BS25 Human smooth muscle cells from the subdermal plexus can be isolated and propagated in vitro: a new model to study vascular biology?

Introduction Smooth muscle cells (SMC) are the principal cell type within the vascular wall and are critical for maintaining blood vessel physiology. Current SMC models are typically isolated from macrovessels including the aorta, coronary arteries or saphenous vein however these tissues require invasive surgery to access. SMC from a more accessible source such as skin would therefore be a valuable addition to the vascular biologists' toolkit. The purpose of this work was to isolate human SMC from the subdermal plexus and characterise their phenotype in vitro to assess suitability as an alternative SMC source for vascular biologists. Methods Primary human SMC were isolated from subdermal plexus (DV) by explant technique from multiple donors undergoing lower limb amputation at the Bradford Royal Infirmary. SMC identity and purity was validated using immunocytochemistry for alpha smooth muscle actin (α-SMA) and smooth muscle myosin heavy chain (SM-MHC). SMC phenotype was assessed by measuring cellular and nuclear morphological parameters (light microscopy and ImageJ), proliferation by cell counting, and expression of SMC-related microRNAs by qPCR. Results All explanted cells stained positively for α-SMA and SM-MHC, confirming their identity as SMC. DV-SMC were spindle-shaped with an average spread cell area of 8279±1459µm2. They were typically mononucleated with over 90% of nuclei appearing ovoid. All cells expressed microRNAs miR-17, miR-29b2, miR-31, miR-130b and miR-491 which have been recently identified as important in SMC phenotypic regulation. Importantly, all of these parameters were consistent in matched cells, up to passage 9 in vitro. Discussion/Conclusion This is the first characterisation of primary SMC from the subdermal plexus. DV-SMC appeared comparable and morphologically similar to other sources of SMC (e.g. saphenous vein) and proliferated in culture. The phenotypic characteristics were stable up to and including passage 9 indicating that DV-SMC are robust, expandable in culture, and make a valuable addition to the sources of SMC that are available for studying human vascular health and disease. Conflict of Interest None