Tissue-engineered Bone Grafts Research Articles

Neo-vascularization and bone formation mediated by fetal mesenchymal stem cell tissue-engineered bone grafts in critical-size femoral defects

Tissue-engineered bone grafts (TEBG) require highly osteogenic cell sources for use in fracture repair applications. Compared to other sources of mesenchymal stem cells (MSC), human fetal MSC (hfMSC) have recently been shown to be more proliferative and osteogenic. We studied the functional performance of hfMSC-mediated TEBG in 7 mm rat femoral critical-sized bone defects (CSD). Dynamically-cultured and osteogenically-primed hfMSC seeded onto macroporous poly-ɛ-caprolactone tri-calcium phosphate scaffolds were transplanted into CSDs. After 12 weeks, hfMSC-mediated TEBG induced 2.1× more new bone formation (43.3 ± 10.5 vs. 21.0 ± 7.4 mm 3, p < 0.05), with greater compact and woven bone, and a 9.8× increase in stiffness (3.9 ± 1.7 vs. 0.4 ± 0.3 mNm/degree, p < 0.05) compared to acellular scaffolds, such that only animals transplanted with TEBG underwent full fracture repair of the CSD. Although hfMSC survived for <4 weeks, by 4 weeks they were associated with a 3.9× larger vasculature network in the defect area (35.2 ± 11.1 vs. 6.5 ± 3.6 mm 3 p < 0.05), suggesting an important role for hfMSC in the promotion of neo-vasculogenesis. We speculate that hfMSC-mediated healing of the CSD by stimulating neo-vascularization through as yet undetermined mechanisms. This proof-of-principle study demonstrates the utility of primitive MSC for bone regeneration, and may be of relevance to vascularization in other areas of regenerative medicine.

Combining Scaffolds and Osteogenic Cells in Regenerative Bone Surgery: A Preliminary Histological Report in Human Maxillary Sinus Augmentation

The following case series evaluated the maxillary sinus augmentation responses to tissue-engineered bone graft obtained by a culture of autogenous osteoblasts seeded on polyglycolic-polylactic scaffolds and calcium phosphate. Sinus floor augmentation was performed bilaterally in five patients (mean age 58.4 years) with tissue-engineered bone (test site - Oral Bone, BioTissue, Freiburg, Germany) or calcium phosphate (control site - Biocoral, Novaxa Spa, Milan, Italy). Biopsies were harvested 6 months after sinus augmentation for histometric evaluation. Volumetric measurements were taken at baseline and 6 months after the surgical procedure. The mean of vertical bone gain was 6.47 +/- 1.39 mm and 9.14 +/- 1.19 mm to test and control sites, respectively. The histological sections depicted mature bone with compact and cancellous areas. All biopsies contained varying percentages of newly formed bone and marrow spaces. The mean of bone tissue in the grafted area was 37.32 +/- 19.59% and 54.65 +/- 21.17% for tissue-engineered bone and calcium phosphate, respectively. Within the limits of the present report, the histological data in humans confirmed that tissue-engineered bone and calcium phosphate allowed newly formed bone after maxillary sinus augmentation.

Synthesis and characterization of biocomposites with different hydroxyapatite–collagen ratios

Hydroxyapatite (HA)-type I collagen (Col) composite is a tissue-engineered bone graft which can act as a carrier or a template structure for cells or any other agents. In this paper, the effect of Col ratio on the scaffold structure and composition was analyzed. Scaffolds composed by HA/Col with different weight ratios (80:20; 50:50; 20:80, and 10:90) were produced by the precipitation method at pH 8-9, 37 degrees C and 6 h of ripening. Using X-ray diffraction data, the Rietveld structure refinement showed that the size of HA crystals along the c-axis direction (002) decreases significantly in the presence of Col. Thus, the HA crystal shape turned from needle-like in pure HA, into spherical, in the 10:90 composite due to Col fibrillogenesis. The homogeneity of the composite was significantly dependent on the amount of Col in it. HA/Col 20/80 composite presented HA particles in a more homogenous way. Such a biocomposite was successfully produced in a rapid way and it is potentially useful for both small tissue repairs and engineering.

A novel technique to reconstruct a boxlike bone defect in the mandible and support dental implants with In vivo tissue-engineered bone.

