Stromal Vascular Fraction Vasculogenesis, Vessel Incorporation, and Integration with Intact Angiogenic Microvascular Networks in an Ex Vivo Cultured Tissue Model

Abstract

Angiogenesis, the growth of new vessels from pre‐existing vessels, is vital to wound healing in the cases of myocardial infarction and peripheral arterial disease. Adipose‐derived stromal vascular fraction (SVF), consisting of endothelial cells, endothelial progenitor cells, pericytes, smooth muscle cells, fibroblasts and immune cells, can be transplanted to assist in wound healing as seen in various clinical trials. However, the spatiotemporal incorporation of the SVF within living tissues remains largely unknown. As such, understanding where and how SVF cells contribute to microvascular growth and remodeling will help guide their therapeutic use. The objective of this study was to evaluate the impact of SVF cells and their fate during microvascular growth utilizing a novel tissue culture model that enables time‐lapse observation of cell dynamics across intact networks. SVF was isolated from adipose of an adult male Wistar rat, labeled with DiI, and seeded onto mesentery tissues harvested from the same rat before culturing in MEM + 10% fetal bovine serum and 1% PenStrep for 3 days. Tissues were then labeled for lectin to identify vessels. Alternatively, SVF was isolated from adipose harvested from adult male or female SD‐EGFP rats, seeded onto lectin labeled mesentery from adult male Wistar rats, placed under the same culture conditions, and imaged every 24 hours. Vascularized area was increased in SVF treated versus control tissues (SVF = 84.5±1.3%; Control = 56.5%; p < 0.001; n = 4 tissues per group). The SVF related microvasculature was characterized by asterisk‐shaped clusters. GFP tracking of SVF revealed vessel segment formation via vasculogenesis containing endothelial cells and pericytes in previously avascular areas. In pre‐vascularized regions, SVF cells contributed to new vessel growth and integration with and along native vessels. SVF cells were observed both in apparent endothelial cell and wrapping pericyte locations. Interestingly, examples of new vessel segments derived from SVF cells were observed along LYVE‐1 positive lymphatic vessels. These results suggest that SVF transplantation increases vascular area through vasculogenesis and contributes to angiogenesis of pre‐existing vasculature. The results also support the use of the rat mesentery culture model as a novel tool for elucidating SVF cell transplant dynamics in an intact tissue environment.Support or Funding InformationFunded by NIH R01AG049821This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.