly greater than those in the nd-CPC and c-CPG groups. Histology showed that the DCP-rich CPC group exhibited the highest degree of bone regeneration and osseointegration. Notably, DCP-rich CPC led to a pronounced phase transformation, generating the greatest amount of poorly crystalline apatite among the three groups, which together with adequate resorption may explain the aforementioned positive findings. We therefore conclude that of the bone graft substitutes considered, DCP-rich CPC has the greatest potential to be used in spinal fusion. PMID

  8. Biofabrication of a PLGA-TCP-based porous bioactive bone substitute with sustained release of icaritin.

    PubMed

    Xie, Xin-Hui; Wang, Xin-Luan; Zhang, Ge; He, Yi-Xin; Leng, Yang; Tang, Ting-Ting; Pan, Xiaohua; Qin, Ling

    2015-08-01

    A phytomolecule, icaritin, has been identified and shown to be osteopromotive for the prevention of osteoporosis and osteonecrosis. This study aimed to produce a bioactive poly (l-lactide-co-glycolide)-tricalcium phosphate (PLGA-TCP)-based porous scaffold incorporating the osteopromotive phytomolecule icaritin, using a fine spinning technology. Both the structure and the composition of icaritin-releasing PLGA-TCP-based scaffolds were evaluated by scanning electron microscopy (SEM). The porosity was quantified by both water absorption and micro-computed tomography (micro-CT). The mechanical properties were evaluated using a compression test. In vitro release of icaritin from the PLGA-TCP scaffold was quantified by high-performance liquid chromatography (HPLC). The attachment, proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) on the composite scaffold were evaluated. Both an in vitro cytotoxicity test and an in vivo test via muscular implantation were conducted to confirm the scaffold's biocompatibility. The results showed that the PLGA-TCP-icaritin composite scaffold was porous, with interconnected macro- (about 480 µm) and micropores (2-15 µm). The mechanical properties of the PLGA-TCP-icaritin scaffold were comparable with those of the pure PLGA-TCP scaffold, yet was spinning direction-dependent. Icaritin content was detected in the medium and increased with time. The PLGA-TCP-icaritin scaffold facilitated the attachment, proliferation and osteogenic differentiation of BMSCs. In vitro cytotoxicity test and in vivo intramuscular implantation showed that the composite scaffold had no toxicity with good biocompatibility. In conclusion, an osteopromotive phytomolecule, icaritin, was successfully incorporated into PLGA-TCP to form an innovative porous composite scaffold with sustained release of osteopromotive icaritin, and this scaffold had good biocompatibility and osteopromotion, suggesting its potential for orthopaedic

  9. Fabrication of calcium phosphate–calcium sulfate injectable bone substitute using hydroxy-propyl-methyl-cellulose and citric acid

    PubMed Central

    Thai, Van Viet

    2010-01-01

    In this study, an injectable bone substitute (IBS) consisting of citric acid, chitosan, and hydroxyl propyl methyl cellulose (HPMC) as the liquid phase and tetra calcium phosphate (TTCP), dicalcium phosphate dihydrate (DCPD) and calcium sulfate dehydrate (CSD, CaSO4·2H2O) powders as the solid phase, were fabricated. Two groups were classified based on the percent of citric acid in the liquid phase (20, 40 wt%). In each groups, the HPMC percentage was 0, 2, and 4 wt%. An increase in compressive strength due to changes in morphology was confirmed by scanning electron microscopy images. A good conversion rate of HAp at 20% citric acid was observed in the XRD profiles. In addition, HPMC was not obviously affected by apatite formation. However, both HPMC and citric acid increased the compressive strength of IBS. The maximum compressive strength for IBS was with 40% citric acid and 4% HPMC after 14 days of incubation in 100% humidity at 37°C. PMID:20333539

  10. Fabrication of calcium phosphate-calcium sulfate injectable bone substitute using hydroxy-propyl-methyl-cellulose and citric acid.

    PubMed

    Thai, Van Viet; Lee, Byong-Taek

    2010-06-01

    In this study, an injectable bone substitute (IBS) consisting of citric acid, chitosan, and hydroxyl propyl methyl cellulose (HPMC) as the liquid phase and tetra calcium phosphate (TTCP), dicalcium phosphate dihydrate (DCPD) and calcium sulfate dehydrate (CSD, CaSO4 x 2H2O) powders as the solid phase, were fabricated. Two groups were classified based on the percent of citric acid in the liquid phase (20, 40 wt%). In each groups, the HPMC percentage was 0, 2, and 4 wt%. An increase in compressive strength due to changes in morphology was confirmed by scanning electron microscopy images. A good conversion rate of HAp at 20% citric acid was observed in the XRD profiles. In addition, HPMC was not obviously affected by apatite formation. However, both HPMC and citric acid increased the compressive strength of IBS. The maximum compressive strength for IBS was with 40% citric acid and 4% HPMC after 14 days of incubation in 100% humidity at 37 degrees C. PMID:20333539

  11. Influence of artificially-induced porosity on the compressive strength of calcium phosphate bone cements.

    PubMed

    Mouzakis, Dionysios; Zaoutsos, Stefanos Polymeros; Bouropoulos, Nikolaos; Rokidi, Stamatia; Papanicolaou, George

    2016-07-01

    The biological and mechanical nature of calcium phosphate cements (CPC's) matches well with that of bone tissues, thus they can be considered as an appropriate environment for bone repair as bone defect fillers. The current study focuses on the experimental characterization of the mechanical properties of CPCs that are favorably used in clinical applications. Aiming on evaluation of their mechanical performance, tests in compression loading were conducted in order to determine the mechanical properties of the material under study. In this context, experimental results occurring from the above mechanical tests on porous specimens that were fabricated from three different porous additives, namely albumin, gelatin and sodium alginate, are provided, while assessment of their mechanical properties in respect to the used porous media is performed. Additionally, samples reinforced with hydroxyapatite crystals were also tested in compression and the results are compared with those of the above tested porous CPCs. The knowledge obtained allows the improvement of their biomechanical properties by controlling their structure in a micro level, and finds a way to compromise between mechanical and biological response. PMID:26945808

  12. Characterization and cytocompatibility of a new injectable multiphasic bone substitute based on a combination of polysaccharide gel-coated OSPROLIFE(®) HA/TTCP granules and bone marrow concentrate.

    PubMed

    Pierini, Michela; Lucarelli, Enrico; Duchi, Serena; Prosperi, Susanna; Preve, Eleonora; Piccinini, Marzio; Bucciotti, Francesco; Donati, Davide

    2016-07-01

    The purpose of this study was to examine the in vitro cytocompatibility of a novel injectable multiphasic bone substitute (MBS) based on polysaccharide gel-coated OSPROLIFE(®) hydroxyapatite (HA)/tetracalcium phosphate (TTCP) granules combined with bone marrow concentrate (BMC). Polysaccharide gel-coated granules loaded in syringe were combined with BMC diluted in ionic crosslinking solution. The product was then maintained in culture to investigate the cytocompatibility, distribution, and osteogenic differentiation function of cells contained in the BMC. The in vitro cytocompatibility was assessed after 0, 24, and 96 h from the injectable MBS preparation using the LIVE/DEAD(®) staining kit. The results highlighted that cells remained viable after combination with the polysaccharide gel-coated granules; also, viability was maintained over time. The distribution of the cells in the product, observed using confocal microscopy, showed viable cells immersed in the polysaccharide gel formed between the granules after ionic crosslinking. The mesenchymal stromal cells (MSC) contained in the injectable MBS, the basic elements for bone tissue regeneration, were able to differentiate toward osteoblasts, producing an osteogenic matrix as evidenced by alizarin red-s (AR-S) staining. In conclusion, we found that the injectable MBS may have the potential to be used as a bone substitute by applying a "one-step" procedure in bone tissue engineering applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 894-902, 2016. PMID:25952003

  13. Development of a bone substitute material based on alpha-tricalcium phosphate scaffold coated with carbonate apatite/poly-epsilon-caprolactone.

    PubMed

    Bang, L T; Ramesh, S; Purbolaksono, J; Long, B D; Chandran, Hari; Ramesh, S; Othman, R

    2015-08-01

    Interconnected porous tricalcium phosphate ceramics are considered to be potential bone substitutes. However, insufficient mechanical properties when using tricalcium phosphate powders remain a challenge. To mitigate these issues, we have developed a new approach to produce an interconnected alpha-tricalcium phosphate (α-TCP) scaffold and to perform surface modification on the scaffold with a composite layer, which consists of hybrid carbonate apatite / poly-epsilon-caprolactone (CO3Ap/PCL) with enhanced mechanical properties and biological performance. Different CO3Ap combinations were tested to evaluate the optimal mechanical strength and in vitro cell response of the scaffold. The α-TCP scaffold coated with CO3Ap/PCL maintained a fully interconnected structure with a porosity of 80% to 86% and achieved an improved compressive strength mimicking that of cancellous bone. The addition of CO3Ap coupled with the fully interconnected microstructure of the α-TCP scaffolds coated with CO3Ap/PCL increased cell attachment, accelerated proliferation and resulted in greater alkaline phosphatase (ALP) activity. Hence, our bone substitute exhibited promising potential for applications in cancellous bone-type replacement. PMID:26225725

  14. Comparison of microstructures and phase compositions of artificial and bone-derived hydroxyapatites by transmission electron microscopy and energy dispersive electron spectroscopy.

    PubMed

    Lee, Jong Kook

    2014-11-01

    Biological problems associated with sintered implants fabricated from artificially synthesized hydroxyapatite include selective dissolution at grain boundaries, microstructural disintegration in the body due to particle loosening, and slow crack growth at the implant surface. In addition, mechanical degradation has been shown to be significant, thus limiting their application as load-bearing medical implants. In contrast, bone-derived hydroxyapatite bioceramics have highly dissolution-resistant properties and excellent biocompatibility in the body. They are also easy to synthesize by thermal decomposition of animal bone. In this study, microstructural observations and crystal phase analysis of bone-derived hydroxyapatite were investigated by TEM and EDS using sintered hydroxyapatite samples. In addition, a comparative investigation into elemental distributions and the microstructures of artificial hydroxyapatite, bovine, and tuna bone-derived hydroxyapatites was performed. Bone-derived HA consists mainly of HA and a small amount of MgO. Hot-pressed HA compacts showed homogeneous microstructures and densities of 95-97%, however, grain sizes and microstructures varied with the starting powders. PMID:25958617

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    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.

  16. [Hydroxyapatite bone substitute (Ostim) in sinus floor elevation. Maxillary sinus floor augmentation: bone regeneration by means of a nanocrystalline in-phase hydroxyapatite (Ostim)].

    PubMed

    Smeets, Ralf; Grosjean, Maurice B; Jelitte, Gerd; Heiland, Max; Kasaj, Adrian; Riediger, Dieter; Yildirim, Murat; Spiekermann, Hubertus; Maciejewski, Oliver

    2008-01-01

    The range of bone regeneration materials suitable for maxillar bone augmentation has increased steadily in the past few years and there is now a wide variety of materials being used. In the present case report, we analyzed the state of bone regeneration after sinus floor augmentation using a nanocrystalline in-phase synthetic anorganic hydroxyapatite bone grafting material (Ostim). A 60-year-old female patient underwent maxillary sinus floor elevation and the cavity was filled with Ostim three years before. Actually, she presented herself with loosening of the dental implant at position 17, as a result of parafunction. At the time of the insertion of a second implant at position 17, bone samples were taken by using a trepan drilling device from the previously augmented area. These samples were analyzed histologically to determine the extent of bone remodeling around the deposits of Ostim. We found that the Ostim deposits were surrounded largely by woven bone and, in parts, by lamellar bone and had facilitated osteoconductive bone regeneration. The adjacent implant, at position 16, which beared a crown exposed to proper biting forces without parafunction, showed proper clinical and radiological characteristics of complete and firm integration into the area which was also filled with Ostim three years ago. We conclude that the use of the nanocrystalline hydroxyapatite Ostim with its stable volume properties appears to be suitable for maxillary sinus floor augmentation. Furthermore, we even found osteoconductive bone regeneration under Ostim near the site of the loosened implant. PMID:18422056

  17. The effect of polystyrene sodium sulfonate grafting on polyethylene terephthalate artificial ligaments on in vitro mineralisation and in vivo bone tissue integration.

    PubMed

    Vaquette, Cédryck; Viateau, Véronique; Guérard, Sandra; Anagnostou, Fani; Manassero, Mathieu; Castner, David G; Migonney, Véronique

    2013-09-01

    This study investigates the impact of polystyrene sodium sulfonate (PolyNaSS) grafting onto the osseo-integration of a polyethylene terephthalate artificial ligament (Ligament Advanced Reinforcement System, LARS™) used for Anterior Cruciate Ligament (ACL). The performance of grafted and non-grafted ligaments was assessed in vitro by culturing human osteoblasts under osteogenic induction and this demonstrated that the surface modification was capable of up-regulating the secretion of ALP and induced higher level of mineralisation as measured 6 weeks post-seeding by Micro-Computed Tomography. Grafted and non-grafted LARS™ were subsequently implanted in an ovine model for ACL reconstruction and the ligament-to-bone interface was evaluated by histology and biomechanical testings 3 and 12 months post-implantation. The grafted ligaments exhibited more frequent direct ligament-to-bone contact and bone formation in the core of the ligament at the later time point than the non-grafted specimens, the grafting also significantly reduced the fibrous encapsulation of the ligament 12 months post-implantation. However, this improved osseo-integration was not translated into a significant increase in the biomechanical pull-out loads. These results provide evidences that PolyNaSS grafting improved the osseo-integration of the artificial ligament within the bone tunnels. This might positively influence the outcome of the surgical reconstructions, as higher ligament stability is believed to limit micro-movement and therefore permits earlier and enhanced healing. PMID:23790438

  18. Effect of a carbonated HAP/β-glucan composite bone substitute on healing of drilled bone voids in the proximal tibial metaphysis of rabbits.

