Therapies aimed at manipulating microvasculature require the ability to generate both blood and lymphatic vessels. Adipose-derived stromal vascular fraction (SVF), consisting of endothelial cells, progenitor cells, pericytes, smooth muscle cells, fibroblasts, and immune cells, has emerged as a heterogeneous cell composition able to promote blood vessel formation and growth, but whether SVF forms lymphatic vessels remains unknown. The objective of this study was to evaluate whether SVF can form lymphatic vessels. SVF was isolated from C57BL/6 mouse inguinal adipose tissue, characterized for prevalence of blood (PECAM+) and lymphatic (Prox1+, Podoplanin+, LYVE-1+) endothelial cells and cultured with avascular mouse mesentery tissues for up to 9 days. The presence of lymphatic endothelial cells in SVF is supported by the percentages of PECAM+ cells that are also positive for lymphatic markers. By day 1 after SVF seeding, cells established PECAM+ segments, and by day 3 cell clusters with segment extensions were observed. At later time points, segments established network of blood vessels. In parallel, a subset of structures positive for lymphatic marker labeling and characterized by a rounded shape (termed "blebs") connected with nearby SVF-derived blood vessel and were changing shape over time. Our findings provoke a new research area focused on the ability for SVF to form lymphatic vessels.
Keywords: lymphangiogenesis; stem cell development; stromal vascular fraction; vasculogenesis.