Reversal of activation of human myofibroblast-like cells by culture on a basement membrane-like substrate

Background: Liver injury transforms hepatic stellate cells into myofibroblast (MFB)-like cells. With recovery from injury, MFBs undergo apoptosis, but it is unknown whether they can also revert to quiescence. Aim: To determine whether human (h)MFBs become quiescent if cultured on a basement membrane-like substrate (Matrigel™). Methods: hMFBs obtained from cirrhotic liver were re-cultured on plastic or Matrigel™. Expression of genes of collagen metabolism was assayed before and after transforming growth factor β (TGFβ) and Oncostatin M (OSM) stimulation. Results: hMFBs had typical MFB-like morphology, with abundant α-smooth muscle actin (SMA) but no cytoplasmic lipid droplets. hMFBs re-cultured on Matrigel™ reverted to αSMA-negative, lipid droplet-positive quiescent morphology. αSMA, collagen α1(1) (COL1A1) and collagen α2(1) (COL1A2) messages were upregulated in hMFBs cultured on plastic, but suppressed by Matrigel™. The opposite was true for metalloproteinase-1 mRNA. OSM but not TGFβ reduced αSMA mRNA by 30% while TGFβ but not OSM upregulated COL1A1 mRNA by 48%, in hMFBs on plastic. TGFβ and OSM stimulated COL1A1 gene expression in Matrigel™ by 50 and 60%, respectively. Conclusions: Matrigel™ culture de-activates hMFBs yet collagen gene expression still responds to fibrogenic cytokines. The responses of hMFB gene expression to TGFβ and OSM, are regulated differently by the extracellular matrix.