    PubMed

    Borkowski, Leszek; Pawłowska, Marta; Radzki, Radosław P; Bieńko, Marek; Polkowska, Izabela; Belcarz, Anna; Karpiński, Mirosław; Słowik, Tymoteusz; Matuszewski, Łukasz; Ślósarczyk, Anna; Ginalska, Grażyna

    2015-08-01

    A novel elastic hydroxyapatite-based composite of high surgical handiness has been developed. Its potential application in orthopedics as a filler of bone defects has been studied. The biomaterial was composed of carbonated hydroxyapatite (CHAP) granules and polysaccharide polymer (β-1,3-glucan). Cylinders of 4mm in diameter and 6mm in length were implanted into bone cavities created in the proximal metaphysis of tibiae of 24 New Zealand white rabbits. 18 sham-operated animals were used as controls. After 1, 3 or 6 months, the rabbits were euthanized, the bones were harvested and subjected to analysis. Radiological images and histological sections revealed integration of implants with bone tissue with no signs of graft rejection. Peripheral quantitative computed tomography (pQCT) indicated the stimulating effect of the biomaterial on bone formation and mineralization. Densitometry (DXA) analysis suggested that biomineralization of bones was preceded by bioresorption and gradual disappearance of porous ceramic granules. The findings suggest that the CHAP-glucan composite material enables regeneration of bone tissue and could serve as a bone defect filler. PMID:26042691

  19. Hemozymes peroxidase activity of artificial hemoproteins constructed from the Streptomyces lividans xylanase A and iron(III)-carboxy-substituted porphyrins.

    PubMed

    Ricoux, Rémy; Dubuc, Roger; Dupont, Claude; Marechal, Jean-Didier; Martin, Aurore; Sellier, Marion; Mahy, Jean-Pierre

    2008-04-01

    To develop artificial hemoproteins that could lead to new selective oxidation biocatalysts, a strategy based on the insertion of various iron-porphyrin cofactors into Xylanase A (Xln10A) was chosen. This protein has a globally positive charge and a wide enough active site to accommodate metalloporphyrins that possess negatively charged substituents such as microperoxidase 8 (MP8), iron(III)-tetra-alpha4-ortho-carboxyphenylporphyrin (Fe(ToCPP)), and iron(III)-tetra-para-carboxyphenylporphyrin (Fe(TpCPP)). Coordination chemistry of the iron atom and molecular modeling studies showed that only Fe(TpCPP) was able to insert deeply into Xln10A, with a KD value of about 0.5 microM. Accordingly, Fe(TpCPP)-Xln10A bound only one imidazole molecule, whereas Fe(TpCPP) free in solution was able to bind two, and the UV-visible spectrum of the Fe(TpCPP)-Xln10A-imidazole complex suggested the binding of an amino acid of the protein on the iron atom, trans to the imidazole. Fe(TpCPP)-Xln10A was found to have peroxidase activity, as it was able to catalyze the oxidation of typical peroxidase cosubstrates such as guaiacol and o-dianisidine by H2O2. With these two cosubstrates, the KM value measured with the Fe(TpCPP)-Xln10A complex was higher than those values observed with free Fe(TpCPP), probably because of the steric hindrance and the increased hydrophobicity caused by the protein around the iron atom of the porphyrin. The peroxidase activity was inhibited by imidazole, and a study of the pH dependence of the oxidation of o-dianisidine suggested that an amino acid with a pKA of around 7.5 was participating in the catalysis. Finally, a very interesting protective effect against oxidative degradation of the porphyrin was provided by the protein. PMID:18324756

  20. Fabrication of Bone like Composites Material and Evaluation of its Ossiferous Ability

    NASA Astrophysics Data System (ADS)

    Hisamori, Noriyuki; Kimura, Megumi; Morisue, Hikaru; Matsumoto, Morio; Toyama, Yoshiaki

    Many kinds of materials are currently used as artificial bone substitutes. Hydroxyapatite (HA), the same as the main inorganic component of bone, is one of commonly used bio-ceramics and has excellent bioactivity and biocompatibility with hard tissues. However, it has problems as the bone filler or bone tissue-engineering scaffold due to low fracture toughness and low degradation rate. Recently, biodegradable materials for bone tissue have been developed to respond the requirement. Collagen, the same as the main organic component of bone, is biocompatible, biodegradable and promotes cell adhesion. A composites associated with HA is expected to have early osteoconduction and bone replacement ability. The present study was to fabricate bone-like composites consist of HA and collagen. Besides the ossiferous ability of the material in vivo is evaluated by using rabbits. Bone-like composites were successfully fabricated in this study, associating the collagen with HA. And the composites presented good osteoconductive and bone replacement potential.

  1. Behavior of POP-calcium carbonate hydrogel as bone substitute with controlled release capability: a study in rat.

    PubMed

    Dewi, Anne Handrini; Ana, Ika Dewi; Wolke, Joop; Jansen, John

    2015-10-01

    Gypsum or calcium sulfate (CS) or plaster of Paris (POP) is considered as a fast degradable material that usually resorbs before the bone defect area is completely filled by new bone. In this study, the incorporation of CaCO3 hydrogel into POP in different compositions was proposed to enhance the bone biological activity of POP and to decrease its degradability. The mechanical and degradation properties of the various materials were characterized by in vitro analysis. Subsequently, the materials were inserted into cylindrically sized bone defects as created into the femoral condyle of rats and left in situ for 1, 4, and 8 weeks. Histological analysis of the retrieved specimens indicated that the addition of CaCO3 hydrogel into POP increased bone formation, angiogenesis and collagen density and resulted into faster bone formation and maturation. It was also confirmed that the degradation rate of the POP decreased by the addition of CaCO3 hydrogel. The in vivo findings did corroborate with the in vitro analysis. In conclusion, the incorporation of CaCO3 hydrogel provides a promising technology to improve the properties of POP, the oldest biomaterial used for bone grafting. PMID:25809017

  2. Applicability of cranial models in urethane resin and foam as a substitute for bone: are synthetic materials reliable?

    PubMed

    Muccino, Enrico; Porta, Davide; Magli, Francesca; Cigada, Alfredo; Sala, Remo; Gibelli, Daniele; Cattaneo, Cristina

    2013-09-01

    As literature is poor in functional synthetic cranial models, in this study, synthetic handmade models of cranial vaults were produced in two different materials (a urethane resin and a self-hardening foam), from multiple bone specimens (eight original cranial vaults: four human and four swine), in order to test their resemblance to bone structure in behavior, during fracture formation. All the vaults were mechanically tested with a 2-kg impact weight and filmed with a high-speed camera. Fracture patterns were homogeneous in all swine vaults and heterogeneous in human vaults, with resin fractures more similar to bone fractures. Mean fracture latency time extrapolated by videos were of 0.75 msec (bone), 1.5 msec (resin), 5.12 msec (foam) for human vaults and of 0.625 msec (bone), 1.87 msec (resin), 3.75 msec (foam) for swine vaults. These data showed that resin models are more similar to bone than foam reproductions, but that synthetic material may behave quite differently from bone as concerns fracture latency times. PMID:23865474

  3. Complex reconstruction of the dorsal hand using the induced membrane technique associated with bone substitute: A case report

    PubMed Central

    Guillier, David; Rizzi, Philippe; De Taddeo, Alice; Henault, Benoit; Tchurukdichian, Alain; Zwetyenga, Narcisse

    2016-01-01

    Introduction High-energy trauma of the hand often causes tissue loss involving bone, tendon and skin and is sometimes accompanied by devascularization of digits. Bone stabilization is the first step in the management of such injuries. Materials and methods A young patient presented composite tissue loss of the dorsum of his right (dominant) hand following an accident with a surface planer. Tissue loss involved the diaphyses of the first 4 metacarpals, tendons and skin with almost complete amputation of the 3rd finger. Bone stabilization comprised osteosynthesis using pins associated with cement to fill the bone defect. Hunter tendon rods were used for tendon repair and a pedicle groin flap (McGregor) was used to achieve skin coverage. The cement was replaced with autologous cortico-cancellous bone graft combined with bone paste (Nanostim) 3 months after the cement stabilization. Results Eleven months after the accident, the patient was able to return to work as a carpenter. Pinch and Grasp strength in the injured hand were half that in the contralateral hand, but there was no loss of sensitivity. Mobility was very satisfactory with a Kapandji score of 9 and a mean TAM of 280°. The patient can write, open a bottle and does not feel limited for everyday activities. Radiographically, the bone of the 3 reconstructed metacarpals appears consolidated. Conclusion The induced membrane technique allowed the reconstruction of small bone deficits in the long bones of the hand in a two-step procedure, the first step taking place in an emergency context of composite tissue trauma. PMID:27077131

  4. Magnetic Hydroxyapatite Bone Substitutes to Enhance Tissue Regeneration: Evaluation In Vitro Using Osteoblast-Like Cells and In Vivo in a Bone Defect

    PubMed Central

    Panseri, Silvia; Cunha, Carla; D'Alessandro, Teresa; Sandri, Monica; Russo, Alessandro; Giavaresi, Gianluca; Marcacci, Maurilio; Hung, Clark T.; Tampieri, Anna

    2012-01-01

    In case of degenerative disease or lesion, bone tissue replacement and regeneration is an important clinical goal. In particular, nowadays, critical size defects rely on the engineering of scaffolds that are 3D structural supports, allowing cellular infiltration and subsequent integration with the native tissue. Several ceramic hydroxyapatite (HA) scaffolds with high porosity and good osteointegration have been developed in the past few decades but they have not solved completely the problems related to bone defects. In the present study we have developed a novel porous ceramic composite made of HA that incorporates magnetite at three different ratios: HA/Mgn 95/5, HA/Mgn 90/10 and HA/Mgn 50/50. The scaffolds, consolidated by sintering at high temperature in a controlled atmosphere, have been analysed in vitro using human osteoblast-like cells. Results indicate high biocompatibility, similar to a commercially available HA bone graft, with no negative effects arising from the presence of magnetite or by the use of a static magnetic field. HA/Mgn 90/10 was shown to enhance cell proliferation at the early stage. Moreover, it has been implanted in vivo in a critical size lesion of the rabbit condyle and a good level of histocompatibility was observed. Such results identify this scaffold as particularly relevant for bone tissue regeneration and open new perspectives for the application of a magnetic field in a clinical setting of bone replacement, either for magnetic scaffold fixation or magnetic drug delivery. PMID:22685602

  5. Comparison of cell viability and morphology of a human osteoblast-like cell line (SaOS-2) seeded on various bone substitute materials: An in vitro study

    PubMed Central

    Ayobian-Markazi, Nader; Fourootan, T.; Kharazifar, M. J.

