[Changes of different cell subsets in thymus and spleen of mice at different growth stages and the facilitating effect of ROCK inhibitor on thymus regeneration in aged mice].

Objective To investigate the changes of subsets of thymocytes, thymic epithelial cells (TECs) and T lymphocytes in the spleen of mice at different growth stages, and to explore the effect of Rho-associated coiled-coil protein kinase (ROCK) inhibitor on thymus regeneration in aged mice. Methods The thymus and spleens were harvested from female C57BL/6 mice at juvenile, mature adult, middle-aged and aged phases. The subsets of thymocytes, TECs and T cells in the spleen were analyzed by flow cytometry (FCM). TECs of aging mice were treated with ROCK inhibitor in vitro. Cell proliferation was observed using fluorescence immune-linked spot analyzer. Aged mice of 20-month old were treated with ROCK inhibitor in vivo. The changes of thymocytes, TECs and T cell subgroups in the spleen were detected with FCM. Results The total numbers of thymocytes and TECs as well as the number of each cell subpopulation decreased significantly with aging. The proportions of CD4+ naive T cells, CD8+ naive T cells and CD4+ recent thymus emigrant cells (RTEs) in the spleen showed significant decreasing trends although there were not obvious changes in the proportions of CD4+ T cells and CD8+ T cells in the spleen of mice during aging. ROCK inhibitor facilitated the proliferation of TECs in aging mice in vitro. ROCK inhibitor also increased the numbers of the subsets of thymocytes, TECs and T cells in the spleen of aged mice significantly. Conclusion The mouse thymus undergoes progressing degeneration with aging. ROCK inhibitor has potential of relieving the atrophy of thymus, facilitating thymus regeneration in aged mice.