Component changes of calcium and phosphorus in osteogeneis by lengthening procedures in adult canines

Objective:To explore chemical component changes of dog bone at different lengthening time and in different bone regions of interest, and to evaluate the mineralization during Iiizarov lengthening process.Methods:The ash weight, the concentrations of calcium,phosphorus and the calcium/phosphorus ratio were measured at different intervals(2,4,6,8,12 weeks) since lengthening and the lengthened part was compared with a control area at each interval.Results:The ash weight, the concentrations of calcium and phosphorus in the lengthened area differed at all development time.The calcium/phosphorus(Ca/P) ratio in the lengthened region remained significantly lower than that in the control region up to 12 weeks after the lengthening.Conclusions:These results suggest that also other inorganic ions play an important role in the mineralization process and that they become relatively more important since 8 weeks after the lengthening.     

Relationship among bone mineral density, collagen composition, and biomechanical properties of callus in the healing of osteoporotic fracture

Objective： To study the change and relationship among bone mineral density （BMD）, collagen composition and biomechanical properties of the callus in the healing process of osteoporotic fracture. Methods： The osteoporotic rat model and fracture model were established through bilateral ovariectomy （OV＇X） and osteotomy of the middle shaft of the right hind tibiae, respectively. Ninety female SD rats were randomly divided into OVX group and sham group. With the samples of blood and callus, roentgenoraphic and histological observation were performed for the assessment of the healing progress of the fracture, and the serum concentration of TRAP-5b, proportion of type I collagen, BMD and biomechanical properties of the callus were measured. Results： The OVX group experienced a significant delay of fracture healing. The mean serum concentration of TRAP-5b of rats in the OVX group was much higher than that in the sham group after the operation （P 〈 0.05）, but the difference at the same time point after fracture was smaller than that before fracture （P 〈 0.05）. The BMD of the callus in both groups reached the peak value at the 6 th week after fracture while the proportion of the type I collagen and the biomechanical strength reached the peak at the 8th week. Conclusions. The deficiency of estrogen after the ovariectomy could induce the up-regulation of the osteoclasts activities, whereas the potency of further activation after fracture was depressed. Although the synthesis of collagen together with its mineralization determines the biomechanical properties of new bone, the accumulation of collagen could be assessed as an index in the prediction of biomechanical strength of bones independent of the bone mineral deposition.     

The biomechanics of point contact-dynamic compression plate and its effects on bone perfusion

Objective: To compare the mechanical properties of point contact-dynamic compression plate (PC-DCP) and its effects on cortical bone perfusion with that of dynamic compression plates (DCP) in goat tibiae. Methods: Twenty pairs of matched fresh goat tibiae were used. A transverse fracture model was established. The fractures with a 3mm interspace between the fracture ends were subject to fixations with the DCPs and the PC-DCPs respectively, then the four-points bending tests and the torsion tests were conducted to compare the mechanical properties of the PC-DCP with that of DCP. Another 13 sexually mature goats underwent fixations with the DCPs and the PC-DCPs, respectively, at the mid-shafts of the intact bilateral tibiae. Ischemic zones were observed at four time points (1 day ,2,6, and 12 weeks after operation) using disulphine blue staining technique. Results: There were no significant differences in mechanical properties, such as bend- and torsion-resistance, between the DCPs and the PC-DCPs. One day, 2, and 6 weeks after operation, on the side of DCP fixation, outer cortical bone ischemia under the plate persisted, and this condition did not reverse until 12 weeks after operation. However, on the side of PC-DCP fixation, cortical bone ischemia occurred only in the periphery of the screw holes and at the contact sites of the PC NUTs 1 day after operation, and it disappeared at 2 weeks after operation. Conclusions: The PC-DCP has similar biomechanical properties of the DCP, byt is less detrimental to local bone blood circulation than the conventional plates.     

