Pro-myogenic and low-oxygen culture increases expression of contractile smooth muscle markers in human fibroblasts

Smooth muscle cells (SMCs) are essential for tissue engineering strategies to fabricate organs such as blood vessels, the oesophagus and bladder, and to create disease models of these systems. In order for such therapies and models to be feasible, SMCs must be sourced effectively to enable production of large numbers of functional cells. In vitro, SMCs divide slowly and demonstrate short proliferative lifespans compared with other types of cells, including stem cells and fibroblasts, limiting the number of cells that can be derived from expansion in culture of a primary isolation. As such, it would be beneficial to better understand the factors underlying induction and maintenance of SMC phenotypes, in order to produce new sources of SMCs for tissue engineering and disease modelling. Here we report the ability of human dermal fibroblasts to display patterns of gene expression resembling contractile SMCs when cultured under conditions that are known to promote a contractile phenotype in SMCs, including culture on collagen IV, low-serum culture, TGF-1 treatment and hypoxia. These factors drive expression of the myogenic transcription factor myocardin, as well as expression of several of its gene targets that are known contributors to contractile phenotype in SMCs, including smooth muscle alpha actin, calponin, and myosin heavy chain. Our results suggest that culture conditions associated with culture of SMCs may be sufficient to induce myogenic gene expression patterns and potential myogenic function in non-muscle cells.