Objective To review the research progress of the osteogenic effect of strontium (Sr) and its application in the orthopaedics. Methods The recent literature concerning the osteogenic effect of Sr and its application in orthopaedics at home and abroad was extensively reviewed, and the research and development were summarized. Results Both in vivo and in vitro studies showed that Sr could enhance bone formation and inhibit bone resorption. Clinically, Sr was applied for treatment of osteoporosis, composite biomaterials in tissue engineering, and treatment of bone tumors and bone metastases. Conclusion Sr is one important combined element of alternative materials in bone tissue engineering, and can strengthen the mechanical and biological properties of the bone replacement material, so it has some development potential in bone tissue engineering.
ObjectiveTo investigate the regulatory effect of simvastatin on osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) at middle/late stages by p38MAPK pathway under condition of osteoinductive environment. MethodsThe bone marrow of bilateral femur and tibia were harvested from 20 4-week-old female Sprague Dawley rats. BMSCs were isolated and cultured with whole bone marrow culture method; the second generation of cells were randomly divided into 5 groups: control group (complete medium, CM), simvastatin group (simvastatin medium, SIM), osteogenic induction group (osteogenic induction medium, OM), simvastatin and osteogenic induction group (simvastatin+osteogenic induction medium, OM+SIM), and blocker group (SB203580+simvastatin+osteogenic induction medium, OM+SIM+SB). MTT assay was used to detect the cell activity in CM group and SIM group at 2, 3, 4, 5, and 6 days, ELISA method to measure the content of alkaline phosphatase (ALP) in OM group and OM+SIM group at 7 and 14 days. The mRNA and protein expressions of osteocalcin (OCN) were detected by real-time quatitative PCR and Western blot after 1, 12, and 24 hours of osteogenic induction at 21 and 28 days. The protein expressions of phospho-p38 (p-p38) and p38 in OM group, OM+SIM group, and OM+SIM+SB group were detected by Western blot at the best induction time of simvastatin. ResultsMTT assay showed that no significant difference was found in absorbance (A) value between CM group and SIM group at each time point (P > 0.05), indicating no effect of 1×10-7 mol/L simvastatin on cell viability. ELISA results showed that ALP content significantly increased in OM+SIM group when compared with OM group at 7 and 14 days; the ALP content was significantly higher at 7 days than 14 days in OM group and OM+SIM group (P < 0.05). OCN mRNA and protein expressions at 12 hours were significantly higher than those at other time points in each group (P < 0.05), and the expressions of OM+SIM group was significantly higher than those of OM group (P < 0.05). The best induction time of simvastatin was 12 hours. At 12 hours after blocking intervention, the p-p38/p38 in OM+SIM+SB group was significantly lower than that in OM group and OM+SIM group (P < 0.05), and the p-p38/p38 in OM+SIM group was significantly higher than that in OM group (P < 0.05). ConclusionSimvastatin can increase the mRNA and protein expression levels of OCN and the protein of p-p38 in osteogenic differentiation of BMSCs at middle/ late stages, and its best induction time is 12 hours.
ObjectiveTo summarize the research progress of the effects and mechanisms of Hedgehog signaling pathway in regulating bone formation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). MethodsThe related literature concerning the regulations and mechanism of Hedgehog signaling pathway in osteogenic differentiation of BMSCs and bone formation in vivo, in vitro, and ex vivo studies in recent years was analyzed and summarized. ResultsThe in vitro studies indicate that Hedgehog signaling pathway can promote osteogenic differentiation of BMSCs via activation of key molecules Smoothened (Smo) and Gli1 which are downstream of Hedgehog signaling, and Hedgehog signaling can activate mTORC2-Akt signaling by upregulation of insulin-like growth factor which has similar effects. Hedgehog signaling regulates osteoblast differentiation via activation of Hh-Smo-Ptch1-Gli signaling pathway and inhibition of Hh-Gαi-RhoA stress fibre signaling. Hedgehog signaling can regulate key molecules of osteogenesis Runx2 for promoting osteogenic differentiation and matrix mineralization by synergism of bone morphogenetic protein and Wnt signaling, and promotes bone formation and repair and healing for bone defect and bone graft model in vivo. ConclusionHedgehog signaling can regulate bone formation and osteogenic differentiation of BMSCs via activation of Hedgehog signaling and other signaling pathways. Hedgehog signaling pathway may be a potential target for developing treatment for bone related diseases of osteoporosis and fracture healing disorders.
