RETINOIC ACID DOWN-REGULATES BONE MORPHOGENETIC PROTEIN 7 EXPRESSION IN RAT WITH CLEFT PALATE

Objective To evaluate the effects of retinoic acid （RA） on expression of bone morphogenetic protein 7 （ BMP-7 ） in rat fetus with cleft palate, and the effects of RA on proliferation and apoptosis of osteoblasts. Methods All-trans RA （ATRA） was used to induce congenital cleft palate in Wistar rat. BMP-7 mRNA expression in maxillary bone tissue of fetal rats was measured by Northern blotting analysis. Flow cytometry and MTF assay were used to measure the apoptosis and proliferation of ATRA-treated MC-3T3-E1 cells. BMP-7 mRNA and protein expressions in ATRA-treated MC-3T3-E1 cells were detected by RT-PCR and Western blotting analysis. Remilts ATRA could induce cleft palate of rat fetus. The incidence rate of cleft palate induced by 100 mg/kg AT-RA （45.5%） was significantly higher than 50 mg/kg ATRA （ 12.5%, P 〈 0. 05 ）. BMP-7 mRNA expression decreased in maxillary bone tissue of rat fetus with cleft palate. MC-3T3-E1 cells proliferation treated with 1 × 10^-6 mol/L ATRA decreased by 60%, the cell apoptosis increased by 2 times. BMP-7 mRNA and protein levels in MC-3T3-E1 cells treated with 1 × 10^-6 mol/L ATRA decreased by 60% and 80%, respectively, compared with ATRA-untreated cells （ P 〈 0.05 ）. Conclusions BMP-7 may play an important role in embryonic palate development. RA may possess the ability to down-regulate cell proliferation through regulation of BMP-7 gene expression.

Bone morphogenetic protein 7 mediates stem cells migration and angiogenesis:therapeutic potential for endogenous pulp regeneration

Pulp loss is accompanied by the functional impairment of defense,sensory,and nutrition supply.The approach based on endogenous stem cells is a potential strategy for pulp regeneration.However,endogenous stem cell sources,exogenous regenerative signals,and neovascularization are major difficulties for pulp regeneration based on endogenous stem cells.Therefore,the purpose of our research is to seek an effective cytokines delivery strategy and bioactive materials to reestablish an ideal regenerative microenvironment for pulp regeneration.In in vitro study,we investigated the effects of Wnt3a,transforming growth factor-beta 1,and bone morphogenetic protein 7(BMP7)on human dental pulp stem cells(h-DPSCs)and human umbilical vein endothelial cells.2D and 3D culture systems based on collagen gel,matrigel,and gelatin methacryloyl were fabricated to evaluate the morphology and viability of h-DPSCs.In in vivo study,an ectopic nude mouse model and an in situ beagle dog model were established to investigate the possibility of pulp regeneration by implanting collagen gel loading BMP7.We concluded that BMP7promoted the migration and odontogenic differentiation of h-DPSCs and vessel formation.Collagen gel maintained the cell adhesion,cell spreading,and cell viability of h-DPSCs in 2D or 3D culture.The transplantation of collagen gel loading BMP7 induced vascularized pulp-like tissue regeneration in vivo.The injectable approach based on collagen gel loading BMP7 might exert promising therapeutic application in endogenous pulp regeneration.

Potential bone-inducing activity in vitro of recombinant human bone morphogenetic protein-7 from a CHO expression system

Objective: To express the recombinant human bone morphogenetic protein-7(rhBMP-7) in Chinese hamster ovary(CHO) cells, and to establish the in vitro biological activity assay of rhBMP-7.Methods: Human BMP-7 cDNA was subcloned into p114 mammalian expression vector and transfected to CHO cells by using the Lipofectamine 2000 transfection method. CHO cell supernatants were harvested and analyzed to identify the molecule mass of secreted rhBMP-7 and examine its biological activity in vitro to stimulate the synthesis of alkaline phophatase(ALP), a characteristic of osteoblast phenotypes. Results: rhBMP-7 was produced stably in CHO cells, as a processed mature disulfide-linked homodimer, with an apparent molecular mass of 36 000. Examination of the rhBMP-7 biological activity showed that rhBMP-7 specifically stimulated the production of ALP(4-fold increase at 100 ng of rhBMP-7/ml). Conclusion: The rhBMP-7 from CHO expression system has significant biological activity in induction of osteoblast phenotype, which demonstrates rhBMP-7 has the potential bone regeneration activity.

