The Effect of Simvastatin on mRNA Expression of Transforming Growth Factor-β1,Bone Morphogenetic Protein-2 and Vascular Endothelial Growth Factor in Tooth Extraction Socket

Aim To determine the effect of local simvastatin application on the mRNA expression level of transforming growth factor-β1 （TGF-β1）, bone morphogenetic protein-2 （BMP-2） and vascular endothelial growth factor （VEGF） in the tooth sockets of rat. Methodology Forty-eight male Wistar rats were randomly divided into experimental and control groups （n=24）. Polylactic acid/polyglycolic acid copolymer carriers, with or without simvastatin, were implanted into extraction sockets of right mandibular incisors. The expression of TGF-β1, BMP-2 and VEGF mRNA was determined by in situ hybridization in the tooth extraction socket at five days, one week, two weeks and four weeks after implantation. Results The fusiform stroma cells in the tooth extraction socket began to express TGF-β1, BMP-2 and VEGF mRNA in both experimental and control groups from one week after tooth extraction until the end of experiment. The expression of TGF-131 and BMP-2 mRNA in the experimental group was significantly up-regulated after one, two and four weeks, and expression of VEGF mRNA was significantly increased after one and two weeks compared with that in the control group. Conclusion The findings indicate that local administration of simvastatin can influence alveolar bone remodeling by regulating the expression of a school of growth factors which are crucial to osteogenesis in the tooth extraction socket.

Drilling Combined with Adipose-derived Stem Cells and Bone Morphogenetic Protein-2 to Treat Femoral Head Epiphyseal Necrosis in Juvenile Rabbits

This study was designed to evaluate the effects of drilling through the growth plate and using adipose-derived stem cells （ADSCs） and bone morphogenetic protein-2 （BMP-2） to treat femoral head epiphyseal ischemic necrosis, which can be done in juvenile rabbits. Passagefour bromodeoxyuridine （BrdU）-labeled ADSCs were cultured, assayed with MTT to determine their viability and stained with alizarin red dye to determine their osteogenic ability. Twomonth-old, healthy male rabbits （1.2 to 1.4 kg, n=45） underwent ischemic induction and were randomly divided into five groups （group A： animal model control; group B： drilling; group C： drilling ＆ ADSCs; group D： drilling ＆ BMP-2; and group E： drilling ＆ ADSCs ＆ BMP-2）. Magnetic resonance imaging （MRI）, X-ray imaging, hematoxylin and eosin staining and BrdU immunofluorescence detection were applied 4, 6 and 10 weeks after treatment. Approximately 90% of the ADSCs were labeled with BrdU and showed good viability and osteogenic ability. Similar results were observed in the rabbits in groups C and E at weeks 6 and 10. The animals of groups C and E demonstrated normal hip structure and improved femoral epiphyseal quotients and trabecular areas compared with those of the groups A and B （P〈0.01）. Group D demonstrated improved femoral epiphyseal quotients and trabecular areas compared with those of groups A and B （P〈0.05）. In summary, drilling through the growth plate combined with ADSC and BMP-2 treatments induced new bone formation and protected the femoral head epiphysis from collapsing in a juvenile rabbit model of femoral head epiphyseal ischemic necrosis.

Regulation of scleral fibroblast differentiation by bone morphogenetic protein-2

Bone morphogenesis proteins(BMPs) are multi-functional growth factors. They are expressed in retina,retinal pigment epithelium(RPE) and sclera and serve as a regulator in the growth and development of the eye. This article reviewed the chondrogenic potency of the sclera,biochemical and pathological changes of myopic scleral tissue and the differentiation of chondrogenesis by BMP-2. We proposed the hypothesis that BMP-2 can regulate differentiate of scleral fibroblasts and affect the development of myopia.

