Objective To compare the effect of guiding boneregeneration between l-ethyl-3(3-diaminopropyol)-carbodiimide(EDAC)crosslinked acellular bovine pericardium (ABP) and medical collagen membrane (CM). Methods Defects of 7 mm×7 mm×5 mm were created in both mandibles of 24 rabbits, which weighted 2.6～3.5 kg. One side defect was covered with EDAC-crosslinked ABP(EDAC-crosslinked ABP group), the other side defect with medical CM as control(CM group). The ability of bone defect repair and change ofboth membrane materials were evaluated by gross observation, histological study and computer graphic analysis in the 4th, 8th, 16th and 24th weeks after operation. Results The surface of bone defects was even, consistent with adjacent normal bonein EDACcrosslinked ABP group, while that of bone defects was of no evenness in CM group in the 16th and the 24th weeks. The histological observation showed that bone trabecula formed in the EDAC-crosslinked ABP group and fibrous connective tissue was seen in CM group in the 16th and the 24th weeks. There were no significant differences in new bone percentage of bone defects between 2 groups inthe 4th and the 8th weeks(P＞0.05). In the 16th week new bone percentage of bone defects was 81.99%±3.92% in EDAC-crosslinked ABP group and 76.35%±4.29% in CM group, showing significant difference (Plt;0.05). The average percentage of absorption in EDAC-crosslinked ABP group was 16.57%, 27.94%, 65.61% and85.72% in the 4th, 8th, 16th and 24th weeks respectively, while that in CM group was more than 50% in the 4th week and completely degraded at the end of 8 weeks. Conclusion EDAC-crosslinked ABP has a better effect on guiding bone regeneration than CM in the repair of bone defects.
OBJECTIVE To investigate the effect of acid fibroblast growth factor (aFGF) on guided bone regeneration (GBR), to study whether aFGF can promote the repairing ability of GBR in bone defect. METHODS 10 mm long segmental defects were created in the diaphyses of both radii in 16 New Zealand rabbits. The defect was bridged with a silicon tube. Human recombinant aFGF was instilled into the tube on the experimental side, while the contralateral tube was instilled with saline as control group. The radiographic, gross and histologic examination of the samples were analyzed at 2, 4, 6 and 8 weeks after operation. RESULTS On the experimental side, there was new bone formation in the bone medullary cavity, the endosteum and the section surface of the cortex at 2 weeks. At 4 weeks, at the center of the blood clot in the tube there was new bone formation and bone defect was completely healed at 8 weeks. On the control side, new bone formation was less in every period compared with that of the experimental side. At 8 weeks, there was only partial healing of the bone defect. CONCLUSION It can be concluded that aFGF can promote new bone formation and facilitate GBR in bone defect.
Bone morphogenetic protein (BMPs) has been so far regarded as one of the highly potent osteoinductive growth factors. Recombinant human bone morphogenetic proteins have been utilized extensively in the disciplines of orthopedics, stomatology, etc. For clinical application, BMPs are usually loaded in carriers with a controlled-release system, to maintain concentration to induce de novo bone formation at the desired site. In this article, the research advancements of the carriers and release systems of BMP are reviewed.