    2012-01-01

    Background: Many studies have shown favorable results following the use of different bone graft materials. The aim of the present study was to evaluate the biocompatibility of four different bone graft materials regarding cell viability and morphology of Human osteoblast-like cells (SaOS-2) in vitro. Materials and Methods: The effects of Bio-Oss®, Tutodent®, Osteon®, and Cerasorb® were studied on the human osteoblast-like cell line to evaluate various parameters. Human osteoblast-like cells were seeded onto the mentioned bone substitute materials (BSMs). Cell differentiation; cell viability and alkaline phosphatase (ALP) activity of the seeded cells were evaluated by means of scanning electron microscopy, cell viability test and phase contrast microscopy Analysis of variance (ANOVA). Tamhane's post-hoc, Kruskal-Wallis Test, and Dunn's Test were used. The results were considered to be statistically significant at P<0.05. Results: The control group (SaOS-2 cells which were incubated in Dulbecco Modified Eagle Medium without any kind of bone graft materials) had the highest level of cell viability (P<0.001), followed by Tutodent®, Osteon®, Cerasorb®, and Bio-Oss®. There was no significant difference in MTT assay results between Tutodent® and the control group (P=0.032). All tested bone graft materials showed significantly higher ALP activity than the control (P<0.001). The Tutodent® group showed the best cell growth among all experimental groups, followed by the Osteon® group. The former had a higher spindle-like morphology with good attachment to the surface. Cells cultivated on the surfaces of the Cerasorb® and Bio-Oss® granules had more round morphologies. Conclusion: This in vitro study demonstrated that all tested BSMs can provide good cell differentiation but a lower rate of proliferation. PMID:22363369

  6. Comparison of Silicate-Substituted Calcium Phosphate (Actifuse) with Recombinant Human Bone Morphogenetic Protein-2 (Infuse) in Posterolateral Instrumented Lumbar Fusion

    PubMed Central

    Licina, Paul; Coughlan, Marc; Johnston, Emma; Pearcy, Mark

    2015-01-01

    Study Design Randomized controlled trial. Objective The aim of this study was to assess the efficacy of the bone grafting substitute silicate-substituted calcium phosphate (SiCaP) compared with recombinant human bone morphogenetic protein 2 (rhBMP-2) and to evaluate the clinical outcomes over a period of 2 years. Methods Patients undergoing PLF surgery for DDD at a single center were recruited and randomized to one of two groups: SiCaP (n = 9) or rhBMP-2 (n = 10). One patient withdrew prior to randomization and another from the rhBMP-2 group after randomization. The radiologic and clinical outcomes were examined and compared. Fusion was assessed at 12 months with computed tomography and plain radiographs. Clinical outcomes were evaluated by recording measures of pain, quality of life, disability, and neurologic status from 6 weeks to 2 years postoperatively. Results In the SiCaP and rhBMP-2 groups, fusion was observed in 9/9 and 8/9 patients, respectively. Pain and disability scores were reduced and quality of life increased in both groups. Leg pain, disability, and satisfaction scores were similar between the groups at each postoperative point; however, back pain was less at 6 weeks and quality of life was higher at 6 months in the SiCaP group than the rhBMP-2 group. Conclusions SiCaP and rhBMP-2 were comparable in terms of achieving successful bone growth and fusion. Both groups achieved similar alleviation of pain and improved quality of life and neurologic, satisfaction, and return to work outcomes following PLF surgery. PMID:26682097

  7. P-15 small peptide bone graft substitute in the treatment of non-unions and delayed union. A pilot clinical trial

    PubMed Central

    Orozco, Rafael; Villar, Jose Luis; Arrizabalaga, Federico

    2006-01-01

    Treatment of non-unions and delayed unions often requires osteogenic material. Recently, a biomimetic bone matrix that simulates the cellular environment of hard tissue, identified as P-15, was introduced to the orthopaedic community. A total of 22 patients with mal-union or delayed union fractures was treated from June 2000 to October 2003 with P15- bone graft substitute (P15-BGS) in the site of fracture and mostly with internal fixation. Patients were examined by independent radiographic analysis. Assessment criteria included time elapsed until bone bridging and time to full consolidation. In addition, histological assessment of the callus was done at the time of recovery of metal implants in five patients. Full consolidation was achieved in 90% (20 out of 22) of the patients treated with P15-BGS. The average time for full consolidation was 4.2 months. Histological assessment of the fracture callus in five of the patients confirmed the positive clinical and radiographic results. P15-BGS appears to offer a safe, economical and clinically useful alternative to autograft in the repair of ununited fractures. These results compare favourably with those in the published literature as an alternative to autograft. PMID:16761146

  8. Indirect rapid prototyping of biphasic calcium phosphate scaffolds as bone substitutes: influence of phase composition, macroporosity and pore geometry on mechanical properties.

    PubMed

    Schumacher, M; Deisinger, U; Detsch, R; Ziegler, G

    2010-12-01

    While various materials have been developed for bone substitute and bone tissue engineering applications over the last decades, processing techniques meeting the high demands of scaffold shaping are still under development. Individually adapted and mechanically optimised scaffolds can be derived from calcium phosphate (CaP-) ceramics via rapid prototyping (RP). In this study, porous ceramic scaffolds with a periodic pattern of interconnecting pores were prepared from hydroxyapatite, β-tricalcium phosphate and biphasic calcium phosphates using a negative-mould RP technique. Moulds predetermining various pore patterns (round and square cross section, perpendicular and 60° inclined orientation) were manufactured via a wax printer and subsequently impregnated with CaP-ceramic slurries. Different pore patterns resulted in macroporosity values ranging from about 26.0-71.9 vol% with pore diameters of approximately 340 μm. Compressive strength of the specimens (1.3-27.6 MPa) was found to be mainly influenced by the phase composition as well as the macroporosity, both exceeding the influence of the pore geometry. A maximum was found for scaffolds with 60 wt% hydroxyapatite and 26.0 vol% open porosity. It has been shown that wax ink-jet printing allows to process CaP-ceramic into scaffolds with highly defined geometry, exhibiting strength values that can be adjusted by phase composition and pore geometry. This strength level is within and above the range of human cancellous bone. Therefore, this technique is well suited to manufacture scaffolds for bone tissue engineering. PMID:20953674

  9. Acid-resistant calcium silicate-based composite implants with high-strength as load-bearing bone graft substitutes and fracture fixation devices.

    PubMed

    Wei, Chung-Kai; Ding, Shinn-Jyh

    2016-09-01

    To achieve the excellent mechanical properties of biodegradable materials used for cortical bone graft substitutes and fracture fixation devices remains a challenge. To this end, the biomimetic calcium silicate/gelatin/chitosan oligosaccharide composite implants were developed, with an aim of achieving high strength, controlled degradation, and superior osteogenic activity. The work focused on the effect of gelatin on mechanical properties of the composites under four different kinds of mechanical stresses including compression, tensile, bending, and impact. The evaluation of in vitro degradability and fatigue at two simulated body fluid (SBF) of pH 7.4 and 5.0 was also performed, in which the pH 5.0 condition simulated clinical conditions caused by bacterial induced local metabolic acidosis or tissue inflammation. In addition, human mesenchymal stem cells (hMSCs) were sued to examine osteogenic activity. Experimental results showed that the appropriate amount of gelatin positively contributed to failure enhancement in compressive and impact modes. The 10wt% gelatin-containing composite exhibits the maximum value of the compressive strength (166.1MPa), which is within the reported compressive strength for cortical bone. The stability of the bone implants was apparently affected by the in vitro fatigue, but not by the initial pH environments (7.4 or 5.0). The gelatin not only greatly enhanced the degradation of the composite when soaked in the dynamic SBF solution, but effectively promoted attachment, proliferation, differentiation, and formation of mineralization of hMSCs. The 10wt%-gelatin composite with high initial strength may be a potential implant candidate for cortical bone repair and fracture fixation applications. PMID:27254281

  10. Membranes and Bone Substitutes in a One-Stage Procedure for Horizontal Bone Augmentation: A Histologic Double-Blind Parallel Randomized Controlled Trial.

    PubMed

    Merli, Mauro; Moscatelli, Marco; Mariotti, Giorgia; Pagliaro, Umberto; Breschi, Lorenzo; Mazzoni, Annalisa; Nieri, Michele

    2015-01-01

    The aim of this histologic, double-blind, parallel, randomized controlled trial was to compare anorganic bone mineral-collagen membranes (BB) and betatricalcium phosphate-pericardium collagen membranes (CJ) in a one-stage procedure for horizontal bone augmentation. A biopsy was performed in the regenerated area at abutment connection 6 months after surgery. Five patients were assigned and treated with the BB combination and five patients were treated with the CJ combination. At abutment connection, 6 months after grafting, no significant differences were evident in the histomorphometric comparisons, even if the percentage of residual graft, using the marrow spaces and soft tissue as a reference, tended to be greater in the CJ group (P = .0759). PMID:26133135

  11. Selenium-Substituted Hydroxyapatite/Biodegradable Polymer/Pamidronate Combined Scaffold for the Therapy of Bone Tumour

    PubMed Central

    Oledzka, Ewa; Sobczak, Marcin; Kolmas, Joanna; Nalecz-Jawecki, Grzegorz

    2015-01-01

    The present study evaluated a new concept of combined scaffolds as a promising bone replacement material for patients with a bone tumour or bone metastasis. The scaffolds were composed of hydroxyapatite doped with selenium ions and a biodegradable polymer (linear or branched), and contained an active substance—bisphosphonate. For this purpose, a series of biodegradable polyesters were synthesized through a ring-opening polymerization of ε-caprolactone or d,l-lactide in the presence of 2-hydroxyethyl methacrylate (HEMA) or hyperbranched 2,2-bis(hydroxymethyl)propionic acid polyester-16-hydroxyl (bis-MPA) initiators, substances often used in the synthesis of medical materials. The polymers were obtained with a high yield and a number-average molecular weight up to 45,300 (g/mol). The combined scaffolds were then manufactured by a direct compression of pre-synthesized hydroxyapatite doped with selenite or selenate ions, obtained polymer and pamidronate as a model drug. It was found that the kinetic release of the drug from the scaffolds tested in vitro under physiological conditions is strongly dependent on the physicochemical properties and average molecular weight of the polymers. Furthermore, there was good correlation with the hydrolytic biodegradation results of the scaffolds fabricated without drug. The preliminary findings suggest that the fabricated combined scaffolds could be effectively used for the sustained delivery of bioactive molecules at bone defect sites. PMID:26389884

  12. Selenium-Substituted Hydroxyapatite/Biodegradable Polymer/Pamidronate Combined Scaffold for the Therapy of Bone Tumour.

    PubMed

    Oledzka, Ewa; Sobczak, Marcin; Kolmas, Joanna; Nalecz-Jawecki, Grzegorz

    2015-01-01

    The present study evaluated a new concept of combined scaffolds as a promising bone replacement material for patients with a bone tumour or bone metastasis. The scaffolds were composed of hydroxyapatite doped with selenium ions and a biodegradable polymer (linear or branched), and contained an active substance-bisphosphonate. For this purpose, a series of biodegradable polyesters were synthesized through a ring-opening polymerization of ε-caprolactone or d,l-lactide in the presence of 2-hydroxyethyl methacrylate (HEMA) or hyperbranched 2,2-bis(hydroxymethyl)propionic acid polyester-16-hydroxyl (bis-MPA) initiators, substances often used in the synthesis of medical materials. The polymers were obtained with a high yield and a number-average molecular weight up to 45,300 (g/mol). The combined scaffolds were then manufactured by a direct compression of pre-synthesized hydroxyapatite doped with selenite or selenate ions, obtained polymer and pamidronate as a model drug. It was found that the kinetic release of the drug from the scaffolds tested in vitro under physiological conditions is strongly dependent on the physicochemical properties and average molecular weight of the polymers. Furthermore, there was good correlation with the hydrolytic biodegradation results of the scaffolds fabricated without drug. The preliminary findings suggest that the fabricated combined scaffolds could be effectively used for the sustained delivery of bioactive molecules at bone defect sites. PMID:26389884

  13. Silicon Matrix Calcium Phosphate as a Bone Substitute: Early Clinical and Radiological Results in a Prospective Study With 12-Month Follow-up

    PubMed Central

    Pesántez, Carlos Fernando Arias; Oliveira, Leonardo

    2008-01-01

    Introduction Autograft has been the “gold standard” for orthopedic bone grafting applications, but with some clinical challenges. Here we present the rationale and clinical outcomes supporting the use of a bone substitute material that consists of a mixture of two calcium phosphates (HA and ß-TCP), which are integrated into a silicon xerogel matrix, promoting nanocrystalline apatite layers on the surface of the material following implantation into a physiological environment. Methods Twenty-four patients with a median age of 53.80 (36–81) years underwent lumbar spinal fusion for degenerative disease, selected by clinical presentation, X-rays, and MRI findings. Subjects were evaluated preoperatively and postoperatively at 1, 3, 6, and 12 months. The outcome assessment consisted of visual analog scale (VAS), Oswestry Disability Index (ODI), and radiological assessment analyzing the state of fusion on X-ray and CT evaluation by 3 independent radiologists. Results All patients completed 12-month follow-up. The mean VAS decreased from 9.3 (± 0.9) to 2.4 (± 1.6) and the mean ODI decreased from 55.0 (± 9.2) to 19.3 (± 11.4) at 12-month follow-up. Three months after surgery, 10 patients (41.67%) had solid fusion based on analysis of CT scans and dynamic radiographs. At 6 months postoperatively, the fusion rate had increased to 75% (18 patients). Twelve months after surgery, 95.83% of patients had solid fusion (23 patients). Conclusions The clinical results from this study of silicon matrix calcium phosphate are consistent with previous in vitro studies indicating that this material stimulates formation of a bioactive layer and provides an effective bone graft material for lumbar fusion applications. In comparison with previous studies involving rhBMP-2, silicon matrix calcium phosphate provided a lower fusion rate at 3- and 6-month follow-up points, but after 12 months, the fusion rate was similar, with no statistical differences and lower overall costs. No

  14. Negative Effect of Rapidly Resorbing Properties of Bioactive Glass-Ceramics as Bone Graft Substitute in a Rabbit Lumbar Fusion Model

    PubMed Central

    Lee, Jae Hyup; Ryu, Hyun-Seung; Seo, Jun-Hyuk; Lee, Do-Yoon; Chang, Bong-Soon

    2014-01-01

    Background Bioactive glass-ceramics have the ability to directly bind to bones and have been widely used as bone graft substitutes due to their high osteoconductivity and biocompatibility. CaO-SiO2-P2O5-B2O3 glass-ceramics are known to have good osteoconductivity and are used as bone graft extenders. Methods This study aimed to evaluate the effects of the resorbing properties of glass-ceramics in bone fusion after producing and analyzing three types of CaO-SiO2-P2O5-B2O3 glass-ceramics with high osteoconductivity that had enhanced resorption by having an increased B2O3 content. The three types of CaO-SiO2-P2O5-B2O3 glass-ceramics with B2O3 contents of 8.0, 9.0, and 9.5 weight % were designated and grouped as P20B80, P10B90, and P5B95, respectively. Glass-ceramic types were tested for fusion rates and bone formation by employing the lumbar 5-6 intertransverse process fusion model in 51 New Zealand male rabbits. Bioactivity was assessed by soaking in simulated body fluid (SBF). Results In vitro study results showed sufficient hydroxycarbonate apatite layer formation occurred for P20B80 in1 day, for P10B90 in 3 days, and for P5B95 in 5 days after soaking in SBF. For the rabbit lumbar spine posterolateral fusion model, the autograft group recorded a 100% fusion rate with levels significantly higher than those of P20B80 (29.4%), P10B90 (0%), and P5B95 (14.3%), with high resorbing properties. Resorbing property differences among the three glass-ceramic groups were not significant. Histological results showed new bone formation confirming osteoconductivity in all three types of glass-ceramics. Radiomorphometric results also confirmed the resorbing properties of the three glass-ceramic types. Conclusions The high resorbing properties and osteoconductivity of porous glass-ceramics can be advantageous as no glass-ceramics remain in the body. However, their relatively fast rate of resorption in the body negatively affects their role as an osteoconductive scaffold as glass

  15. Experimental study of bone morphogenetic proteins-2 slow release from an artificial trachea made of biodegradable materials: evaluation of stenting time.

