Augmentation of therapeutic augiogenesis using genetically modified human endothelial progenitor cells with altered glycogen synthase kinase-3β activity

Previously we reported that inhibition of glycogen synthase kinase-3β (GSK3β), a key regulator in many intracellular signaling pathways, enhances the survival and migration of vascular endothelial cells. Here we investigated the effect of inhibition of GSK3β activity on the angiogenic function of endothelial progenitor cell (EPC) and demonstrated a new therapeutic angiogenesis strategy using genetically modified EPC. As we previously reported, two biologically distinct types of EPC, spindle-shaped "early EPC" and cobblestone-shaped "late EPC" could be cultivated from human peripheral blood. Catalytically inactive GSK3β gene was transduced into both EPC. Inhibition of GSK3β signaling pathway led to increased nuclear translocation of β-catenin and increased secretion of angiogenic cytokines (vascular endothelial growth factor and interleukin-8). It enhanced the survival and proliferation of early EPC, whereas it promoted the survival and differentiation of late EPC. Transplantation of either of these genetically modified EPC into the ischemic hind limb model of athymic nude mouse significantly improved blood flow, limb salvage, and tissue capillary density compared with nontransduced EPC. Inhibition of GSK3β signaling of either of these genetically modified EPC augmented the in vitro and in vivo angiogenic potency of these cell populations. These data provide evidence that GSK3β has a key role in the angiogenic properties of EPC. Furthermore, the genetic modification of EPC to alter this signaling step can improve the efficacy of cell-based therapeutic vasculogenesis.