Objective To compare the effects of hypoxia-inducible drugs using deferoxamine (DFO) and accordion technique (AT) on activating the hypoxia-inducible factor 1α (HIF-1α)/vascular endothelial growth factor (VEGF) signaling pathway to promote bone regeneration and remodelling during consolidation phase of distraction osteogenesis (DO). Methods Forty-five specific-pathogen-free adult male Sprague-Dawley (SD) rats were randomly divided into the control group, DFO group, and AT group, with 15 rats in each group. All rats underwent osteotomy to establish a right femur DO model. Then, continuous distraction was started for 10 days after 5 days of latency in each group. During the consolidation phase after distraction, no intervention was performed in the control group; DFO was locally perfused into the distraction area in the DFO group starting at the 3rd week of consolidation phase; cyclic stress stimulation was given in the AT group starting at the 3rd week of consolidation phase. The general condition of rats in each group was observed. X-ray films were conducted at the end of the distraction phase and at the 2nd, 4th, and 6th weeks of the consolidation phase to observe the calcification in the distraction area. At the 4th and 6th weeks of the consolidation phase, peripheral blood was taken for ELISA detection (HIF-1α, VEGF, CD31, and Osterix), femoral specimens were harvested for gross observation, histological staining (HE staining), and immunohistochemical staining [HIF-1α, VEGF, osteopontin (OPN), osteocalcin (OCN)]. At the 6th week of the consolidation phase, Micro-CT was used to observe the new bone mineral density (BMD), bone volume/tissue volume (BV/TV), trabecular separation (Tb.Sp), trabecular number (Tb.N), and trabecular thickness (Tb.Th) in the distraction area, and biomechanical test (ultimate load, elastic modulus, energy to failure, and stiffness) to detect bone regeneration in the distraction area. Results The rats in all groups survived until the termination of the experiment. ELISA showed that the contents of HIF-1α, VEGF, CD31, and Osterix in the serum of the AT group were significantly higher than those of the DFO group and control group at the 4th and 6th weeks of the consolidation phase (P<0.05). General observation, X-ray films, Micro-CT, and biomechanical test showed that bone formation in the femoral distraction area was significantly better in the DFO group and AT group than in the control group, and complete recanalization of the medullary cavity was achieved in the AT group, and BMD, BV/TV, Tb.Sp, Tb.N, and Tb.Th, as well as ultimate load, elastic modulus, energy to failure, and stiffness in the distraction area, were better in the AT group than in the DFO group and control group, and the differences were significant (P<0.05). HE staining showed that trabecular bone formation and maturation in the distraction area were better in the AT group than in the DFO group and control group. Immunohistochemical staining showed that at the 4th week of consolidation phase, the expression levels of HIF-1α, VEGF, OCN, and OPN in the distraction area of the AT group were significantly higher than those of the DFO group and control group (P<0.05); however, at 6th week of consolidation phase, the above indicators were lower in the AT group than in the DFO group and control group, but there was no significant difference between groups (P>0.05). Conclusion Both continuous local perfusion of DFO in the distraction area and AT during the consolidation phase can activate the HIF-1α/VEGF signaling pathway. However, AT is more effective than local perfusion of DFO in promoting the process of angiogenesis, osteogenesis, and bone remodelling.
Objective To evaluate the effect of internal fixation on the stability of pedicled fascial flap and the osteogenesis of exceed critical size defect (ECSD) of bone so as to provide theory for the clinical application by the radiography and histology observation. Methods The ECSD model of the right ulnar midshaft bone and periosteum defect of 1 cm in length was established in 32 New Zealand white rabbits (aged 4-5 months), which were divided into group A and group B randomly (16 rabbits in each group). The composite tissue engineered bone was prepared by seeding autologous red bone marrow (ARBM) on osteoinductive absorbing material (OAM) containing bone morphogenetic protein and was used repair bone defect. A pedicled fascial flap being close to the bone defect area was prepared to wrap the bone defect in group A (control group). Titanium miniplate internal fixation was used after defect was repair with composite tissue engineered bone and pedicled fascial flap in group B (experimental group). At 2, 4, 6, and 8 weeks, the X-ray films examination, morphology observation, and histology examination were performed; and the imaging 4-score scoring method and the bone morphometry analysis was carried out. Results All rabbits survived at the end of experiment. By X-ray film observation, group B was superior to group A in the bone texture, the space between the bone ends, the radiographic changes of material absorption and degradation, osteogenesis, diaphysis structure formation, medullary cavity recanalization. The radiographic scores of group B were significantly higher than those of group A at different time points after operation (P lt; 0.05). By morphology and histology observation, group B was superior to group A in fascial flap stability, tissue engineered bone absorption and substitution rate, external callus formation, the quantity and distribution area of new cartilage cells and mature bone cells, and bone formation such as bone trabecula construction, mature lamellar bone formation, and marrow cavity recanalization. The quantitative ratio of bone morphometry analysis in the repair area of group B were significantly larger than those of group A at different time points after operation (P lt; 0.05). Conclusion The stability of the membrane structure and the bone defect area can be improved after the internal fixation, which can accelerate bone regeneration rate of the tissue engineered bone, shorten period of bone defect repair, and improve the bone quality.