Use of recombinant human bone morphogenetic protein-2 in spine surgery

Bone morphogenetic proteins are osteoinductive factors which have gained popularity in orthopaedicsurgery and especially in spine surgery. The use of recombinant human bone morphogenetic protein-2 has been officially approved by the United States Food and Drug Administration only for single level anterior lumbar interbody fusion, nevertheless it is widely used by many surgeons with off-label indications. Despite advantages in bone formation, its use still remains a controversial issue and several complications have been described by authors who oppose their wide use.

Bone morphogenetic protein-2 is a negative regulator of hepatocyte proliferation downregulated in the regenerating liver

AIM: To characterize the expression and dynamic changes of bone morphogenetic protein (BMP)-2 in hepatocytes in the regenerating liver in rats after partial hepatectomy (PH), and examine the effects of BMP-2 on proliferation of human Huh7 hepatoma cells. METHODS: Fifty-four adult male Wistar rats were randomly divided into three groups: A normal control (NC) group, a partial hepatectomized (PH) group and a sham operated (SO) group. To study the effect of liver regeneration on BMP-2 expression, rats were sacrificed before and at different time points after PH or the sham intervention (6, 12, 24 and 48 h). For each time point, six rats were used in parallel. Expression and distribution of BMP-2 protein were determined in regenerating liver tissue by Western blot analysis and immunohistochemistry. Effects of BMP-2 on cell proliferation of human Huh7 hepatoma cell line were assessed using an MTT assay.RESULTS: In the normal liver strong BMP-2 expression was observed around the central and portal veins. The expression of BMP-2 decreased rapidly as measured by both immunohistochemistry and Western blot analysis. This decrease was at a maximum of 3.22 fold after 12 h and returned to normal levels at 48 h after PH. No significant changes in BMP-2 immunoreactivity were observed in the SO group. BMP-2 inhibited serum induced Huh7 cell proliferation.CONCLUSION: BMP-2 is expressed in normal adult rat liver and negatively regulates hepatocyte proliferation. The observed down regulation of BMP-2 following partial hepatectomy suggests that such down regulation may be necessary for hepatocyte proliferation.

Alendronate disturbs femoral growth due to changes during immunolocalization of transforming growth factor-β1 and bone morphogenetic protein-2 in epiphyseal plate

BACKGROUND The epiphyseal growth plate is an important anatomical segment localized on the ends of a long bone.Despite the abovementioned atractive reasons for alendronate’s use,few data on the effect of alendronate during epiphyseal growth exist.AIM Verify the effect of alendronate on the growth epiphyseal plate,and compare its effect with the size of the femur during the double-staining of the immunolocalization of transforming growth factor-β1(TGF-β1)and bone morphogenetic protein-2(BMP2)in endochondral ossifing in specimens that have received alendronate.METHODS Forty newborn rats were randomly divided into two groups:a control group(were given applications of 1 mg/kg physiologic saline)and a group that received Alendronate(a dose of 2.5 mg/kg).These groups were then divided into two subgroups for euthanasia in two and 12 d of life.After euthanasia,the femurs were removed,and the femoral bones were measured linearly between the apex of the greater trochanter until the lower intercondylar midlle face to verify the probable bone growth between 3 and 12 d in control and alednroanto treated rats.Posteriorly,the surgical pieces were also sent to the histopathology laboratory to produce histological slides.The obtained slides were stained with hematoxylin and eosin to measure each of the cartilage zones in endochondral development.and other slides were immunohistochemically tested for anti-TGF-β1 and BMP-2 antibodies to investigate the immunolocalization of these proteins in the epiphyseal plaque area.RESULTS On the third day,some diferences between the control group and specimens treated with alendronate were verified.Macroscopiccaly,we found similarities in size between the femoral bones when we compared the control group with the specimens that received alendronate.On the 12^th day,the bone size of the mice receiving the drug was significantly smaller than those of the control group.These results coincide with changes in the TGF-β1 and BMP-2 expression.In the specimens that received alendronate,the TGF-β1 was expressed in some sites of trabecular bone that was neoformed,peripherally to the bone marrow area.The BMP-2 was also positive in proliferative chondrocytes and hypertrofic chondrocytes.On the 12^th day,all layers of chondrocytes exhibited positivity for BMP-2 in the specimens that received alendronate.In the interface between the trabecular bone and cartilage,an area of disorganized bone deposition was evident.Neoformed bone also appeared to be different at 12 d.In the control group,BMP-2 was positive in an intense area of bone trabeculae,whereas the alendronate-treated group showed TGF-β1 positive trabeculae and a greater bone area.CONCLUSION Alendronate alters the immunolocalization of TGF-β1 and BMP-2 simultaneously,a condition that changes the usual histological aspects of the cartilage zone and impairs epiphysis growth and femur growth.

