VEGF secretion by adipose tissue-derived regenerative cells is impaired under hyperglycemic conditions via glucose transporter activation and ROS increase.

Transplantation of cultured adipose-derived regenerative cells (ADRCs) into ischemic tissues promotes neovascularization and blood perfusion recovery. These effects are attenuated in diabetes patients. We examined the effects of hyperglycemia on the angiogenic capacity of ADRCs derived from Wistar rats both in vivo and in vitro. Cultured ADRCs were predominantly composed of CD90 positive cells; prevalence of CD90 positive cells was not affected by hyperglycemia. mRNA and protein levels of vascular endothelial growth factor (VEGF) were significantly decreased in ADRCs under hyperglycemic conditions independent of osmolarity, whereas mRNA levels of hepatocyte growth factor and fibroblast growth factor were unaffected. Since ADRCs express glucose transporter proteins GLUT1, 3 and 4, we examined the effects of the glucose transporter inhibitor phloretin on reactive oxygen species (ROS) and angiogenic factors. Phloretin decreased the glucose uptake rate, reduced ROS, and increased VEGF mRNA in ADRCs exposed to a hyperglycemic condition. In vivo transplantation of ADRCs cultured under hyperglycemic conditions into mouse ischemic limbs resulted in significantly decreased blood perfusion and capillary density in ischemic regions compared with transplantation of ADRCs cultured under normoglycemic conditions. These results suggest that hyperglycemia impaired VEGF production in ADRCs via an increase of ROS, impairing the angiogenic capacity of ADRCs transplanted into ischemic limbs.

Transplantation of freshly isolated adipose tissue-derived regenerative cells enhances angiogenesis in a murine model of hind limb ischemia.

Therapeutic angiogenesis has emerged as one of the most promising therapies for severe ischemic cardiovascular diseases with no optional therapy. Several investigators have reported that transplantation of cultured adipose-derived regenerative cells (cADRCs) to ischemic tissues promotes neovascularization and blood perfusion recovery; however, cell therapy using cultured cells has several restrictions. To resolve this problem, the angiogenic capacity of freshly isolated ADRCs (fADRCs) obtained from Lewis rats was compared with cADRCs, both in vivo and in vitro. Flow cytometric analysis showed that fADRCs contained several cell types such as endothelial progenitor cells and endothelial cells; however, these cells were present in a very small proportion in cADRCs. Transplantation of fADRCs in mice significantly improved blood perfusion, capillary density, and production of several angiogenic factors in transplanted ischemic limbs compared with a saline-injected group, whereas these effects were not observed in the cADRCs-injected group. fADRCs also showed significantly higher expression levels of angiogenic factors than cADRCs in the in vitro study. Furthermore, fADRC stimulated tube formation more remarkably than cADRC in an in vitro tube formation assay. These results suggested that fADRCs have an effective angiogenic capacity, and they would be more valuable as a source for cell-based therapeutic angiogenesis than cADRCs or other stem/progenitor cells.