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

## TL;DR

Progesterone helps amniotic cells maintain a hybrid state that boosts their ability to regenerate tissues and control immune responses.

## Contribution

This study reveals that progesterone stabilizes hybrid epithelial/mesenchymal states in amniotic cells, enhancing their regenerative and immunomodulatory functions.

## Key findings

- Progesterone delays epithelial-mesenchymal transition and promotes hybrid E/M phenotypes in amniotic epithelial cells.
- Hybrid cells show improved collective migration, stemness, and immunomodulation in vitro and in vivo.
- Transplantation of hybrid cells accelerates tendon healing and modulates macrophage polarization in an ovine model.

## 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 in vitro and in vivo. Their regenerative potential was validated by in vitro 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.

•P4 delays EMT and promotes the emergence of AECs with hybrid E/M phenotypes•Hybrid AECs show enhanced stemness, differentiation, and collective migration•In vivo, hybrid AECs accelerate tendon healing and modulate macrophage polarization•Hybrid phenotypes offer a new framework for EMP-based cell therapies

P4 delays EMT and promotes the emergence of AECs with hybrid E/M phenotypes

Hybrid AECs show enhanced stemness, differentiation, and collective migration

In vivo, hybrid AECs accelerate tendon healing and modulate macrophage polarization

Hybrid phenotypes offer a new framework for EMP-based cell therapies

Molecular biology; Immunology; Developmental biology