聚乳酸与重组人骨形成蛋白—2复合植入块修复兔下颌骨缺损…

采用冷冻干燥法，将聚乳酸（ＰＬＡ）制成多孔成形块状，并将ＰＬＡ与重组人骨形成蛋白－２（ｒｈＢＭＰ－２）有效的复合，植入兔下颌骨缺损动物模型，在术后２，４周通过Ｘ线片、组织学观察缺损部位的骨生成情况。结果表明：ＰＬＡ－ｒｈＢＭＰ－２植入组术后２周就有部分新骨形成，术后４周骨生成明显；而单独植入ＰＬＡ组术后４周仅有少量新骨生成。钙含量测定显示ＰＬＡ－ｒｈＢＭＰ－２组高于ＰＬＡ组。结果提示：ＰＬＡ为ＢＭ     

聚乳酸与重组人骨形成蛋白-2复合植入块修复兔下颌骨缺损的早期观察

采用冷冻干燥法，将聚乳酸（ＰＬＡ）制成多孔成形块状，并将ＰＬＡ与重组人骨形成蛋白－２（ｒｈＢＭＰ－２）有效的复合，植入兔下颌骨缺损动物模型，在术后２，４周通过Ｘ线片、组织学观察缺损部位的骨生成情况。结果表明：ＰＬＡ－ｒｈＢＭＰ－２植入组术后２周就有部分新骨形成，术后４周骨生成明显；而单独植入ＰＬＡ组术后４周仅有少量新骨生成。钙含量测定显示ＰＬＡ－ｒｈＢＭＰ－２组高于ＰＬＡ组。结果提示：ＰＬＡ为ＢＭＰ的有效传递系统，ＰＬＡ－ｒｈＢＭＰ－２复合植入块是一种有应用潜能的人工骨替代物。     

聚乳酸及其复合物修复下颌骨缺损的实验研究

目的　聚乳酸与骨形成蛋白复合 ,研究该材料修复颌骨缺损的能力 ,探讨聚乳酸作为骨形成蛋白载体的有效性。方法　 18只日本大耳白兔 ,随机分组 ,在双侧下颌骨体部形成 12 m m× 6 mm的缺损 ,分别植入聚乳酸 -人骨形成蛋白 - 2复合物 (PL A- rh BMP- 2 )、单纯聚乳酸 (PL A) ,于 2、4、8、12周分批处死。通过 X线、组织学染色等方法进行观察。结果　 PL A- rh BMP- 2植入组于术后 2周 ,缺损区部分新骨形成 ;术后 8周 ,大片新骨形成并开始改建 ,术后 12周 ,PL A大部分降解 ,由骨组织修复。结果优于对照组。结论　 PL A可作为 BMP的有效载体 ,PL A-rh BMP- 2是良好的颌骨缺损修复材料     

Intramarrow bone morphogenetic protein 4 gene delivery improves local bone quality in femurs of ovariectomized rabbits

Background: Poor bone quality at implant recipient site is a major risk factor for implant failure. The purpose of this study is to examine the potential of intramarrow bone morphogenetic protein 4 (BMP4) gene delivery for local bone quality improvement. Methods: Adenoviral vector encoding human BMP4 (Ad‐BMP4) was constructed. Adenovirus encoding β‐galactosidase (Ad‐LacZ) was used as a control virus. Ad‐BMP4 and Ad‐LacZ were injected into femurs of ovariectomized rabbits. The temporal changes in bone mineral density at injected areas were determined by repeated measurements by dual‐energy x‐ray absorptiometry at 0, 1, 2, 4, and 8 weeks after injection. The effects of gene delivery on cortical bone and cancellous bone were evaluated by microcomputed tomography analysis and histologic examination at 8 weeks. Results: The bone mineral density of the BMP4 group was significantly higher than the LacZ group at 4 and 8 weeks by 61% and 35%, respectively. Results from microcomputed tomography analysis and histologic examination at 8 weeks indicated thicker cortical bone and denser cancellous bone in the BMP4 group compared to the LacZ group. Conclusions: Intramarrow gene delivery of BMP4 effectively improved local bone quality for at least 8 weeks. The sustained delivery of osteogenic factors via local gene therapy approach may reduce implant failures associated with poor local bone quality.     

