ObjectiveTo investigate the effect of recombinant adenovirus-mediated bone morphogenetic protein 9 (BMP-9) and erythropoietin (EPO) genes co-transfection on osteogenic differentiation of adipose-derived stem cells (ADSCs) in vitro. MethodsThe inguinal adipose tissue was harvested from 4-month-old New Zealand rabbits, ADSCs were isolated with enzyme digestion and adherence method, and multipotent differentiation capacity was identified. The 3rd generation ADSCs were divided into 5 groups: normal cells (group A), empty plasmid control group (group B), BMP-9 or EPO recombinant adenovirus transfected cells (groups C and D), BMP-9 and EPO recombinant adenovirus co-transfected cells (group E). The inverted phase contrast microscope was used to observe the cell growth at 7 days; the expression of cell fluorescence was observed under a fluorescence microscope at 14 days, and viral transfection efficiency was calculated at 48 hours; Western blot was used to detect the expressions of BMP-9 and EPO proteins at 14 days. The expression of alkaline phosphatase (ALP) activity was detected at 3, 7, and 14 days after osteogenic induction, and alizarin red staining was used to detect calcium nodules formation and real-time fluorescence quantitative PCR to detect the expressions of osteopontin (OPN) and osteocalcin (OCN) at 3 weeks. ResultsAt 7 days after transfected, some cells showed oval, round, and irregular shape under the inverted phase contrast microscope in groups A and B; a few fusiform cells were observed in groups C and D; oval cells increased obviously, and there were only few round cells in group E. The fluorescence microscope observation showed that BMP-9 and EPO, BMP-9/EPO recombinant adenovirus could stably transfected ADSCs, with transfection efficiency of 80%-93%. The expressions of BMP-9 and EPO proteins significantly higher in group E than the other groups by Western blot (P < 0.05). The ALP activity significantly increased in group E when compared with that in the other groups at 3, 7, and 14 days after osteogenic induction (P < 0.05); the number of calcium nodules in group E was significantly more than that in the other groups (P < 0.05). Real-time fluorescence quantitative PCR showed that OPN and OCN genes expressions were significantly higher in group E than other groups (P < 0.05), and in groups C and D than groups A and B (P < 0.05). ConclusionRecombinant adenovirus-mediated BMP-9 and EPO genes can transfect ADSCs, which can stably express in ADSCs, BMP-9/EPO genes co-transfection can more promote the expressions of osteoblast-related genes and protein than non-transfected and single gene transfection.
Objective To investigate the effects of the recombinanthuman bone morphogenetic protein 2 (rhBMP-2) and/or the osteogenic agents on proliferation and expression of the osteoblast phenotype differentiation of the SD rat mesenchymal stem cells（MSCs）. Methods The rat MSCs were cultured in vitro and were randomly divided into the experimental groups(Groups A-I) and the control group. In the experimental group, MSCs were induced by rhBMP2 in different doses (10, 50, 100 and 200 μg/L) in Groups BE, the osteogenic agent alone (Group A) and by the combined use of rhBMP-2 ［in different doses (10,50, 100 and 200 μg/L)］ and the osteogenic agent in Groups F-I. The MTT colorimetric assay was used to evaluate the proliferation, and the activities of alkaline phosphatase (ALP) and osteocalcin (OC) were observed at 3, 6, 9, 12 days, respectively. Results The inverted phase contrast microscopy showed that MSCs by primary culture for 12 hours were adhibited, with a fusiform shape at 48 hours. At 4 days they were polygonal or atractoid, and were spread gyrately or radiately at 6 days. At 10 days, they were spread at the bottom of the bottle.The statistical analysis showed that the expression of the osteoblast phenotype differentiation of MSCs could be induced in the experimental groups. The proliferation of MSCs could be enhanced in a dosedependent manner in GroupsB-E. The expression of the osteoblast phenotype differentiation, which was tested by the activities of ALP and OC, was significantly higher in Groups F-I than in Groups A-E. Conclusion The combined use of rhBMP-2 and the osteogenic agents can enhance the MSC proliferation and induce an expressionand maintenance of the osteoblast phenotype differentiation of the rat MSCs.
