Reconstructed Skin by the Self‐Assembly Approach: Is the Stem Cell Niche Present In Vitro?

Abstract

Since stem cells are responsible for the continuous generation of the stratified epithelium, their isolation and preservation upon culture in tissue‐engineered skin (TES) is suitable to allow the long‐term regeneration of these tissues after grafting. The objective of the present study is to evaluate the dynamic of stem cells and their division in TES produced by the self‐assembly approach. The slow‐cycling property of stem cells was used to identify them with bromodeoxyuridine (BrDU) in TES produced by the self‐assembly approach. TES cultured at the air‐liquid interface were treated with BrdU for a 7‐day‐pulse period, followed by a 21‐day‐chase period. Epithelial cells of the TES were dissociated by enzymatic digestion and analyzed by flow cytometer or on tissue sections by imunofluorescence with antibodies raised against BrdU and keratin 19 (K19). Analysis revealed that basal cells have retained the nuclei BrdU labelling after the 21‐day‐chase period and most of these label‐retaining cells expressed the K19. This observation was corroborated by FACS analysis. These results suggest TES reconstructed by the self‐assembly approach provide a three‐dimensional environment that allows the preservation of stem cells in vitro and we conclude that it is suitable for grafting.This work was supported by the CIHR. L.G. is the holder of a Canadian research chair on stem cells and tissue engineering from CIHR.