Objective To summarize the research progress of controlled release of angiogenic factors and osteogenic factors in bone tissue engineering. Methods The domestic and abroad literature on the controlled release structure of growth factors during bone regeneration in recent years was extensively reviewed and summarized. Results The sustained-release structure includes direct binding, microsphere-three-dimensional scaffold structure, core-shell structure, layer self-assembly, hydrogel, and gene carrier. A sustained-release system composed of different sustained-release structures combined with different growth factors can promote bone regeneration and angiogenesis. Conclusion Due to its controllability and persistence, the growth factor sustained-release system has become a research hotspot in bone tissue engineering and has broad application prospects.
ObjectiveTo prepare a bone tissue engineering scaffold for repairing the skull defect of Sprague Dawley (SD) rats by combining exogenous transforming growth factor β1 (TGF-β1) with gelatin methacryloyl (GelMA) hydrogel.MethodsFirstly, GelMA hydrogel composite scaffolds containing exogenous TGF-β1 at concentrations of 0, 150, 300, 600, 900, and 1 200 ng/mL (set to groups A, B, C, D, E, and F, respectively) were prepared. Cell counting kit 8 (CCK-8) method was used to detect the effect of composite scaffold on the proliferation of bone marrow mesenchymal stem cells (BMSCs) in SD rats. ALP staining, alizarin red staining, osteocalcin (OCN) immunofluorescence staining, and Western blot were used to explore the effect of scaffolds on osteogenic differentiation of BMSCs, and the optimal concentration of TGF-β1/GelMA scaffold was selected. Thirty-six 8-week-old SD rats were taken to prepare a 5 mm diameter skull bone defect model and randomly divided into 3 groups, namely the control group, the GelMA group, and the GelMA+TGF-β1 group (using the optimal concentration of TGF-β1/GelMA scaffold). The rats were sacrificed at 4 and 8 weeks after operation, and micro-CT, HE staining, and OCN immunohistochemistry staining were performed to observe the repair effect of skull defects.ResultsThe CCK-8 method showed that the TGF-β1/GelMA scaffolds in each group had a promoting effect on the proliferation of BMSCs. Group D had the strongest effect, and the cell activity was significantly higher than that of the other groups (P<0.05). The results of ALP staining, alizarin red staining, OCN immunofluorescence staining, and Western blot showed that the percentage of ALP positive area, the percentage of alizarin red positive area, and the relative expressions of ALP and OCN proteins in group D were significantly higher than those of the other groups (P<0.05), the osteogenesis effect in group D was the strongest. Therefore, in vitro experiments screened out the optimal concentration of TGF-β1/GelMA scaffold to be 600 ng/mL. Micro-CT, HE staining, and OCN immunohistochemistry staining of rat skull defect repair experiments showed that the new bone tissue and bone volume/tissue volume ratio in the TGF-β1+GelMA group were significantly higher than those in the GelMA group and control group at 4 and 8 weeks after operation (P<0.05).ConclusionThe TGF-β1/GelMA scaffold with a concentration of 600 ng/mL can significantly promote the osteogenic differentiation of BMSCs, can significantly promote bone regeneration at the skull defect, and can be used as a bioactive material for bone tissue regeneration.