兔慢性肝损害急性肝衰竭动物模型的建立

Objective To establish an ideal animal model of acute-on-chronic liver failure (ACLF) in New Zealand white rabbits in order to provide a large animal model for further researches.Methods Totally 75 New Zealand rabbits were randomly divided into experimental group (n =70) and control group (n = 5 ). Rabbits in the experimental group were injected with CCl4 into the abdominal cavity twice every week and the doses of CCl4 were modified according to the index of liver function and the body weight, whereas those in the control group were treated with the same volume of saline. At the 10th week,48 New Zealand rabbits with hepatic fibrosis were randomly assigned to 4 groups and injected with CCl4 as before, D-Gal at a dose of 0. 65 g/kg body weight (BW), 0. 70 g/kg BW and 0. 75 g/kg BW, respectively. By observing and comparing the general state, survival time, biochemical indexes, and the histopathology, a method of establishing a stable animal model of acute hepatic failure was found. Results As compared with those in control group, the levels of ALT, AST, GGT, HA, LN and PC-Ⅲ in the experiment group were increased significantly, while the level of ALB was decreased at the end of 10 weeks. Typical features of hepatic fibrosis and the formation of pseudo-lobules were observed at the end of 10 weeks. After treatment with D-Gal, all rabbits in group Ⅰ survived with minimal changes in liver function tests. In group Ⅱ , there was a temporary hepatic injury, but no hepatic coma. Four of the 12 rabbits died (33. 3% ). In group Ⅲ , biochemical indexes changed obviously 12 h after the administration and hepatic injury reached its peak after 48 h. Ten of 12 rabbits were died of severe hepatic failure with a survival time of ( 53. 00 ± 25. 69) h. Histology of liver section revealed massive necrosis in nodules. In group Ⅳ , hepatic injury occurred early and severely. All the rabbits died of severe hepatic failure with a survival time of (32. 70 ± 17. 46) h. Conclusion The experimental model of ACLF could be established by injected with D-Gal in New Zealand rabbits with hepatic fibrosis, induced by CCl4 intraperitoneal injection for 10 weeks.The one induced by 0. 70 g/kg of D-galactosamine was more stable and showed similar clinical pathophysiological changes in human beings. So it can be a good experimental platform for studies of ACLF.     

兔慢性肝损害急性肝衰竭动物模型的建立

Objective To establish an ideal animal model of acute-on-chronic liver failure (ACLF) in New Zealand white rabbits in order to provide a large animal model for further researches.Methods Totally 75 New Zealand rabbits were randomly divided into experimental group (n =70) and control group (n = 5 ). Rabbits in the experimental group were injected with CCl4 into the abdominal cavity twice every week and the doses of CCl4 were modified according to the index of liver function and the body weight, whereas those in the control group were treated with the same volume of saline. At the 10th week,48 New Zealand rabbits with hepatic fibrosis were randomly assigned to 4 groups and injected with CCl4 as before, D-Gal at a dose of 0. 65 g/kg body weight (BW), 0. 70 g/kg BW and 0. 75 g/kg BW, respectively. By observing and comparing the general state, survival time, biochemical indexes, and the histopathology, a method of establishing a stable animal model of acute hepatic failure was found. Results As compared with those in control group, the levels of ALT, AST, GGT, HA, LN and PC-Ⅲ in the experiment group were increased significantly, while the level of ALB was decreased at the end of 10 weeks. Typical features of hepatic fibrosis and the formation of pseudo-lobules were observed at the end of 10 weeks. After treatment with D-Gal, all rabbits in group Ⅰ survived with minimal changes in liver function tests. In group Ⅱ , there was a temporary hepatic injury, but no hepatic coma. Four of the 12 rabbits died (33. 3% ). In group Ⅲ , biochemical indexes changed obviously 12 h after the administration and hepatic injury reached its peak after 48 h. Ten of 12 rabbits were died of severe hepatic failure with a survival time of ( 53. 00 ± 25. 69) h. Histology of liver section revealed massive necrosis in nodules. In group Ⅳ , hepatic injury occurred early and severely. All the rabbits died of severe hepatic failure with a survival time of (32. 70 ± 17. 46) h. Conclusion The experimental model of ACLF could be established by injected with D-Gal in New Zealand rabbits with hepatic fibrosis, induced by CCl4 intraperitoneal injection for 10 weeks.The one induced by 0. 70 g/kg of D-galactosamine was more stable and showed similar clinical pathophysiological changes in human beings. So it can be a good experimental platform for studies of ACLF.     

