Bone induction using demineralized bone in the rabbit femur: a long-term study

Reparative effect of super active platelet combined with allogeneic bone for large bone defects

In clinical practice, autologous bone transplantation is usually used to treat large-scale bone defects. However, autologous bone can cause complications such as secondary injury to patients, the scarcity of autografts. In this study, the study of using super active platelet lysate (sPL) and allogeneic bone to treat the 15 mm long bone defect in right radius of rabbits, and provide an experimental basis for the next step of clinical bone defect treatment. The critical-size defect of New Zealand white rabbits was made and divided into three groups: autologous bone group, allogeneic bone group, and sPL group. They were euthanized 1, 2, and 3 months after the operation, perform imaging and histological observation on the repair of bone defect area. The results showed that there were varying degrees of new bone in the bone defect. CT data showed that the bone defect repair rate and new bone mass in each group increased month by month (P <.05). Bone tissue (BV) and bone tissue to the total volume (BV/TV, %) in the sPL group > allogeneic bone group, autologous bone group > allogeneic bone group, with statistical significance (P < .05). Compared with the allogeneic bone group, the sPL group can significantly promote the healing of bone defects, enhance the bone density after fracture healing. The repair effect after 3 months was similar to that of the autogenous bone group. The use of allogeneic bone and sPL therapy may become part of a comprehensive strategy for tissue engineering to treat bone defects.

S53P4 bioactive glass scaffolds induce BMP expression and integrative bone formation in a critical-sized diaphysis defect treated with a single-staged induced membrane technique

Critical-sized diaphysis defects are complicated by inherent sub-optimal healing conditions. The two-staged induced membrane technique has been used to treat these challenging defects since the 1980's. It involves temporary implantation of a membrane-inducing spacer and subsequent bone graft defect filling. A single-staged, graft-independent technique would reduce both socio-economic costs and patient morbidity. Our aim was to enable such single-staged approach through development of a strong bioactive glass scaffold that could replace both the spacer and the graft filling. We constructed amorphous porous scaffolds of the clinically used bioactive glass S53P4 and evaluated them in vivo using a critical-sized defect model in the weight-bearing femur diaphysis of New Zealand White rabbits. S53P4 scaffolds and standard polymethylmethacrylate spacers were implanted for 2, 4, and 8 weeks. Induced membranes were confirmed histologically, and their osteostimulative activity was evaluated through RT-qPCR of bone morphogenic protein 2, 4, and 7 (BMPs). Bone formation and osseointegration were examined using histology, scanning electron microscopy, energy-dispersive X-ray analysis, and micro-computed tomography imaging. Scaffold integration, defect union and osteosynthesis were assessed manually and with X-ray projections. We demonstrated that S53P4 scaffolds induce osteostimulative membranes and produce osseointegrative new bone formation throughout the scaffolds. We also demonstrated successful stable scaffold integration with early defect union at 8 weeks postoperative in critical-sized segmental diaphyseal defects with implanted sintered amorphous S53P4 scaffolds. This study presents important considerations for future research and the potential of the S53P4 bioactive glass as a bone substitute in large diaphyseal defects. STATEMENT OF SIGNIFICANCE: Surgical management of critical-sized diaphyseal defects involves multiple challenges, and up to 10% result in delayed or non-union. The two-staged induced membrane technique is successfully used to treat these defects, but it is limited by the need of several procedures and bone graft. Repeated procedures increase costs and morbidity, while grafts are subject to donor-site complications and scarce availability. To transform this two-staged technique into one graft-independent procedure, we developed amorphous porous scaffolds sintered from the clinically used bioactive glass S53P4. This work constitutes the first evaluation of such scaffolds in vivo in a critical-sized diaphyseal defect in the weight-bearing rabbit femur. We provide important knowledge and prospects for future development of sintered S53P4 scaffolds as a bone substitute.