    PubMed

    Yamamoto, Yasumichi; Okamoto, Taku; Goto, Masashi; Yokomise, Hiroyasu; Yamamoto, Masaya; Tabata, Yasuhiko

    2003-01-01

    We manufactured an artificial trachea that slowly releases bone morphogenetic protein 2 (BMP-2) and used it to replace a section of the canine trachea. We made a three-layered prosthesis composed of an outer layer of gelatin sponge, a middle layer of collagen sponge, and an inner silicone tube. BMP-2 solution was soaked into the gelatin sponge layer. An approximately 3 cm length of the canine trachea was resected, and the artificial trachea was inserted into the resulting gap and anastomosed. The implanted portion was covered by periosteum. At 2, 4, and 8 weeks after surgery, the inner silicone tube was removed. Soon after removal of the silicone tube at 2 and 4 weeks, the dogs died of choking because of collapse of the trachea. One dog whose silicone tube was removed at 8 weeks was able to survive without choking. At 6 months after removal of the silicone tube, the bronchoscopic findings revealed that the gap in the trachea had been closed by regenerated tissue and covered by mucosa. We have demonstrated that our artificial trachea slowly releasing BMP-2 requires at least 8 weeks to achieve regeneration of solid tissue to support the tracheal gap. PMID:14524559

  16. Prediction of elasticity constants in small biomaterial samples such as bone. A comparison between classical optimization techniques and identification with artificial neural networks.

    PubMed

    Lucchinetti, E; Stüssi, E

    2004-01-01

    Measuring the elasticity constants of biological materials often sets important constraints, such as the limited size or the irregular geometry of the samples. In this paper, the identification approach as applied to the specific problem of accurately retrieving the material properties of small bone samples from a measured displacement field is discussed. The identification procedure can be formulated as an optimization problem with the goal of minimizing the difference between computed and measured displacements by searching for an appropriate set of material parameters using dedicated algorithms. Alternatively, the backcalculation of the material properties from displacement maps can be implemented using artificial neural networks. In a practical situation, however, measurement errors strongly affect the identification results, calling for robust optimization approaches in order accurately to retrieve the material properties from error-polluted sample deformation maps. Using a simple model problem, the performances of both classical and neural network driven optimization are compared. When performed before the collection of experimental data, this evaluation can be very helpful in pinpointing potential problems with the envisaged experiments such as the need for a sufficient signal-to-noise ratio, particularly important when working with small tissue samples such as specimens cut from rodent bones or single bone trabeculae. PMID:15648663

  17. A bio-artificial poly([d,l]-lactide-co-glycolide) drug-eluting nanofibrous periosteum for segmental long bone open fractures with significant periosteal stripping injuries

    PubMed Central

    Chou, Ying-Chao; Cheng, Yi-Shiun; Hsu, Yung-Heng; Yu, Yi-Hsun; Liu, Shih-Jung

    2016-01-01

    Biodegradable poly([d,l]-lactide-co-glycolide) (PLGA) nanofibrous membrane embedded with two drug-to-polymer weight ratios, namely 1:3 and 1:6, which comprised PLGA 180 mg, lidocaine 20 mg, vancomycin 20 mg, and ceftazidime 20 mg, and PLGA 360 mg, lidocaine 20 mg, vancomycin 20 mg, and ceftazidime 20 mg, respectively, was produced as an artificial periosteum in the treatment of segmental femoral fractures. The nanofibrous membrane’s drug release behavior was assessed in vitro using high-performance liquid chromatography and the disk-diffusion method. A femoral segmental fracture model with intramedullary Kirschner-wire fixation was established for the in vivo rabbit activity study. Twenty-four rabbits were divided into two groups. Twelve rabbits in group A underwent femoral fracture fixation only, and 12 rabbits in group B underwent femoral fracture fixation and were administered the drug-loaded nanofibers. Radiographs obtained at 2, 6, and 12 weeks postoperatively were used to assess the bone unions. The total activity counts in animal behavior cages were also examined to evaluate the clinical performance of the rabbits. After the animals were euthanized, both femoral shafts were harvested and assessed for their torque strengths and toughness. The daily in vitro release curve for lidocaine showed that the nanofibers eluted effective levels of lidocaine for longer than 3 weeks. The bioactivity studies of vancomycin and ceftazidime showed that both antibiotics had effective and sustained bactericidal capacities for over 30 days. The findings from the in vivo animal activity study suggested that the rabbits with the artificial drug-eluting periosteum exhibited statistically increased levels of activity and better clinical performance outcomes compared with the rabbits without the artificial periosteum. In conclusion, this artificial drug-eluting periosteum may eventually be used for the treatment of open fractures. PMID:27022261

  18. The effect of immobilization of heparin and bone morphogenic protein-2 to bovine bone substitute on osteoblast-like cell's function

    PubMed Central

    Huh, Jung-Bo; Kim, Sung-Eun; Song, Se-Kyung; Yun, Mi-Jung; Shim, Ji-Suk; Lee, Jeong-Yol

    2011-01-01

    PURPOSE This study was performed to investigate the ability of recombinant human-bone morphogenic protein-2 immobilized on a heparin-grafted bone substrate to enhance the osteoblastic functions. MATERIALS AND METHODS The Bio-Oss®, not coated with any material, was used as a control group. In rhBMP-2-Bio-Oss® group, rhBMP-2 was coated with Bio-Oss® using only deep and dry methods (50 ng/mL, 24 h). In heparinized rhBMP-2-Bio-Oss® group, dopamine was anchored to the surface of Bio-Oss®, and coated with heparin. rhBMP-2 was immobilized onto the heparinized- Bio-Oss® surface. The release kinetics of the rhBMP-2-Bio-Oss® and heparinized rhBMP-2-Bio-Oss® were analyzed using an enzyme-linked immunosorbent assay. The biological activities of the MG63 cells on the three groups were investigated via cytotoxicity assay, cell proliferation assay, alkaline phosphatase (ALP) measurement, and calcium deposition determination. Statistical comparisons were carried out by one-way ANOVA test. Differences were considered statistically significant at *P<.05 and **P<.001. RESULTS The heparinized rhBMP-2-Bio-Oss® showed more sustained release compared to the rhBMP-2-Bio-Oss® over an extended time. In the measurement of the ALP activity, the heparinized group showed a significantly higher ALP activity when compared with the non-heparinized groups (P<.05). The MG63 cells cultivated in the group with rhBMP-2 showed increased calcium deposition, and the MG63 cells from the heparinized group increased more than those that were cultivated in the non-heparinized groups. CONCLUSION Heparin increased the rhBMP-2 release amount and made sustained release possible, and heparinized Bio-Oss® with rhBMP-2 successfully improved the osteoblastic functions. PMID:22053246

  19. Structural and mechanical properties of the coral and nacre and the potentiality of their use as bone substitutes

    NASA Astrophysics Data System (ADS)

    Hamza, Samir; Slimane, Noureddine; Azari, Zitouni; Pluvinage, Guy

    2013-01-01

    The main objective of this work is to develop resistant compact material samples with different porosities from coral and nacre adapted to the filling of bone cavities. The characterization of materials was conducted using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and laser granulometry. The micro-hardness and the influence of porosity on the mechanical behavior of these biomaterials under compression as well as three-points bending tests were also assessed. Both materials showed similar particles size ranging from 50 to 100 μm in diameter, distributed according to the Gauss curve. The modal particle size, the median D50 and D90-D10 are the most important parameters which allow for the distinction between coral and nacre samples. The two biomaterials showed a micro hardness (138-167 HV for coral and 261-340 HV for nacre) higher than that of bovine bones (55-70 HV). The maximum compression stresses were 32.82 MPa for coral and 37.06 MPa for nacre at 50% of porosity. S-N curve with ASME format is constructed to predict the fatigue life extended from 101 to 106 cycles, which reveals an endurance limit at a compression stress ratio of about 10.

  20. Optimization of composition, structure and mechanical strength of bioactive 3-D glass-ceramic scaffolds for bone substitution.

    PubMed

    Baino, Francesco; Ferraris, Monica; Bretcanu, Oana; Verné, Enrica; Vitale-Brovarone, Chiara

    2013-03-01

    Fabrication of 3-D highly porous, bioactive, and mechanically competent scaffolds represents a significant challenge of bone tissue engineering. In this work, Bioglass®-derived glass-ceramic scaffolds actually fulfilling this complex set of requirements were successfully produced through the sponge replication method. Scaffold processing parameters and sintering treatment were carefully designed in order to obtain final porous bodies with pore content (porosity above 70 %vol), trabecular architecture and mechanical properties (compressive strength up to 3 MPa) analogous to those of the cancellous bone. Influence of the Bioglass® particles size on the structural and mechanical features of the sintered scaffolds was considered and discussed. Relationship between porosity and mechanical strength was investigated and modeled. Three-dimensional architecture, porosity, mechanical strength and in vitro bioactivity of the optimized Bioglass®-derived scaffolds were also compared to those of CEL2-based glass-ceramic scaffolds (CEL2 is an experimental bioactive glass originally developed by the authors at Politecnico di Torino) fabricated by the same processing technique, in an attempt at understanding the role of different bioactive glass composition on the major features of scaffolds prepared by the same method. PMID:22207602

  1. A bone substitute with high affinity for vitamin D-binding protein―relationship with niche of osteoclasts

    PubMed Central

    Ikeda, Tohru; Kasai, Michiyuki; Tatsukawa, Eri; Kamitakahara, Masanobu; Shibata, Yasuaki; Yokoi, Taishi; Nemoto, Takayuki K; Ioku, Koji

    2014-01-01

    The biological activity of osteoblasts and osteoclasts is regulated not only by hormones but also by local growth factors, which are expressed in neighbouring cells or included in bone matrix. Previously, we developed hydroxyapatite (HA) composed of rod-shaped particles using applied hydrothermal methods (HHA), and it revealed mild biodegradability and potent osteoclast homing activity. Here, we compared serum proteins adsorbed to HHA with those adsorbed to conventional HA composed of globular-shaped particles (CHA). The two ceramics adsorbed serum albumin and γ-globulin to similar extents, but affinity for γ-globulin was much greater than that to serum albumin. The chemotactic activity for macrophages of serum proteins adsorbed to HHA was significantly higher than that of serum proteins adsorbed to CHA. Quantitative proteomic analysis of adsorbed serum proteins revealed preferential binding of vitamin D-binding protein (DBP) and complements C3 and C4B with HHA. When implanted with the femur of 8-week-old rats, HHA contained significantly larger amount of DBP than CHA. The biological activity of DBP was analysed and it was found that the chemotactic activity for macrophages was weak. However, DBP-macrophage activating factor, which is generated by the digestion of sugar chains of DBP, stimulated osteoclastogenesis. These results confirm that the microstructure of hydroxyapatite largely affects the affinity for serum proteins, and suggest that DBP preferentially adsorbed to HA composed of rod-shaped particles influences its potent osteoclast homing activity and local bone metabolism. PMID:24286277

  2. Fabrication and characterization of polycaprolactone cross- linked and highly-aligned 3-D artificial scaffolds for bone tissue regeneration via electrospinning technology

    NASA Astrophysics Data System (ADS)

    Gorodzha, S. N.; Surmeneva, M. A.; Surmenev, R. A.

    2015-11-01

    Novel technologies allowed the scientific community to develop scaffolds for regeneration of bone tissue. A successful scaffold should possess specific macroscopic geometry and internal architecture to perform biological and biophysical functions. In this study the process of polycaprolactone microfibrous development with either cross-linked or highly-aligned three-dimensional artificial mats via electrospinning technology for potential application in tissue engineering is described. The morphology and size of electrospun fibers were assessed systematically by varying the rotation speed of grounded collector. It was found that the diameter of the fibers decreased by increasing the rotation speed of collector. The morphology of the fibers changed from cross-linked to highly-aligned at appr. 1000-1100 rpm.

