Activation of Transcription Factor GAX and Concomitant Downregulation of IL-1β and ERK1/2 Modulate Vascular Smooth Muscle Cell Phenotype in 3D Fibrous Scaffolds

Since vascular smooth muscle cells (VSMCs) display phenotypic plasticity in response to changing environmental cues, understanding the molecular mechanisms underlying the phenotypic modulation mediated by a three-dimensional (3D) scaffold is important to engineer functional vasculature. Following cell seeding into 3D scaffolds, the synthetic phenotype is desired to enable cells to expand rapidly and produce and assemble extracellular matrix components, but must revert to a quiescent contractile phenotype after tissue fabrication to impart the contractile properties found in native blood vessels. This study shows that 3D electrospun fibrous scaffolds regulate human coronary artery smooth muscle cells (HCASMCs) toward a more synthetic phenotype characterized by reduced contractile markers, such as smooth muscle alpha-actin and calponin. The reduction in contractile markers expression was mediated by endogenously expressed proinflammatory cytokine interleukin-1 beta (IL-1 beta). 3D topography transiently induces concomitant upregulation of IL-1 beta and MAPK ERK1/2 through nuclear factor-kappa B-dependent signaling pathway. An early burst of expression of IL-1 beta is essential for suppression of the homeobox transcription factor Gax and related cyclin-dependent kinase inhibitor p21(Cip1), which are key regulators for cells exiting from cell cycle. Our findings provide new insights for understanding signaling mechanisms of HCASMCs in electrospun 3D fibrous scaffolds, which have considerable value for application in vascular tissue engineering.