Construction of Adeno-associated Virus System for Human Bone Morphogenetic Protein 7 Gene

To construct the recombinant adeno-associated virus （rAAV） vector with human bone morphogenetic protein 7 （BMP7） and observe the BMP7 mRNA expression in vitro, BMP7 CDS sequence was cloned into expression plasmid pAAV-MCS of AAV Helper Free System. The recombinant plasmid was identified with enzyme digestion and sequencing. The recombinant plasmid, pAAV-RC, pHelper were co-transfected into AAV-293 cells according to the calcium phosphate-based protocol. The viral stock was collected by 4 rounds of freeze/thaw. After purified and concentrated, the recombinant virus titer was determined by dot-blot assay. HEK293 cells were transfected with the recombinant virus at different MOI, and the expression of BMP7 mRNA was detected by RT-PCR. The results showed rAAV-BMP7 was constructed and packaged successfully. The physical particle titer was 2.5×10^11 vector genomes/mL. There was different expression level of BMP7 mRNA after transfecton. These data suggested that recombinant AAV mediated a stable expression of hBMP7 mRNA in 293 cells. The AAV production method may pave the way of an effective strategy for the jaw bone defection around dental implants.

Expression of bone morphogenetic protein 7 in the cerebral cortex of rats after ischemic-hypoxic injury

BACKGROUND： Some researches demonstrate that exogenous bone morphogenetic protein 7 （BMP-7） can protect ischemic cerebral nerve tissue and promote recovery of motor energy function; however, there is lack of direct evidences of endogenous BMP-7 effect. OBJECTIVE： To observe the expression of endogenous BMP-7 in nerve tissue with ischemic-hypoxic injury and investigate the possible effects on damaged nerve tissue. DESIGN： Observational contrast animal study. SETTING： Department of Anatomy and Histoembryology, Peking University Health Science Center. MATERIALS： The experiment was carried out in the Nerve Researching Laboratory of Anatomy Department, Peking University Health Science Center from October 2006 to March 2007. A total of 25 adult male SD rats weighing 250 - 300 g and several newborn SD rats were selected from Experimental Animal Center, Peking University Health Science Center. Rabbit-anti-BMP-7 polyclonal antibody was provided by Wuhan Boster Company. METHODS： ① Adult rats were randomly divided into ischemia group （n =10）, sham operation group （n = 10） and normal group （n =5）. Right external-internal carotid artery occlusion was used to infarct middle cerebral artery of adult rats in the ischemia group so as to copy focal cerebral infarction models. Line cork was inserted in crotch of internal and external carotid artery of adult rats in the sham operation group, while adult rats in the normal group were not given any treatments. ② Cerebral cortex of newborn rats was separated to obtain cell suspension. Cells which were cultured for 10 days were divided into control group and hypoxia/reoxygenation group. And then, cells in the hypoxia/reoxygenation group were cultured in hypoxic incubator for 4 hours and given reoxygenation for 24 hours. MAIN OUTCOME MEASURES： Immunohistochemical method was used to measure expression of BMP-7 in cerebral cortex at 24 hours after ischemia/reperfusion culture and in primary hypoxic culture. RESULTS： ① At 24 hours after cerebral ischemia, expression of BMP-7 in cerebral cortex on ischemic side was stronger than that on non-ischemic side in adult rats; meanwhile, numbers of cell expression were increased. However, expression of BMP-7 was not detected in bilateral cerebral cortex of adult rats in both control group and sham operation group. ② After hypoxia of cerebral cortex in primary culture, positive products of BMP-7 were observed in plasma of neuron, but expression of BMP-7 was not found in normal cerebral cortex. CONCLUSION： Endogenous BMP-7 has protective effects on nerve tissue induced by ischemic-hypoxic injury.