Direct bone induction in the subperiosteal space of rat calvaria with demineralized bone allografts.

In order to clarify the understanding of bone induction with crude bone morphogenetic protein (BMP)-containing allografts in subperiosteal conditions, chondrogenesis and osteogenesis were histologically evaluated following the implantation of the demineralized bone (DB) in the subperiosteal space of calvaria of 30 Wistar rats. On the forehead of the rat, DB particles were placed onto the denuded calvarial bone and covered by the skin-periosteum flap without any perforations of the marrow space of the calvaria. Sintered hydroxylapatite particles (HA) were also placed as a control. In the DB group, new bone formation on the surface of calvaria was achieved between 2 and 8 weeks after the operation. However, no chondrogenesis was seen throughout the experimental period. In the HA implantation group, fibrous tissue encapsulation of HA particles was generally seen. These results suggest that DB containing crude BMP might have the capacity for direct osteoblast induction from undifferentiated mesenchymal progenitor cells in vivo in specific situations, that is, in a subperiosteal space of uninjured rat calvaria.     

The effect of rhBMP-2 around endosseous implants with and without membranes in the canine model

BACKGROUND: Bone morphogenetic protein (BMP) is a potent differentiating agent for cells of the osteoblastic lineage. It has been used in the oral cavity under a variety of indications and with different carriers. However, the optimal carrier for each indication is not known. This study examined a synthetic bioabsorbable carrier for BMP used in osseous defects around dental implants in the canine mandible. METHODS: Twelve canines had their mandibular four premolars and first molar teeth extracted bilaterally. After 5 months, four implants were placed with standardized circumferential defects around the coronal 4 mm of each implant. One-half of the defects received a polylactide/glycolide (PLGA) polymer carrier with or without recombinant human BMP-2 (rhBMP-2), and the other half received a collagen carrier with or without rhBMP-2. Additionally, one-half of the implants were covered with a non-resorbable (expanded polytetrafluoroethylene [ePTFE]) membrane to exclude soft tissues. Animals were sacrificed either 4 or 12 weeks later. Histomorphometric analysis included the percentage of new bone contact with the implant, the area of new bone, and the percentage of defect fill. This article describes results with the PLGA carrier. RESULTS: All implants demonstrated clinical and radiographic success with the amount of new bone formed dependent on the time and presence/absence of rhBMP-2 and presence/absence of a membrane. The percentage of bone-to-implant contact was greater with rhBMP-2, and after 12 weeks of healing, there was approximately one-third of the implant contacting bone in the defect site. After 4 weeks, the presence of a membrane appeared to slow new bone area formation. The percentage of fill in membrane-treated sites with rhBMP-2 rose from 24% fill to 42% after 4 and 12 weeks, respectively. Without rhBMP-2, the percentage of fill was 14% rising to 36% fill, respectively. CONCLUSIONS: After 4 weeks, the rhBMP-2-treated sites had a significantly higher percentage of contact, more new bone area, and higher percentage of defect fill than the sites without rhBMP-2. After 12 weeks, there was no significant difference in sites with or without rhBMP-2 regarding percentage of contact, new bone area, or percentage of defect fill. In regard to these three outcomes, comparing the results with this carrier to the results reported earlier with a collagen carrier in this study, only the area of new bone was significantly different with the collagen carrier resulting in greater bone than the PLGA carrier. Thus, the PLGA carrier for rhBMP-2 significantly stimulated bone formation around dental implants in this model after 1 month but not after 3 months of healing. The use of this growth factor and carrier combination appears to stimulate early bone healing events around the implants but not quite to the same degree as a collagen carrier.     

