The role of cardiomyocytic FOXP3 and extracellular vesicle-mediated delivery of FOXP3 into cardiomyocytes for treating pathological cardiac hypertrophy

While forkhead helix transcription factor P3 (FOXP3) is a key regulator in T cells, we previously reported its anti-hypertrophic role in cardiomyocytes. In the present study, by overexpressing FOXP3 and using RNA-seq, we found that FOXP3 suppresses pathological cardiac hypertrophy by upregulating ferritin heavy chain 1, thereby inhibiting ferroptosis. However, data from the single-RNA sequence database showed that the in vivo cardiomyocytes exhibit minimal Foxp3 mRNA, despite the presence of FOXP3 protein. Here, we identified cardiac microenvironment-derived extracellular vesicles (cEVs) carrying FOXP3 protein as the source of cardiomyocytic FOXP3. Leveraging this intercellular delivery mechanism, we demonstrate that administering FOXP3 + cEVs from healthy hearts mitigates isoproterenol (ISO)-induced ferroptosis and hypertrophy. Due to the impracticality of large-scale production of cEVs, we identified the Jurkat cell as an alternative source of FOXP3 + EVs. The Jurkat cell-derived EVs (jEVs) increased the content of cardiomyocytic FOXP3, thereby reversing hypertrophic responses. Moreover, we engineered Jurkat cells to increase FOXP3 content in the jEVs, thereby obtaining FOXP3-enriched jEVs that exhibited superior attenuation of hypertrophy and suppression of ferroptosis compared to native EVs. These findings suggest that increasing the content of FOXP3 protein in cardiomyocytes through engineered FOXP3-enriched extracellular vesicles offers a novel strategy for treating cardiac hypertrophy. FOXP3-enriched extracellular vesicles produced via FOXP3 overexpression in Jurkat T cells significantly reverse pathological hypertrophic reaction in cardiomyocytes via upregulating FTH1 expression and inhibiting ferroptosis.