Bone morphogenetic protein-7 induced bone marrow stromal cells differentiate into neuron-like cells

Bone morphogenetic protein-7 is widely accepted as an inducer for bone marrow stem cells differentiating into osteoblasts and chondrocytes. Whether bone marrow stromal cells differentiate into neuron-like cells remains unclear. The current study examined the presence of positive cells for intermediate filament protein and microtubule associated protein-2 in the cytoplasm of bone marrow stromal cells induced by bone morphogenetic protein-7 under an inverted microscope, while no expression of glial fibrillary acidic protein was found. Reverse transcription PCR electrophoresis also revealed a positive target band for intermediate filament protein and microtubule-associated protein 2 mRNA. These results confirmed that bone morphogenetic protein-7 induces rat bone marrow stromal cells differentiating into neuron-like cells.

Molecular Cloning and Sequence Analysis of FullLength cDNA Encoding Human Bone Morphogenetic Protein—7

Objective:To clone the full-length human bane morphogenetic protein-7 (BMP-7 ) gene and analyse its sequence, to aid in investigation of its function and structure. Methods : Total RNA was isolated from Chinese fetal kidney by the acid gmnidinium thiocyanate phenol-chloroform method. Two overlapping segments of human BMP- 1 cDNA were obtained by reverse transcription (RT)-PCR. Following application, the two segments were ligated to each other and subcloned into POEM-T easy vector to form PEGM-T easy/hBMP-7 recombinant plasmid. Sanger dideoxy chain-termination method was used to sequence the cDNA. Results. There was 750 bp fragment obtained RT-PCR using #2 primer from 5' end of BMP-7 gene (PCR by using # 2 and # 1) ,and 540 bp fragment from 3' end was generated by KT-PCR using # 4 primer (PCR using # 3 and # 4). Full-length cDNA encoding BMP-7 was obtained by religation of two segments. When compared with hBMP-7 sequence in Gene bank (XM30619) ,our full-length BMP-7 cDNA has a G instead of a T at nucleotide 862. This change results in valine substituting for phenylalanine in the protein. Conclusion. This is the first time that BMP-7 cDNA was successfully cloned from Chinese fetal kidney. BMP-7 cDNA plays an important role in healing injuries of the osteo-articular system. This makes BMP-7 is an attractive target far various clinical applications.

The Use of Bone Morphogenetic Protein-7 and Resveratrol in Collagen Type II of Articular Cartilage

This study aimed to investigate the effects of resveratrol and bone morphogenetic protein 7 on type II collagen from superficial and middle zone of porcine articular chondrocytes. Articular cartilage was isolated from dissected porcine knee joint n = 12. Isolated cells were plated as monolayers at a density of 1 × 105 cells/well in 12-well culture plates and incubated at 37℃ in a humid atmosphere of 5% carbon dioxide and 95% air. Cell cultures were treated for four days with various concentrations of bone morphogenetic protein-7 and resveratroL Cells were then collected and analysed for collagen type II expression by real time polymerase chain reaction and protein level quantification by enzyme-linked immunosorbent assay. Cartilage tissue sections were localised for collagen type II by immunohistochemistry. Moreover, resveratrol and bone morphogenetic protein-7 effects on cartilage matrix contents were analysed by histology. Resveratrol and bone morphogenetic protein-7 stimulates expression of collagen type II mRNA and protein level accumulation in the surface zone and middle zone at 50μM ＋ 300 ng/ml （RSV ＋ BMP-7）. Immunohistochemistry results confirmed the presence of collagen type II on articular cartilage. Histological tissue sections confirmed that chondrocytes were obtained from different zones of articular cartilage. The study suggests that a combination of bone morphogenetic protein-7 and resveratrol up-regulate the expression and synthesis of collagen type II.