Effect of a fibrin-fibronectin sealing system as a carrier for recombinant human bone morphogenetic protein-4 on bone formation in rat calvarial defects

BACKGROUND: Bone morphogenetic proteins (BMPs) have been shown to play an important role in bone formation during development and wound healing. Despite there being good prospects for BMP applications, an ideal carrier system for BMPs has yet to be determined. The purpose of this study was to evaluate the possibility of a fibrin-fibronectin sealing system (FFSS) as a carrier for recombinant human BMP-4 (rhBMP-4) and to evaluate the genuine osteoconductive potential of the FFSS in a rat calvarial defect model. METHODS: An 8-mm, calvarial, critical-size osteotomy defect was created in each of 30 male Sprague-Dawley rats. Three groups of 10 animals each received rhBMP-4 (0.025 mg/ml) in the FFSS, FFSS control, or sham-surgery control. The groups were evaluated using histologic and histometric parameters following 2- and 8-week healing intervals (five animals per group per healing interval). RESULTS: Surgical implantation of rhBMP-4/FFSS resulted in enhanced local bone formation at 2 and 8 weeks. New bone formation was also evident in the FFSS control; however, the amount of defect closure, new bone area, and bone density was significantly greater in the rhBMP-4/FFSS group (P < 0.05). At 8 weeks, the quantity of the new bone was greater than that observed at 2 weeks, and the specimens showed a more advanced stage of remodeling and consolidation in both groups (P < 0.05). Only very limited bone formation was observed in the sham-surgery control. CONCLUSION: The results of the present study indicated that the FFSS has osteoconductive potential and may be employed as a carrier for BMPs.     

Bone induction in subcutaneous tissue in rats by a newly developed DNA-coated atelocollagen and bone morphogenetic protein

A unique biomaterial, a mixture of DNA and collagen (DNA/collagen), was developed and its efficacy as a carrier matrix for bone morphogenetic protein (BMP) was evaluated histologically. The material was prepared as a composite of DNA from salmon milt and pepsin-digested type I collagen (atelocollagen) from bovine dermis. Phase-contrast and fluorescence microscopy showed atelocollagen fibres with DNA coating. The dose-response and time-course of bone induction by BMP in DNA/collagen (5 x 10 x 1 mm) in the subcutaneous tissue was investigated in 20 male Wistar rats. The BMP/DNA/collagen induced new bone in a dose-dependent manner (0, 25, 50 or 100 micrograms of BMP). Histological examination in the time-course study showed that the BMP (100 micrograms)/DNA/collagen induced bone formation, while the DNA/collagen alone resulted in the accumulation of fibroblasts. These results indicate that the DNA/collagen is effective as a carrier matrix for BMP. It provides a cell anchorage for differentiation of osteoblasts and is absorbed as bone matures.     

Effect of recombinant human bone morphogenetic protein-2 on bone formation in alveolar ridge defects in dogs

This study was designed to evaluate the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) combined with poly D, L lactic-co-glycolic acid (PLGA)/gelatin sponge complex (PGS) on the formation of bone in critically sized marginal defects of the mandible in dogs. Three months after extraction of the pre-molar teeth, rectangular bone defects (10 x 8 x 7 mm) were made in both sides of the mandible. A PGS block soaked in rhBMP-2 (400 microgram/ml) was implanted into one defect (BMP (+) group). As control, an untreated PGS block was implanted into the contralateral defect (BMP (-) group). 2, 4, 8, and 12 weeks after implantation, the defects were examined. In the BMP (+) group, newly formed bone was found in all defects from 4 weeks onward and was marked at 12 weeks. In contrast, the BMP (-) group showed no appreciable new bone formation, even at 12 weeks. Moreover, density of newly formed bone in the BMP (+) group was similar to that of the surrounding cortical bone at 12 weeks. These findings suggest that rhBMP-2/PGS is an effective bone substitute for reconstructive surgery of the dog mandible.     

