Selective Interference Targeting of Lnk in Umbilical Cord-Derived Late Endothelial Progenitor Cells Improves Vascular Repair, Following Hind Limb Ischemic Injury, via Regulation of JAK2/STAT3 Signaling

Abstract

The Lnk adaptor protein is a strong negative regulator that affects self-renewal of hematopoietic stem cells and vascular repair in injured tissues. However, the signaling mechanisms through which these proteins influence the vascular regeneration function of endothelial progenitor cells (EPCs) remain unknown. In this study, we investigated the effect of Lnk-targeted small interfering RNA (si-lnk) on the clonogenic proliferative potential and vascular regenerative function of EPCs and the activation of the JAK/STAT3 signaling pathway. Treatment with stem cell factor (SCF) increased the clonogenic proliferation of si-lnk EPCs. Importantly, activation of the JAK2/STAT3 pathway was enhanced in SCF-sensitized si-lnk EPCs. In a hind limb model of ischemia, transplantation of si-lnk EPCs increased the blood flow ratio, capillary density, proliferation, and survival of transplanted cells, and the secretion of pivotal angiogenic cytokines at ischemic sites. These results provide strong evidence that si-lnk regulates the clonogenic proliferative potential of EPCs through the activation of the JAK2/STAT3 signaling pathway, thereby accelerating angiogenesis and promoting repair in injured hind limb ischemia. STEM CELLS

Specific disruption of Lnk in murine endothelial progenitor cells promotes dermal wound healing via enhanced vasculogenesis, activation of myofibroblasts, and suppression of inflammatory cell recruitment

“…Our findings indicated that wound repair was significantly enhanced in Lnk-deficient mice as compared with wild-type mice. However, wound repair is a complex biological process that requires several cell types [1, 2], and the Lnk adaptor protein affects various of cell types, including hematopoietic stem cells [24], T cells [25], macrophages [26], EPCs [13, 14], and endothelial cells [27]. Therefore, to focus on one of the populations involved in the wound-healing process, we performed flow cytometry in the wound tissues to search for the recruitment of a specific cell population, and demonstrated that Lnk deficiency in mice specifically increased the recruitment of the EPC population to the injury sites.…”

“…Our previous studies showed that Lnk deficiency in mice promotes EPC kinetics and neovascularization in response to angiogenic cytokines, such as SCF, VEGF, and SDF-1 [13]. In addition, Lnk-deficient EPCs increase the clonogenic proliferation via activation of the JAK-STAT3 signal pathway [14]. These findings strongly support the notion that Lnk deficiency in mice promotes wound repair through the recruitment of EPCs and improves EPC cellular bioactivities, which are initiating steps of vascular repair, which is tightly regulated by the Lnk adaptor protein for cellular homeostasis.…”

“…Our previous studies showed that Lnk deficiency enhances the capacity for cell growth, endothelial commitment, mobilization, and recruitment of EPCs [13]. Moreover, selective downregulation of Lnk in EPCs promotes vascular repair and neovascularization in a murine model of hindlimb ischemia through regulation of the JAK2/STAT3 axis [14]. …”

Does Mechanical Stress Regulate the Angiogenic Profile of Endothelial Progenitor Cells?

“…Accordingly, the survival of engrafted cells and subsequent angiogenesis are considerably insufficient after cell transplantation. 15) In this study, Bai, et al proposed a novel means to overcome this problem, which is pharmacological inhibition of aPKC as a means to recover VEGFR endocytosis and the angiogenic properties of EPCs impaired by mechanical stretch. 8) However, some issues remain to be overcome.…”

Lnk is an important modulator of insulin-like growth factor-1/Akt/peroxisome proliferator-activated receptor-gamma axis during adipogenesis of mesenchymal stem cells

“…In the immune system, Lnk regulates B cell production by negatively regulating pro-B-cell expansion [11]. Lnk also acts as a negative regulator of stem cell factor (SCF)-c-Kit signaling pathway [1213]. Lnk is positively regulated by IGF-1 in T cells from CHO, suggesting that it functions as both a positive and negative regulator of receptor tyrosine kinase signaling [14].…”