Osteogenic differentiation of human synovium-derived mesenchymal stem cells from osteoarthritic knee joints

Rui Yun-feng; Lin Yu-cheng; Chen Hui; Wang Chen

doi:10.3969/j.issn.2095-4344.2013.45.004

Abstract：BACKGROUND:Mesenchymal stem cells are commonly used in tissue engineering, while whether <br> synovium-derived mesenchymal stem cells from human knee joints can make a role in repair and regeneration of bone tissue as the appropriate seed cells need to be further verified. <br> OBJECTIVE:To study the osteogenic differentiation potential of synovium-derived mesenchymal stem cells which were harvested from human knee joint with end-stage osteoarthritis in vitro. Meanwhile, to identify the osteogenic characteristics of these induced synovium-derived mesenchymal stem cells. <br> METHODS:cellpopulations were enzymatical y released from the synovial membrane obtained from total knee arthroplasty. Nucleated cells were plated at an appropriate density (200 cells/cm2) for expansion at the maximum rate without colony-to-colony contact. Monoclone was obtained by selecting as primary synovium-derived mesenchymal stem cells. After primary cultured in control medium and expanded to three passages, synovium-derived mesenchymal stem cells were subjected to in vitro assays to investigate their osteogenesis potential in osteogenic medium containing dexamethasone,β-glycerophosphate and ascorbic acid. <br> RESULTS AND CONCLUSION:Nucleated cells from the synovial membrane formed single cel-derived colonies, which were of polygon shape and star shape, uniform in size. After three passages, homogeneous populations of fibroblast-like cells were observed. Under appropriate culture conditions, synovium-derived mesenchymal stem cells were induced to differentiate to the osteocyte lineages which had typical“slabstone”appearance of osteoblasts. Osteogenesis was stained positively for alkaline phosphatase staining at day 7 and formed mineralized nodular structures at day 21, which was confirmed by Alizarin red staining. Alkaline phosphatase activity assay showed a rise after the osteogenesis induction and reached the peak at day 7. Expressions of osteocyte specific genes, such as col agen type Ⅰ, Runx2, bone-binding protein and osteopontin, were al detected. These genes were expressed positively in osteogenic medium, and the mRNA expressions of col agen type Ⅰ, Runx2, bone-binding protein and osteopontin were enhanced significantly after 21 days. Our study demonstrates that synovium-derived mesenchymal stem cells isolated from knee joint of end-stage osteoarthritis patients could be induced into osteoblasts in vitro, and these induced cells have typical osteogenesis characteristics. Synovium-derived mesenchymal stem cells may play a role in the regenerative response during the process of bone injury, which are promising candidates for bone tissue engineering.