  3. Nano-TiO2/PEEK bioactive composite as a bone substitute material: in vitro and in vivo studies

    PubMed Central

    Wu, Xiaomian; Liu, Xiaochen; Wei, Jie; Ma, Jian; Deng, Feng; Wei, Shicheng

    2012-01-01

    Background Compared with titanium (Ti) and other metal implant materials, poly(ether-ether ketone) (PEEK) shows outstanding biomechanical properties. A number of studies have also reported attractive bioactivity for nano-TiO2 (n-TiO2). Methods In this study, n-TiO2/PEEK nanocomposites were prepared, taking advantage of the unique properties of both PEEK polymer and n-TiO2. The in vitro and in vivo bioactivity of these nanocomposites was assessed against a PEEK polymer control. The effect of surface morphology or roughness on the bioactivity of the n-TiO2/PEEK nanocomposites was also studied. n-TiO2/PEEK was successfully fabricated and cut into disks for physical and chemical characterization and in vitro studies, and prepared as cylindrical implants for in vivo studies. Their presence on the surface and dispersion in the composites was observed and analyzed by scanning and transmission electron microscopy and X-ray photoelectron spectroscopy. Results Bioactivity evaluation of the nanocomposites revealed that pseudopods of osteoblasts preferred to anchor at areas where n-TiO2 was present on the surface. In a cell attachment test, smooth PEEK showed the lowest optical density value (0.56 ± 0.07) while rough n-TiO2/PEEK exhibited the highest optical density value (1.21 ± 0.34, P < 0.05). In in vivo studies, the percent bone volume value of n-TiO2/PEEK was approximately twice as large as that of PEEK (P < 0.05). Vivid three-dimensional and histologic images of the newly generated bone on the implants further supported our test results. Conclusion Our study demonstrates that n-TiO2 significantly improves the bioactivity of PEEK, especially if it has a rough composite surface. A n-TiO2/PEEK composite with a rough surface could be a novel alternative implant material for orthopedic and dental applications. PMID:22419869

  4. In vitro evaluation of alginate encapsulated adipose-tissue stromal cells for use as injectable bone graft substitute

    SciTech Connect

    Abbah, S.A.; Lu, W.W. . E-mail: wwlu@hkusua.hku.hk; Chan, D.; Cheung, K.M.C.; Liu, W.G.; Zhao, F.; Li, Z.Y.; Leong, J.C.Y.; Luk, K.D.K.

    2006-08-18

    This study aims to investigate the survival and osteogenic behavior of murine-derived adipose-tissue stromal cells (ATSCs) encapsulated in alginate microcapsules thereby instigating further studies in this cell delivery strategy for in vivo osteogenesis. Cell viability was quantified using a tetrazolium-based assay and osteogenic differentiation was evaluated by both alkaline-phosphatase (ALP) histochemistry and osteocalcin mRNA analysis. Following microencapsulation, cell numbers increased from 3.9 x 10{sup 3} on day 1 to 7.8 x 10{sup 3} on day 7 and maintained excellent viability in the course of 21-day culture. ALP was 6.9, 5.5, and 3.2 times higher than monolayer cultures on days 7, 14, and 21, respectively. In addition, osteocalcin mRNA was detectable in encapsulated cultures earlier (day 14) than monolayer cultures. We conclude that alginate microcapsules can act as three-dimensional matrix for ATSC proliferation and has potential for use as injectable, biodegradable scaffold in bone tissue engineering.

  5. Accuracy of Cone Beam Computed Tomography, Photostimulable Phosphor Plate Digital Radiography and Conventional Radiography for Detection of Artificial Cancellous Bone Defects

    PubMed Central

    Bardal, Roghieh; Jahanihashemi, Hassan; Mostafavi, Maryam; Kalhor, Esmaeil; Tofangchiha, Maryam; Dehghani, Mahdieh

    2015-01-01

    Objectives: The optimal goal of radiography is to provide high-quality diagnostic images with the least patient radiation dose. The aim of this study was to evaluate the accuracy of cone-beam computed tomography (CBCT) and intraoral photostimulable phosphor plate (PSP) digital and film-based conventional radiography for detection of artificial cancellous bone defects. Materials and Methods: Five dry human mandibles were used in this study. The mandibles were placed inside a water bath made of plexiglass plates; then PSP and CBCT scans were obtained. The mandibles were cut by a coping saw in buccolingual dimension and oval defects measuring 6.1×6.1 mm, 3×6.1 mm and 4×4 mm were created by a milling machine in the spongy bone. After fixing the two parts together (buccal and lingual), radiographs were repeated. Presence or absence of defects on images was evaluated and recorded by the two observers. Using SPSS 16, compatibility level, sensitivity, specificity and receiver operating curve (ROC) analysis were determined for each observer. Results: The intraobserver agreement in all three imaging modalities was low to moderate (kappa≤0.613). The inter-observer agreement in all the three imaging modalities was moderate (kappa=0.406). The area under the curve (AUC) of the imaging modalities in each observation was not significantly different. The area under the curve based on defect size for the two observers was not significantly different either. Conclusion: Defects confined to spongy bone can be identified on film and PSP radiographs and CBCT scans. However, interpretation of PSP images and CBCT scans needs greater expertise and skills. PMID:27507990

  6. [Artificial ossification of muscular flap after plastic surgery of the bone cavity under the effect of electric current].

    PubMed

    Tkachenko, S S; Mussa, M; Rutskiĭ, V V

    1978-03-01

    Experiments in rabbits revealed that transplantation of a muscular flap on the central feeding pedicle in the tibis medullary canal and its electro-stimulation with direct microelectric current of 18-20 muA with the alternating polarity speeded up the process of reorganization of the muscular flap in the depth of which new osseous tissue was forming. Electrostimulation of osteogenesis in case of the muscular plastic transplantation promotes restoration of the anatomic integrity of the bone. PMID:667330

  7. Nano-hydroxyapatite composite biomaterials for bone tissue engineering--a review.

    PubMed

    Venkatesan, Jayachandran; Kim, Se-Kwon

    2014-10-01

    In recent years, significant development has been achieved in the construction of artificial bone with ceramics, polymers and metals. Nano-hydroxyapatite (nHA) is widely used bioceramic material for bone graft substitute owing to its biocompatibility and osteoconductive properties. nHA with chitin, chitosan, collagen, gelatin, fibrin, polylactic acid, polycaprolactone, poly(lactic-co-glycolic) acid, polyamide, polyvinyl alcohol, polyurethane and polyhydroxybutyrate based composite scaffolds have been explored in the present review for bone graft substitute. This article further reviews the preparative methods, chemical interaction, biocompatibiity, biodegradation, alkaline phosphatase activity, mineralization effect, mechanical properties and delivery of nHA-based nanocomposites for bone tissue regeneration. The nHA based composite biomaterials proved to be promising biomaterials for bone tissue engineering. PMID:25992432

  8. Comparison and preparation of multilayered polylactic acid fabric strengthen calcium phosphate-based bone substitutes for orthopedic applications.

    PubMed

    Chen, Wen-Cheng; Ko, Chia-Ling; Yang, Jia-Kai; Wu, Hui-Yu; Lin, Jia-Horng

    2016-03-01

    An attempt to maintain the three-dimensional space into restorative sites through the conveniently pack porous fillers are general used strategy. Advancement in the manufacturing protective shells in the scaffolds, which would be filled with brittle ceramic grafts for the development of highly connective pores provides the approach to solve crack problem for generating the tissues. Therefore, multilayered braided and alkalized poly(lactic acid) (PLA) composites with calcium phosphate bone cement (CPC) were synthesized and compared. The PLA/CPC composites were divided into various groups according to a series of heat-treatment temperatures (100-190 °C) and periods (1-3 h) and then characterized. The effects of 24-h immersion on the strength decay resistance of the samples were compared. Results showed that the residual oil capped on the surfaces of alkalized PLA braid was removed, and the structure was unaltered. However, the reduced tensile stress of alkalized PLA braids was due to ester-group formation by hydrolysis. Mechanical test results of PLA/CPC composites showed that the strength significantly increased after heat treatment, except when the heating temperature was higher than the PLA melting point at approximately 160-170 °C. The degree of PLA after recrystallization became higher than that of unheated composites, thereby leading to reduced strength and toughness of the specimen. Braiding fibers of biodegradable PLA reinforced and toughened the structure particularly of the extra-brittle material of thin-sheet CPC after implantation. PMID:26280316

  9. Characterization of bacterial artificial chromosome transgenic mice expressing mCherry fluorescent protein substituted for the murine smooth muscle-alpha-actin gene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Smooth muscle a actin (SMA) is a cytoskeletal protein expressed by mesenchymal and smooth muscle cell types, including mural cells(vascular smooth muscle cells and pericytes). Using Bacterial Artificial Chromosome (BAC) recombineering technology, we generated transgenic reporter mice that express a ...

  10. Microstructural and in vitro characterization of SiO2-Na2O-CaO-MgO glass-ceramic bioactive scaffolds for bone substitutes.

    PubMed

    Vitale-Brovarone, C; Vernè, E; Bosetti, M; Appendino, P; Cannas, M

    2005-10-01

    In the present research work, the preparation and characterization of bioactive glass-ceramic scaffolds for bone substitutes are described. The scaffolds were prepared by starch consolidation of bioactive glass powders belonging to the SiO2-Na2O-CaO-MgO system using three different organic starches (corn, potatoes and rice) as reported in a previous screening process. The scaffolds, characterized by scanning electron microscopy, showed a porous structure with highly interconnected pores. The pores sizes assessed by mercury intrusion porosimetry put in evidence the presence of pores of 50-100 microm. The structure of the scaffolds was investigated by X-ray diffraction and revealed the glass-ceramic nature of the obtained material. The mechanical properties of the scaffolds were evaluated by means of compressive tests on cubic samples and the obtained results demonstrated their good mechanical strength. The in vitro bioactivity of the scaffolds was tested by soaking them in a simulated body fluid (SBF) and by subsequently characterizing the soaked surfaces by SEM, EDS and X-ray diffraction. Good in vitro bioactivity was found for the starting glass and for the obtained scaffolds. Moreover, the scaffold bioresorption, tested by measuring the samples weight loss in SBF at different periods of time, showed a partial resorption of the scaffolds. Cell culture testing of the three different scaffolds indicated no differences in cell number and in alkaline phosphatase activity; the morphology of the osteoblasts showed good spreading, comparable to bulk material which was used as the control. PMID:16167099

  11. Artificial dental root made of natural calcium carbonate (Bioracine).

    PubMed

    Camprasse, S; Camprasse, G; Pouzol, M; Lopez, E

    1990-01-01

    'Bioracine' is an artificial dental root made of natural calcium carbonate (Pinctade maxima mother of pearl). This non-biodegradable material is very close to bone tissue in its physicochemical composition and presents remarkable hardness, resistance and elasticity. Bioracine is a buried dental implant with a special screw thread, presenting a large surface which shows pores of 2-3 mum. A histological study of the interface between the implant and human maxillary bone demonstrated an extraordinary cellular union between these two tissues. Furthermore, bioracine presents two new technical innovations: a periprosthetic epithelial attachment of connective tissue with an active shock absorbing system. Bioracine is an exceptional dental root substitute that matches the biological properties of natural bone. PMID:10147506

  12. Divergent Rules for Pollen and Nectar Foraging Bumblebees – A Laboratory Study with Artificial Flowers Offering Diluted Nectar Substitute and Pollen Surrogate

    PubMed Central

    Konzmann, Sabine; Lunau, Klaus

    2014-01-01

    Almost all bees collect nectar and pollen from flowers. Female bees collect pollen to provision their nest cells, whereas they use nectar for individual energy supply and nest cell provisioning. Bees fine-tune nectar foraging to the amount and to the concentration of nectar, but the individual bees' response to variability of amount and concentration of pollen reward has not yet been studied thoroughly in laboratory settings. We developed an experimental set-up in which bumblebees simultaneously collected sugar solution and pollen from artificial flowers; natural pollen was mixed with cellulose powder or glass powder as a pollen surrogate. Here we show that bumblebee (Bombus terrestris) workers do not specialise in nectar or pollen collection, but regularly collect both rewards on the same day. When offered a fixed pollen reward and varied amounts and concentrations of sugar solution, the bumblebees fine-tuned sugar solution foraging dependent on both the volume and concentration, with strong preferences for the highest concentration and the greatest volume. In the reciprocal tests, when offered a fixed sugar reward and varied amounts and concentrations of pollen mixed with a nutrient-free pollen surrogate, the bumblebees follow more an all-or-none rule for pollen, accepting all amounts and concentrations except pure surrogate. It is discussed how the bumblebees' ability to sense sugar, and their apparent inability to sense the pollen protein content, shaped their foraging behaviour. It is argued that the rarity of nectar mimicry and the frequency of pollen mimicry in natural flowers might be interpreted in the context of divergent abilities of nectar and pollen recognition in bees. PMID:24637406

  13. Bilayer oxidized regenerated cellulose/poly ε-caprolactone knitted fabric-reinforced composite for use as an artificial dural substitute.

