Keratose Hydrogel Drives Differentiation of Cardiac Vascular Smooth Muscle Progenitor Cells: Implications in Ischemic...

Peripheral artery disease (PAD) is a common vascular disorder in the extremity of limbs with limited clinical treatments. Stem cells hold great promise for the treatment of PAD, but their therapeutic efficiency is limited due to multiple factors, such as poor engraftment and non-optimal selection of cell type. To date, stem cells from a variety of tissue sources have been tested, but little information is available regarding vascular smooth muscle cells (VSMCs) for PAD therapy. The present study examines the effects of keratose (KOS) hydrogels on c-kit⁺/CD31^- cardiac vascular smooth muscle progenitor cell (cVSMPC) differentiation and the therapeutic potential of the resultant VSMCs in a mouse hindlimb ischemic model of PAD. The results demonstrated that KOS but not collagen hydrogel was able to drive the majority of cVSMPCs into functional VSMCs in a defined Knockout serum replacement (SR) medium in the absence of differentiation inducers. This effect could be inhibited by TGF-β₁ antagonists. Further, KOS hydrogel increased expression of TGF-β₁-associated proteins and modulated the level of free TGF-β₁ during differentiation. Finally, transplantation of KOS-driven VSMCs significantly increased blood flow and vascular densities of ischemic hindlimbs. These findings indicate that TGF-β₁ signaling is involved in KOS hydrogel-preferred VSMC differentiation and that enhanced blood flow are likely resulted from angiogenesis and/or arteriogenesis induced by transplanted VSMCs.