Adipose-derived stem cells (ASCs) are an abundant and easily accessible multipotent stem cell source with potential application in smooth muscle regeneration strategies. In 3D collagen hydrogels, we investigated whether sustained release of growth factors (GF) PDGF-AB and TGF-β1 from GF-loaded microspheres could induce a smooth muscle cell (SMC) phenotype in ASCs, and if the addition of uniaxial cyclic stretch could enhance the differentiation level. This study demonstrated that the combination of cyclic stretch and GF release over time from loaded microspheres potentiated the differentiation of ASCs, as quantified by protein expression of early to late SMC differentiation markers (SMA, TGLN and smooth muscle MHC). The delivery of GFs via microspheres produced large ASCs with a spindle-shaped, elongated SMC-like morphology. Cyclic strain produced the largest, longest, and most spindle-shaped cells regardless of the presence or absence of growth factors or the growth factor delivery method. Protein expression and cell morphology data confirmed that the sustained release of GFs from GF-loaded microspheres can be used to promote the differentiation of ASCs into SMCs and that the addition of uniaxial cyclic stretch significantly enhances the differentiation level, as quantified by intermediate and late SMC markers and a SMC-like elongated cell morphology.
Keywords: adipose-derived stem cells; bladder; cell morphology; cell shape; cyclic stretch; growth factors; microspheres; smooth muscle tissue engineering; sphincter; vascular tissue engineering.