The purpose of this study was to investigate the feasibility of using in vivo tissue-engineered (TE) bone to repair boxlike mandibular defect and support dental implant, and then provide experimental evidence for the future application of the novel technique in the clinical setting. The TE bone graft was constructed in vivo by implanting osteoinductive calcium phosphate (Ca-P) ceramics in the femoral muscles of dog for 8 weeks, then was transplanted to repair the autogeneic boxlike bone defect site created in one side of the mandible and simultaneously support a dental implant, while in the opposite side of the mandibular defect, the same ceramic was used directly as control. 8 weeks after transplantation, samples were harvested for analysis. The results demonstrated that the technique of in vivo tissue engineering improved the mechanical and biologic properties of ceramics significantly. After transplantation, the in vivo TE ceramic-bone grafts were involved in bone metabolism of the host and fused well with the host bone. The dental implants were stable and had been integrated with both TE bone grafts and autologous bone. Therefore, it is feasible to construct a live bone graft with osteoinductive Ca-P ceramics in vivo, then repair a mandibular bone defect, and support a dental implant. In conclusion, in vivo TE bone is a promising technique for bone repair.

Bone regeneration in sinus lifts: comparing tissue-engineered bone and iliac bone

Lifting of the sinus floor is a standard procedure for bony augmentation that enables dental implantation. Although cultivated skin and mucosal grafts are often used in plastic and maxillofacial surgery, tissue-engineered bone has not achieved the same success. We present the clinical results of dental implants placed after the insertion of periosteum-derived, tissue-engineered bone grafts in sinus lifts. Periosteal cells were isolated from biopsy specimens of periosteum, resuspended and cultured. The cell suspension was soaked in polymer fleeces. The cell–polymer constructs were transplanted by sinus lift 8 weeks after harvesting. The patients ( n = 35) had either one or both sides operated on. Seventeen had a one-stage sinus lift with simultaneous implantation (54 implants). In 18 patients the implants were inserted 3 months after augmentation (64 implants). Selected cases were biopsied. A control group (41 patients: one stage = 48 implants, two stage = 135 implants) had augmentation with autologous bone only. They were followed up clinically and radiologically for at least 24 months. Both implants and augmentation were significantly more successful in the control group. Failure of augmentation of the tissue-engineered bone was more common after large areas had been augmented. Eleven implants were lost in the study group and only one in the control group. Lifting the sinus floor with autologous bone is more reliable than with tissue-engineered transplants. Although lamellar bone can be found in periosteum-derived, tissue-engineered transplants, the range of indications must be limited.

Growth of Bone Marrow Derived Osteoblast-Like Cells into Coral Implant Scaffold: Preliminary Study on Malaysian Coral

Problem statement: Biomaterial fabrication in Malaysia started as a co nsequence of the demand for cheaper implant materials. Various biomaterials have been developed utilizing local resources like Malaysian coral. Locally processed Malaysian coral need to be complemented with proper evaluation and testing including toxicology, biocompatibility, mechanical properties, physicochemical characterization and in vivo testin g. The present study was carried out to assess natural coral of porites species as scaffold combin ed with in vitro expanded Bone Marrow Derived Osteoblast-Like cells (BM-DOL), in order to develop a tissue-engineered bone graft in a rat model. Approach: Coral was used in a block shape with a dimension o f 10 mm length × 5 mm width × 5 mm thickness. BM-DOL cells were seeded into porous coral scaffold in a density of 5 ×10 6 mL -1 . After 7 days of in vitro incubation in osteogenic medium, one block was processed for light (LM) and Scanning Electron Microscopy (SEM) observations while the other blocks were implanted subcutaneously in the back of 5 weeks-old Sprague-Dawely rats for 3 months. Coral blocks without cells were implanted as a control. The implants har vested and processed for gross inspection, histological and scanning electron microscopy obser vations. Results: Both LM and SEM showed attachment of well arrangement multilayer cells ins ide the pores of in vitro seeded coral scaffolds. Gross inspection of all in vivo coral-cell complexe s implants revealed vascularized like bone tissue formation. Histological sections revealed mature bo ne formation occurred in the manner resemble intramembraneous bone formation. SEM observations revealed multi-layer cellular proliferation with abundant collagen covered the surface of coral impl ants. Control group showed resorbed coral block. Conclusion: This study demonstrated that Malaysian coral can b e use as a suitable scaffold material for delivering bone marrow mesenchymal stem cells in tissue engineering and therefore, offers a great potential to enhance bone healing around implants i n a compromised bone bed.

