Purpose: Stem cell therapy is a promising therapeutic option for treating ischemic events. The proangiogenic effects of transplanted stem/progenitor cells are critical for their capacity to contribute to significant functional improvement. However, it has been shown that diabetes affects several cell populations that have been suggested to promote neovascularization, as circulating endothelial and bone marrow derived progenitor cells, limiting their therapeutic potential. The impact of diabetes on adipose derived stem cells (ASCs) remains unclear. Therefore, in the present study we explored in depth the functional consequences of diabetes on the angiogenic potential of ASCs.
Methods: ASCs were isolated and cultured from subcutaneous adipose tissue of Zucker Diabetic Fatty rats (ASCsZDF) and their non-diabetic controls (ASCsZLC). ASCs phenotype was evaluated by flow cytometry and real time PCR. To assess the proangiogenic activity of ASCs, the in vitro and in vivo ability to form new vessels was investigated by endothelial cell differentiation (ECD), in vivo matrigel plug angiogenesis (iMPA) assay and hindlimb ischemia (HLI) murine model. Their paracrine effects on human microvascular endothelial cell line (HMEC-1) migration were evaluated by in vitro wound healing assay carried out in a confluent ASCs and HMEC-1 coculture system.
Results: The angiogenic potential of ASCsZDF was significantly reduced over that of ASCsZLC. ECD was significantly impaired and the ability to develop capillary-like networks in vitro was reduced in ASCsZDF (p=0.01). Wound healing assay showed that ASCsZLC induced the polarized migration of HMEC-1, whereas in cocultures with ASCsZDF HMEC-1 displayed a greatly reduced migration. Consistently, ASCsZDF showed an impaired capacity to stimulate newly formed microvessels in vivo. The iMPA-ASCsZLC-neovessels had significantly higher content of haemoglobin than iMPA-controls without cells (p-value=0.0239) that had similar content than iMPA- ASCsZDF-neovessels. Consistently, a higher level of von Willebrand factor was evident in the neovascularized-plugs of the iMPA-ASCsZLC. In the HLI murine model, ASCsZDF showed a reduced ability to induce new capillaries formation.
Conclusions: The present study reveals by in vitro and in vivo models that diabetes induces an impaired angiogenic potential on the stem cells repository maintains in their subcutaneous fat storage. Diabetic ASCs have a limited capacity to improve neovascularization in autologous stem cells therapy.