Ningxue Shengban decoction containing serum alleviates immune thrombocytopenia by modulating CD4+T cells balance via BMSCs-Exo-miR-199a-5p

• BMSCs-Exo modulates CD4+ T cell balance via miR-199a-5p, promoting Treg/Th2 and suppressing Th1/Th17 responses. • NXSBD-containing serum enhances the immunomodulatory effect of BMSCs-Exo by increasing miR-199a-5p levels. • BMSCs-Exo treatment ameliorates ITP pathology in mice, increasing platelet counts and reducing autoantibody levels. • Pretreatment with NXSBD-containing serum yields superior therapeutic efficacy of BMSCs-Exo, suggesting a novel combination strategy for ITP.