ObjectiveTo observe the genes expression of hypoxia inducible factor 1α (HIF-1α) and HIF-2α by inducing chondrogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) so as to provide a fundamental basis for HIF involving in the mechanism of chondrogenesis. MethodsHigh density pellet of hBMSCs was obtained by centrifugation and cultured with H-DMEM medium containing 2% fetal bovine serum (control group) and with chondrogenic medium (chondrogenic induction group) under hypoxia (2%O2) for 3 weeks. Immunohistochemistry staining was utilized to identify extracellular proteoglycan and collagen type Ⅱ at 3 weeks after culture. Western blot was applied for measuring HIF-1α and HIF-2α protein levels at 1 week after culture. Real-time quantitative PCR was performed to detect the genes expressions of HIF-1α, HIF-2α, Sox-9, collagen type Ⅱ, collagen type X, and Aggrecan at 1, 2, and 3 weeks after culture. ResultsToluidine blue staining showed sparse nucleus in the control group, and dense nucleus in the chondrogenic induction group;extracellular matrix staining was deeper in the chondrogenic induction group than the control group. Immunohistochemical staining for collagen type Ⅱ was positive in cytoplasm;when compared with the chondrogenic induction group, the control group showed sparse and light-coloured nucleus. At 1 week after culture, the protein expression levels of HIF-1α and HIF-2α in the chondrogenic induction group were significantly lower than those in the control group (t=8.345, P=0.001;t=7.683, P=0.002). When compared with control group, the HIF-1α mRNA expression was significantly down-regulated at 1 week and significantly up-regulated at 2 weeks in chondrogenic induction group (P<0.05), but no significant difference was found at 3 weeks between the 2 groups (P>0.05). And the mRNA expression of HIF-2α was significantly down-regulated and mRNA expression of Sox-9 was significantly up-regulated after chondrogenic differentiation when compared with the control group (P<0.01). The mRNA expressions of collagen type Ⅱ and collagen type X were significantly up-regulated at 2 and 3 weeks after chondrogenic differentiation when compared with the control group (P<0.05). And the mRNA expression of Aggrecan was significantly up-regulated at each time point after chondrogenic differentiation (P<0.05). ConclusionHIF-1α may involve the hBMSCs chondrogenic differentiation under hypoxia, while HIF-2α expression is depressed throughout the period and may have negative effect on differentiation.
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.
Objective To review the research progress of the current methods of inducing bone marrow mesenchymal stem cells (BMSCs) to chondrogenic differentiation in vitro so as to provide references for researches in cartilage tissue engineering. Methods Various methods of inducing BMSCs differentiation into the chondrogenic l ineage in vitro inrecent years were extensively reviewed and analyzed. Results Adding exogenous growth factors is still the mainly methodof inducing BMSCs differentiation into the chondrogenic l ineage; among the members, transforming growth factor β (TGF-β) family is recognized as the most important chondrogenic induction factor. Other important inducing factors include various chemical factors, physical factors, transgenic methods, and the microenvironmental induction. But the problems of low inducing efficiency and unstable inducing effects still exist. Conclusion The progress of chondrogenic induction of BMSCs promotes its util ization in cartilage tissue engineering. Further researches are needed for establ ishing more efficient, simpler, and safer inducing methods.
ObjectiveTo study the effect of transforming growth factor β3 (TGF-β3), bone morphogenetic protein 2 (BMP-2), and dexamethasone (DEX) on the chondrogenic differentiation of rabbit synovial mesenchymal stem cells (SMSCs). MethodsSMSCs were isolated from the knee joints of 5 rabbits (weighing, 1.8-2.5 kg), and were identified by morphogenetic observation, flow cytometry detection for cell surface antigen, and adipogenic and osteogenic differentiations. The SMSCs were cultured in the PELLET system for chondrogenic differentiation. The cell pellets were divided into 8 groups: TGF-β3 was added in group A, BMP-2 in group B, DEX in group C, TGF-β3+BMP-2 in group C, TGF-β3+DEX in group E, BMP-2+DEX in group F, and TGF-β3+BMP-2+DEX in group G; group H served as control group. The diameter, weight, collagen type II (immuohistochemistry staining), proteoglycan (toluidine blue staining), and expression of cartilage related genes [real time quantitative PCR (RT-qPCR) technique] were compared to evaluate the effect of cytokines on the chondrogenic differentiation of SMSCs. Meanwhile, the DNA content of cell pellets was tested to assess the relationship between the increase weight of cell pellets and the cell proliferation. ResultsSMSCs were isolated from the knee joints of rabbits successfully and the findings indicated that the rabbit synovium-derived cells had characteristics of mesenchymal stem cells. The diameter, weight, collagen type II, proteoglycan, and expression of cartilage related genes of pellets in groups A-F were significantly lower than those of group G (P<0.05). RT-qPCR detection results showed that the relative expressions of cartilage related genes (SOX-9, Aggrecan, collagen type II, collagen type X, and BMP receptor II) in group G were significantly higher than those in the other groups (P<0.01). Meanwhile, with the increase of the volume of pellet, the DNA content reduced about 70% at 7 days, about 80% at 14 days, and about 88% at 21 days. ConclusionThe combination of TGF-β3, BMP-2, and DEX can make the capacity of chondrogenesis of SMSCs maximized. The increase of the pellet volume is caused by the extracellular matrix rather than by cell proliferation.