Intramarrow bone morphogenetic protein 4 gene delivery enhances early implant stability in femurs of ovariectomized rabbits

Background: Sufficient early implant stability is critical to prevent excessive micromovement of the implant during peri‐implant healing and to ensure the success of osseointegration. Implants placed in osteoporotic bones are often associated with low early implant stability. The purpose of this study is to determine the effects of intramarrow bone morphogenetic protein 4 (BMP4) gene delivery on early implant stability and peri‐implant healing. Methods: Adenoviruses encoding human BMP4 or LacZ were introduced into the femoral osteotomy sites immediately before implant placement in ovariectomized rabbits. The implant stability was determined by resonance frequency analysis at weeks 0, 4, and 8. Changes in cortical bone thickness and intrascrew bone formation at weeks 4 and 8 were evaluated by microcomputed tomography analysis and undecalcified histologic examination, respectively. Results: Intramarrow BMP4 gene delivery resulted in more improvement in implant stability at both weeks 4 and 8. Increased increment in peri‐implant cortical bone thickness and better intrascrew bone formation were found in the BMP4 group compared to the LacZ group. Conclusion: The results of this study suggest that intramarrow adenoviral gene delivery of BMP4 enhances peri‐implant bone healing and improves early implant stability in osteoporotic rabbit femurs.     

Experimental study on bone formation potential of cryopreserved human bone marrow mesenchymal cell/hydroxyapatite complex in the presence of recombinant human bone morphogenetic protein-2

Secondary bone grafting in the alveolar cleft is one of the most important treatment modalities for patients with a cleft lip and palate. In children, however, harvesting a sufficient amount of bone graft from the donor site is difficult, and the procedure imposes a heavy burden on the patients. This problem may be resolved if autologous transplantation can be performed using a cell-hybrid type of artificial bone prepared with the patient's own bone marrow cells through a tissue engineering technique. In the current study, we examined the possibility of achieving such an autologous transplantation using cryopreserved human bone marrow cells. Human bone marrow cells were grown in culture and cryopreserved, and the cells preserved for 3 years and the cells preserved for 3 months were then thawed and recultivated. In one experiment, the recultivated cells were seeded onto a complex composed of porous hydroxyapatite and bone morphogenetic protein (BMP), and the complex was grafted subcutaneously in nude mice. In another experiment, the cells were seeded onto the porous hydroxyapatite and cultivated for 10 days before grafting in a medium supplemented with BMP. The bone formation potential of the cells was compared between these two experiments. Formation of mature bone was observed 2 weeks after transplantation in the former experiment, whereas only scarce bone formation was evident 4 weeks after transplantation in the latter experiment. It is therefore assumed that exposing the cultured human bone marrow cells to a high concentration of BMP in vivo strongly promotes bone formation.     

基因重组人骨形成蛋白-2与珊瑚/聚乳酸复合异位诱导成骨的实验研究

目的 :观察基因重组人骨形成蛋白 - 2 (rhBMP - 2 )和珊瑚 /聚乳酸形成复合人工骨的异位诱导成骨活性。方法 :把rhBMP - 2和珊瑚 /聚乳酸形成复合人工骨。进行小鼠肌内种植 1、3、6周后 ,组织学观察其异位诱导成骨活性。结果 :rhBMP - 2赋予珊瑚 /聚乳酸骨诱导能力 ,珊瑚 /聚乳酸则充当rhBMP - 2的载体和释放系统 ,对BMP的活性未产生不利影响。与单纯的珊瑚 /聚乳酸相比 ,这种复合人工骨以软骨内成骨的方式诱导成骨。结论 :rhBMP - 2 /珊瑚 /聚乳酸复合人工骨具有良好的生物相容性和骨诱导活性 ,是一种较理想的骨移植替代材料     

Periodontal repair in dogs: evaluation of a bioabsorbable space-providing macroporous membrane with recombinant human bone morphogenetic protein-2