Transplantation of BMP-7 gene-transfected bone marrow mesenchymal stem cells for the treatment of spinal cord injury in rats

Background:Spinal cord injury(SCI)is a serious traumatic disease of the central nervous system,and there is currently no effective treatment for SCI because of its complicated pathophysiology.Bone marrow mesenchymal stem cells(BMSCs)have multidirectional differentiation abilities.Our study aims to explore the effects of bone morphogenetic protein 7(BMP-7)-modified BMSCs transplantation on the repair of SCI in rats.Methods:In this study,a rat spinal cord injury model was established with the modified Allen method.Then,BMSCs transfected with the BMP7 gene were transplanted to treat the spinal cord injury in rats.Forty Sprague-Dawley rats were randomly divided into the sham operation group(sham group),spinal cord injury group(model group),BMSC treatment group(BMSC group)and LV-BMP7-BMSC treatment group(LV-BMP7-BMSC group).The Basso,Beattie,and Bresnahan(BBB)score was used to evaluate the recovery of hindlimb function in the rats.The levels of neurofilament protein NF-200(NF-200)and glial fibrillary acidic protein(GFAP)were detected by immunofluorescence,RT-PCR and Western blotting.Results:At 14 d,21 d,and 28 d after treatment,the BBB score of the rats in the LV-BMP7-BMSC group was higher than that of the rats in the model group and BMSC group.The results showed that NF-200 was expressed at the local spinal cord injury site.Compared with that of the sham group,the NF-200 expression level of the BMSC group and LV-BMP7-BMSC group was increased(P<0.05).The results showed that the mRNA expression levels of NF-200 in the spinal cord tissue of the BMSC group and LV-BMP7-BMSC group were increased compared with those of the sham group(P<0.05).The western blotting results further confirmed the PCR results.Conclusion:BMP-7 gene-modified BMSC transplantation can promote the repair of spinal cord functions after SCI in rats.

EXPRESSION OF rhBMP-7 GENE IN TRANSDUCED BONE MARROW DERIVED STROMAL CELLS

OBJECTIVE: To explore the possibility of expression of exogenous gene in transduced bone marrow derived stromal cells (BMSCs). METHODS: The marker gene, pbLacZ, was transferred into cultured BMSCs and the expression of transduced gene by X-gal staining was examined. Then plasmid pcDNA3-rhBMP7 was delivered to cultured BMSCs. Through immunohistochemical staining and RT-PCR assay, the expression of rhBMP7 gene was detected. RESULTS: The exogenous gene could be expressed efficiently in transduced BMSCs. CONCLUSION: The present study provided a theoretical basis to gene therapy on the problems of bone and cartilage tissue.

Effects of Houttuynia Cordata Thumb on Expression of BMP-7 and TGF-β_1 in the Renal Tissues of Diabetic Rats

Objective： To explore the effects of Houttuynia Cordata Thumb （HCT 鱼腥草 Yu Xing Cao） on expression of transforming growth factor-β1 （TGF-β1） and bone morphogenetic protein-7 （BMP-7） in the renal tissues of diabetic rats. Methods： The diabetic rats induced by intravenous injection of streptozotocin（STZ） were randomly divided into a model group, a HCT group and a lotensin group, with normal rats designated as the controls. 8 weeks later, the ratio of kidney weight to body weight, the glomerular area, the excretion of β 2-microglobin （β2-MG） in 24-hr urine, the albumin excretion in 24-hr urine, and creatinine clearance rate （CCR） were investigated. The expression of TGF- β 1, BMP-7 and collagen I in the renal tissues was observed with the immunohistochemical method and by the semi-quantitative assay. Results： The overgrowth of glomerulus, the excretion of β 2-MG in 24-hr urine, the albumin excretion rate in 24-hr urine and CCR in the HCT group significantly reduced （P〈0.05）, and the expression of TGF-β1 and collagen I significantly decreased （P〈0.05）, but BMP-7 significantly increased （P〈0.05） in the HCT group as compared with those in the model group, with no significant difference as compared with the lotensin group （P〉0.05）. Conclusion： HCT has a protective effect on the renal tissues in diabetic rats, which is probably correlated with the decrease of the expression of TGF-β1 and collagen I and with the increase of the expression of BMP-7 in the renal tissues.