Reconstruction of caprine mandibular segmental defect by tissue engineered bone reinforced by titanium reticulum

Objective: To investigate the feasibility of using natural poritos as scaffolds in bone tissue engineering (TE) and repair of caprine mandibular segmental defect with titanium reticulum reinforced. Methods: Natural poritos with a pore of 190-230 μn in size and porosity of about 50% -65% was molded into the shape of granules 5 mm×5 mm×5 mm in size. Expanded autologous caprine marrow mesenchymal stem cells were induced by recombinant human morphogenetic protein-2 ( rhBMP2 ) to improve osteoblastic phenotype. Then marrow derived osteoblasts were seeded into poritos in density of 4×107/ml and incubated in vitro for 48 hours prior to implantation. Then osteoblastic cells/poritos complexes were implanted into mandibular defect and the defect was reinforced by titanium reticulum. Implantation of poritos alone acted as the control. Bone regeneration was assessed 4, 8, 16 weeks after implantation using roentgenographic analysis and histological observation was done after 16 weeks. Results: New bone could be observed histologically on the surface and in the pores of natural coral in all specimens in the cell-seeding group, whereas in the control group there was no evidence of osteogenesis process in the center of the construction. The results showed that new bone grafts were successfully restored 16 weeks after implantation. Conclusions: This study suggests the feasibility of using porous coral as scaffold material transplanted with marrow derived osteoblasts by TE method. By means of titanium reticulum reinforcement, mandibular defect could be successfully restored. It shows the potentiality of using this method for the reconstruction of bone defect in clinic.     

Demineralization and pathological physiology of the skeleton in paraplegic rats

Summary The mechanism of bone loss after a spinal cord section with paraplegia is still largely unknown. The purpose of this study was to investigate in paraplegic rats the rate and distribution of bone loss, changes in bone calcium metabolism, and bone blood flow. Female Sprague-Dawley rats aged 100–120 days were rendered paraplegic by sectioning the spinal cord at the 11th dorsal vertebra. By comparison with their sham-operated controls (SO controls), we found a diminished bone calcium content in the tibia and femur (paralyzed region) and in the humerus (supralesional region) of the paraplegic animals. In the femur bone calcium loss was present within a week and at 12 weeks had reached 22%; in the tibia it started at about 2 weeks and at 12 weeks had reached 15%; in the humerus it started at about 5 weeks and reached 7.5%. It was not uniform and was greatest in the metaphyseal-epiphyseal regions on either side of the femorotibial joint. The blood flow in femur and tibia was measured by the technique of arteriolar blockade of 15 μm microspheres. It was continuously higher in the paraplegic animals than in the SO controls, from 1 to 12 weeks. In both groups, paraplegics and controls, the bone blood flow was unequally distributed in the two bones; it was greatest in the same metaphyseal-epiphyseal regions contiguous to the femorotibial joint. The 72 h⁴⁵Ca clearance by the femur and tibia was lower in the paraplegic animals, indicating that bone deposition had slowed down and perhaps that resorption had occurred. The fact that the site of maximum bone calcium loss and the site where the blood flow was greatest are the same suggests a close relationship between the increased blood flow and demineralization, whether it be causal or not.     

A biomechanical investigation on the incorporation of cortical allograft in rabbit ulna defects

Objective:To explore the changes of biomechanical properties of cortical allograft in different mechanical environments.Methods:Cortical allograft was transplanted to each side of the midshaft diaphyseal ulna of each one of 40 rabbits.The left transplanted allograft underwent normal physiological load,while the right one underwent lower load.After animals were killed,specimens were taken for examination of bone mineral density,bone porosity and maximal three-point-bend breaking load.Results:The union strength of allograft-host bone junction was increased constantly;meanwhile,the internal creeping substitution led to an initial greater weakening of the cortical allograft itself and a later recovery of its strength.In comparison,the union strength of the normally loaded graft-host bone construct was significantly higher than that of the lower loaded side at the 8th and 16the week after transplantation.At the 16th week,there was greater bone strength in normally loaded graft than that in lower loaded graft.conclusions:The internal repair can lead to initial preater weakening of cortical allograft and later gradual recovery of its strength.The effect of physiological load can accelerate the improvement of the biomechanical properties of allograft.     