Objective To explore the osteogenic potential of cervical intervertebral disc fibroblasts in vitro, to investigate the regulatory factors of recombinant human bone morphogenetic protein 2(rhBMP-2) and tumor necrosis factor α(TNF-α) on osteogenic phenotype of fibroblasts and to discuss the condition that facilitates osteogenesis of fibroblasts. Methods Theannulus fibroblasts cell lines of experiment goats were established in vitro and the biologicspecificity was found. According to different medias, 4 groups were included in this experiment: control group, TNF-α group ( 50 U/ml TNF-α), rhBMP-2 group (0.1 μg/ml rhBMP-2) and TNF-α+rhBMP-2 group (50 U/ml TNF-α+0.1 μg/ml rhBMP-2). Thefibroblasts were incubated in the media for about 3 weeks,and then the markers for osteogenic features were investigated by biochemistry, histochemistry observations. Results rhBMP-2 and TNF-α had no effect on the proliferation of fibroblasts from the experiment goats. rhBMP-2 or TNF-α could stimulate fibroblasts to secrete alkaline phosphatase and collagen type Ⅰ. The combined use of rhBMP-2 and TNF-α or the single use of rhBMP-2 could make fibroblasts to secrete osteocalin and the morphological changes of the fibroblasts were very obvious. Histochemical study of the nodules with specific new bone labeler(Alizarin red S) revealed positive reaction, denoting that the nodules produced by the fibroblasts werebone tissues. There was statistically significant difference(Plt;0.05) inALP activity between 3 experimental groups and control group and in secretion of osteocalcin between rhBMP-2 group, TNF-α+rhBMP-2 group and control group. Conclusion The results point out clearly that rhBMP-2 can induce theosteogenic potential of annulus fibroblasts in vitro.
The osteogenc potential of bone marrow has been proved by experiment. To investigate more in details, bone marrow was obtained from the trochanteric region of femur of NewZealand rabbit in 4 to 8 weeks old. After being cultured in vitro for one week, the hematopoietic component of the bone marrow had disappeared, thus the stromal cells were obtained. Then the stromal cells were subcultured in cultural fluid containing dexamethasone (10-8 mol/L) and natrium glycerophosphate (10mmol/L). Under the phasecontrast microscope, it was found that being cultured for 15 days. The stromal cells were lined up in one layer and late the secretion activity was increased and gradually transformed into multilayer structure and was congregated into diffused opaque clusters in twenty days. During culture, the cells were examined by tetracycline fluorescence label, histochemistry stains, transmission electron microscopy, scanning electron microscopy and energy dispersive X-ray microanalysis. The results showed that the morphological and biological characteristics of the cultured stromal cells derived from the bone marrow were similiar to those of osteoblasts and could synthesized mineralized new bone tissue in vitro.
Objective To review the osteogenic mechanism and osteogenic effects of bone morphogenetic protein 6 (BMP-6) so as to provide the basis for further research of BMP-6. Methods The related articles about the osteogenic mechanism and the osteogenic effects of BMP-6 in experimental animals were extensively summarized. Results BMP-6 from bone matrix can transduct the osteogenic signal to bone marrow mesenchymal stem cells (BMSCs) by means of Smad protein signal transduction pathway. And the BMSCs which received the signals will differentiate into osteoblasts and chondroblasts. Therefore, BMP-6 plays an important role in the development and maturation of bone and cartilage. In addition, BMP-6 has a close relation with bone diseases, such as fracture, osteoporosis, and bone tumor. Conclusion The deep research of BMP-6 is expected to provide a new therapeutic approach for treating bone diseases of nonunion, osteoarthritis, and osteoporosis.
ObjectiveTo investigate the role of the forkhead/Fox transcription factor 2 (Foxc2) over-expression in regulating osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) by Wnt-β-catenin signaling pathways in vitro so as to provide the experimental basis for repairing osteonecrosis of the femoral head. MethodsThe recombinant lentivirus carrying green fluorescent protein (group A) or Foxc2 (group B) were used to transfect the fifth generation rabbit BMSCs, and untransfected BMSCs served as a control (group C). The cell viability was measured with water soluble tetrazolium-1 (WST-1) regent at 72 hours after transfection. After 2 weeks of transfection, the expression of β-catenin in BMSCs was detected by real time fluorescence quantitative PCR, Western blot, and immunofluorescence staining. Meanwhile, the β-catenin inhibitors XAV-939 (0, 0.1, and 1.0 μmol/L) was added in group B; at 2 weeks after osteogenic and adipogenic induction, the gene and protein expressions of collagen type I (COL I), osteocalcin (OCN), and peroxisome proliferator activated receptor gamma 2 (PPARγ-2) were detected by real time PCR and Western blot. ResultsWST-1 results showed that the cell viability of group B (130.85%±0.15%) was significantly higher than that of group A (100.45%±0.35%) (t=7.500, P=0.004) at 72 hours after transfection. At 2 weeks after transfection, the gene and protein expressions of β-catenin in group B were significantly higher than those in group A (P<0.01). After XAV-939 was added in group B, the mRNA and protein expressions of OCN and COL I gradually decreased; the mRNA and protein expressions of PPARγ-2 significantly increased (P<0.05), showing a dose-dependent manner. ConclusionThe over-expression of Foxc2 gene in BMSCs may promote osteogenic differentiation by Wnt-β-catenin signaling pathway.
