Angiogenesis by transplantation of HIF‐1α modified EPCs into ischemic limbs

Abstract

Hypoxia inducible factor-1 alpha (HIF-1 alpha) is a key determinant of oxygen-dependent gene regulation in angiogenesis. HIF-1 alpha overexpression may be beneficial in cell therapy of hypoxia-induced pathophysiological processes, such as ischemic heart disease. To address this issue, human peripheral blood mononuclear cells (PBMNCs) were induced to differentiate into endothelial progenitor cells (EPCs), and then were transfected with either an HIF-1 alpha-expressing or a control vector and cultured under normoxia or hypoxia. Hypoxia-induced HIF-1 alpha mRNA and protein expression was increased after HIF-1 alpha transfection. This was accompanied by VEGF mRNA induction and increased VEGF secretion. Hypoxia-stimulated VEGF mRNA induction was significantly abrogated by HIF-1 alpha-specific siRNA. Functional studies showed that HIF-1 alpha overexpression further promoted hypoxia-induced EPC differentiation, proliferation and migration. The expressions of endothelial cell markers CD31, VEGFR2 (Flk-1) and eNOS as well as VEGF and NO secretions were also increased. Furthermore, in an in vivo model of hindlimb ischemia, HIF-1 alpha-transfected EPCs homed to the site of ischemia. A higher revascularization potential was also demonstrated by increased capillary density at the injury site. Our results revealed that endothelial progenitor cells ex vivo modification by hypoxia inducible factor-1 alpha gene transfection is feasible and may offer significant advantages in terms of EPC expansion and treatment efficacy.

MicroRNA-138 inhibits hypoxia-induced proliferation of endothelial progenitor cells via inhibition of HIF-1α-mediated MAPK and AKT signaling

“…Furthermore, it was observed that miR-138 negatively mediates levels of HIF-1α protein in EPCs, and overexpression of miR-138 was found to decrease hypoxia-induced HIF-1α expression in EPCs. Jiang et al (26) reported that HIF-1α overexpression promoted hypoxia-induced EPC differentiation, proliferation and migration. Therefore, the inhibitory effect of miR-138 overexpression on hypoxia-induced EPCs proliferation may occur by inhibiting the hypoxia-induced upregulation of HIF-1α expression.…”

Intravenous Administration of Endothelial Colony-Forming Cells Overexpressing Integrin β1 Augments Angiogenesis in Ischemic Legs

“…Integrin b 1 was chosen for use in the present study in an effort to facilitate homing of the ECFCs to the ischemic tissue, which would be expected to abundantly express ECM. Although ECFCs have been genetically modified in a number of earlier studies, most of those involved overexpression of angiogenic factors (e.g., vascular endothelial growth factor, hypoxia inducible factor-1a, hepatocyte growth factor, or endothelial nitric oxide synthase) in an effort to strengthen or accelerate the angiogenic function of ECFCs, not to facilitate homing [27][28][29][30][31][32]. Our approach might be unique in that context.…”

Synergistic effect of HIF-1α gene therapy and HIF-1-activated bone marrow-derived angiogenic cells in a mouse model of limb ischemia

“…While this work was in progress, several attempts to improve the efficacy of so-called ''endothelial progenitor cell'' therapy through expression of HIF-1␣, using vectors that were transduced by either electroporation (33) or adenoviral transduction (34), were reported. Although promising, these reports used the wild-type HIF-1␣ sequence, thus relying on continuous hypoxic culture to avoid degradation of HIF-1.…”