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) technologies have been shown to significantly support alveolar bone formation. Biomaterial limitations, however, have restricted the biologic potential for onlay indications. The objective of this study was to evaluate regeneration of alveolar bone and periodontal attachment, and biomaterials reaction following surgical implantation of a space-providing, bioabsorbable, macroporous, polyglycolic acid-trimethylene carbonate (PGA-TMC) membrane combined with a rhBMP-2 construct in a discriminating onlay defect model. METHODS: Routine supraalveolar periodontal defects were created at the mandibular premolar teeth in 9 beagle dogs. Contralateral jaw quadrants in subsequent animals were randomly assigned to receive the dome-shaped PGA-TMC (100 to 120 microm pores) membrane with rhBMP-2 (0.2 mg/mL) in a bioresorbable hyaluronan (Hy) carrier or the PGA-TMC membrane with Hy alone (control). The gingival flaps were advanced to submerge the membranes and teeth and sutured. Animals were euthanized at 8 and 24 weeks postsurgery for histologic observations. RESULTS: Jaw quadrants receiving the PGA-TMC membrane alone experienced exposures at various time points throughout the study. Jaw quadrants receiving the PGA-TMC/rhBMP-2 combination remained intact, although one site experienced a late minor exposure. Newly formed alveolar bone approached and became incorporated into the macroporous PGA-TMC membrane in sites receiving rhBMP-2. The PGA-TMC biomaterial was occasionally associated with a limited inflammatory reaction. Residual PGA-TMC could not be observed at 24 weeks postsurgery. Residual Hy could not be observed at any time interval. Regeneration of alveolar bone height (means +/- SD) was significantly increased in sites receiving the PGA-TMC/rhBMP 2 combination compared to control (3.8 +/- 1.3 versus 0.7 +/- 0.5 mm at 8 weeks and 4.6 +/- 0.8 versus 2.1 +/- 0.4 mm at 24 weeks; P < 0.05). Limited cementum regeneration was observed for PGA-TMC/rhBMP-2 and PGA-TMC control sites. Ankylosis compromised regeneration in sites receiving PGA-TMC/rhBMP-2. CONCLUSIONS: The bioabsorbable, space-providing, macroporous PGA-TMC membrane appears to be a compatible biomaterial for bone augmentation procedures. rhBMP-2 significantly enhances alveolar bone augmentation and soft tissue healing when combined with the PGA-TMC membrane.     

Influence of bone morphogenetic protein and proportion of hydroxyapatite on new bone formation in biphasic calcium phosphate graft: Two pilot studies in animal bony defect model

PurposeThe purpose of these two pilot studies using animal bony defect models was to evaluate the influence of bone morphogenetic protein (BMP) and proportion of hydroxyapatite (HA)/beta-tricalcium phosphate (β-TCP) in biphasic calcium phosphate (BCP) graft on new bone formation.MethodsIn this study, four kinds of synthetic osteoconductive bone materials known for bone growth scaffold, OSTEON™II(HA:β-TCP 30:70), OSTEON™III (HA:β-TCP 20:80), OSTEON™II Collagen, and OSTEON™III Collagen, were prepared as BCP graft materials. In pilot study 1, three BCP materials (OSTEON™II, OSTEON™III, and OSTEON™II Collagen) were grafted in rabbit calvarial defects after impregnating in rhBMP-2. OSTEON™II without the rhBMP-2 impregnation was included in the study as the control. The amount of new bone was examined and measured histologically at 2, 4, and 8 weeks. In pilot study 2, four BCP materials (OSTEON™II, OSTEON™III, OSTEON™II Collagen, and OSTEON™III Collagen) were grafted in beagle dog mandibular defects after soaking in the rhBMP-2. The amount of total bone and new bone were measured three-dimensionally using microCT and healing process was examined histologically at 2, 4, and 8 weeks.ResultsIn pilot study 1, rhBMP-2 impregnated groups showed more new bone formation than the rhBMP-2 free group. In pilot study 2, increased new bone formation was observed in time-dependent manner after graft of BCP and BCP-collagen (OSTEON™II, OSTEON™III, OSTEON™II Collagen, and OSTEON™III Collagen) impregnated with rhBMP-2. Also, BCP with a higher proportion of HA (30% HA) showed more favorable result in new bone formation and space maintenance, especially at the 8 weeks.ConclusionFrom the results of the pilot studies, rhBMP-2 played positive roles in new bone formation and BCP could become a scaffold candidate for rhBMP-2 impregnation to induce new bone formation. Moreover, BCP with a higher proportion of HA (30% HA) could be considered more appropriate for rhBMP-2 carrier.     