The three-dimensional (3D) printed bone tissue repair guide scaffold is considered a promising method for treating bone defect repair. In this experiment, chitosan (CS), sodium alginate (SA), and mineralized collagen (MC) were combined and 3D printed to form scaffolds. The experimental results showed that the printability of the scaffold was improved with the increase of chitosan concentration. Infrared spectroscopy analysis confirmed that the scaffold formed a cross-linked network through electrostatic interaction between chitosan and sodium alginate under acidic conditions, and X-ray diffraction results showed the presence of characteristic peaks of hydroxyapatite, indicating the incorporation of mineralized collagen into the scaffold system. In the in vitro collagen release experiments, a weakly alkaline environment was found to accelerate the release rate of collagen, and the release amount increased significantly with a lower concentration of chitosan. Cell experiments showed that scaffolds loaded with mineralized collagen could significantly promote cell proliferation activity and alkaline phosphatase expression. The subcutaneous implantation experiment further verified the biocompatibility of the material, and the implantation of printed scaffolds did not cause significant inflammatory reactions. Histological analysis showed no abnormal pathological changes in the surrounding tissues. Therefore, incorporating mineralized collagen into sodium alginate/chitosan scaffolds is believed to be a new tissue engineering and regeneration strategy for achieving enhanced osteogenic differentiation through the slow release of collagen.
Objective As one of the adult stem cells, adi pose-derived stem cells (ADSCs) have become an important seed cell source for tissue engineering recently. But whether the thawed cryopreserved ADSCs could be used to tissue engineered bone remains unknown. To investigate the effect of cryopreservation on the growth and osteogenesis of ADSCs invitro. Methods The ADSCs were isolated from the adipose aspirates by collagenase digestion method. For the experimental group, the 2nd generation cells were stored with a simple method of cryopreservation by slow cool ing with dimethyl sulphoxide as a cryoprotectant and rapid thawing. After cryopreserved in l iquid nitrogen for 4 weeks, ADSCs were recovered and cultured in osteogenic media, with non-cryopreserved ADSCs as the control group. The osteogenic differentiation was evaluated by alkal ine phosphatase (ALP) staining and Al izarin red O staining at 2 and 3 weeks respectively. The cell growth and osteogenesis of ADSCs were further determined using DNA assay and the ALP activity and calcium content were measured. Results The survival percentage of the cryopreserved cells was 90.44% ± 2.62%. The cell numbers and ALP activity increased with osteogenic induction time, and reach plateaus at 7 days and 11 days, respectively. The ALP staining and Al izarin red O staining results were both positive at 2 weeks and 3 weeks after osteogenic induction, respectively. And no significant difference in the cells number, ALP activity, and calcium content were found between experimental group and control group (P gt; 0.05). Conclusion Cryopreservation does not affect the growth and osteogenesis of ADSCs, and the cryopreserved ADSCs can be used as cell source for tissue engineered bone.
To study the method of isolating and culturing synovium-derived MSCs (SMSCs), and to investigate its multiple differentiation potential in vitro. Methods Three 2-month-old Changfeng hybrid swines weighing 8-10 kg (male and female) were used. SMSCs were harvested from the synovium of swine knee joints and cultured in vitro. When the SMSCs at passage 3 reached confluence, basic culture medium was removed, and the multi ple differentiationpotential of SMSCs was demonstrated in specific induction media (experimental group). The cells at passage 3 cultured with basic culture medium served as control group. After 21 days of chondrogenic differentiation, the cells underwent toluidine blue staining, immunohistochemistry staining and real-time fluorescence quantitative PCR detection. After 10 and 21 days of osteogenic differentiation, the cells underwent ALP staining and Al izarin red staining, respectively. After 21 days of adipogenic differentiation, the cells underwent Oil red O staining. Results SMSCs displayed long and thin or polygonal morphology 24 hours after culture. They prol iferated fast 48 hours after culture and presented large number of spindle-shaped cells with few globular cells 72 hours after culture. For the experimental group 21 days after chondrogenic induction, the cells were positive for toluidine blue staining with the formation of Aggrecan outside the cells; the immunohistochemistry staining revealed the expression of Col II; the real-time fluorescence quantitative PCR detection showed that the expressions of Col II A1, Aggrecan and SOX9 mRNA of the experimental group were greater than that of control group (P lt; 0.05). The cells were positive for ALP staining 10 days after osteogenic induction, and positive for Al izarin red staining 21 days after osteogenic induction, with the formation of calcium nodules. Oil red O staining displayed the formation of l i pid droplets inside the cells 21 days after adi pogenic induction. For the control group, the results of all the staining assays were negative except the ALP staining presenting with sl ight positive result. Conclusion SMSCs can be isolated from knee joint of swine and proliferate and differentiate into osteogenic, adi pogenic and chondrogenic cells in vitro. SMSCs may be a promising source of seed cells for tissue engineering.
