PURPOSE. Fetal cartilage-derived stem cells (FCSCs) have been shown to contribute to OA therapy as novel cells with anti-inflammatory properties. However, efforts to enhance the anti-inflammatory ability of FCSCs have not yet been conducted. In this study, the anti-inflammatory properties of FCSCs were increased by priming and evaluated in inflammatory synoviocytes.
METHODS. FCSCs were isolated from the fetal cartilage tissue. Priming was carried out by stimulating FCSCs using a priming factor such as Poly(I:C), IFN-γ, TNF-α and IL-1β and cell culture supernatants were obtained as conditioned media (CM). The anti-inflammatory effects of FCSCs were evaluated by treating CM in inflammatory synoviocytes. The evaluation was carried out by confirming the expression of the pro-inflammatory gene TNF-α, IL-1β and IL-6 through qRT-PCR. In addition, the concentration of PGE2 secreted by inflammatory synoviocytes was measured through ELISA. To identify the factors that affect the anti-inflammatory effects of FCSCs, the growth factors (IGF-1, TGF-β and FGF-2) were measured with qRT-PCR and the expression of IDO-1 was confirmed with western blotting. We also identified various secreted factors in the CM of FCSCs through Protein Array. Finally, we analyzed the characteristics of FCSCs using a Microscope, FACS and Histologic analysis to confirm that the stem cell characters are maintained.
RESULTS. When TNF-α (10 ng/mL) and IL-1β (15 ng/mL) were treated with FCSCs for 24 h, the anti-inflammatory properties of FCSCs were most significantly increased. In inflammatory synoviocytes treated with CM of primed-FCSCs, the expression of the pro-inflammatory gene TNF-α, IL-1β and IL-6 decreased. In addition, the concentration of PGE2 was significantly reduced in CM of primed-FCSCs. The anti-inflammatory effects of FCSCs were maximized when the concentration of CM was doubled. The expression of IGF-1, TGF-β, FGF-2 and IDO-1 significantly increased after priming, and the Protein Array confirmed an increase in the secretion of more than 20 proteins at the primed-FCSCs. The cell morphology and size did not differ in normal- and primed-FCSCs, and stem cell marker was maintained. Histologic analysis confirmed that the multilineage differentiation potential of FCSCs was maintained.
CONCLUSIONS. In conclusion, this study demonstrated that CM of Primed-FCSCs showed higher ability to inhibit inflammatory events in synoviocytes than those of CM of unprimed-FCSCs. Moreover, probably upregulated anti-inflammatory factors mediated anti-inflammatory effects of FCSCs.