Biocompatibility of Poly-ε-caprolactone-hydroxyapatite composite on mouse bone marrow-derived osteoblasts and endothelial cells

BackgroundTissue-engineered bone may be developed by seeding the cells capable of both osteogenesis and vascularization on biocompatible composite scaffolds. The current study investigated the performance of mice bone marrow-derived osteogenic cells and endothelial cells as seeded on hydroxyapatite (HA) and poly-ε-caprolactone (PCL) composite scaffolds.MethodsMononuclear cells were induced to osteoblasts and endothelial cells respectively, which were defined by the expression of osteocalcin, alkaline phosphatase (ALP), and deposits of calcium-containing crystal for osteoblasts, or by the expression of vascular endothelial growth factor receptor-2 (VEGFR-2) and von Willebrand factor (vWF), and the formation of a capillary network in Matrigel™ for endothelial cells. Both types of cell were seeded respectively on PCL-HA scaffolds at HA to PCL weight ratio of 1:1, 1:4, or 0:1 and were evaluated using scanning electron microscopy, ALP activity (of osteoblasts) and nitric oxide production (of endothelial cells) plus the assessment of cell viability.ResultsThe results indicated that HA led to a positive stimulation of osteoblasts viability and ALP activity, while HA showed less influence on endothelial cells viability. An elevated nitric oxide production of endothelial cells was observed in HA-containing group.ConclusionSupplement of HA into PCL improved biocompatible for bone marrow-derived osteoblasts and endothelial cells. The PCL-HA composite integrating with two types of cells may provide a useful system for tissue-engineered bone grafts with vascularization.

A biaxial rotating bioreactor for the culture of fetal mesenchymal stem cells for bone tissue engineering

The generation of effective tissue engineered bone grafts requires efficient exchange of nutrients and mechanical stimulus. Bioreactors provide a manner in which this can be achieved. We have recently developed a biaxial rotating bioreactor with efficient fluidics through in-silico modeling. Here we investigated its performance for generation of highly osteogenic bone graft using polycaprolactone–tricalcium phosphate (PCL–TCP) scaffolds seeded with human fetal mesenchymal stem cell (hfMSC). hfMSC scaffolds were cultured in either bioreactor or static cultures, with assessment of cellular viability, proliferation and osteogenic differentiation in vitro and also after transplantation into immunodeficient mice. Compared to static culture, bioreactor-cultured hfMSC scaffolds reached cellular confluence earlier (day 7 vs. day 28), with greater cellularity (2×, p < 0.01), and maintained high cellular viability in the core, which was 2000 μm from the surface. In addition, bioreactor culture was associated with greater osteogenic induction, ALP expression (1.5× p < 0.01), calcium deposition (5.5×, p < 0.001) and bony nodule formation on SEM, and in-vivo ectopic bone formation in immunodeficient mice (3.2×, p < 0.001) compared with static-cultured scaffolds. The use of biaxial bioreactor here allowed the maintenance of cellular viability beyond the limits of conventional diffusion, with increased proliferation and osteogenic differentiation both in vitro and in vivo, suggesting its utility for bone tissue engineering applications.

Experimental study on spinal fusion induced by hBMP-4 gene modified tissue engineered bone

