Abstract 209: Human Umbilical Vein Endothelial Cell Conditioned Medium in the Presence of High Glucose Increases in vitro Adipose-derived Stem Cells Proliferation and in vivo Vascularization

Abstract

Background: Diabetes type 1 and 2 cause hyperglycemia and result in endothelial dysfunction with endothelial vessel and poor wound healing. Adipose-derived stem cells (ASCs), progenitor cells in wound healing, show decreased function under hyperglycemic conditions in vitro and in vivo . We hypothesized that exposing ASCs in the presence of high glucose with the human umbilical vein endothelial cell (HUVEC) secretome will reverse the deleterious effects of glucose on ASCs and subsequently enhance angiogenesis and wound healing. Methods: Human umbilical vein endothelial cells (HUVEC) were treated with glucose (30mM) and the conditioned media (CM) were collected every 3 days. ASCs were then co-cultured with EC/CM for 2 weeks. To produce thermal denaturation of protein, EC/CM was heated at 95 0 C for 30 mins. Cell activity, proliferation, and endothelial-like properties of ASCs were determined by MTT assays, growth curves, and real-time RT-PCR, respectively. EC/CM treated ASC were injected into a normal or diabetic murine left thigh muscle at three different points with hindlimb ischemia. After 4 weeks injection, animals were sacrificed. H & E and double immunostaining for CD31 and anti-human nuclei were used to determine if the ASCs primed with EC/CM underwent neovascularization. Results: In fact, ASCs increased in proliferation when co-cultured with HUVEC/CM (1.4 fold) when compared with controls. This promoting effect was lost in heated HUVEC/CM, indicating that the active molecules are of protein origin. After 10 days stimulated with EC/CM an increase in mRNA expression levels of EC markers were also observed in high glucose (30mM) EC/CM environment including CD31 (2-fold), vWF (1.1-fold), and eNOS (3.2-fold) when compared to ASCs cultured in M199. H & E and immunohistochemical staining results showed elevated vessel density and CD31 + cell levels in HUVEC-primed ASC injection sites of diabetic mice when compared with the control animals. Conclusions: HUVEC secrete protein factors that increase proliferation and endothelial differentiation of ASCs under diabetic conditions. Injection of ischemic hindlimbs in diabetic mice with HUVEC-primed ASCs leads to improved angiogenesis.