ObjectiveTo study the immunogenicity of human bone marrow mesenchymal stem cells (BMSCs) and the suppression ability to the proliferation of peripheral blood mononuclear cell (PBMC) during osteogenic, chondrogenic, and adipogenic differentiations. MethodsBMSCs were isolated from bone marrow of healthy donors and were induced to osteogenic, chondrogenic, and adipogenic differentiations for 7, 14, and 21 days. The expressions of human leukocyte antigen (HLA) class I and class II were detected by flow cytometry. PBMC were isolated from peripheral blood of healthy donors and were co-cultured with BMSCs at a ratio of 10∶1 for 5 days. The suppression ability of undifferentiated and differentiated BMSCs to proliferation of PBMC were detected by flow cytometry. ResultsThe HLA class I expression was observed but almost no expression of HLA class II was seen in undifferentiated BMSCs. There was no obviously change of the HLA class I and class II expressions during osteogenic and chondrogenic differentiations (P>0.05), and a low expression of HLA class II was kept. The HLA class I expression gradually increased at 14 and 21 days after adipogenic differentiation, showing significant differences when compared with the value at 0 and 7 days (P<0.05);the HLA class II expression also gradually increased at 7, 14, and 21 days after adipogenic differentiation, showing significant differences when compared with the value at 0 day (P<0.05). There was no proliferation of PBMC without the stimulation of CD3 and CD28 microspheres and significant proliferation was observed when CD3 and CD28 microspheres were added, and undifferentiated BMSCs could significantly inhibit the proliferation of PBMC. There was no obvious change of the ability of BMSCs to inhibit the proliferation of PBMC during osteogenic and chondrogenic differentiations (P>0.05);and the ability of BMSCs to inhibit the proliferation of PBMC was gradually weakened at 7, 14, and 21 days after adipogenic differentiation, showing significant differences among different time points (P<0.05). ConclusionBMSCs maintain low immunogenicity and strong immune suppression ability during osteogenic and chondrogenic differentiations, which are suitable for allogenic tissue engineering repair and cell transplantation. However, increased immunogenicity and decreased immune suppression ability after adipogenic differentiation may not be suitable for allogenic tissue engineering repair and cell transplantation.