Kinetic studies of bone and mineral metabolism during treatment with (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) in rats

Summary Dose-related effects of APD on bone metabolism and Ca homeostasis were studied in rats. The experimental approach consisted of longitudinal and cross-sectional observations, aiming at a kinetic interpretation. Bone and cartilage resorption was inhibited within 2–8 days at doses between 0.16 and 16 μmol/kg body weight/day. This was followed by changes in bone apposition that needed at least 23 days for a maximal effect. The time lag created a transient dissociation between resorption and apposition resulting in excess Ca and P retention, adding to increased metaphyseal bone mass. At high doses of APD (≥40 μmol/kg/day) the mineral content of new matrix decreased, associated with impairment of longitudinal growth of long bones. It is concluded that the lower doses of APD inhibited resorption of bone and cartilage, possibly by physicochemical stabilization of bone mineral, whereas the effect on bone apposition was due to a cellular homeostatic mechanism. Inhibition of growth and of matrix calcification, requiring much higher doses, may be due to a direct, toxic effect on bone cells. The modes of action of APD are discussed in relation to EHDP and Cl₂MDP.     

Dose-dependent effects of combined IGF-I and TGF-β1 application in a sheep cervical spine fusion model

Combined IGF-I and TGF-β1 application by a poly-(D,L-lactide) (PDLLA) coated interbody cage has proven to promote spine fusion. The purpose of this study was to determine whether there is a dose-dependent effect of combined IGF-I and TGF-β1 application on intervertebral bone matrix formation in a sheep cervical spine fusion model. Thirty-two sheep underwent C3/4 discectomy and fusion. Stabilisation was performed using a titanium cage coated with a PDLLA carrier including no growth factors in group 1 (n=8), 75 μg IGF-I plus 15 μg TGF-β1 in group 2 (n=8), 150 μg IGF-I plus 30 μg TGF-β1 in group 3 (n=8) and 300 μg IGF-I plus 60 μg TGF-β1 in group 4 (n=8). Blood samples, body weight and temperature were analysed. Radiographic scans were performed pre- and postoperatively and after 1, 2, 4, 8, and 12 weeks. At the same time points, disc space height and intervertebral angle were measured. After 12 weeks, the animals were killed and fusion sites were evaluated using quantitative computed tomographic (CT) scans to assess bone mineral density, bone mineral content and bony callus volume. Biomechanical testing was performed and range of motion, and neutral and elastic zones were determined. Histomorphological and histomorphometrical analysis were carried out and polychrome sequential labelling was used to determine the time frame of new bone formation. In comparison to the group without growth factors (group 1), the medium- and high-dose growth factor groups (groups 3 and 4) demonstrated a significantly higher bony callus volume on CT scans, a higher biomechanical stability, an advanced interbody bone matrix formation in histomorphometrical analysis, and an earlier bone matrix formation on fluorochrome sequence labelling. Additionally, the medium- and high-dose growth factor groups (groups 3 and 4) demonstrated a significantly higher bony callus volume, a higher biomechanical stability in rotation, and an advanced interbody bone matrix formation in comparison to the low-dose growth factor group (group 2). No significant difference could be determined between the medium- and the high-dose growth factor groups (groups 3 and 4, respectively). The local application of IGF-I and TGF-β1 by a PDLLA-coated cage significantly improved results of interbody bone matrix formation in a dose-dependent manner. The best dose-response relationship was achieved with the medium growth factor dose (150 μg IGF-I and 30 μg TGF-β1). With an increasing dose of these growth factors, no further stimulation of bone matrix formation was observed. Although these results are encouraging, safety issues of combined IGF-I and TGF-β1 application for spinal fusion still have to be addressed. This study was carried out with the support of the MBI – Max Biedermann Institut der Steinbeis Stiftung (RS/KF-82042).     