Implantation of xenogeneic bone combined with recombinant human bone morphogenetic protein-2 into bone defect—An scanning electron microscopic study

To determine the ability of a new type of composite xenogeneic bone grafting to repair bone defect. Methods: The new type of composite xenogeneic bone was obtained by combining the chemically treated cance1lous bone with recombinant human bone morphogenetic protein-2 (rhBMP-2). It was implanted on the bone defect of rabbit. Results: There was a large amount of new bone formation within the combined material and the amount was increasing as the time elapsed. In contrast, there was a lot of fibrous tissue with a little new bone formed on the area of the bone defect when the treated cancellous bone was implanted alone. Conclusion: The results imply that the rhBMP-2 plays a very important role in new bone formation and the composite xenogeneic bone appear to be an ideal material for repair of bone defect.

Expression of mature peptide of human bone morphogenetic protein-2 in Escherichia coli

To express die mature peptide of human bone morphogenetic protein-2 in Escherichia coil. Methods: TheDNA fragment encoding the mature peptide of human bone morphogenetic protein-2 (hBMP-2m) was inserted into expression vectorpDH in which foreign gene was controlled by PRPL promoters. E. coli DH5a transformed with recombinant plasmid pDHB2m wasinduced at 42℃to express the target protein. The expressed product was partially purified and refolded, and then implanted intorat thigh muscles to assay its bone inductive activity. Results: After induction, a protein band on SDS-PAGE gel with an apparentmol. wt. of 13kD was observed to anticipate in the strain carrying pDHB2m, but not in the control. The expressed hBMP-2m accounted for 45%-60% of the total bacterial protein. The expressed product existed in a form of inclusion body. After partially purified and refolded, rhBMP-2m could induce the formation of cartilage and bone tissue heterotopically. Conclusion: The maturepeptide of human bone morphogenetic protein-2 has ben successfully expressed in E. coli and the product has ectopic bone inductive activity.

Bone morphogenetic protein-6 suppresses TGF-β_(2)-induced epithelial-mesenchymal transition in retinal pigment epithelium

AIM:To evaluate the effect of bone morphogenetic protein-6(BMP-6)on transforming growth factor(TGF)-β_(2)-induced epithelial-mesenchymal transition(EMT)in retinal pigment epithelium(RPE).METHODS:Adult retinal pigment epithelial cell line(ARPE-19)were randomly divided into control,TGF-β_(2)(5μg/L),and BMP-6 small interfering RNA(siRNA)group.The cell morphology was observed by microscopy,and the cell migration ability were detected by Transwell chamber.The EMT-related indexes and BMP-6 protein levels were detected by Western blotting.Furthermore,a BMP-6 overexpression plasmid was constructed and RPE cells were divided into the control group,TGF-β_(2)+empty plasmid group,BMP-6 overexpression group,and TGF-β_(2)+BMP-6 overexpression group.The EMT-related indexes and extracellular regulated protein kinases(ERK)protein levels were detected.RESULTS:Compared with the control group,the migration of RPE cells in the TGF-β_(2) group was significantly enhanced.TGF-β_(2) increased the protein expression levels ofα-smooth muscle actin(α-SMA),fibronectin and vimentin but significantly decreased the protein levels of E-cadherin and BMP-6(P<0.05)in RPE.Similarly,the migration of RPE cells in the BMP-6 siRNA group was also significantly enhanced.BMP-6 siRNA increased the protein expression levels ofα-SMA,fibronectin and vimentin but significantly decreased the protein expression levels of E-cadherin(P<0.05).Overexpression of BMP-6 inhibited the migration of RPE cells induced by TGF-β_(2) and prevented TGF-β_(2) from affecting EMT-related biomarkers(P<0.05).CONCLUSION:BMP-6 prevents the EMT in RPE cells induced by TGF-β_(2),which may provide a theoretical basis for the prevention and treatment of proliferative vitreoretinopathy.