聚乳酸和骨生长因子复合植入块修复骨缺损的实验研究

目的 探讨碱性成纤维细胞生长因子对重组人骨形成蛋白２诱导骨形成的影响,评价多孔聚乳酸复合人工骨修复骨缺损的作用。方法 在５６例下颌骨缺损的兔模型中分别植入ＰＬＡ／ｒｈＢＭＰ－２／ｂＦＧＦ、ＰＬＡ＝ｒｈＢＭＰ－２、ＰＬＡ／ｂＦＧＦ、ＰＬＡ并设空白对照。植入后２、４、８周行Ｘ线摄片和组织学观察骨缺损区骨形成的情况。结果 ３种材料复合物较两赤道昨合物成骨更好,而后者又 单一的ＰＬＡ成骨好,所有含骨生长因     

Alveolar ridge augmentation using implants coated with recombinant human bone morphogenetic protein-2: radiographic observations

Objectives: Effective carrier technologies and dosing appear critical for the successful use of bone morphogenetic proteins (BMPs). This study evaluated radiographically the potential of a purpose‐designed titanium porous‐oxide implant surface combined with recombinant human BMP‐2 (rhBMP‐2) to stimulate alveolar ridge augmentation. Material and methods: Twelve young‐adult Labrador dogs were used. Three 10‐mm titanium implants per jaw quadrant were placed 5 mm into the alveolar ridge following extraction of the premolar teeth and reduction of alveolar ridge. Six animals received implants coated with rhBMP‐2 at 0.75 or 1.5 mg/ml randomized to contralateral jaw quadrants. Another six animals received implants coated with rhBMP‐2 at 3 mg/ml or uncoated control using the same split‐mouth design. The mucoperiosteal flaps were advanced, adapted, and sutured to submerge the implants. Radiographic registrations were made immediately postsurgery (baseline), and at weeks 4 and 8 (end of study). Results: rhBMP‐2‐coated implants exhibited robust radiographic bone formation extending to and above the implant platform from week 4 (P<0.01). Some rhBMP‐2‐coated implants showed voids within the newly formed bone that gradually resolved and/or implant displacement, being severe in two animals receiving implants coated with rhBMP‐2 at 3 mg/ml. Controls showed limited, if any, new bone formation at weeks 4 and 8 postsurgery. There were no significant differences among the rhBMP‐2 groups in bone gain. Conclusions: The titanium porous‐oxide surface serves as an effective carrier for rhBMP‐2, showing a clinically significant potential to stimulate local bone formation. With the carrier technology used, therapeutic dosage appears to be in the range of 0.75–1.5 mg/ml.     

BMP2/7 heterodimer is a stronger inducer of bone regeneration in peri-implant bone defects model than BMP2 or BMP7 homodimer

This study aimed to compare the effects of bone morphogenetic protein BMP2/7 heterodimer and BMP homodimers on bone regeneration in bone defects model. Identical peri-implant bone defects model were created using proper controls on the frontal skull in 18 minipigs. Collagen sponges with low-dose (30 ng/mL) BMP2/7 heterodimer, BMP2 or BMP7 homodimer were filled in the defects. New bone formation and the expression of type I collagen (Col1), alkaline phosphatase (ALP) and osteocalcin (OCN) were evaluated after 2, 3, and 6 weeks of implantation. BMP2/7 resulted in significantly higher new bone areas percentage in the defect region than BMP2 and BMP7 (p<0.05). Immunohistochemical staining of Col1, ALP and OCN was stronger in BMP2/7 group than BMP2, BMP7 and control group (p<0.05). These results demonstrate that BMP2/7 heterodimer is a stronger inducer of osteoblastogenesis and could be applied at low dose to reduce the cost and side effects of BMP homodimers.     