消旋聚乳酸/羟基磷灰石/脱钙骨基质的制备及其体外降解特性研究

目的：探讨消旋聚乳酸／羟基磷灰石／脱钙骨基质（PDLLA／HA／DBM）R的制备方法及其体外降解特性。方法：按重量比PDLLA：HA：DBM＝1．5－2．1－1．5：1，应用乳液共混法，制备PDLLA／HA／DBM生物复合材料，通过体外降解实验，观察其在磷酸盐缓冲液（PBS，PH7．4）中重量，生物力学及PH值的动态变化，结果：采用乳液共混法，不需加温，可将PDLLA、HA、DBM一次性复合,制成生物复合材料PDLLA／HA／DBM。孔隙率为71．3％；扫描电镜显示复合材料孔径为100－400μm；降解过程中；PDLLA溶液的PH值2周内轻度下降，而后明显下降，4周时PH值为4．0；PDLLA／HA／DBM溶液的PH值在12周的降解过程中十分稳定，12周时PH值为6．4。PDLLA重量在0－4周时变化较小，4周后下降加快，12周时为初始重量的50％； 量在0－5周时变化比较小，5周后下降加快，12周时为初始重量的60％。PDLLA的初始抗压强度为1．33MP a，PDLLA／HA／DBM的初始抗压强度为1．71MPa，两者有统计学意义（P＜0．05）；PDLLA强度在0－3周下降较小，3周后下降较快，12周仅0．11Mpa；PDLLA／HA／DBM强度在0－4周下降较小，4周后下降较快，12周时为0．21 Mpa；。结论：乳液共混法是制备骨修复材料的新方法，PDLLA／HA／DBM作为一种新型治疗骨缺损的材料，具有良好的孔隙率及降解特性。     

颗粒骨的制备及修复骨缺损的研究

目的 观察聚磷酸钙纤维(CPPF)磷酸钙骨水泥(CPC)、微小颗粒骨复合物体外降解特性及体内修复骨缺损的能力.方法 将CPPF、CPC、微小颗粒骨按质量比1∶4∶4制成复合人工骨,通过PH值、重量、抗压强度的变化,观察人工骨在pH7.4的37℃磷酸盐缓冲液(PBS)中的降解性能.通过大体、X光片、组织学观察及力学测试来检测复合人工骨的体内修复骨缺损的能力.结果 体外实验证实:CPPF/CPC/颗粒骨复合材料孔隙率为72.1%,CPC/颗粒骨孔隙率为58.2%;扫描电镜显示CPPF/CPC/颗粒骨复合材料的孔径为100～400 μm,CPC/颗粒骨为50～300 μm;两组样品溶液pH值在12周内基本维持恒定;CPPF/CPC/颗粒骨复合材料0～4周重量变化较小,4～8周下降较快,12周为初始重量50%,CPC/颗粒骨复合材料在0～6周变化较小,6周后重量下降较快,12周时为初始重量70%;CPPF/CPC/颗粒骨复合材料初始抗压强度9.28 MPa,CPC/颗粒骨复合材料初始抗压强度6.21 Mpa,两者有统计学意义.CPPF/CPC/颗粒骨强度在0～4周下降较慢,4周后下降较快,12周时为0.1,8 MPa,CPC/颗粒骨强度均匀下降,12周时为0.24 MPa.体内实验:CPPF/CPC/颗粒骨复合材料修复骨缺损效果优于其他各组,且差异有统计学意义(P＜0.05).结论 复合材料以其优良的生物学性能有望成为理想的骨替代材料.     

Repair of large segmental bone defects using bone marrow stromal cells with demineralized bone matrix

Objective: The aim of the present study was to evaluate the effect of tissue‐engineered constructs on repair of large segmental bone defects in goats. Methods: Allogenic demineralized bone matrix (aDBM) was seeded with autologous marrow stromal cells (aMSC) for seven days to construct DBM–MSC grafts prior to implantation. 24 goats were randomly divided into three groups (eight in each). In each group, 3 cm diaphyseal femoral defects were created unilaterally, and subsequently filled with the DBM‐MSC grafts, DBM alone and an untreated control, respectively. Radiological analysis and biomechanical evaluation were performed at 12 and 24 weeks after operation. Results: Obvious increases in radiological scoring and biomechanical strength were found in the DBM‐MSC group when compared to the DBM group. X‐ray examination showed excellent bone healing in the DBM‐MSC group, whereas only partial bone repair was seen in the DBM group, and no healing in untreated controls. Histologically, a tendency to bone regeneration and remodeling was far more obvious for the DBM‐MSC group than the DBM only and untreated controls. Conclusion: Our results strongly suggest that transplantation of bone MSC within a DBM could have advantages for the bone repair of large segmental defects.     