Association between two polymorphisms of the bone morphogenetic protein-2 gene with genetic susceptibility to ossification of the posterior longitudinal ligament of the cervical spine and its severity

Background Ossification of the posterior longitudinal ligament （OPLL） has a strong genetic background. Previous studies have shown that bone morphogenetic protein-2 （BMP2） and BMP2 mRNA are expressed in ossifying matrix and chondrocytes adjacent to cartilaginous areas of OPLL tissues and mesenchymal cells with fibroblastic features in the immediate vicinity of the cartilaginous areas. It is suggested that BMP2 plays different roles in the different stages of development of OPLL. However, it remains unknown which factors induce ligament cells to produce BMP2. Methods OPLL patients （n=-192） and non-OPLL controls （n=304） were studied. Radiographs of the cervical spine were analyzed for extent of OPLL. We investigated whether single nucleotide polymorphisms of exons 3（-726） T/C and 3（-583） NG in the BMP2 gene are statistically associated with genetic susceptibility to OPLL in Chinese Han subjects. Results There was no statistical difference between the occurrence of exons 3（-726） T/C and 3（-583） NG and the occurrence of OPLL in the cervical spine. However, there was a significant association between occurrence of exon 3（-726） T/C polymorphism and occurrence of OPLL in males of cases and controls in the cervical spine. In addition, no significant association was found between the exons 3（-726） T/C and 3（-583） A/G with number of ossified cervical vertebrae in OPLL patients. Conclusions Exon 3（-583） A/G polymorphism in BMP2 gene is not associated with the occurrence and the extent of OPLL in the cervical spine. Chinese Han male patients with TC and CC genotypes in exon 3（-726） T/C have genetic susceptibility to OPLL but not to more extensive OPLL in the cervical spine.

Effects of Roughly Focused Extracorporeal Shock Waves Therapy on the Expressions of Bone Morphogenetic Protein-2 and Osteoprotegerin in Osteoporotic Fracture in Rats

Background：Roughly focused extracorporeal shock waves therapy （ESWT） is characterized by a wide focal area,a large therapy zone,easy positioning,and less pain during treatment.The purpose of this study was to investigate the effects of roughly focused ESWT on the expression of osteoprotegerin （OPG） and bone morphogenetic protein-2 （BMP-2） in osteoporotic fractures in rats.Methods：Seventy-two female Sprague-Dawley （SD） rats,3 months old,were divided into sham-operated group （n =6） and an ovariectomized （OVX） group （n =66）.Sixty OVX SD rats were used as a model of double proximal tibial osteotomy and inner fixation.The osteotomy site in the left tibia was treated with roughly focused ESWT once at an energy density of 0.26 mJ/mm^2,60 doses/min,and 2000 pact quantities.The contralateral right tibia was left untreated and served as a control.Expression of OPG and BMP-2 in the callus of the osteoporotic fracture area was assessed using immunohistochemistry,real-time polymerase chain reaction （PCR）,and Western blotting analysis.Results：Bone mineral density （BMD） at the proximal tibia,femur,and L5 spine was significantly reduced after ovariectomy.BMD of proximal tibia was 12.9% less in the OVX group than that in the sham-operated group.Meanwhile,bilateral oophorectomy resulted in a lower trabecular bone volume fraction （BV/TV） in the proximal tibia of the sham-OVX animals.Three months after bilateral oophorectomy,BV/TV was 14.29% of baseline BV/TV in OVX legs versus 45.91% in the sham-OVX legs （P 〈 0.001）.These data showed that the SD rats became a suitable model of osteoporosis,3 months after they were OVX.Immunohistochemical analysis showed higher levels of BMP-2 and OPG expression in the treatment group than those in the control group.Compared with the contralateral controls,decreased expression of OPG and BMP-2 at 3 days after roughly focused ESWT,followed by a later increase at 7 days,was indicated by real-time PCR and Western blotting analysis.The OPG messenger RNA （mRNA） expression levels peaked at 6 weeks after the shock wave treatment,paired with a much earlier （at 4 weeks） increase of BMP-2,and declined close to normal at 8 weeks.Conclusions：Roughly focused ESWT may promote the expression of OPG and BMP-2 in the osteoporotic fracture area in rats.BMP-2 and OPG may act synergistically and may lead to a significant enhancement of bone formation and remodeling.

