X-ray irradiation selectively kills thymocytes of different stages and impairs the maturation of donor-derived CD4^+CD8^+ thymocytes in recipient thymus

The aim of the present study was to determine whether the sensitivity of thymocytes to X-ray radiation depends on their proliferative states and whether radiation impairs the maturation of donor-derived thymocytes in recipient thymus.We assigned 8-week-old C57BL/6J mice into three treatment groups：1） untreated;2） X-ray radiation;3） X-ray radiation plus bone marrow transplantation with donor bone marrow cells from transgenic mice express-ing enhanced green fluorescent protein（GFP） on a universal promoter.After 4 weeks,the size of the thymus,the number and proliferation of thymocytes and ratios of different stage thymocytes were analyzed by immunohisto-chemistry and flow cytometry.The results showed that：1） CD4＋CD8＋ thymocytes were more sensitive to X-ray radiation-induced cell death than other thymocytes;2） the proliferative capacity of CD4＋CD8＋ thymocytes was higher than that of other thymocytes;3） the size of the thymus,the number of thymocytes and ratios of thymo-cytes of different stages in irradiated mice recovered to the normal level of untreated mice by bone marrow trans-plantation;4） the ratio of GFP-positive CD4＋CD8＋ thymocytes increased significantly,whereas the ratio of GFP-positive CD4＋ or CD8＋ thymocytes decreased significantly.These results indicate that the degree of sensitivity of thymocytes to X-ray radiation depends on their proliferative states and radiation impairs the maturation of donor-derived CD4＋CD8＋ thymocytes in recipient thymus.

Bioactive materials from berberine-treated human bone marrow mesenchymal stem cells promote alveolar bone regeneration by regulating macrophage polarization

Alveolar bone regeneration has been strongly linked to macrophage polarization.M1 macrophages aggravate alveolar bone loss,whereas M2 macrophages reverse this process.Berberine(BBR),a natural alkaloid isolated and refined from Chinese medicinal plants,has shown therapeutic effects in treating metabolic disorders.In this study,we first discovered that culture supernatant(CS)collected from BBR-treated human bone marrow mesenchymal stem cells(HBMSCs)ameliorated periodontal alveolar bone loss.CS from the BBR-treated HBMSCs contained bioactive materials that suppressed the M1 polarization and induced the M2 polarization of macrophages in vivo and in vitro.To clarify the underlying mechanism,the bioactive materials were applied to different animal models.We discovered macrophage colony-stimulating factor(M-CSF),which regulates macrophage polarization and promotes bone formation,a key macromolecule in the CS.Injection of pure M-CSF attenuated experimental periodontal alveolar bone loss in rats.Colony-stimulating factor 1 receptor(CSF1R)inhibitor or anti-human M-CSF(M-CSF neutralizing antibody,Nab)abolished the therapeutic effects of the CS of BBR-treated HBMSCs.Moreover,AKT phosphorylation in macrophages was activated by the CS,and the AKT activator reversed the negative effect of the CSF1R inhibitor or Nab.These results suggest that the CS of BBR-treated HBMSCs modulates macrophage polarization via the M-CSF/AKT axis.Further studies also showed that CS of BBR-treated HBMSCs accelerated bone formation and M2 polarization in rat teeth extraction sockets.Overall,our findings established an essential role of BBR-treated HBMSCs CS and this might be the first report to show that the products of BBR-treated HBMSCs have active effects on alveolar bone regeneration.