Progesterone-driven stabilization of hybrid E/M states in amniotic epithelial cells enhances regeneration and immune modulatory capacities.

Abstract

Epithelial-mesenchymal plasticity (EMP) plays a pivotal role in development, regeneration, and disease progression. In this study, we demonstrate that progesterone (P4) delays EMP in amniotic epithelial cells (AECs), promoting the emergence of hybrid epithelial/mesenchymal (E/M) phenotypes. These hybrid cells co-express E and M traits and exhibit distinct surface markers. Compared to fully M, hybrid AECs display enhanced collective migration, upregulation of stemness transcription factors, and enhanced immunomodulatory properties <i>in vitro</i> and <i>in vivo</i>. Their regenerative potential was validated by <i>in vitro</i> tendon differentiation on PLGA-fleeces and in an ovine tendon injury model, where the transplantation of hybrid AECs accelerated early regeneration. This effect was associated with a timely transition from inflammation to proliferation, mediated by macrophage polarization and extracellular matrix remodeling. Our findings reveal that P4 maintains AECs in a functionally hybrid E/M state, conferring regenerative and immunomodulatory advantages. These results offer insights into the physiological regulation of EMP and support the therapeutic relevance of hybrid AECs as promising candidates for cell-based regenerative medicine therapy.