A single nucleotide polymorphism in the human bone morphogenetic protein-2 gene （109T〉G） affects the Smad signaling pathway and the predisposition to ossification of the posterior longitudinal ligament of the spine

Background Although various systemic and local factors such as abnormal carbohydrate or calcium metabolism, aging, and hormonal disturbances have been suggested as causes of ossification of the posterior longitudinal ligament （OPLL）, the etiology of OPLL is not fully understood. The purpose of this study was to investigate whether bone morphogenetic protein （BMP）-2 is a candidate gene to modify the susceptibility of OPLL and the mechanism of signal transduction in ossification. Methods A total of 420 OPLL patients and 506 age- and sex-matched controls were studied. The complete coding sequence of the human BMP-2 gene was analyzed using polymerase chain reaction （PCR） and direct sequencing. All single nucleotide polymorphisms （SNPs） were detected and genotyped. BMP-2 expression vectors containing positive polymorphisms were constructed and transfected into the C3H10T1/2 cells. The expression of BMP-2 and the Smad signal pathway in positive cell clones were detected by Western blotting. The alkaline phosphatase （ALP） activity was determined using quantitative detection kits. Results The frequencies for the 109T〉G and 570A〉T polymorphisms were different between the case and control groups. The ＂TG＂ genotype in 109T〉G polymorphism is associated with the occurrence of OPLL, the frequency of the ＂G＂ allele is significantly higher in patients with OPLL than in control subjects （P 〈0.001）. The ＂AT＂ genotype in 570A〉T polymorphism is associated with the occurrence of OPLL, the frequency of the ＂T＂ allele is significantly higher in patients with OPLL than in control subjects （P=0.005）. Western blotting analysis revealed that the expression of P-Smadl/5/8 protein transfected by wild-type or mutant expression vectors were significantly higher than control groups （P 〈0.05）, but there was no statistical difference in each experimental group （P 〉0.05）. The expression of Smad4 protein transfected by wild-type or mutant expression vectors was significantly higher than control groups （P 〈0.05）. The expression of Smad4 protein transfected by pcDNA3.1-BMP2 （109G） and pcDNA3.1-BMP2 （109G, 570T） was significantly higher than the other experimental groups （P 〈0.05）. The increase in ALP activity has been detected in pcDNA3.1-BMP2 （109G） and pcDNA3.1-BMP2 （109G, 570T） transfected cells up to 4 weeks after stable transfection. Activity of ALP was （30.56±0.46） nmol.min^-1.mg^-1 protein and （29.62±0.68） nmol.min^-1.mg^-1 protein, respectively. This was statistically different compared with the other experimental groups （P 〈0.05）. Conclusions BMP-2 is the predisposing gene of OPLL. The ＂TG＂ genotype in the 109T〉G and the ＂AT＂ genotype in the 570A〉T polymorphisms are associated with the occurrence of OPLL. The 109T〉G polymorphism in exon-2 of the BMP-2 gene is positively associated with the level of Smad4 protein expression and the activity of ALP. The Smad mediated sicjnaling pathway plays an important role durincl the Datholoqical process of OPLL induced by SNPs of BMP-2 aene.