Objective To study the method of inducing human marrow mesenchymal stem cells (MSCs) into osteoblasts directionally and to identify osteogenesis characteristics. Methods MSCs were isolated from adult marrow using density gradient separation method and were cultured in conditioned medium containing Dex 10 -8 mol/L，β-GP 10 mmol/L，and AA 50 μg/ml. The MSCs attachment formed soon and passage 3 cells were chosen to check osteogenesis characteristics, including alkaline phosphatase assay with modified calcium-cobalt staining method, type Ⅰ collagen assay with immunohistochemistry, osteopontin and osteonectin assay with in situ hybridization and calcium nodes assay with Von Kossa staining. Results Passage 3 MSCs had typical appearance of osteoblasts and could be passaged continuously till passage 10. The rate of ALP expression was 85%. The expressions of collagen type Ⅰ, osteopontin and osteonectin were positive and calcium nodeswere seen by Von Kossa staining. Conclusion We have successfully induced human MSCs into osteoblasts; the induced cells have typical osteogenesis characteristics.
ObjectiveTo explore the potential role of WNT6 in the proliferation, differentiation, and migration of bone marrow mesenchymal stem cells (BMSCs). MethodsMouse BMSCs were cultured to the cell fusion of 30%-50%, and divided into different groups. WNT6 knockdown included 3 experiment groups:cells transfected with WNT6 specific short hairpin RNA (shRNA) (group A1), cells transfected with control shRNA group (group B1), and nontransfected cells (group C1). WNT6 over-expression included 3 groups:cells transfected with WNT6 recombinant plasmid (group A2), cells transfected with blank vector (group B2), and non-transfected cells (group C2). After transfection, the stably transfected cells were cultured for 48 hours. Cell morphology was observed under inverted microscope; real-time fluorescent quantitative PCR was used to analyze WNT6 mRNA levels; Western blot was used to detect WNT6 and Ki67 protein expressions; cell proliferation was assayed by MTT method, and cell migration was detected by Transwell assay. After cells were cultured in osteogenic differentiation medium for 12 days, the alkaline phosphatase (ALP) activity and calcium deposits were detected by biochemical determination. ResultsThe inverted microscope observation showed that the cell morphology were similar among groups A1, B1, C1, and A2, B2, C2. The WNT6 mRNA and protein levels, Ki67 protein level, cell proliferation, cell migration, ALP activity, and calcium deposition in group A1 were all significantly lower than those in groups B1 and C1 (P<0.05), but there was no significant difference between groups B1 and C1 (P>0.05). On the contrary, the above indexes in group A2 were all significantly higher than those in groups B2 and C2 (P<0.05), but no significant difference was shown between groups B2 and C2 (P>0.05). ConclusionWNT6 can promote the proliferation and migration, as well as can enhance osteogenic differentiation ability in mouse BMSCs.
ObjectiveTo investigate the specific microRNA (miRNA) in osteogenic and chondrogenic differentiations of C3H10T1/2 cells. MethodsC3H10T1/2 cells were induced to differentiate into osteoblasts and chondrocytes.Specific miRNA more than 2 fold change and 2 average normalized probe signal between C3H10T1/2 and C3H10T1/2-derived osteoblast,and between C3H10T1/2 and C3H10T1/2-derived chondrocytes were screened out by miRNA microarray,and verified by real-time fluorescence quantitative PCR (RT-qPCR). ResultsAlkaline phosphatase expression of osteogenic induced group was significantly higher than that of control group at 7 days after induced (P<0.05).RT-qPCR results showed the expressions of Runx2,serine protease (Sp7),collagen type I,and osteopontin (OPN) genes were significantly increased at 7,14,and 21 days after induced when compared with before induced (P<0.05).Western blot results showed the expressions of Runx2,Sp7,collagen type I,and OPN proteins of osteogenic induced group were significantly higher than those of control group at 21 days after induced (P<0.05).The expressions of SOX9,collagen type Ⅱ,Aggrecan,and Has2 were significantly increased at 5,10,and 15 days after induced when compared with before induced (P<0.05).The expressions of SOX9,collagen type 2,Aggrecan,and Has2 proteins of chondrogenic induced group were significantly higher than those of control group at 15 days after induced (P<0.05).Totally,10 osteogenic and 3 chondrogenic miRNA more than 2 fold change and 2 average normalized probe signal were screened out by miRNA microarray.RT-qPCR results of these specific miRNAs were similar to microarray results except miR-455-3p. ConclusionSpecific miRNAs are screened out by microarray and it is a good foundation for the future study on miRNA functional verification and target gene prediction.