Mapping of the Human Amniotic Membrane: In Situ Detection of Microvesicles Secreted by Amniotic Epithelial Cells

The potential clinical applications of human amniotic membrane (hAM) and human amniotic epithelial cells (hAECs) in the field of regenerative medicine have been known in literature since long. However, it has yet to be elucidated whether hAM contains different anatomical regions with different plasticity and differentiation potential. Recently, for the first time, we highlighted many differences in terms of morphology, marker expression, and differentiation capabilities among four distinct anatomical regions of hAM, demonstrating peculiar functional features in hAEC populations. The aim of this study was to investigate in situ the ultrastructure of the four different regions of hAM by means of transmission electron microscopy (TEM) to deeply understand their peculiar characteristics and to investigate the presence and localization of secretory products because to our knowledge, there are no similar studies in the literature. The results of this study confirm our previous observations of hAM heterogeneity and highlight for the first time that hAM can produce extracellular vesicles (EVs) in a heterogeneous manner. These findings should be considered to increase efficiency of hAM applications within a therapeutic context.