Reconstruction of orbital defect in rabbits with composite of calcium phosphate cement and recombinant human bone morphogenetic protein-2

Background Calcium phosphate cement （CPC） is a biocompatible and osteoconductive bone substitute, and recombinant human bone morphogenetic protein-2 （rhBMP-2） has strong osteoinductibility, therefore we developed a composite bone substitute with CPC and rhBMP-2 and evaluate its reconstruction effect in rabbit orbital defect.Methods Thirty-six rabbits were randomly divided into two groups and a 5 mmx5 mmx2 mm bone defect in the infraorbital rim was induced by surgery in each orbit （72 orbits in all）. The orbital defects were treated with pure CPC or composite of CPC and rhBMP-2. The osteogenesis ability of different bone substitute was evaluated by gross observation, histological examination, histomorphometrical evaluation, compressive load-to-failure testing, and scanning electron microscope （SEM）.Results Gross observation showed that both bone substitutes were safe and effective for reconstruction of orbital defect. However, histological examination, histomorphometrical evaluation and SEM showed that CPC/rhBMP-2 group had faster speed in new bone formation and degradation of substitute material than CPC group. Compressive load-to-failure testing showed that CPC/rhBMP-2 group had stronger compressive strength than CPC group at every stage with significant difference （P ＜0.05）.Conclusion Composite of CPC/rhBMP-2 is an ideal bioactive material for repairing orbital defect, with good osteoconductibility and osteoinductibility.

Upregulation of Cartilage Oligomeric Matrix Protein and Bone Morphogenetic Protein-2 May Associate with Calcific Aortic Valve Disease

Objective:Calcific aortic valve disease(CAVD)affects millions of elderly people,and there is currently no effective way to stop or slow down its progression.Therefore,exploring the pathogenesis of CAVD is very important for prevention and treatment.Cartilage oligomeric matrix protein(COMP)have important role in cell phenotype change.This study is aimed to confirm whether COMP participate in CAVD and try to find the possible mechanisms.Methods:Human aortic valve tissues from Nanjing First Hospital(CAVD group,n=20;control group,n=11)were harvested.The expression level of COMP was tested by western blot and immunohistochemistry.Dual immunofluorescence staining was used for locating COMP.Bone morphogenetic protein-2(BMP2)signalling were tested by western blot.The animal model was also used to detect COMP level by immunohistochemistry.Results:The results showed that the expression level of COMP was significantly increased in the calcific valve samples when compared with that of the control valve(P<0.05);COMP was expressed near the calcific nodules and co-localized with a-smooth muscle actin(a-SMA).The protein levels of BMP2 and p-Smads 1/5/9 were markedly more highly expressed in the CAVD group than the control group(P<0.05).Furthermore,immunofluorescence detection showed that COMP and BMP2 were co-located in calcific valves.Conclusions:The above results suggested that upregulation of COMP and BMP2 may be associated with aortic valve calcification and that COMP may become a potential therapeutic target in human CAVD.

Chondrogenic Differentiation of Mouse Bone Marrow Mesenchymal Stem Cells Induced by Cartilage-derived Morphogenetic Protein-2 In Vitro

To study the cartilage differentiation of mouse mesenchymal stem cells （MSCs） induced by cartilage-derived morphogenetic proteins-2 in vitro, the MSCs were isolated from mouse bone marrow and cultured in vitro. The cells in passage 3 were induced into chondrogenic differentiation with different concentrations of recombinant human cartilage-derived morphogenetic proteins-2 （0, 10, 20, 50 and 100 ng/mL）. After 14 days of induction, morphology of cells was observed under phase-contrast microscope. Collagen Ⅱ mRNA and protein were examined with RT-PCR, Western blotting and immunocytochemistry respectively and the sulfate glycosaminoglycan was measured by Alcian blue staining. RT-PCR showed that CDMP-2 could promote expression of collagen Ⅱ mRNA in an dose-dependant manner, especially at the concentration of 50 ng/mL and 100 ng/mL. Immunocytochemistry and Western blotting revealed a similar change. Alcian blue staining exhibited deposition of typical cartilage extracellular matrix. Our results suggest that mouse bone marrow mesencymal stem cells can differentiate into chondrogenic phonotype with the induction of CDMP-2 in vitro, which provides a basis for further research on the role of CDMP-2 in chondrogenesis.