    PubMed

    Suwanprateeb, Jintamai; Luangwattanawilai, Ticomporn; Theeranattapong, Thunyanun; Suvannapruk, Waraporn; Chumnanvej, Sorayouth; Hemstapat, Warinkarn

    2016-07-01

    A novel bilayer knitted fabric-reinforced composite for potentially being used as a dural substitute was developed by solution infiltration of oxidized regenerated cellulose knitted fabric (ORC) with poly ε-caprolactone (PCL) solution at various concentrations ranging 10-40 g/100 mL. It was found that the density of all formulations did not differ significantly and was lower than that of the human dura. Microstructure of the samples typically comprised a bilayer structure having a nonporous PCL layer on one side and the ORC/PCL composite layer on another side. Tensile modulus and strength of the samples initially decreased with increasing PCL solution concentration for up to 20 g/100 mL and re-increased again with further increasing PCL solution concentration. Strain at break of all formulations were not significantly different. Watertight test revealed that all composites could prevent leakage at the pressure within the normal range of intracranial pressure. In vitro degradation study revealed that the weight loss percentage and change in tensile properties of all samples displayed biphasic profile comprising an initially rapid decrease and followed by a gradual decrease with incubation times afterward. Micro and macro porous channels were observed to be in situ generated in the composite layer by ORC dissolution and PCL resorption during degradation while nonporous layer remained relatively unchanged. The degradation rate was found to decrease with increasing PCL solution concentration. In vitro biocompatibility using alamar blue assay on selected samples showed that fibroblasts could attach and proliferate well at all incubation periods. PMID:27278580

  14. Mesenchymal Stem Cells and Platelet Gel Improve Bone Deposition within CAD-CAM Custom-Made Ceramic HA Scaffolds for Condyle Substitution

    PubMed Central

    Ciocca, L.; Donati, D.; Ragazzini, S.; Dozza, B.; Rossi, F.; Fantini, M.; Spadari, A.; Romagnoli, N.; Landi, E.; Tampieri, A.; Piattelli, A.; Iezzi, G.; Scotti, R.

    2013-01-01

    Purpose. This study evaluated the efficacy of a regenerative approach using mesenchymal stem cells (MSCs) and CAD-CAM customized pure and porous hydroxyapatite (HA) scaffolds to replace the temporomandibular joint (TMJ) condyle. Methods. Pure HA scaffolds with a 70% total porosity volume were prototyped using CAD-CAM technology to replace the two temporomandibular condyles (left and right) of the same animal. MSCs were derived from the aspirated iliac crest bone marrow, and platelets were obtained from the venous blood of the sheep. Custom-made surgical guides were created by direct metal laser sintering and were used to export the virtual planning of the bone cut lines into the surgical environment. Sheep were sacrificed 4 months postoperatively. The HA scaffolds were explanted, histological specimens were prepared, and histomorphometric analysis was performed. Results. Analysis of the porosity reduction for apposition of newly formed bone showed a statistically significant difference in bone formation between condyles loaded with MSC and condyles without (P < 0.05). The bone ingrowth (BI) relative values of split-mouth comparison (right versus left side) showed a significant difference between condyles with and without MSCs (P < 0.05). Analysis of the test and control sides in the same animal using a split-mouth study design was performed; the condyle with MSCs showed greater bone formation. Conclusion. The split-mouth design confirmed an increment of bone regeneration into the HA scaffold of up to 797% upon application of MSCs. PMID:24073409

  15. A comparative study of the effects of different bioactive fillers in PLGA matrix composites and their suitability as bone substitute materials: A thermo-mechanical and in vitro investigation.

    PubMed

    Simpson, R L; Nazhat, S N; Blaker, J J; Bismarck, A; Hill, R; Boccaccini, A R; Hansen, U N; Amis, A A

    2015-10-01

    Bone substitute composite materials with poly(L-lactide-co-glycolide) (PLGA) matrices and four different bioactive fillers: CaCO3, hydroxyapatite (HA), 45S5 Bioglass(®) (45S5 BG), and ICIE4 bioactive glass (a lower sodium glass than 45S5 BG) were produced via melt blending, extrusion and moulding. The viscoelastic, mechanical and thermal properties, and the molecular weight of the matrix were measured. Thermogravimetric analysis evaluated the effect of filler composition on the thermal degradation of the matrix. Bioactive glasses caused premature degradation of the matrix during processing, whereas CaCO3 or HA did not. All composites, except those with 45S5 BG, had similar mechanical strength and were stiffer than PLGA alone in compression, whilst all had a lower tensile strength. Dynamic mechanical analysis demonstrated an increased storage modulus (E') in the composites (other than the 45S5 BG filled PLGA). The effect of water uptake and early degradation was investigated by short-term in vitro aging in simulated body fluid, which indicated enhanced water uptake over the neat polymer; bioactive glass had the greatest water uptake, causing matrix plasticization. These results enable a direct comparison between bioactive filler type in poly(α-hydroxyester) composites, and have implications when selecting a composite material for eventual application in bone substitution. PMID:26164218

  16. Artificial limb connection

    NASA Technical Reports Server (NTRS)

    Owens, L. J.

    1974-01-01

    Connection simplifies and eases donning and removing artificial limb; eliminates harnesses and clamps; and reduces skin pressures by allowing bone to carry all tensile and part of compressive loads between prosthesis and stump. Because connection is modular, it is easily modified to suit individual needs.

  17. Elastic Stable Intramedullary Nailing (ESIN), Orthoss® and Gravitational Platelet Separation - System (GPS®): An effective method of treatment for pathologic fractures of bone cysts in children

    PubMed Central

    2011-01-01

    Background The different treatment strategies for bone cysts in children are often associated with persistence and high recurrence rates of the lesions. The safety and clinical outcomes of a combined mechanical and biological treatment with elastic intramedullary nailing, artificial bone substitute and autologous platelet rich plasma are evaluated. Methods From 02/07 to 01/09 we offered all children with bone cysts the treatment combination of elastic intramedullary nailing (ESIN), artificial bone substitute (Orthoss®) and autologous platelet rich plasma, concentrated by the Gravitational Platelet Separation (GPS®) - System. All patients were reviewed radiologically for one year following the removal of the intramedullary nailing, which was possible because of cyst obliteration. Results A cohort of 12 children (4 girls, 8 boys) was recruited. The mean patient age was 11.4 years (range 7-15 years). The bone defects (ten humeral, two femoral) included eight juvenile and four aneurysmal bone cysts. Five patients suffered from persistent cysts following earlier unsuccessful treatment of humeral bone cyst after pathologic fracture; the other seven presented with acute pathologic fractures. No peri- or postoperative complications occurred. The radiographic findings showed a total resolution of the cysts in ten cases (Capanna Grade 1); in two cases a small residual cyst remained (Capanna Grade 2). The intramedullary nails were removed six to twelve months (mean 7.7) after the operation; in one case, a fourteen year old boy (Capanna Grade 2), required a further application of GPS® and Orthoss® to reach a total resolution of the cyst. At follow-up (20-41 months, mean 31.8 months) all patients showed very good functional results and had returned to sporting activity. No refracture occurred, no further procedure was necessary. Conclusions The combination of elastic intramedullary nailing, artificial bone substitute and autologous platelet rich plasma (GPS®) enhances the

  18. Clinical use and safety of a novel gentamicin-releasing resorbable bone graft substitute in the treatment of osteomyelitis/osteitis

    PubMed Central

    Fleiter, N.; Walter, G.; Bösebeck, H.; Vogt, S.; Büchner, H.; Hirschberger, W.; Hoffmann, R.

    2014-01-01

    Objective A clinical investigation into a new bone void filler is giving first data on systemic and local exposure to the anti-infective substance after implantation. Method A total of 20 patients with post-traumatic/post-operative bone infections were enrolled in this open-label, prospective study. After radical surgical debridement, the bone cavity was filled with this material. The 21-day hospitalisation phase included determination of gentamicin concentrations in plasma, urine and wound exudate, assessment of wound healing, infection parameters, implant resorption, laboratory parameters, and adverse event monitoring. The follow-up period was six months. Results Systemic exposure to gentamicin after implantation was very low as local gentamicin concentrations were measured in wound exudate after six to ten hours. There were no signs of infectious complication throughout the clinical phase. Four patients had recurrent infections several weeks to months after implantation. The outcome was deemed successful by remission of infection in 16 (80%) of these problematic long-term treated patients. Safety laboratory measurements did not indicate nephrotoxic or hepatotoxic effects. Conclusions Local application of calcium sulphate/carbonate bone void filler comprising gentamicin revealed sufficient active local levels of the antibiotic by simultaneous significant low systemic exposure in patients with mostly chronic osteomyelitis/osteitis. The material was safe and well tolerated. Cite this article: Bone Joint Res 2014;3:223–9. PMID:25005841

  19. A histological study of non-ceramic hydroxyapatite as a bone graft substitute material in the vertical bone augmentation of the posterior mandible using an interpositional inlay technique: A split mouth evaluation.

    PubMed

    Bechara, Karen; Dottore, Alexandre M; Kawakami, Paulo Y; Gehrke, Sergio A; Coelho, Paulo G; Piattelli, Adriano; Iezzi, Giovanna; Shibli, Jamil Awad

    2015-11-01

    The aim of this study was to compare the influence of graft material (non-ceramic hydroxyapatite versus autologous bone) on bone behaviour and perform a resonance frequency analysis of implants placed in augmented sites to evaluate stability. For this study, 11 patients with bilateral edentulous areas in the mandibular posterior region were selected. Alveolar augmentation osteotomies were bilaterally (split mouth design) performed. In one hemiarch, the space generated by the osteotomy was grafted with an interpositional intra-oral autologous bone graft (control group). In the other hemiarch, the space generated by the osteotomy was grafted with an interpositional non-ceramic hydroxyapatite (ncHA) (test group). The groups were randomized. After 6 months of healing, a bone sample was retrieved from each side for histological evaluation using a trephine drill that was 2-mm in internal diameter. The implant stability quotient (ISQ) was measured by the resonance frequency immediately following implant placement at baseline and after 6 months of follow-up. Good incorporation of the graft was observed in both groups; however, in the test group, a residual-grafted material was observed. Bone density and marrow spaces were similar between groups. Correlations between the ISQ values and the histometric variables were not observed (p>0.05). The results of this trial suggest that both intra-oral autologous bone and ncHA may be elected as interpositional grafting materials to vertically augment posterior atrophic mandibles. PMID:26325427

  20. Genotoxicity effect, antioxidant and biomechanical correlation: experimental study of agarose-chitosan bone graft substitute in New Zealand white rabbit model.

    PubMed

    Jebahi, Samira; Ben Saleh, Ghada; Saoudi, Mongi; Besaleh, Salma; Oudadesse, Hassane; Mhadbi, Moufida; Rebai, Tarek; Keskes, Hassib; El Feki, Abdelfattah

    2014-08-01

    Bone loss associated with skeletal trauma or metabolic diseases often requires bone grafting. In such situations, a biomaterial is necessary for migrated cells to produce new tissue. In this study, agarose-chitosan was implanted in the femoral condyle of New Zealand White rabbits that were divided into three groups: Group I was used as control; Groups II and III were used as implanted tissue with agarose-chitosan and presenting empty defects, respectively. This study evaluated the agarose-chitosan biocompatibility by determining the in vivo genotoxicity, oxidative stress balance that correlated with the hardness mechanical property. Moreover, the histopathological and quantitative elements analyzed by using inductively coupled plasma optical emission spectrometry were determined. After 30 days of implantation, the in vivo analysis of genotoxicity showed that agarose-chitosan did not induce chromosome aberration or micronucleus damage. A significant decrease in thiobarbituric and acid-reactive substance was observed after agarose-chitosan implantation in the bone tissue. Superoxide dismutase, catalase and glutathione peroxidase were significantly enhanced in agarose-chitosan-treated group compared with that of control group. A negative correlation coefficient of the mechanical property with malonyldialdehyde level was detected (R = -0.998). The histological study exhibited a significantly increased angiogenesis and newly formed tissue. No presence of inflammatory process, necrotic or fibrous tissue was detected. Major and trace elements such as Ca, P, Zn, Mg and Fe were increased significantly in the newly formed bone. These findings show that agarose-chitosan biomaterial implantation might be effective for treating trauma and bone regeneration. PMID:25205747

  1. Skin Substitutes

    PubMed Central

    Howe, Nicole; Cohen, George

    2014-01-01

    In a relatively short timespan, a wealth of new skin substitutes made of synthetic and biologically derived materials have arisen for the purpose of wound healing of various etiologies. This review article focuses on providing an overview of skin substitutes including their indications, contraindications, benefits, and limitations. The result of this overview was an appreciation of the vast array of options available for clinicians, many of which did not exist a short time ago. Yet, despite the rapid expansion this field has undergone, no ideal skin substitute is currently available. More research in the field of skin substitutes and wound healing is required not only for the development of new products made of increasingly complex biomolecular material, but also to compare the existing skin substitutes. PMID:25371771

  2. Cellulose Nanocrystals--Bioactive Glass Hybrid Coating as Bone Substitutes by Electrophoretic Co-deposition: In Situ Control of Mineralization of Bioactive Glass and Enhancement of Osteoblastic Performance.