Three-Dimensional Printed BGS Treat a Large Bone Defect in a Rabbit Model

This study aimed to evaluate if the 3D printed bioactive glass porous scaffolds (BGS) can improve the reconstruction of the large bone defect. A rabbit model of large bone defects was established by making a 1.0 or 1.5 cm segmental defect in the middle of the femur bone. Then a 1.0 or 1.5 cm BGS was implanted into the bone defect. X-ray imaging showed that in both 1.0 and 1.5 cm groups, the newly formed bone tissue could be observed at 4 weeks after implantation, but a strengthened ossification trend could be observed at different time points. In the 1.0 cm group, a larger number of newly formed bone tissues were observed at 4 weeks, and in the 1.5 group, more newly formed bone tissues were found at 8 weeks. Nevertheless, ossified tissue generation on the BGS mainly completed at 12 weeks after implantation in both groups. The H&E staining revealed that the 3D BGS was easily degraded to form osteoid-like material in vivo, where the neo-ossification gradually occurred from the edge to the center. Immunohistochemical analysis showed that in the 1.0 group, protein expressions of three osteogenesis-related genes- BMP, collagen I and RUNX-2-all peaked at 8 weeks, and then gradually decreased at 12 and 18 weeks. In the 1.5 group, BMP and collagen I peaked at 18 weeks.

Bone in Growth in bFGF Versus BMP Combined with bFGF Saturated PLA-PEG-PLA: Experiment in Surgically Created Rabbit Mandibular Defects

A triblock polymer of LPLA and PEG 1000 and 3400 at 3% and 9% was formed by ring opening under nitrogen atmosphere at 120°C and then, in one group, bFGF was added, while in the other both bFGF and BMP were added, leaving one group as a control. Gross, radiographic, histological and scanning electronic microscope observations were done. With the help of motic images advanced 3.0 new bone formed, calculated as a percentage of total selected area and, using SAS6.12, results were analyzed. Statistical analysis between groups showed that, at 2 weeks, the PLA-PEG-PLA + bFGF + BMP group had the highest amount of new bone formation, as a percentage of new bone over total surface area, at 48% followed by the PLA-PEG-PLA + bFGF group at 39%, then the PLA-PEG-PLA=BMP group at 29%. The PLA-PEGPLA group trailed in at 18% (statistical significance, p <0.05=0.0001). After 4 weeks, the experimental groups B and D had almost equal new bone formation (62% and 64% respectively), but still significantly different from the control group and BMP2 group, with 43% and 38% respectively ( p <0.05=0.0001). After 8 weeks, there was no difference in the amount of bone regeneration ( p >0.05=0.87).

Within the groups, the control group exhibited steady incremental new bone formation at 2, 4 and 8 weeks, starting out at 18%, followed by 42% and lastly 65%. Interestingly this phenomenon also applied to group C (BMP2 group) but not to the B group (bFGF group). The differences at the respective consecutive time of examination were statistically significant ( p <0.05=0.0001). However, in both experimental groups B and D there was statistically significant difference between new bone formed at 2 weeks compared to that at 4 weeks, but thereafter the increment was negligible.

Evaluation of bone formation after grafting with deproteinized bovine bone and mineralized allogenic bone

PURPOSE

The purpose of this study was to evaluate the ability of new bone formation of deproteinized bovine bone (Bio-Oss) and mineralized allogenic bone (Tutoplast).

MATERIALS AND METHODS

Sixty rats were divided into control and experimental groups (groups 1 and 2): control group, unfilled control; group 1, Bio-Oss; group 2, Tutoplast, respectively. The animals were killed after 6 and 12 weeks, and newly formed bone was analyzed histomorphometrically.

RESULTS

In the control group, some new bone formed in the rim of the defect area. In the group 1, newly formed bone was thinner than the adjacent normal bone, and Bio-Oss particles were observed. In the group 2, showed a pattern of gradual fusion with adjacent bone, as well as particles in some areas, similar to the Bio-Oss-treated group. In the 12-week groups, the amount of new bone formation was significantly higher in the experimental groups than in the control group, and it was significantly higher in group 2 than in group 1.