Mechanical loading induced expression of bone morphogenetic protein-2, alkaline phosphatase activity, and collagen synthesis in osteoblastic MC3T3-E1 cells

Background Bone morphogenetic protein （BMP）-2, alkaline phosphatase （ALP）, and collagen type I are known to play a critical role in the process of bone remodeling. However, the relationship between mechanical strain and the expression of BMP-2, ALP, and COL-I in osteoblasts was still unknown. The purpose of this study was to investigate the effects of different magnitudes of mechanical strain on osteoblast morphology and on the expression of BMP-2, ALP, and COL-I. Methods Osteoblast-like cells were flexed at four deformation rates （0, 6%, 12%, and 18% elongation）. The expression of BMP-2 mRNA, ALP, and COL-I in osteoblast-like cells were determined by real-time quantitative reverse transcription polymerase chain reaction, respectively. The results were subjected to analysis of variance （ANOVA） using SPSS 13.0 statistical software. Results The cells changed to fusiform and grew in the direction of the applied strain after the mechanical strain was loaded. Expression level of the BMP-2, ALP, and COL-I increased magnitude-dependently with mechanical loading in the experimental groups, and the 12% elongation group had the highest expression （P 〈0.05）. Conclusion Mechanical strain can induce morphological change and a magnitude-dependent increase in the expression of BMP-2, ALP, and COL-I mRNA in osteoblast-like cells, which might influence bone remodeling in orthodontic treatment.

Effect of nano-hydroxyapatite/collagen composite and bone morphogenetic protein-2 on lumbar intertransverse fusion in rabbits

Objective: To investigate the effect of nano hydroxyapatite/collagen (nHA/collagen) composite as a graft extender and enhancer when combined with recombinant human bone morphogenetic protein 2 (rhBMP 2) on lumbar intertransverse fusion in rabbits. Methods: Sixty four adult female New Zealand white rabbits, aged 1 year and weighing 3.5 4.5 kg, underwent similar posterolateral intertransverse process arthrodesis and were randomly divided into 4 groups based on different grafts: autogenous cancellous bone alone (ACB group), nHA/collagen alone (HAC group), half autogenous cancellous bone and half nHA/collagen (ACB+HAC group) and nHA/collagen combined with rhBMP 2 (HAC+BMP group). The fusion masses were analyzed by manual palpation, radiography, biomechanical testing and histological examination. Results: Fusion was observed in 4 cases in the 6th week and in 5 cases in the 10th week after surgery in ACB group. No case showed fusion in HAC group. In ACB+HAC group, there was fusion in 3 cases in the 6th week and in 4 cases in the 10th week after surgery. In HAC+BMP group, fusion in 1 case was found in the 4th week, in 5 cases in the 6th week and in 6 cases in the 10th week after surgery. It suggested that ACB, ACB+HAC and HAC+BMP groups showed similar fusion ratio and mechanical strength in the 6th and 10th week after surgery. According to the microstructure analysis of the samples, nHA/collagen had no negative effect when implanted together with ilium autograft. In HAC+BMP group, new bone like tissue was observed in the 2nd week postoperatively, and nearly all of the implanted composites were replaced by mature bone matrix and new bones in 10th week postoperatively. Conclusions: The nHA/collagen, especially combined with rhBMP 2, is a promising bone substitute, for it has quick biodegradation, fine bone bending ability, and high osteoconductivity on posterolateral spinal fusion in rabbits.