Directed Differentiation of Skin-Derived Precursors Into Functional Vascular Smooth Muscle Cells

Abstract

Objective— The goal of this study was to characterize the factors and conditions required for smooth muscle cell (SMC)–directed differentiation of Sox2 + multipotent rat and human skin-derived precursors (SKPs) and to define whether they represent a source of fully functional vascular SMCs for applications in vivo. Methods and Results— We found that rat SKPs can differentiate almost exclusively into SMCs by reducing serum concentrations to 0.5% to 2% and plating them at low density. Human SKPs derived from foreskin required the addition of transforming growth factor-β1 or -β3 to differentiate into SMCs, but they did so even in the absence of serum. SMC formation was confirmed by quantitative reverse transcription–polymerase chain reaction, immunocytochemistry, and fluorescence-activated cell sorting, with increased expression of smoothelin-B and little to no expression of telokin or smooth muscle γ-actin, together indicating that SKPs differentiated into vascular rather than visceral SMCs. Rat and human SKP-derived SMCs were able to contract in vitro and also wrap around and support new capillary and larger blood vessel formation in angiogenesis assays in vivo. Conclusion— SKPs are Sox2 + progenitors that represent an attainable autologous source of stem cells that can be easily differentiated into functional vascular SMCs in defined serum-free conditions without reprogramming. SKPs represent a clinically viable cell source for potential therapeutic applications in neovascularization.