MSCs promote intrathymic T-lymphocyte development. The number and proportion of CD4⁺CD8⁺ DP thymocytes and thymic Tregs, the ratio of CD3⁺CD4⁺:CD3⁺CD8⁺ T cells, Treg proportion, yield of CD4⁺ T cells and Tregs in the blood were assessed on day 20 and day 40 after HCT with flow cytometry. The results are shown as mean ± SE (n = 4-6). (A) Representative flow patterns of CD4⁺CD8⁺ DP thymocytes. (B) Percentage and yield of DP thymocytes, data shown as the mean ± SE (n = 4-6). (C) Representative flow patterns of gated CD4⁺ single-positive thymocytes shown as CD25 vs FoxP3. (D) Percentage and yield of CD4⁺CD25⁺FoxP3⁺, data shown as the mean ± SE (n = 4-6). (E) Representative flow patterns of gated CD3⁺ T cells in the blood shown as CD4 vs CD8. (F) The ratio of CD4⁺ T cells to CD8⁺ T cells and yield of CD4⁺ T cells, data shown as the mean ± SE (n = 4-6). (G) Representative flow patterns of gated CD4⁺ T cells in the peripheral blood shown as CD25 vs FoxP3. (H) Percentage and yield of CD25⁺FoxP3⁺ in CD4⁺ T cells, data shown as the mean ± SE (n = 4-6). ∗P ＜ .05; ∗∗P ＜ .01; ∗∗∗P ＜ .001; ∗∗∗∗P ＜ .0001.