Objective To explore the impact of basic fibroblast growth factor (bFGF) and parathyroid hormone-related protein (PTHrP) on early and late chondrogenic differentiation of rabbit bone marrow mesenchymal stem cells (BMSCs) induced by transforming growth factor β1 (TGF-β1). Methods BMSCs were isolated from 3 healthy Japanese rabbits (2-month-old, weighing 1.6-2.1 kg, male or female), and were clutured to passage 3. The cells were put into pellet culture system and were divided into 5 groups according to different induce conditions: TGF-β1 group (group A), TGF-β1/bFGF group (group B), TGF-β1/21 days bFGF group (group C), TGF-β1/PTHrP group (group D), and TGF-β1/21 days PTHrP group (group E). At the beginning, TGF-β1 (10 ng/mL) was added to all groups, then bFGF and PTHrP (10 ng/mL) were added to groups B and D respectively; bFGF and PTHrP (10 ng/mL) were added to groups C and E at 21 days respectively. The gene expressions of collagen type I (Col I), Col II, Col X, matrix metalloproteinases (MMP)-13, and alkaline phosphatase (ALP) activity were detected once every week for 6 weeks. The 1, 9-dimethylmethylene blue (DMMB) staining was used to observe the extracellular matrix secretion at 6 weeks. Results The expression of Col I in groups C and E showed a significant downward trend after 3 weeks; the expression in group A was significantly higher than that in groups C and E at 4 and 5 weeks (P lt; 0.05), and than that in groups B and D at 3-6 weeks (P lt; 0.05); and significant differences were found between groups B and C at 3 and 4 weeks, and between groups D and E at 3 weeks (P lt; 0.05). After 3 weeks, the expressions of Col II and Col X in groups C and E gradually decreased, and were significantly lower than those in group A at 4-6 weeks (P lt; 0.05). Groups B and D showed no significant difference in the expressions of Col II and Col X at all time points, but there was significant difference when compared with group A (P lt; 0.05). MMP-13 had no obvious expression at all time points in group A; significant differences were found between group B and groups A, C at 3 weeks (P lt; 0.05); and the expression was significantly higher in group D than in groups A and E (P lt; 0.05). ALP activity gradually increased with time in group A; after 4 weeks, ALP activity in groups C and E obviously decreased, and was significantly lower than that in group A (P lt; 0.05); there were significant differences between groups B and C, and between groups D and E at 2 and 3 weeks (P lt; 0.05). DMMB staining showed more cartilage lacuna in group A than in the other groups at 6 weeks. Conclusion bFGF and PTHrP can inhibit early and late chondrogenic differentiation of BMSCs by changing synthesis and decomposition of the cartilage extracellular matrix. The inhibition is not only by suppressing Col X expression, but also possibly by suppressing other chondrogenic protein.
Objective To summarize the regulations of Hedgehog signal ing pathway on the prol iferation and multidifferentiation of mesenchymal stem cells (MSCs). Methods The related l iterature in recent years concerning the regulations of Hedgehog signal ing pathway on the biological characteristics of MSCs was reviewed and analyzed. Results Hedgehog signal ing pathway promoted the prol iferation of MSCs, and played a major role in the induction of osteogenic and chondrogenic differentiations, but it inhibited the adi pocytic differentiation. Conclusion The regulations of Hedgehog signal ing pathway in MSCs multidifferentiation and prol iferation could be used as the new therapeutic targets of tissue ischemia, osteoporosis, achondroplasia, obesity, and so on.
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.
ObjectiveTo investigate the microRNA (miRNA) expression profile during chondrogenic differentiation of human adipose-derived stem cells (hADSCs), and assess the roles of involved miRNAs during chondrogenesis. MethodshADSCs were harvested and cultured from donors who underwent elective liposuction or other abdominal surgery. When the cells were passaged to P3, chondrogenic induction medium was used for chondrogenic differentiation. The morphology of the cells was observed by inverted phase contrast microscopy. Alcian blue staining was carried out at 21 days after induction to access the chondrogenic status. The expressions of chondrogenic proteins were detected by ELISA at 0, 7, 14, and 21 days. The miRNA expression profiles at pre- and post-chondrogenic induction were obtained by microarray assay, and differentially expressed miRNAs were verified by real-time quantitative PCR (qRT-PCR). The targets of the miRNAs were predicted by online software programs. ResultshADSCs were cultured successfully and induced with chondrogenic medium. At 21 days after chondrogenic induction, the cells were stained positively for alcian blue staining. At 7, 14, and 21 days after chondrogenic induction, the levels of collogen type Ⅱ, Col2a1, aggrecan, Col10a1, and chondroitin sulfate in induced hADSCs were significantly higher than those in noninduced hADSCs (P<0.05). Eleven differentially expressed miRNAs were found, including seven up-regulated and four down-regulated. Predicted target genes of the differentially expressed miRNAs were based on the overlap from three public prediction algorithms, with the known functions of regulating chondrogenic differentiation of stem cells, selfrenewal, signal transduction, intracellular signaling cascade, and cell cycle control. ConclusionA group of miRNAs and their target genes are identified, which may play important roles in regulating chondrogenic differentiation of hADSCs. These results will facilitate the initial understanding of the molecular mechanism of chondrogenic differentiation in hADSCs and subsequently control hADSCs differentiation, and provide high performance seed cells for cartilage tissue engineering.