羟基磷灰石/聚DL乳酸内固定材料对骨折愈合的影响

目的 评价自行研制的可吸收羟基磷灰石／聚ＤＬ乳酸（ＨＡ／ＰＤＬＬＡ）复合内固定材料对实验性松质骨骨折愈合的影响。方法 取２５只兔作右股骨髁松质骨横形截骨,用ＨＡ／ＰＤＬＬＡ棒内固定。术后１、２、４、６和１２周作Ｘ线摄片、组织学和超微结构观察。结果 骨折均在６周内愈合,无炎性细胞聚集。经航向间观察可见多形核白细胞和巨噬细胞１周时较多,２周时减少,炎症期和清扫期未见明显延长;２周时以成纤维细胞为主,４     

Demineralized bone matrix and hydroxyapatite/tri-calcium phosphate mixture for bone healing in rats

Purpose: Hydroxyapatite/tri-calcium phosphate (HA/TCP) mixture is an osteoconductive material used as a bone graft substitute, and demineralised bone matrix (DBM) is an osteoinductive material. A combination of DBM and HA/TCP mixture would probably create a composite with both osteoconductive and osteoinductive properties. The purpose of this study was to determine the effect of the combination of DBM and HA/TCP mixture on healing of rat radius segmental defects. Methods: Twenty-four adult male Wistar rats were used. Bilateral radial defects were created in each animal. Radial defects were implanted with DBM, HA/TCP mixture and a combination of both substances. Control defects were left unfilled. Ten weeks after implantation, the animals were sacrificed, and the radii were evaluated by radiograhic and histopathological studies. Results: The use of DBM alone demonstrated improved healing on radiographic and histological studies compared to other groups and the control group. There were no differences between the other two groups and the control group. Conclusion: The DBM group showed the best healing response. Combined use of DBM and HA/TCP mixture did not improve bone healing, and the osteoinductive properties of DBM were inhibited by HA/TCP mixture.     

The merit of sintered PDLLA/TCP composites in management of bone fracture internal fixation

Polyesters based on lactic acid have been reported in terms of safety and biodegradation in human beings for 2 decades. The greatest advantage of such material is its degradation conducted only by hydrolysis, whereby the ester backbones are supposed to be unchained in the aqueous condition. The final degradable products are carbon dioxide and water which can be metabolized and digested in the physiological environment. The goal of this study was aimed at developing a composite sintered with poly-DL-lactide (PDLLA) and tricalcium phosphate (TCP) ceramic particles for orthopedic application. The TCP particles in a range of 30-60 wt% with 5 wt% increments were doped into the PDLLA matrix which was prepared by melting and hot pressing techniques for the reinforcement. The basic mechanical strength, biodegradable behavior, and biological response of the composites were investigated in the study. Various techniques such as pH meter, UV, Fourier-transform infrared, and x-ray diffractometer were used to examine and record the degradable process of the composites soaked in saline for 1-16 weeks. The rabbit femur condyle fracture fixation test was used to evaluate tissue compatibility and the effects of bone fracture fixation on the composites. Histological observation and x-ray photography were used for investigating assistance. The mechanical strength of the composites initially increased with TCP additions up to 50wt%, but thereafter they showed no significant difference (p < 0.05). The composite with 50 wt% TCP addition showed greater mechanical strength and had good agreement with cortical bone in terms of its elastic modulus of 30-40 GPa. The weight loss of the pure PDLLA soaked in the saline started at 4 weeks and reached 95% after 16 weeks. The composites compared with pure PDLLA, however, showed no apparent evidence of degradation after soaked for 12 weeks. The possible mechanisms for the delayed degradation of the composites in saline might have been solution penetration retardation by the ceramic particles and chemical bonds formed between the interface of the TCP particles and the PDLLA matrix. In the histological evaluation of the rabbit femur condyle fracture fixation test, the surface of the composite with 50 wt% TCP addition was attached by the newly generated bone without fibrous tissue around 8 weeks after implantation. The fractured bone was gradually healed and the composite firmly and properly fixed on the fracture area during the implanted period, which provided a breeding environment for normal bone remodeling. The developed composite was thought to be an alternative material for orthopedic application in the future, especially for bone screws and bone plates.     

负载骨形态发生蛋白与血管内皮生长因子的超聚消旋乳酸修复兔桡骨缺损的实验研究

[目的] 探讨同时负载BMP、VEGF的PDLLA材料的体内成骨能力,以得到一种较好的可吸收骨构建材料.[方法] 成骨细胞分离培养后负载到PDLLA材料中进行兔桡骨缺损修复实验,术后4、8、12 周行X线、组织学及扫描电镜观察骨生成状况, 12周行生物力学测试(三点折弯强度).[结果] 术后实验组各观察阶段骨形成明显高于对照组,第12周三点折弯强度与对照组相比差异有显著性(P<0.01).[结论] 负载BMP及VEGF两种细胞因子PDLLA支架材料修复兔桡骨缺损效果明显优于负载单一细胞因子PDLLA支架材料, 是一种有临床应用前景的骨移植材料.     