To evaluate the efficacy of hBMP-4 gene modified tissue engineered bone graft in the enhancement of rabbit spinal fusion and find an ideal kind of substitute for the autograft bone. Rabbit BMSCs were cultured and transfected with AAV-hBMP-4 using different MOI value. The optimal MOI value were determined by observing cell's morphology change. BMSCs were then transfected with AAV-hBMP4 and AAV-EGFP respectively, following which the transfected cells were evenly suspended in a collagen sponge I, and implanted to either side of the L5,6 intertransverse spaces posterolateral in the New Zealand rabbits to induce spinal fusion. Fourteen rabbits were randomly divided into 2 groups. Group 1: AAV-hBMP-4 transfected BMSCs in the right side (hBMP-4 side) and autograft bone in the left side. Group 2: AAV-hBMP-4 transfected BMSCs in the right side (hBMP-4 side) and AAV-EGFP transfected BMSCs in the left side (EGFP side). Radiographs and three-dimensional CT of the spine, manual palpation, gross and histological examination of the fusion masses for all the animals were performed subsequent to animals having been sacrificed at 12 weeks after surgery. Evaluation has been taken in 12 New Zealand rabbits delivered into 2 groups which meet the criterion after operation. Eleven in 12 implemented sides involved hBMP-4 achieved bony fusion, to which 5 in 6 autografted sides was similar. But only 2 in 6 sides in EGFP-group achieved bony fusion meanwhile. Three-dimensional CT scan and palpation also evidenced the results. Bone formation was observed obviously on specimen both in hBMP4 sides and autografted ones. EGFP-group also got bony integration, but the quantity was small. Tissue-engineered bone graft constructed from application of hBMP4 is a fine substitute for autograft. Effective enhancement of bony integration in spinal fusion surgery has been evidenced in vivo.

Successful Repair of a Critical-Sized Bone Defect in the Rat Femur with a Newly Developed External Fixator

Regeneration of segmental bone defects has been a clinical challenge. Recent advances in the field of tissue engineering have developed new procedures enabling bone regeneration. Small animal models capable of supporting weight-bearing femoral defects are integral parts of orthopedic biomedical research. However, a drawback of bone healing research is the lack of stable and adaptable fixation devices for small animals. Therefore, we developed and evaluated an adjustable external fixation device in the maintenance of non-healable (ie critical-sized) segmental defects, and in the fixation of tissue-engineered bone grafts in a rat model. Male Sprague-Dawley rats (n = 24) underwent a femoral osteotomy to create a non-healing segmental defect (6 mm size), which was stabilized with the fixator. A treatment group (12 rats) received tissue-engineered bone graft implants consisting of biphasic calcium phosphate blocks seeded with bone mesenchymal stem cells, while other 12 animals received no bone graft (non-treatment group). The osteotomy gap remained unchanged in the non-treatment group over the 12-week period, indicating that the 6-mm bone defect is really non-healable in the rat femur and that the device has sufficient stability for the management of critical-sized femoral defects. At 12 weeks, the treatment group maintained the bone length throughout the study period and showed bridging of the defect, with remarkable new bone formation. In contrast, the non-treatment group showed marginal new bone formation, but no apparent healing. In conclusion, the novel device provides substantial benefits in the maintenance of critical-sized femoral defects and tissue-engineered bone grafts in a rat model.

Tissue Engineered Bone Grafts: Biological Requirements, Tissue Culture and Clinical Relevance

The tremendous need for bone tissue in numerous clinical situations and the limited availability of suitable bone grafts are driving the development of tissue engineering approaches to bone repair. In order to engineer viable bone grafts, one needs to understand the mechanisms of native bone development and fracture healing, as these processes should ideally guide the selection of optimal conditions for tissue culture and implantation. Engineered bone grafts have been shown to have capacity for osteogenesis, osteoconduction, osteoinduction and osteointegration - functional connection between the host bone and the graft. Cells from various anatomical sources in conjunction with scaffolds and osteogenic factors have been shown to form bone tissue in vitro. The use of bioreactor systems to culture cells on scaffolds before implantation further improved the quality of the resulting bone grafts. Animal studies confirmed the capability of engineered grafts to form bone and integrate with the host tissues. However, the vascularization of bone remains one of the hurdles that need to be overcome if clinically sized, fully viable bone grafts are to be engineered and implanted. We discuss here the biological guidelines for tissue engineering of bone, the bioreactor cultivation of human mesenchymal stem cells on three-dimensional scaffolds, and the need for vascularization and functional integration of bone grafts following implantation.

