Cell surface markers and exogenously induced PpIX in synovial mesenchymal stem cells

The aim of present study was to assess the expression of surface markers and the accumulation of protoporphyrin IX in synovial mesenchymal stem cells (SMSCs). SMSC from patients with rheumatoid arthritis (RA, n = 5) and osteoarthritis (OA, n = 5-6) were characterized and their PpIX accumulation rates were evaluated by flow cytometry. The expression of the 21 out of 24 tested surface markers, related to stem-like features and aggressiveness of cells showed no statistically significant differences between RA and OA groups. However, the cells from RA group had the significantly lower levels of expression for the integrin-associated protein CD47 and the grow factor receptor CD271 (P = 0.018), while the higher levels of cell membrane zinc-dependent metalloproteinase CD10 (P = 0.006), as compared to the cells from OA group. Comparison of the mean intensities of PpIX fluorescence revealed no statistically significant differences between the RA and OA groups, as well as no relation to proliferation rates or cell size, although some conspicuous distinction in PpIX accumulation was observed in certain specimens within these groups, suggesting possibilities of this method application for characterization of individual SMSC populations. CD10, CD47, and CD271 were differently expressed in RA and OA SMSC, while had no direct association with the PpIX fluorescence intensity.