Figure 2.

Interaction with M1MФ Increased Immunosuppressive Properties of MSCs by Upregulating PGE2 Secretion and IDO Activation

(A) MSCs were cultivated alone or with M1MФ or M2MФ for 24 hr. After magnetic separation, immunosuppression capacity of MΦ-primed MSCs was assayed. Data are mean percentage immunosuppression ± SEM (n = 10 independent experiments). ^∗∗p < 0.01.

(B) Percentage of Th1 (IFN-γ⁺) and Th2 (IL-4⁺) T cells induced after co-culture with MSCs unprimed or primed for 24 hr with M1MФ or M2MФ. Data are mean percentage of positive cells ± SEM (n = 3 independent experiments).

(C) MSCs were co-cultured (CC) with MΦ or cultivated in a Transwell system (TW) for 24 hr. After magnetic separation, immunosuppression properties of MSCs were assayed as described. Data are mean percentage immunosuppression ± SEM (n = 3 independent experiments). ^∗p < 0.05; ns, not significant.

(D and E) MSCs were co-cultured (CC) or cultivated in a TW system with M1MФ or M2MФ for 24 hr. After sorting, MSCs or MΦ-primed MSCs were plated for 24 hr and supernatants were harvested. (D) L-Kynurenin and tryptophan concentration were assayed by ELISA and L-kynurenin/tryptophan ratio was determined to evaluate IDO enzymatic activity. (E) PGE2 secretion was measured to evaluate COX2 enzymatic activity. Data are mean ± SEM kynurenin/tryptophan ratio (n = 4 independent experiments) and PGE2 concentration (n = 5 independent experiments). ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001; ns, not significant.