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AB0065 Early and late effects of human adipose tissue derived stem cells on osteoarthritic cartilage explants in vitro

Background Articular cartilage damage in osteoarthritis (OA) is characterized by degeneration of the extracellular matrix. Matrix metalloproteinases (MMPs) play a crucial role in the modulations of cell-matrix interactions and degradation of cartilage. MMPs are controlled through activation of proenzymes and the inhibition of active enzymes by tissue inhibitors of metalloproteinases (TIMPs). Adipose tissue derived stem cells (ADSCs) are close to mesenchymal stem cells from bone marrow in their anti-inflammatory and supportive for tissues repair effect, moreover, ADSCs are much easier available. Objectives To evaluate early and late effects of ADSCs for OA cartilage for the development of the cell therapy in OA, using their paracrine and chondroprotective effects. Objectives In vitro cocultures of ADSC with articular cartilage explants (CE) were performed for 3, 7 and 21 days. To further reproduce the OA conditions co-cultures were also stimulated with IL-1β. Secretion of TIMPs, MMPs, and other factors was determined in coculture supernatants by ELISA. Expression of genes in CE associated with chondrogenesis was analyzed by RT-qPCR. Methods we performed in vitro ADSC cocultures with articular cartilage explants (CE) for 3, 7 and 21 days. To further reproduce the OA conditions co-cultures were also stimulated with IL-1β. Secretion of TIMPs, MMPs, and other factors was analyzed in coculture supernatants by ELISA. Expression of genes associated with chondrogenesis was analyzed in CE by RT-qPCR. Results The both, ADSC and CE produced TIMP-1, TIMP-2 and TIMP-3 as well as gelatinases MMP-2 and MMP-9 at early stage (days 3 & 7) of cocultures and also later, on day 21. On the contrary to the other MMPs, suppressive role of MMP-2 in arthritis has been demonstrated. No or low production of VCAM-1, MMP-1, MMP-3, and MMP-13 was determined in supernatants of ADSC, whereas CE cocultures with the cells resulted in significant suppression of the both, mRNA and protein MMP-13 on days 3 & 7, but in particular on day 21. Cocultures with ADSC changed gene expression profile in CE, with the most pronounced up-regulation of COL1A1 gene on days 3&7, the effect being absent on day 21. Although increase in collagen type I production is generally considered as a sign of fibrosis, it has also been demonstrated during cartilage development and possibly may reflect early events of the repair. Stimulation with IL-1β differentially modulated gene expression and production of MMPs and TIMPs in cocultures. Histological examination has shown a tendency to extracellular matrix improvement in the osteoarthritic CE cocultured with ADSC, suggesting chondroprotective effects of those cells. Conclusions Secretory profile and results of histological analysis suggest possible beneficial effects of ADSC in prevention of cartilage from degeneration during OA. Production of MMP2 and MMP9 might be implicated in increased COL1A1 expression in CE. Down-regulation of MMP13 and COL10A1 genes in CE cocultured with ADSC implies antihypertrophic effects of ADSC. Disclosure of Interest None Declared