    PubMed

    Chen, Qiang; Garcia, Rosalina Pérez; Munoz, Josemari; Pérez de Larraya, Uxua; Garmendia, Nere; Yao, Qingqing; Boccaccini, Aldo R

    2015-11-11

    Surface functionalization of orthopedic implants is being intensively investigated to strengthen bone-to-implant contact and accelerate bone healing process. A hybrid coating, consisting of 45S5 bioactive glass (BG) individually wrapped and interconnected with fibrous cellulose nanocrystals (CNCs), is deposited on 316L stainless steel from aqueous suspension by a one-step electrophoretic deposition (EPD) process. Apart from the codeposition mechanism elucidated by means of zeta-potential and scanning electron microscopy measurements, in vitro characterization of the deposited CNCs-BG coating in simulated body fluid reveals an extremely rapid mineralization of BG particles on the coating (e.g., the formation of hydroxyapatite crystals layer after 0.5 day). A series of comparative trials and characterization methods were carried out to comprehensively understand the mineralization process of BG interacting with CNCs. Furthermore, key factors for satisfying the applicability of an implant coating such as coating composition, surface topography, and adhesion strength were quantitatively investigated as a function of mineralization time. Cell culture studies (using MC3T3-E1) indicate that the presence of CNCs-BG coating substantially accelerated cell attachment, spreading, proliferation, differentiation, and mineralization of extracellular matrix. This study has confirmed the capability of CNCs to enhance and regulate the bioactivity of BG particles, leading to mineralized CNCs-BG hybrids for improved bone implant coatings. PMID:26460819

  3. Hierarchical Structure of Articular Bone-Cartilage Interface and Its Potential Application for Osteochondral Tissue Engineering

    NASA Astrophysics Data System (ADS)

    Bian, Weiguo; Qin, Lian; Li, Dichen; Wang, Jin; Jin, Zhongmin

    2010-09-01

    The artificial biodegradable osteochondral construct is one of mostly promising lifetime substitute in the joint replacement. And the complex hierarchical structure of natural joint is important in developing the osteochondral construct. However, the architecture features of the interface between cartilage and bone, in particular those at the micro-and nano-structural level, remain poorly understood. This paper investigates these structural data of the cartilage-bone interface by micro computerized tomography (μCT) and Scanning Electron Microscope (SEM). The result of μCT shows that important bone parameters and the density of articular cartilage are all related to the position in the hierarchical structure. The conjunctions of bone and cartilage were defined by SEM. All of the study results would be useful for the design of osteochondral construct further manufactured by nano-tech. A three-dimensional model with gradient porous structure is constructed in the environment of Pro/ENGINEERING software.

  4. Artificial Limbs

    MedlinePlus

    ... you are missing an arm or leg, an artificial limb can sometimes replace it. The device, which ... activities such as walking, eating, or dressing. Some artificial limbs let you function nearly as well as ...

  5. Artificial Intelligence.

    ERIC Educational Resources Information Center

    Waltz, David L.

    1982-01-01

    Describes kinds of results achieved by computer programs in artificial intelligence. Topics discussed include heuristic searches, artificial intelligence/psychology, planning program, backward chaining, learning (focusing on Winograd's blocks to explore learning strategies), concept learning, constraint propagation, language understanding…

  6. Artificial Intelligence.

    ERIC Educational Resources Information Center

    Information Technology Quarterly, 1985

    1985-01-01

    This issue of "Information Technology Quarterly" is devoted to the theme of "Artificial Intelligence." It contains two major articles: (1) Artificial Intelligence and Law" (D. Peter O'Neill and George D. Wood); (2) "Artificial Intelligence: A Long and Winding Road" (John J. Simon, Jr.). In addition, it contains two sidebars: (1) "Calculating and…

  7. Nanostructured Biomaterials for Tissue Engineered Bone Tissue Reconstruction

    PubMed Central

    Chiara, Gardin; Letizia, Ferroni; Lorenzo, Favero; Edoardo, Stellini; Diego, Stomaci; Stefano, Sivolella; Eriberto, Bressan; Barbara, Zavan

    2012-01-01

    Bone tissue engineering strategies are emerging as attractive alternatives to autografts and allografts in bone tissue reconstruction, in particular thanks to their association with nanotechnologies. Nanostructured biomaterials, indeed, mimic the extracellular matrix (ECM) of the natural bone, creating an artificial microenvironment that promotes cell adhesion, proliferation and differentiation. At the same time, the possibility to easily isolate mesenchymal stem cells (MSCs) from different adult tissues together with their multi-lineage differentiation potential makes them an interesting tool in the field of bone tissue engineering. This review gives an overview of the most promising nanostructured biomaterials, used alone or in combination with MSCs, which could in future be employed as bone substitutes. Recent works indicate that composite scaffolds made of ceramics/metals or ceramics/polymers are undoubtedly more effective than the single counterparts in terms of osteoconductivity, osteogenicity and osteoinductivity. A better understanding of the interactions between MSCs and nanostructured biomaterials will surely contribute to the progress of bone tissue engineering. PMID:22312283

  8. Can Positron Emission Tomography and Computed Tomography Be a Substitute for Bone Marrow Biopsy in Detection of Bone Marrow Involvement in Patients with Hodgkin’s or Non-Hodgkin’s Lymphoma?

    PubMed Central

    Çetin, Güven; Çıkrıkçıoğlu, M. Ali; Özkan, Tuba; Karatoprak, Cumali; Ar, M. Cem; Eşkazan, Ahmet Emre; Ayer, Mesut; Cerit, Abdullah; Gözübenli, Kübra; Börkü Uysal, Betül; Erdem, Simge; Ergül, Nurhan; Tatar, Gamze; Çermik, T. Fikret

    2015-01-01

    Objective: Positron emission tomography and computed tomography (PET/CT) has become an important part of staging and treatment evaluation algorithms of lymphoma. We aimed to compare the results of PET/CT with bone marrow biopsy (BMB) with respect to bone marrow involvement (BMI) in patients with Hodgkin’s lymphoma (HL) and aggressive non-Hodgkin’s lymphoma (aNHL). Materials and Methods: The medical files of a total of 297 patients diagnosed with HL or aNHL and followed at the hematology clinics of 3 major hospitals in İstanbul between 2008 and 2012 were screened retrospectively and 161 patients with classical HL and aNHL were included in the study. The patients were referred for PET/CT and BMB at the initial staging. BMB was performed as the reference standard for the evaluation of BMI. Results: There were 61 (38%) HL and 100 (62%) aNHL patients. Concordant results were revealed between PET/CT and BMB in 126 patients (78%) (52 HL, 74 aNHL), 20 with positive PET/CT and BMB results and 106 with negative PET/CT and BMB results. There were discordant results in 35 patients (9 HL, 26 aNHL), 16 of them with positive BMB and negative PET/CT results and 19 of them with negative BMB and positive PET/CT results. Conclusion: We observed that PET/CT is effective to detect BMI, despite it alone not being sufficient to evaluate BMI in HL and aNHL. Bone marrow trephine biopsy and PET/CT should be considered as mutually complementary methods for detection of BMI in patients with lymphoma. In suspected focal involvement, combining biopsy and PET/CT might improve staging results. PMID:25912844

  9. Alternative agents versus prophylactic platelet transfusion for preventing bleeding in patients with thrombocytopenia due to chronic bone marrow failure: a network meta-analysis and systematic review

    PubMed Central

    Desborough, Michael; Estcourt, Lise J; Chaimani, Anna; Doree, Carolyn; Hopewell, Sally; Trivella, Marialena; Hadjinicolaou, Andreas V; Vyas, Paresh; Stanworth, Simon J

    2016-01-01

    This is the protocol for a review and there is no abstract. The objectives are as follows: To compare the relative efficacy of different treatments for thrombocytopenia (artificial platelet substitutes, platelet-poor plasma, fibrinogen, rFVIIa, rFXIII, thrombopoietin mimetics, antifibrinolytic drugs or platelet transfusions) in patients with chronic bone marrow failure and to derive a hierarchy of potential alternate treatments to platelet transfusions. PMID:27069420

  10. Solvent substitution

    SciTech Connect

    Not Available

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated.

  11. Prethymic nylon wool-passed bone marrow cells, substituting for helper T cells, can augment the generation of cytotoxic T lymphocytes from their precursors.

    PubMed

    Tanabe, M J

    1991-01-01

    Nylon wool-passed bone marrow (NW-BM) cells treated with anti-Thy.1 monoclonal antibody and complement were added to a mixed lymphocyte culture which contained a limiting number of lymph node cells, as responder cells, and a sufficient number of mitomycin-c-treated allogeneic spleen cells as stimulator cells. NW-BM cells of the same MHC haplotype as responder cells enhanced the generation of allo-specific cytotoxic T lymphocytes (CTL) not only at a relatively high dose (3 x 10(3) cells/well) of responder cells, but also at an extremely dilute dose (1 x 10(3) cells/well). NW-BM cells which had a third-party MHC haplotype, a haplotype different from both responder and stimulator cells, also enhanced the generation of CTL at relatively high doses, but not at low doses, of responder cells. NW-BM cells which had MHC haplotypes identical with those of responder cells induced CTL from helper T cell-depleted responder cells, but NW-BM cells which had the third-party haplotype did not. These results showed that the enhancing effects of NW-BM cells of the same MHC haplotype as responder cells might be due to a specific helper effect and the enhancing effect of NW-BM cells of the third-party haplotype might be due to a nonspecific filler effect, which only conditioned the cultured cells. It was also found that, to exhibit the helper effect, NW-BM cells had to possess MHC class II, but not MHC class I, molecules in common with CTL precursors. This study showed that in the induction of CTL, prethymic NW-BM cells had a capability comparable to that of mature helper T cells. PMID:1839692

  12. IL-2/α-IL-2 Complex Treatment Cannot Be Substituted for the Adoptive Transfer of Regulatory T cells to Promote Bone Marrow Engraftment.

    PubMed

    Mahr, Benedikt; Unger, Lukas; Hock, Karin; Pilat, Nina; Baranyi, Ulrike; Schwarz, Christoph; Maschke, Svenja; Farkas, Andreas Michael; Wekerle, Thomas

    2016-01-01

    Cell therapy with recipient Tregs achieves engraftment of allogeneic bone marrow (BM) without the need for cytoreductive conditioning (i.e., without irradiation or cytotoxic drugs). Thereby mixed chimerism and transplantation tolerance are established in recipients conditioned solely with costimulation blockade and rapamycin. However, clinical translation would be substantially facilitated if Treg-stimulating pharmaceutical agents could be used instead of individualized cell therapy. Recently, it was shown that interleukin-2 (IL-2) complexed with a monoclonal antibody (mAb) (clone JES6-1A12) against IL-2 (IL-2 complexes) potently expands and activates Tregs in vivo. Therefore, we investigated whether IL-2 complexes can replace Treg therapy in a costimulation blockade-based and irradiation-free BM transplantation (BMT) model. Unexpectedly, the administration of IL-2 complexes at the time of BMT (instead of Tregs) failed to induce BM engraftment in non-irradiated recipients (0/6 with IL-2 complexes vs. 3/4 with Tregs, p<0.05). Adding IL-2 complexes to an otherwise effective regimen involving recipient irradiation (1Gy) but no Treg transfer indeed actively triggered donor BM rejection at higher doses (0/8 with IL-2 complexes vs. 9/11 without, p<0.01) and had no detectable effect at two lower doses (3/5 vs. 9/11, p>0.05). CD8 T cells and NK cells of IL-2 complex-treated naïve mice showed an enhanced proliferative response towards donor antigens in vitro despite the marked expansion of Tregs. However, IL-2 complexes also expanded conventional CD4 T cells, CD8 T cells, NK cells, NKT cells and notably even B cells, albeit to a lesser extent. Notably, IL-2 complex expanded Tregs featured less potent suppressive functions than in vitro activated Tregs in terms of T cell suppression in vitro and BM engraftment in vivo. In conclusion, these data suggest that IL-2 complexes are less effective than recipient Tregs in promoting BM engraftment and in contrast actually trigger BM

  13. IL-2 / α-IL-2 Complex Treatment Cannot Be Substituted for the Adoptive Transfer of Regulatory T cells to Promote Bone Marrow Engraftment

    PubMed Central

    Mahr, Benedikt; Unger, Lukas; Hock, Karin; Pilat, Nina; Baranyi, Ulrike; Schwarz, Christoph; Maschke, Svenja; Farkas, Andreas Michael; Wekerle, Thomas

    2016-01-01

    Cell therapy with recipient Tregs achieves engraftment of allogeneic bone marrow (BM) without the need for cytoreductive conditioning (i.e., without irradiation or cytotoxic drugs). Thereby mixed chimerism and transplantation tolerance are established in recipients conditioned solely with costimulation blockade and rapamycin. However, clinical translation would be substantially facilitated if Treg-stimulating pharmaceutical agents could be used instead of individualized cell therapy. Recently, it was shown that interleukin-2 (IL-2) complexed with a monoclonal antibody (mAb) (clone JES6-1A12) against IL-2 (IL-2 complexes) potently expands and activates Tregs in vivo. Therefore, we investigated whether IL-2 complexes can replace Treg therapy in a costimulation blockade-based and irradiation-free BM transplantation (BMT) model. Unexpectedly, the administration of IL-2 complexes at the time of BMT (instead of Tregs) failed to induce BM engraftment in non-irradiated recipients (0/6 with IL-2 complexes vs. 3/4 with Tregs, p<0.05). Adding IL-2 complexes to an otherwise effective regimen involving recipient irradiation (1Gy) but no Treg transfer indeed actively triggered donor BM rejection at higher doses (0/8 with IL-2 complexes vs. 9/11 without, p<0.01) and had no detectable effect at two lower doses (3/5 vs. 9/11, p>0.05). CD8 T cells and NK cells of IL-2 complex-treated naïve mice showed an enhanced proliferative response towards donor antigens in vitro despite the marked expansion of Tregs. However, IL-2 complexes also expanded conventional CD4 T cells, CD8 T cells, NK cells, NKT cells and notably even B cells, albeit to a lesser extent. Notably, IL-2 complex expanded Tregs featured less potent suppressive functions than in vitro activated Tregs in terms of T cell suppression in vitro and BM engraftment in vivo. In conclusion, these data suggest that IL-2 complexes are less effective than recipient Tregs in promoting BM engraftment and in contrast actually trigger BM

  14. Bone Grafts

    MedlinePlus

    A bone graft transplants bone tissue. Surgeons use bone grafts to repair and rebuild diseased bones in your hips, knees, spine, and sometimes other bones and joints. Grafts can also repair bone loss caused by some ...