Use of Engineered Bone for Sinus Augmentation

Tissue-engineered bone grafts represent an appealing alternative for maxillary sinus augmentation because they eliminate the significant drawbacks associated with extra- and intraoral bone-harvesting procedures. In the present case series, we document the outcomes of sinus augmentation surgery using tissue-engineered bone grafts. Three patients requiring bilateral sinus augmentation received tissue-engineered bone grafts combined with xenograft prior to implant placement. Implants were placed and loaded 6 and 12 months postaugmentation, respectively. Radiographs were taken and clinical examinations were performed preoperatively and at 4, 6, 12, and 18 months postaugmentation. Biopsies were obtained at 4 and 6 months postaugmentation. Standardized orthopantomograms were used to measure the posterior maxilla bone height. None of the patients experienced untoward complications during or following the therapeutic procedures. Ten implants were inserted into the augmented sinuses and loaded. Biopsies revealed a lack of inflammation or pathology; newly formed fibrous bone with osteoblastic activity and xenograft particles was evident. Compared to 4 months postaugmentation, augmented tissue was more mature at 6 months. The postoperative (18 months) bone height in augmented areas was significantly greater than the preoperative height (P <0.0001), representing an approximately 4.5-fold increase in bone height. Sinus augmentation using tissue-engineered bone grafts was successful in all three cases, permitting the subsequent insertion and loading of dental implants. The present cases demonstrated the feasibility of using engineered bone for sinus augmentation. Controlled clinical trials will be required to evaluate this new and evolving treatment modality.

The biomaterial influences the ossification after sinus floor elevation using tissue-engineered bone grafts

Sinus floor elevation is the standard procedure that allows dental implant insertion in the atrophic posterior maxilla. Instead of autogenous bone, tissue-engineered bone grafts can be used, but clear comparative clinical studies also assessing the influence of the biomaterial are missing. In six patients, tissue-engineered bone grafts were used in eight sinus floor elevations. After culturing osteoblast-like cells from biopsies of the maxilla, they were seeded on scaffolds made either from demineralised bovine bone matrix (DBBM) or from solvent-dehydrated mineralised bone (SDBB), and grafted. In all patients primary wound healing was without complications, except for one patient in the SDBB group. After 12 months, implant insertion was possible only in the SDBB group; in the DBBM group, fibrous connective tissue was found in an attempt of implant insertion. After 5 months, implant placement was performed in one patient of each group. However, the two implants inserted in the DBBM group were lost after 6 weeks. Histology of the bone cores in the DBBM group at 5 months showed lamellar bone and osteoid, and at 12 months showed fibrous connective tissue. Inflammation and some resorption of the scaffold was found 5 months after SDBB grafting, and after 12 months cancellous bone formation encapsulating SDBB remnants were observed. These preliminary data suggest that the preparation method of the bovine bone matrix, in particular the mineral content, and therefore the mechanical stability may have some influence on the generation of new bone.

Bone formation after sinus augmentation with engineered bone

The aim of the following investigation was to quantify the resorption rate of tissue-engineered bone grafts in the maxillary sinus using volume measurements. Sinus floor augmentation using autologous bone grafts from the iliac crest (n=17, group 1) was compared with commercially produced transplants of human cells seeded on polyglycolid-polylactid (PLGA) scaffolds (Oral Bone) (n=14, group 2). The total resorption rate for autologous transplants 3 months post operation was 29%, while the tissue-engineered bone showed a resorption rate of 90%. The autologous bone had a bone density of up to 266-551 Hounsfield units (HU), while sufficient mineralization of tissue-engineered bone was found in only one case (152 HU). In this clinical study, the use of autologous cancellous bone grafts in sinus augmentation was more reliable than scaffolds containing cultured osteoblasts. Further tissue-engineered bone transplants should be examined to draw general conclusions about the use of tissue-engineered grafts compared with autologous bone grafts for maxillary sinus augmentation.

Microdamage and bone mechanobiology

Mechanobiology is concerned with the relationships between mechanical forces and biological processes. Bone adapts to altered mechanical loading by modelling and remodelling. Microdamage is a stimulus for adaptation as shown by a sheep overload model. If microdamage accumulates it leads to fracture failure, notably in osteoporosis. Detection methods, based on chelating fluorochromes and radiopaque agents, will enable microdamage to be quantified and, along with bone mass, aid in fracture prediction and prevention. Mechanobiological principles can be utilised to create tissue engineered bone grafts in cases of bone loss due to trauma, malignancy or resorption.