Failure to induce supracrestal bone growth between and around partially inserted titanium implants using bone morphogenetic protein (BMP): an experimental study in dogs

The effect of bone morphogenetic protein on supracrestal bone growth around partially inserted implants in a dog model is described. The lower premolar teeth (P1, P2, P3 and P4) were extracted on both sides of the mandible in six dogs. At a surgical exposure 12 weeks later, two 10-mm turned titanium implants were partially inserted, approximately 15 mm apart, in the areas of the P1 and P3 in each side of the mandible, allowing five threads to protrude from the bone crest. A titanium mesh was fastened to the coronal aspect of the two fixtures and the space beneath the mesh was filled with bone morphogenetic protein (S300 BMP) in combination with an insoluble bone matrix carrier, or with the carrier alone. The mesh was covered with an ePTFE membrane. Thus, a space for potential bone formation was created between the two implants. The surgical flaps were coronally positioned and secured with vertical mattress sutures. After 16 weeks of healing, biopsy specimens were retrieved and examined histologically. Bone was not formed around the protruding implants or in the created space between the implants in any case. The carrier was incompletely resorbed. We conclude that supracrestal bone growth beyond the crestal limit with or without BMP in such a large space as in this experimental design may not be possible.     

透明质酸改性聚乳酸支架组织工程软骨的构建

目的 利用透明质酸( hyaluronic acid,HA)改性聚乳酸(polylactic acid,PLA)支架来构建同种异体组织工程软骨,分析探讨HA改性PLA支架构建组织工程软骨的可行性.方法 采用盐析法制备出高孔隙率的PLA支架,采用低浓度NaOH、碳化二亚胺和HA进行支架改性.支架预湿后接种第3代兔髁突软骨细胞悬液,体外培养1周后用于动物实验.软骨细胞-HA改性PLA支架复合体为实验组,软骨细胞-PLA支架复合体为对照组.分别于4、6、8周按照标记取出植入物,进行组织学检测.利用ImageJ软件进行免疫组化染色阳性强度的分析.结果 细胞-支架复合体植入后,未产生排斥反应.HE染色结果示软骨样组织形成.Masson染色及甲苯胺蓝染色结果显示染色逐渐加深.Ⅱ型胶原免疫组化染色随时间增加阳性强度增加,实验组4、6、8周时的免疫组化染色强度差异有统计学意义(F=26.68,P=0.000),对照组4、6、8周时的免疫组化染色强度差异有统计学意义(F=20.59,P=0.000).相同时间点实验组Ⅱ型胶原分泌强度高于对照组.结论 利用HA改性PLA支架可以构建同种异体软骨,且其质量高于未改性PLA.     

Endocultivation: the influence of delayed vs. simultaneous application of BMP-2 onto individually formed hydroxyapatite matrices for heterotopic bone induction

When bone morphogenetic protein (BMP) is delivered to matrices in vivo may affect tissue engineered bone constructs for jaw reconstruction after cancer surgery. This study compared the effects of BMP application at different times after matrix implantation for heterotopic bone induction in a rat model. Hydroxyapatite blocks were implanted unilaterally onto the surface of the latissimus dorsi muscle. A second block was implanted onto the contralateral muscle after 1, 2 or 4 weeks and 200μg rhBMP-2 was injected into the blocks on both sides. Bone formation and density inside the blocks was analysed by CT and histology. 8 weeks after BMP application increases in bone density within the scaffolds were most pronounced in the simultaneous application group (179 HU). Less pronounced increases were observed for the 1 (65 HU), 2 (58 HU) and 4 (31 HU; p<0.0001) week delay group. Homogeneous bone induction started from the central channel of the blocks. Capillaries and larger vessels were seen in all constructs, samples receiving delayed BMP treatment demonstrated significantly greater neovascularization. Delayed application of BMP was less effective for heterotopic bone formation than simultaneous application. A central channel allows homogeneous bone induction directly from the centre of the blocks.