CONCLUSION

Although Tutoplast and Bio-Oss graft materials seem to be useful for bone grafts, Tutoplast showed more active new bone formation than Bio-Oss.

Comparison of Two Different Fixation Techniques for a Segmental Defect in a Rat Femur Model

Studies have attempted to identify the osteogenic effects of bone morphogenetic proteins using a rat femur model, which commonly involves the creation of a critical size defect followed by internal fixation of the femur. Among the most familiar fixation methods are either plating or intramedullary placement of a Kirschner wire (K-wire). There are advantages and disadvantages to each method; however, this study attempts to identify the best method by exploring the histological effects of each technique. The experiment involved two groups with no added treatment: Group P (plate fixation method) and Group K (K-wire fixation method). The animals were allowed a 4-week interval for the femurs to heal, and proximal, distal, and two midshaft cuts were examined under high-power microscopy after the fixation apparatus was removed. Group K exhibited a peculiar fibrotic healing pattern that followed the shaft of the then vacated K-wire and there was minimal new viable bone formation. Group P, however, exhibited a more natural ingrowth of newly formed bone that began at the proximal and distal cuts and proceeded centrally into the core of the defect. Due to the fibrotic tissue in Group K, this study shows that the model is insufficient due to the micromotion created and thus supports plating of critical defects as the fixation method of choice due to the creation of a stable healing environment.

Combined Bone Allograft and Adipose-Derived Stem Cell Autograft in a Rabbit Model

Currently available options for the repair of bony defects have substantial limitations. Much work has looked to the possibility of engineering bone using stem cells. These tissue-engineering efforts have focused on calvarial defect models, which have the advantages of minimal load-bearing and a large surface area. This study aims to solve the somewhat more challenging problem of repairing segmental bony defects such as those of the mandible and long bones. Four groups of decellularized bone tubes with cortical perforations were implanted subcutaneously in a rabbit model: empty bone tubes, bone tubes containing fibrin glue alone, bone tubes containing fibrin glue and freshly isolated autologous adipose-derived stem cells (ASCs), and bone tubes containing fibrin glue and predifferentiated autologous ASCs. Results showed a foreign body response characterized by fibrous capsule formation with minimal angiogenesis and no evidence of osteoblastic activity. Substantial changes are needed if this model is to become viable.

In vivo bone engineering in a rabbit femur

The repair of bone defects in reconstructive surgery has significant limitations. Donor site morbidity, limited supply of autograft, and risks and complications associated with allografting and synthetic bone substitutes are among the most significant. In an effort to address these problems, the search for an ideal bone replacement has led to the development of a new method of poly(lactide-co-glycolide) (PLGA) foam processing, enabling the production of a biodegradable scaffold with similar porosity to human trabecular bone. In this study, these scaffolds were evaluated for bone repair in vivo in a femoral critical-sized segmental defect in New Zealand White (NZW) rabbits. Three groups of nine animals were investigated. In the first group, the critical-sized defects were empty. Scaffolds alone were implanted in the second group, whereas autologous bone marrow cell-loaded scaffolds were implanted in the third group. Animals ambulated freely for 8 weeks after surgery, and bone formation throughout the defects was serially assessed radiographically and quantified using a bone formation index (BFI) measure. Postmortem radiography and histology were also undertaken to examine bone formation. There was a significant effect of applying this technology to the amount of bone formed in the defects as determined by the BFI (F = 3.41, P < 0.05). The mean BFI for the cell-loaded scaffolds was greater than for the control group at all measured time points (2-, 4-, 6-, and 8-week radiographs). This difference was significant for the 2- and 8-week radiographs (P < 0.05). Qualitative histological assessment confirmed these findings. We concluded from these findings that these PLGA scaffolds loaded with marrow-derived progenitor cells yield significant bone formation in a critical-sized rabbit femoral defect. This technology comprising a novel scaffold design and autologous cells may provide an alternative to current strategies for reconstruction of bony defects.