Transfection of Articular Chondrocytes with rhBMP7 Gene and Its Expression

In order to investigate the possibility of expression of exogenous gene in transduced articular chondrocytes, plasmid pcDNA3 rhBMP7 was delivered to cultured chondrocytes. Through immunohistochemical staining and RT PCR assay, the expression of rhBMP7 gene was detected. And the bioactivity of transgene expression product was detected through MTT assay as well. It was confirmed that exogenous gene could be expressed efficiently in transduced chondrocytes and the transgene expression product had obvious bioactivity. The present study provided a theoretical basis for gene therapy on the problems of articular cartilge.

Expression of BMP-7 and its receptors in renal tubolo-interstitial fibrosis induced with unilateral ureteral obstruction in rats

Objective:To study the changes of the expression of bone morphogenetic protein-7(BMP-7) and its receptors(BMPR-Ⅱ,ALK2,ALK3 and ALK6) in the renal tubulointerstitial fibrosis induced with unilateral ureteral obstruction in rats. Methods: Sixty Wistar male rats were divided randomly into the normal control,sham-operation and unilateral ureteral obstruction(UUO) groups and the rats were killed on the 1st,3rd,7th and 14th postoperative days respectively.The mRNA level of BMP-7,BMPR-Ⅱ,ALK2,ALK3 and ALK6 was determined with RT-PCR.The site and level of protein expression of BMP-7 were observed with immunohistochemical staining. Results: The mRNA level of BMP-7,BMPR-Ⅱ,ALK2 and ALK3 was significantly decreased in the rats of UUO group than in those of the sham-operation group but the mRNA level of ALK6 showed no obvious changes in all the rats.Immunohistochemical staining revealed that the protein of BMP-7 was mainly expressed in the renal tubules and interstitial tissue of the kidneys in normal rats but it was decreased gradually along with the unilateral ureteral obstruction. Conclusion: It is found that the loss of BMP-7 and its receptors including BMPR-Ⅱ,ALK2 and ALK3 occurs in the early phase of renal tubulointerstitial fibrosis before the appearance of other pathological changes in the kidney and may play an important role in the occurrence and progress of renal tubulointerstitial fibrosis.

Role of BMP-7 and TGF-β_1 expression in renal tubulo-interstitial lesion of Wistar rats induced by unilateral ureteral obstruction

Objective: To explore the role of bone morphorgenetic protein-7 （BMP-7） in the renal tubulo-interstitial lesions induced by unilateral ureteral obstruction （UUO）. Methods: Sixty Wistar rats were equally and randomly divided into normal control, sham operation and UUO groups, and respectively sacrificed on the 1st, 3rd, 7th, 14th day after the time of UUO operation. The mRNA levels of BMP-7 and TGF-β1 in the renal tissues were examined by RT-PCR. The expression sites and levels of BMP-7 and TGF-β1 proteins were detected by immunohistochemistry staining. Results:Compared to control groups, the level of BMP-7 mRNA was significantly decreased, but that of TGF-β1 mRNA was significantly increased in UUO rats. Immunohistochemistry staining indicated that BMP-7 mainly expressed in the renal tubules and interstitum, rarely in the glomeruli. In UUO rats, the expression of BMP-7 protein was decreased, but that of TGF-β1 was increased in an obstruction dependent manner. Conclusion:The down- regulation of BMP-7 is observed in the early phase of fibrotic process of the renal interstitium, suggesting it may be involved in the formation and development of the tubulo-interstitial lesions.