GMSC‐Exo therapy influences the polarization of Th cells in vivo. (A, C, E) Representative flow cytometry images show the expression of CD4+INF‐γ+ Th1, CD4+IL‐17A+ Th17 cells and CD4+CD25+FoxP3+ Treg in the spleens and LNs of three groups of CIA mice. (B, D, F) GMSC‐Exo and GMSC significantly decreased the percentage of CD4+INF‐γ+ Th1 and CD4+IL‐17A+ Th17 cells in the mouse spleen and LN, and increased the percentage of CD4+CD25+FoxP3+ Treg, whereas PBS did not significantly alter the frequencies of the subset Th cells in the CIA mice. n = 6 in each group. The animal experiments were performed in three independent experiments. *p < 0.05, **p < 0.01. Values are given as mean ± SD. CIA, collagen‐induced arthritis; GMSC, gingival mesenchymal stem cells; GMSC‐Exo, gingival mesenchymal stem cell‐derived exosomes; LNs, lymph nodes; NS, not significant; PBS, phosphate‐buffered saline