ObjectiveTo observe the change of stromal cell-derived factor 1α/cysteine X cysteine receptor 4 (SDF-1α/CXCR4) signaling pathway during the process of axial stress stimulation promoting bone regeneration, and to further explore its mechanism.MethodsA total of 72 male New Zealand white rabbits were selected to prepare the single cortical bone defect in diameter of 8 mm at the proximal end of the right tibia that repaired with deproteinized cancellous bone. All models were randomly divided into 3 groups (n=24). Group A was treated with intraperitoneally injection of PBS; Group B was treated with stress stimulation and intraperitoneally injection of PBS; Group C was treated with stress stimulation and intraperitoneally injection of AMD3100 solution. The X-ray films were taken and Lane-Sandhu scores of bone healing were scored at 2, 4, 8, and 12 weeks after operation, while specimens were harvested for HE staining, immunohistochemical staining of vascular endothelial growth factor (VEGF) and CXCR4, and Western blot (SDF-1α and CXCR4). The bone healing area was scanned by Micro-CT at 12 weeks after operation, and the volume and density of new bone were calculated.ResultsX-ray film showed that the Lane-Sandhu scores of bone healing in group B were significantly higher than those in groups A and C at 4, 8, and 12 weeks after operation (P<0.05). Micro-CT scan showed that the bone defect was repaired in group B and the pulp cavity was re-passed at 12 weeks after operation. The volume and density of new bone were higher in group B than in groups A and C (P<0.05). HE staining showed that the new bone growth in bone defect area and the degradation of scaffolds were faster in group B than in groups A and C after 4 weeks. The immunohistochemical staining showed that the expressions of VEGF and CXCR4 in 3 groups reached the peak at 4 weeks, and group B was higher than groups A and C (P<0.05). Western blot analysis showed that the expressions of SDF-1α and CXCR4 in group B were significantly higher than those in groups A and C at 4 and 8 weeks after operation (P<0.05).ConclusionAxial stress stimulation can promote the expression of SDF-1α in bone defect tissue, activate and regulate the CXCR4 signal collected by marrow mesenchymal stem cells, and accelerate bone regeneration in bone defect area.
OBJECTIVE To repair long bone segmental defects using biodegradable poly epsilon-caprolactone (PCL) and polylactic acid(PLA) co-polymer membranes, and explore its role and mechanism in guided bone regeneration (GBR). METHODS Rabbit radial segmental defects (1.2 cm in length, retain the periosteum) were created in this study, 24 animals were divided into 2 groups. The membranes were used to enclose the defects in experimental group, and no treatment in control group. After 3, 6, and 12 weeks of operation, X-ray, gross and histological examinations were observed. RESULTS The bone regeneration of experimental group was better than that of control group. Three weeks after operation, obvious external callus along the membrane were found in experimental group, and bony linking composed of external callus bridge were found in 6 weeks after operation. After 12 weeks of operation, callus bridge outside the membrane and bony reunion inside the membrane were achieved in experimental group. While in control group, typical nonunion was observed after 6 weeks of operation. CONCLUSION Guided bone regeneration can be achieved by using biodegradable membrane. The defects are repaired by the means of outside membrane callus and relatively late inside membrane callus. The membrane can prevent the ingrowth of fibrous tissue into defect area, thus nonunion are avoid, and keep a high concentration of nutritive elements, also serve as a frame for osteocyte growth to enhance bone healing.
OBJECTIVE To confirm membrane-guided tissue regeneration in the healing course of segmental bone defects and study the mechanism. METHODS Segmental, 1 cm osteoperiosteal defects were produced in both radii of 12 rabbits. One side was covered with hydroxyapatite/polylactic acid(HA/PLA) membrane encapsulated as a tube. The contralateral side served as an untreated control. Healing courses were detected by radiographic and histologic examinations. RESULTS All control sides showed nonunion, whereas there were consistent healing pattern in test sides. CONCLUSION Membrane technique can promote bone regeneration.