ABSTRACT
Human amniotic epithelial cells (hAECs) have been the object of intense research due to their potential therapeutic use. In this paper, we present molecular evidence of a bona fide epithelial to mesenchymal transition (EMT) undergone by hAECs. Amniotic membrane (AM)-derived hAECs showed the presence of typical epithelial markers such as E-cadherin and cytokeratins. hAECs in culture, however, underwent morphological changes acquiring a mesenchymal shape. Epithelial cell markers were lost and typical mesenchymal markers, such as vimentin and α-SMA, appeared. Several genes associated with EMT, such as SNAI1, MMP9, PAI1, or ACTA2, increased their expression. The expression of the transcription activators KLF4 or MTA3 was consistent with the downregulation of CDH1. We have shown that hAECs undergo EMT due to the autocrine production of TGF-ß. Furthermore, the addition of the TGF-ß receptor I (ALK5) inhibitor SB-431542 or TGF-ß neutralizing antibody to hAECs prevented EMT and preserved the hAECs' epithelial phenotype. Altogether, these results suggest that cultured hAECs undergo EMT through the autocrine production of TGF-ß.
Subject(s)
Amnion/cytology , Autocrine Communication , Epithelial Cells/metabolism , Epithelial-Mesenchymal Transition , Transforming Growth Factor beta/metabolism , Antibodies, Neutralizing/pharmacology , Autocrine Communication/drug effects , Benzamides , Biomarkers/metabolism , Cell Proliferation/drug effects , Cell Shape/drug effects , Cells, Cultured , Dioxoles , Epithelial Cells/cytology , Epithelial Cells/drug effects , Epithelial-Mesenchymal Transition/drug effects , Epithelial-Mesenchymal Transition/genetics , Epithelium/drug effects , Epithelium/metabolism , Gene Expression Regulation/drug effects , Humans , Kruppel-Like Factor 4 , Mesoderm/drug effects , Mesoderm/metabolism , Phosphorylation/drug effects , Signal Transduction/drug effects , Signal Transduction/geneticsABSTRACT
Large-surface or deep wounds often become senescent in the inflammatory or proliferation stages and cannot progress to reepithelialization. This failure makes intervention necessary to provide the final sealing epithelial layer. The best current treatment is autologous skin graft, although there are other choices such as allogenic or autologous skin substitutes and synthetic dressings. Amniotic membrane (AM) is a tissue of interest as a biological dressing due to its biological properties and immunologic characteristics. It has low immunogenicity and beneficial reepithelialization effects, with antiinflammatory, antifibrotic, antimicrobial, and nontumorigenic properties. These properties are related to its capacity to synthesize and release cytokines and growth factors. We report the use of AM as a wound dressing in two patients with large and deep traumatic wounds. Negative pressure wound therapy followed by AM application was capable of restoring skin integrity avoiding the need for skin graft reconstruction. AM induced the formation of a well-structured epidermis. To understand this effect, we designed some assays on human keratinocyte-derived HaCaT cells. AM treatment of HaCaT induced ERK1/2 and SAP/JNK kinases phosphorylation and c-jun expression, a gene critical for keratinocytes migration; however, it did not affect cell cycle distribution. These data suggest that AM substantially modifies the behavior of keratinocytes in chronic wounds, thereby allowing effective reepithelialization.
