<i>In Vitro</i> Hepatocyte Differentiation of Human Adipose-Derived Stem Cells Under Hypoxia and Photobiomodulation Irradiation

Stem cells may be manipulated <i>in vitro</i> to induce hepatic differentiation. We investigated the effect of hypoxia and photobiomodulation therapy (PBMT) on the hepatogenic differentiation of human adipose-derived stem cells (hASCs). hASCs were exposed to different carbon dioxide concentrations with photobiomodulation (PBM) using low-level light. Cell survival and secretion of hepatocyte growth factor (HGF) of the hASCs were evaluated by immunostaining and Western blot analyses. Hepatic differentiation was assessed via immunocytochemical staining, fluorescence-activated cell sorting, and Western blot analysis for liver-specific genes and proteins, including albumin (ALB), cytokeratins 8/18, and alpha-fetoprotein (AFP). PBM therapy has been shown to enhance proliferation and cytokine secretion of a number of cells. The expression profiles of ALB, AFP, and cytokeratin 8/18 demonstrated that when HGF, hypoxia, or PBMT were treated individually, incomplete hepatocyte differentiation was achieved. In contrast, quantitative analysis of ALB, cytokeratins 8/18, and AFP showed that HGF was enhanced significantly by hypoxia+PBM treatment. The obtained cell populations contained progenitors that expressed both hepatic ALB and cytokeratin 8/18 markers, as well as AFP. These data suggest that PBMT and hypoxia are effective biostimulators of hASCs in hepatogenic differentiation, which enhances the survival of hASCs and stimulates the secretion of growth factors.