Ex Vivo Priming of Endothelial Progenitor Cells With SDF-1 Before Transplantation Could Increase Their Proangiogenic Potential

Abstract

Objectives-As SDF-1 and its cognate receptor CXCR4 play a key role in the survival and mobilization of immature cells, we examined whether preconditioning of endothelial progenitor cells (EPCs) with SDF-1 could further promote their capacity to enhance angiogenesis. Methods and Results-EPC exposure to 100 ng/mL SDF-1 for 30 min induced a proangiogenic phenotype, with cell migration and differentiation into vascular cords in Matrigel and increased their therapeutic potential in a nude mouse model of hindlimb ischemia. This pretreatment enhanced EPC adhesion to activated endothelium in physiological conditions of blood flow by stimulating integrin-mediated EPCs binding to endothelial cells. Pretreated EPCs showed significantly upregulated surface ␣4 and ␣M integrin subunit expression involved in the homing of immature cells to a neovasculature and enhanced FGF-2 and promatrix metalloproteinase (MMP)-2 secretion. All these effects were significantly attenuated by EPC incubation with AMD-3100, a CXCR4 antagonist, by prior HSPGs disruption and by HUVEC incubation with anti-intercellular adhesion molecule1 (ICAM-1) and anti-vascular cell adhesion molecule (VCAM) blocking antibodies. Pretreated EPCs adhered very rapidly (within minutes) and were resistant to shear stresses of up to 2500s Ϫ1 . Key Words: endothelial progenitor cells Ⅲ SDF-1 Ⅲ ischemia Ⅲ HSPGs Ⅲ adhesion T he discovery of bone marrow-derived endothelial progenitor cells (EPCs) in peripheral blood prompted an intensive search for new ways of inducing neovascularization in patients with heart and limb ischemia, based on transplantation of bone marrow-or peripheral blood-derived EPCs. 1,2 Several studies indicated that local implantation of ex vivoexpanded EPCs improved neovascularization of damaged tissues in animal models of hindlimb ischemia. [2][3][4][5] Contrary to differentiated endothelial cells, administration of EPCs led to increased blood flow in ischemic limbs of nude mice. These immature cells promote neovascularization by differentiating in situ into endothelial cells and by secreting growth factors, cytokines, and proteases that support angiogenic and vasculogenic processes. 6 -8 However, transplantation of autologous EPCs has several limitations, including the limited supply of expanded progenitors, the time required to harvest, expand, and reinject autologous EPCs, and poor graft efficiency. In addition, EPCs appear to undergo unfavorable functional changes during the expansion procedure. 9 This may explain why the capacity of injected EPCs to promote neovascularization is highly variable and depends on the experimental model. 1,10 The yield is currently so low that very large blood volumes would have to be processed to obtain sufficient EPCs for therapeutic use. The required number of EPCs can be reduced by using local infusion 3,5,11 or by concomitant infusion of proangiogenic proteins. 4,12 In addition, EPCs can be activated before their injection 3,5,10 or mobilized into the circulation by cytokines. 7,13 Cytokines released by damaged ti...

Imaging CXCR4 Signaling with Firefly Luciferase Complementation

“…[12][13][14] Disrupting CXCR4 signaling also may benefit cancer therapy by inhibiting tumor angiogenesis, 4 while proangiogenic functions of CXCR4 may be exploited for cell-based therapies in ischemic vascular disease. 15 In addition, CXCR4 acts as a coreceptor for HIV, and binding of the Nef protein from HIV to CXCR4 initiates an apoptotic signaling cascade in cells. 16 Collectively, these studies highlight the diverse biologic effects of CXCL12-CXCR4 and the need to better understand how activation and inhibition of this signaling pathway regulates mechanisms of disease, especially as these processes occur in vivo.…”

Effects of plant lectin and extracts on adhesion molecules of endothelial progenitors

“…Exogenous cells and/or exogenous factors delivery, to produce activated EPCs that can be more robust than non-activated cells, seems to be a promising therapeutic strategy [29]. It has previously been shown that ex vivo priming of EPCs with chemokines, such as SDF-1, before transplantation, could increase their proangiogenic potential [30]. For that reason, priming of EPCs with plant lectin or extracts prior to their systemic/local delivery may stimulate their adhesion to endothelial cells and thus augment the efficiency of cell therapy for ischemic vascular diseases.…”

Prolonged transendothelial migration of human haematopoietic stem and progenitor cells (HSPCs) towards hydrogel-released SDF1

“…radiation, invasive surgery). The tissue repair process can be enhanced by angiogenetic properties of CXCL12-CXCR4 axis ( [40] and reviewed in [13]) in case of the hindlimb ischemia [41], stroke and heart myocardial infarction [42][43] or liver damage [44]. Collagen-1-Heparin matrix immobilisation of SDF-1 can provide such a tool for site-targeted and localized elevation of SDF-1.…”