Anorganic Bone Mineral Coated with Tetra-Cell Adhesion Molecule Enhances Bone Formation in Rabbit Calvarial Defects

This study was performed to evaluate the effect of anorganic bone mineral (ABM) coated with Tetra-Cell Adhesion Molecule (T-CAM) for bone formation in rabbit calvarial defects and compare the capability of bone formation in ABM coated with T-CAM (ABM/T-CAM) to that in commercially available ABM coated with a synthetic peptide (P-15) which mimics the cell-binding domain of type I collagen, PepGen P-15TM. T-CAM composed of four cell adhesion molecules (RGD, PHSRN, EPDIM, and YH) was synthesized and ABM/T-CAM were prepared by absorbing T-CAM on ABM (OsteoGraf/N-300; Densply Friadent Ceramed Corp., USA). Two 9-mm diameter, full-thickness calvarial defects were made in each rabbit parietal bone and sixteen adult male rabbits were used in this experiment. The defects were reconstructed according to four treatment groups: unfilled, BM-grafted, PepGen P-15TM-grafted, and ABM/T-CAM-grafted. The animals were sacrificed at 2 and 4 weeks after surgery for histologic and histomorphometric evaluation. An active new bone formation were observed in the defects of ABM/T-CAM and PepGen P-15TM grafted groups at 2 and 4 weeks of healing in histologic observation. The results of histomorphometric analysis revealed higher new bone formation in ABM/T-CAM-grafted (14.62±0.6% at 2 weeks, 15.33±2.4% at 4 weeks) and PepGen P-15TM-grafted (12.46±1.0% at 2 weeks, 18.14±1.7% at 4 weeks) groups than in unfilled control (7.03±2.3% at 2 weeks, 8.71±3.4% at 4 weeks) and ABMgrafted (6.59±1.7% at 2 weeks, 9.25±0.8% at 4 weeks) groups at 2 and 4 weeks of healing with statistical significance (P&lt;0.01). The results of this study indicated that the immobilizing T-CAM on ABM enhances the capability of bone substitutes to serve as an effective habitat for bone forming cells in vivo. In conclusion, we suggested that this composite graft material, ABM/T-CAM may be served as an effective tissue-engineered bone graft material in osseous reconstructive surgery.

Experimental Study of Vascularized Tissue-Engineered Bone Grafts

Vascularized bone grafting has become a useful method for treatment of large bone defects and infected nonunions that lack adequate blood supply. This method has disadvantages, however, such as donor-site complications. To overcome these disadvantages, the authors developed a new method for creating vascularized tissue-engineered bone grafts in an experimental model. Fisher rat bone marrow mesenchymal stem cells were cultured for 2 weeks in fully opened, interconnected, porous hydroxyapatite ceramic. The composites of mesenchymal stem cells and hydroxyapatite were implanted in the medial calf region together with the saphenous vascular bundle in syngeneic rats. Two weeks after implantation, the vascular pedicle with the implants was exposed and covered with silicone rubber to prevent vascular invasion through surrounding tissues (vascularized mesenchymal stem cell/hydroxyapatite implants). In addition, nonvascularized mesenchymal stem cell/hydroxyapatite implants were created with a ligated vascular pedicle. Implants of vascularized hydroxyapatite alone were prepared as a control. All implants were retrieved 4 weeks after surgery. Histologically, de novo bone formations were observed in the vascularized implants. This was in contrast with only necrotic tissue observed in the nonvascularized implants. Bone formation was not observed entirely in the vascularized hydroxyapatite-alone implants. For biochemical analysis, alkaline phosphatase activity and osteocalcin content of the vascularized mesenchymal stem cell/hydroxyapatite implants were significantly higher than those of the nonvascularized mesenchymal stem cell/hydroxyapatite and vascularized hydroxyapatite-alone implants. The results of this study indicated that the vascularized tissue-engineered bone grafts could be transferred as free vascularized grafts to lesions that lack adequate blood supply.