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.
ObjectiveTo study the immunological properties of osteogenically differentiated umbilical cord blood derived mesenchymal stem cells (UCB-MSCs). MethodsUCB-MSCs were isolated from the umbilical cord vein, and were expanded; the cells at passage 3 were osteogenically induced for 2 weeks in vitro. The expressions of human leukocyte antigen I (HLA-I) and HLA-Ⅱ molecules were observed by flow cytometry analysis before and after osteogenic induction. Peripheral blood T lymphocytes were isolated and cultured with osteoblastic induced or non-osteoblastic induced UCB-MSCs in different cell concentrations of 1×102, 1×103, 1×104, and 1×105 cells/well. The intake value of 3H-thymidine was calculated with luminescence counter. Then T lymphocytes were pretreated with PHA, and co-cultured with osteoblastic induced and non-osteoblastic induced UCB-MSCs as described above. IL-2 was further added to test the reversed effect of T lymphocytes proliferation stimulated by UCB-MSCs. Finally, to investigate whether the immunomodulatory effects on T lymphocytes proliferation depend on direct or indirect cell contact, the Transwell chamber culture system of UCB-MSCs and T lymphocytes was established. ResultsFlow cytometry analysis showed that non-osteoblastic induced UCB-MSCs expressed HLA-I but did not express HLA-Ⅱ; the expression of HLA-Ⅱ increased in osteoblastic induced UCB-MSCs. No T lymphocyte response was stimulated by non-osteoblastic induced UCB-MSCs, but osteoblastic induced UCB-MSCs could stimulate the proliferation of allogeneic T lymphocytes, especially after IFN-γ treatment. Non-osteoblastic induced UCB-MSCs of 1×104 and 1×105 cells/well could suppress the proliferation of T lymphocytes evoked by PHA, and this suppression could be reversed by the addition of IL-2. While osteoblastic induced UCB-MSCs did not have such suppressive effect. The results of the Transwell culture system also showed that non-osteoblastic induced UCB-MSCs could obviously inhibit the proliferation of T lymphocytes, but the osteoblastic induced UCB-MSCs could not. ConclusionThe immunological properties of UCB-MSCs will change accordingly after osteogenic induction, so UCB-MSCs might not be suitable for the seed cells of bone tissue engineering.
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 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 investigate the effect of cyclic stretch stress on the osteogenic differentiation of human cartilage endplate-derived stem cells (CESCs). MethodsCESCs were isolated from the endplate cartilage tissues by the method of agarose suspension culture system. The endplate cartilage tissue was harvested for immunohistochemical staining. Flexercell-4000TM Tension Plus system was used to apply cyclic stretch on CESCs at a frequency of 1 Hz and at a stretch rate of 10% for 1, 6, 12, or 24 hours (experimental group). No stretch stress was performed on CESCs in the same culture condition (control group). After mechanical loading, the protein expression of bone morphogenetic protein 2 (BMP-2) was measured by Western blot, and gene expressions of runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), and SOX9 were detected by real-time fluorescent quantitative PCR. ResultsImmunohistochemical staining showed BMP-2 protein expression in chondrocytes. The continuous cyclic stretch stress of 10% can increase the expression of BMP-2 protein in CESCs. Significant differences were observed in the expressions of BMP-2 protein (P<0.05) between 2 groups at the other time points except at 1 hour (P>0.05), in a time-dependent manner. The real-time fluorescent quantitative PCR indicated that the gene expressions of Runx2 and ALP showed an increasing tendency with time in the experimental group when compared with the control group, but there was down-regulated expression of SOX9. Significant difference was found in mRNA expressions of Runx2 and ALP at 12 and 24 hours and in mRNA expressions of SOX9 at 6, 12, and 24 hours between 2 groups (P<0.05), in a time-dependent manner. ConclusionCyclic stretch stress may induce osteogenic differentiation of CESCs by regulating the expressions of some genes related osteogenesis in CESCs.