重组人骨形态发生蛋白-2用于人工关节生物固定方法的研究

目的 探讨复合重组人骨形态发生蛋白-2(rhBMP2)植入体对骨-假体界面骨长入及结合强度的作用。方法将多孔金属表面植入体(PCA)与复合．rhBMP2的PCA植入体、HA涂层植入体及：PCA表面喷涂HA植入体植入犬皮质骨并综合运用X线摄片、软X线照相、不脱钙骨组织磨片、荧光显微镜检查、骨组织计量学分析及生物力学测定等方法对骨-植入体界面的骨长入及界面的结合强度进行了比较分析。结果术后软X线照相、组织学、骨组织计量学及生物力学比较分析显示复合rhBMP2的植入体在各时间组的新生骨形成率和界面剪切强度均优于其它各组;以4周时最为明显,且差异有非常显著意义。结论植入体复合rhBMP2后在促进早期骨-假体界面的骨长入和结合强度方面优于其它各种方法,有利于早期骨与假体间的结合和固定。     

丝素蛋白/羟基磷灰石组织工程化骨修复兔桡骨节段性骨缺损

目的 探讨丝素蛋白/羟基磷灰石(SF/HA)组织工程化骨的成骨作用,以期为临床治疗骨缺损提供新的人工骨材料.方法 将SF/HA与成骨诱导的兔骨髓基质干细胞(BMSCs)复合,构建组织工程化骨.取54只兔于左侧桡骨中上段制备15 mm节段性骨缺损.实验分3组(A、B组各24只,C组6只):A组:植入SF/HA组织工程化骨,B组:单纯植入SF/HA;C组:骨缺损区不植入任何材料.于术后4、8、12及16周摄X线片,并于16周行螺旋CT扫描重建,观察骨缺损修复及骨塑形情况,参照Lane-Sandhu X线评分标准对各组骨缺损的骨修复程度评分.骨痂标本行 HE染色组织学观察,按照Lane-Sandhu组织学评分法比较12周和16周时各组的骨修复情况. 结果 术后16周,X线片示A组髓腔通畅,新骨塑形好,骨皮质连续;B组缺损区有缩小,两断端不连接;C组缺损区无明显骨痂生长.16周时螺旋CT扫描重建显示:A组骨塑形明显,骨缺损完全修复;B组有部分皮质骨形成,缺损区不能完全修复;C组骨缺损基本无修复.每组术后4、8、12、16周不同时间点的放射学评分差异均有统计学意义(P＜0.05).术后12、16周时3组间Lane-Sandhu组织学评分差异均有统计学意义(P＜0.05). 结论 SF/HA组织工程化骨具有良好的节段性骨缺损修复能力,但SF/HA本身缺乏骨诱导作用,单独修复节段性骨缺损作用有限.     

Recombinant human bone morphogenetic protein-2 potentiates the in vivo osteogenic ability of marrow/hydroxyapatite composites

A composite of marrow mesenchymal stem cells (MSCs) and porous hydroxyapatite (HA) has bone-forming capability. To promote the capability, we added recombinant human bone morphogenetic protein-2 (BMP) to the composite. The bone formation was assessed by rat subcutaneous implantation of 4 different kinds of implants, i.e., HA alone, BMP/HA composites, MSCs/HA composites, and the composites containing BMP (MSCs/BMP/HA). Both HA and the BMP/HA composites did not show bone formation at any time after implantation. The MSCs/HA composites showed moderate bone formation at 4 weeks and extensive bone formation at 8 weeks. The MSCs/BMP/HA composites showed obvious bone formation together with active osteoblasts at 2 weeks and more bone formation at 4 and 8 weeks. The MSCs/BMP/HA composites demonstrated high alkaline phosphatase and osteocalcin expression at both the protein and gene levels. These results indicate that the combination of MSCs, porous HA, and BMP synergistically enhances osteogenic potential and provides a rational basis for their clinical application in bone reconstruction surgery.