Anchoring Dental Implant in Tissue-Engineered Bone Using Composite Scaffold: A Preliminary Study in Nude Mouse Model

The purpose of this study was to fabricate a tissue-engineered bone graft anchoring dental implant with bone marrow stromal cell (bMSC) seeded coral-implant composite scaffold. Titanium dental implants (3 mm in diameter) were inserted into the cylinder coral scaffolds (5 mm in diameter and 1 mm in wall thickness). bMSCs were isolated from iliac bone marrow of adult New Zealand White rabbits, induced by dexamethasone and seeded into the composite scaffold at the density of 2 x 10 8 /mL in 200 muL medium. Nine cell coral-implant complexes were incubated in vitro for 5 days. One complex was processed for scanning electronic microscopy. The other 8 complexes, together with 4 coral scaffold without cell acting as control, were implanted subcutaneously into nude mice back. At 1 and 2 months after implantation, 4 specimens from the experiment group and 2 specimens from the control group were harvested respectively. New bone restoration and new bone integration with dental implant were evaluated by gross inspection, manual handling test, radiographic examination, and histologic observation. Specimens harvested at 2 months after implantation were red and similar to native bone. Manual handling test showed that dental implants were fixed in the newly formed bone. Radiographic examination showed that most of the coral scaffold had been absorbed. Bone density x-ray shadow could be observed around the dental implant. Histologic examination showed that large amount of new bone formed around the dental implants and integrated well with the implants in some area. In the control group no bone formation was observed both macroscopically and microscopically. The results of the study suggested that the tissue-engineered bone of bMSCs seeded natural coral-implant composite scaffold is promising for dental implant anchoring, which has positive implication for clinical jaw reconstruction.

Treatment of Pseudoarthrosis Using Tissue-Engineered Bone Graft

Subjects were graft patients with pseudoarthrosis (average age, 60.3 years; range, 17-85 years). Pseudoarthrosis affected the thoracolumbar spine, the femur, the clavicle, the humerus and the metatarsal. From the ilium (tibia in one patient), 10-20 ml of bone marrow fluid was collected, and then, it was immediately transferred to the culture room and incubated in a flask containing MEM with 15% autologous or fetal bovine serum, etc.. After 2 weeks in primary culture, cells were released by trypsin treatment and were subsequently incubated with porous beta-TCP in order to prepare tissue-engineered artificial bone, according to the previously reported modified culturing technique. Tissue-engineered artificial bone was grafted around the non-union site of each affected long bone, while tissue-engineered artificial bone was grafted via the pedicle of each affected vertebral body. In all patients, favorable bone formation was seen at three months after surgery. In the patients with pseudoarthrosis of the spine, CT and MRI confirmed favorable vertebral body formation. In the patients with pseudoarthrosis of a long bone, the artificial bone was remodeled and favorable bone union was confirmed. In 2 patients in whom bone biopsy was performed during pin removal, bone regeneration was confirmed histologically. With present type of tissue-engineered artificial bone, an artificial material with a high bone regeneration capacity can be prepared by aspiration, which is minimally invasive, and thus when compared to iliac bone grafts, it is possible to radically reduce postoperative pain without damage of autologous bone.

Construction of an injectable tissue-engineered bone graft using autologous PRP and radiographic evaluation of its effect on repairing segmental radial defects in rabbits

目的 用自体富血小板血浆(PRP)、骨髓基质干细胞(BMSCs)和纤维蛋白胶(FG)构建可注射型组织工程骨并从放射学方面评价其修复自体兔桡骨缺损的效果. 方法 36只新西兰兔随机分为 A、B、C三组,每组 12只.所有动物术前 1周抽取耳背中央动脉血提取 PRP. A组于术前 1～ 2个月抽取双髂骨处骨髓并培养出 BMSCs,在体外与 FG及自体 PRP构建成可注型组织工程骨,植入自体桡骨 1.5cm节段性骨缺损,为实验组. B、C两组分别植入 PRP+ FG、FG于同样骨缺损处为对照组.另取 4只桡骨同样部位和大小骨缺损旷置作为空白组.术后 4、8、12周时摄前臂正位 X线片.用放射影像学评分和图像分析 X线阻射影比较骨缺损的修复情况. 结果 A、B两组骨缺损放射影像学评分以及新生骨痂的密度在 4、8、12周均优于 C组 (P 0.05),但在新生骨痂密度上, A >B >C(P< 0.05).空白组术后 16周骨缺损无愈合. 结论 PRP对骨缺损愈合有明显促进作用,复合 PRP的可注射型材料与 BMSCs构建组织工程骨可修复兔桡骨节段性骨缺损。