  15. Bone tumor

    MedlinePlus

    Tumor - bone; Bone cancer; Primary bone tumor; Secondary bone tumor ... The cause of bone tumors is unknown. They often occur in areas of the bone that grow rapidly. Possible causes include: Genetic defects ...

  16. Artificial Intelligence.

    ERIC Educational Resources Information Center

    Smith, Linda C.; And Others

    1988-01-01

    A series of articles focuses on artificial intelligence research and development to enhance information systems and services. Topics discussed include knowledge base designs, expert system development tools, natural language processing, expert systems for reference services, and the role that artificial intelligence concepts should have in…

  17. Artificial intelligence

    SciTech Connect

    Firschein, O.

    1984-01-01

    This book presents papers on artificial intelligence. Topics considered include knowledge engineering, expert systems, applications of artificial intelligence to scientific reasoning, planning and problem solving, error recovery in robots through failure reason analysis, programming languages, natural language, speech recognition, map-guided interpretation of remotely-sensed imagery, and image understanding architectures.

  18. Artificial Intelligence.

    ERIC Educational Resources Information Center

    Thornburg, David D.

    1986-01-01

    Overview of the artificial intelligence (AI) field provides a definition; discusses past research and areas of future research; describes the design, functions, and capabilities of expert systems and the "Turing Test" for machine intelligence; and lists additional sources for information on artificial intelligence. Languages of AI are also briefly…

  19. Sensory Substitution

    NASA Astrophysics Data System (ADS)

    Verrillo, Ronald T.

    The idea that the cutaneous surface may be employed as a substitute for the eyes and ears is by no means a modern notion. Although the sense of touch has long been considered as a surrogate for both the visual and auditory modalities, the focus of this chapter will be on the efforts to develop a tactile substitute for hearing, especially that of human speech. The visual system is our primary means of processing information about environmental space such as orientation, distance, direction and size. It is much less effective in making temporal discriminations. The auditory system is unparalleled in processing information that involves rapid sequences of temporal events, such as speech and music. The tactile sense is capable of processing both spatial and temporal information although not as effective in either domain as the eye or the ear.

  20. [Bone grafts in orthopedic surgery].

    PubMed

    Zárate-Kalfópulos, Barón; Reyes-Sánchez, Alejandro

    2006-01-01

    In orthopedic surgery the demand for the use of bone grafts increases daily because of the increasing quantity and complexity of surgical procedures. At present, the gold standard is the autologous bone graft but the failure rate, morbidity of the donor site and limited availability have stimulated a proliferation for finding materials that work as bone graft substitutes. In order to have good success, we must know the different properties of these choices and the environment where the graft is going to be used. As bone graft substitutes and growth factors become clinical realities, a new gold standard will be defined. Tissue engineering and gene therapy techniques have the objective to create an optimum bone graft substitute with a combination of substances with properties of osteconduction, osteogenesis and osteoinduction. PMID:16875525

  1. Artificial urushi.

    PubMed

    Kobayashi, S; Uyama, H; Ikeda, R

    2001-11-19

    A new concept for the design and laccase-catalyzed preparation of "artificial urushi" from new urushiol analogues is described. The curing proceeded under mild reaction conditions to produce the very hard cross-linked film (artificial urushi) with a high gloss surface. A new cross-linkable polyphenol was synthesized by oxidative polymerization of cardanol, a phenol derivative from cashew-nut-shell liquid, by enzyme-related catalysts. The polyphenol was readily cured to produce the film (also artificial urushi) showing excellent dynamic viscoelasticity. PMID:11763444

  2. Nanocomposites and bone regeneration

    NASA Astrophysics Data System (ADS)

    James, Roshan; Deng, Meng; Laurencin, Cato T.; Kumbar, Sangamesh G.

    2011-12-01

    This manuscript focuses on bone repair/regeneration using tissue engineering strategies, and highlights nanobiotechnology developments leading to novel nanocomposite systems. About 6.5 million fractures occur annually in USA, and about 550,000 of these individual cases required the application of a bone graft. Autogenous and allogenous bone have been most widely used for bone graft based therapies; however, there are significant problems such as donor shortage and risk of infection. Alternatives using synthetic and natural biomaterials have been developed, and some are commercially available for clinical applications requiring bone grafts. However, it remains a great challenge to design an ideal synthetic graft that very closely mimics the bone tissue structurally, and can modulate the desired function in osteoblast and progenitor cell populations. Nanobiomaterials, specifically nanocomposites composed of hydroxyapatite (HA) and/or collagen are extremely promising graft substitutes. The biocomposites can be fabricated to mimic the material composition of native bone tissue, and additionally, when using nano-HA (reduced grain size), one mimics the structural arrangement of native bone. A good understanding of bone biology and structure is critical to development of bone mimicking graft substitutes. HA and collagen exhibit excellent osteoconductive properties which can further modulate the regenerative/healing process following fracture injury. Combining with other polymeric biomaterials will reinforce the mechanical properties thus making the novel nano-HA based composites comparable to human bone. We report on recent studies using nanocomposites that have been fabricated as particles and nanofibers for regeneration of segmental bone defects. The research in nanocomposites, highlight a pivotal role in the future development of an ideal orthopaedic implant device, however further significant advancements are necessary to achieve clinical use.

  3. Scaffold Design for Bone Regeneration

    PubMed Central

    Polo-Corrales, Liliana; Latorre-Esteves, Magda; Ramirez-Vick, Jaime E.

    2014-01-01

    The use of bone grafts is the standard to treat skeletal fractures, or to replace and regenerate lost bone, as demonstrated by the large number of bone graft procedures performed worldwide. The most common of these is the autograft, however, its use can lead to complications such as pain, infection, scarring, blood loss, and donor-site morbidity. The alternative is allografts, but they lack the osteoactive capacity of autografts and carry the risk of carrying infectious agents or immune rejection. Other approaches, such as the bone graft substitutes, have focused on improving the efficacy of bone grafts or other scaffolds by incorporating bone progenitor cells and growth factors to stimulate cells. An ideal bone graft or scaffold should be made of biomaterials that imitate the structure and properties of natural bone ECM, include osteoprogenitor cells and provide all the necessary environmental cues found in natural bone. However, creating living tissue constructs that are structurally, functionally and mechanically comparable to the natural bone has been a challenge so far. This focus of this review is on the evolution of these scaffolds as bone graft substitutes in the process of recreating the bone tissue microenvironment, including biochemical and biophysical cues. PMID:24730250

  4. Bone Diseases

    MedlinePlus

    ... avoid smoking and drinking too much alcohol. Bone diseases can make bones easy to break. Different kinds ... break Osteogenesis imperfecta makes your bones brittle Paget's disease of bone makes them weak Bones can also ...

  5. Polish artificial heart program.

    PubMed

    El Fray, Miroslawa; Czugala, Monika

    2012-01-01

    Despite significant advances in the development of artificial heart substitutes, anthrombogenic materials and surfaces remain to be the main challenge for implants, which can prevent thrombosis that leads to rejection. The goal of material engineering is essentially to design polymeric materials of high durability and optimal thrombogenicity in mechanical heart prosthesis, being developed recently in a frame of the polish artificial heart program. For these reasons, various surface modifications are being continuously developed for a 'gold standard' material, which is a polyurethane (PU) thermoplastic elastomer and they will be shortly reviewed. However, new polymeric materials can meet medical word's attention if they are able to provide similar or better characteristics in term of bulk and surface properties. Specifically, if they will show appropriate surface topography, which is the most influential in determining the response of live tissues toward biomaterials. Nanostructured polyester thermoplastic elastomers of high biodurability as an alternative to PU materials for artificial heart are challenging new materials, and they will be discussed briefly. PMID:22110047

  6. Vitreous Substitutes.

    PubMed

    Foster, William Joseph

    2008-04-01

    Modern vitreoretinal surgery is a young science. While tremendous developments have occurred in instrument design and technique since Machemer first described vitrectomy surgery in 1973[1], the application of advanced materials concepts to the development of intra-ocular compounds is a particularly exciting area of research. To date, the development of vitreous substitutes has played a significant role in enabling the dramatic and progressive improvement in surgical outcome, but perhaps no other area of research has the potential to further improve the treatment of retinal detachment and other retinal disorders. While prior research has focused solely upon the ability of a compound to re-attach the retina, future research should seek to enable the surgeon to inhibit the development of proliferative vitreoretinopathy and re-detachment, the integration of stem-cell therapies with surgical retina, long-term delivery of medications to the posterior segment, and the promotion of more rapid and complete visual rehabilitation. PMID:19343097

  7. Artificial noses.

    PubMed

    Stitzel, Shannon E; Aernecke, Matthew J; Walt, David R

    2011-08-15

    The mammalian olfactory system is able to detect many more odorants than the number of receptors it has by utilizing cross-reactive odorant receptors that generate unique response patterns for each odorant. Mimicking the mammalian system, artificial noses combine cross-reactive sensor arrays with pattern recognition algorithms to create robust odor-discrimination systems. The first artificial nose reported in 1982 utilized a tin-oxide sensor array. Since then, however, a wide range of sensor technologies have been developed and commercialized. This review highlights the most commonly employed sensor types in artificial noses: electrical, gravimetric, and optical sensors. The applications of nose systems are also reviewed, covering areas such as food and beverage quality control, chemical warfare agent detection, and medical diagnostics. A brief discussion of future trends for the technology is also provided. PMID:21417721

  8. Bone cysts: unicameral and aneurysmal bone cyst.

    PubMed

    Mascard, E; Gomez-Brouchet, A; Lambot, K

    2015-02-01

    Simple and aneurysmal bone cysts are benign lytic bone lesions, usually encountered in children and adolescents. Simple bone cyst is a cystic, fluid-filled lesion, which may be unicameral (UBC) or partially separated. UBC can involve all bones, but usually the long bone metaphysis and otherwise primarily the proximal humerus and proximal femur. The classic aneurysmal bone cyst (ABC) is an expansive and hemorrhagic tumor, usually showing characteristic translocation. About 30% of ABCs are secondary, without translocation; they occur in reaction to another, usually benign, bone lesion. ABCs are metaphyseal, excentric, bulging, fluid-filled and multicameral, and may develop in all bones of the skeleton. On MRI, the fluid level is evocative. It is mandatory to distinguish ABC from UBC, as prognosis and treatment are different. UBCs resolve spontaneously between adolescence and adulthood; the main concern is the risk of pathologic fracture. Treatment in non-threatening forms consists in intracystic injection of methylprednisolone. When there is a risk of fracture, especially of the femoral neck, surgery with curettage, filling with bone substitute or graft and osteosynthesis may be required. ABCs are potentially more aggressive, with a risk of bone destruction. Diagnosis must systematically be confirmed by biopsy, identifying soft-tissue parts, as telangiectatic sarcoma can mimic ABC. Intra-lesional sclerotherapy with alcohol is an effective treatment. In spinal ABC and in aggressive lesions with a risk of fracture, surgical treatment should be preferred, possibly after preoperative embolization. The risk of malignant transformation is very low, except in case of radiation therapy. PMID:25579825

  9. Artificial sweeteners: safe or unsafe?

    PubMed

    Qurrat-ul-Ain; Khan, Sohaib Ahmed

    2015-02-01

    Artificial sweeteners or intense sweeteners are sugar substitutes that are used as an alternative to table sugar. They are many times sweeter than natural sugar and as they contain no calories, they may be used to control weight and obesity. Extensive scientific research has demonstrated the safety of the six low-calorie sweeteners currently approved for use in foods in the U.S. and Europe (stevia, acesulfame-K, aspartame, neotame, saccharin and sucralose), if taken in acceptable quantities daily. There is some ongoing debate over whether artificial sweetener usage poses a health threat .This review article aims to cover thehealth benefits, and risks, of consuming artificial sweeteners, and discusses natural sweeteners which can be used as alternatives. PMID:25842566

  10. Artificial Intelligence.

    ERIC Educational Resources Information Center

    Wash, Darrel Patrick

    1989-01-01

    Making a machine seem intelligent is not easy. As a consequence, demand has been rising for computer professionals skilled in artificial intelligence and is likely to continue to go up. These workers develop expert systems and solve the mysteries of machine vision, natural language processing, and neural networks. (Editor)