Abstract 15750: Identification of Human Circulating Lymphatic Endothelial Progenitor Cells from Blood
Background- Emerging evidence has suggested a contribution of bone marrow (BM) and peripheral blood (PB) cells to lymphatic vessel formation. Although we recently reported identity of lymphatic endothelial progenitor cell (LEPC) in mouse BM, the phenotype of such cells in human has yet to be identified. Here, we investigate the identity of human BM and PB-derived lymphatic endothelial progenitor cells and their role in lymphatic neovascularization.
Methods and Results- Culture of BM- and PB-mononuclear cells isolated from human in the presence of vascular endothelial growth factors A and C and epidermal growth factor resulted in expression of lymphatic endothelial cell markers such as PROX1, PODOPLANIN (POD), LYVE1 and VEGFR3 at the mRNA and protein levels. Among these cells, POD+ cells were isolated by fluorescence-activated cell sorting and characterized by flow cytometry and immunocytochemistry. These sorted POD+ cells expressed higher levels of lymphatic endothelial cells (LEC) markers, are enriched with stem/progenitor cell makers. On further cultivation, they generated cells similar to lymphatic endothelial cells. Next, to evaluate the potential of POD+ cells for the formation of new lymphatic vessels in vivo, we injected culture-isolated or freshly isolated BM- and PB-derived POD+ cells into wound and lymphedema models. Immunohistochemistry demonstrated that the injected cells were incorporated into the lymphatic vasculature, displayed LEC phenotypes, and increased lymphatic vascular density in tissues, suggesting new lymphatic vessel formation through lymphvasculogenesis. POD+ cells also expressed high levels of lymphangiogenic cytokines, suggesting a lymphangiogenic or paracrine role of these cells.
Conclusions- Our results provide compelling evidence that BM and PB include POD+ cells in human, and these culture-derived or primarily isolated POD+ cells function as LEPCs and participate in postnatal lymphatic neovascularization through both lymphvasculogenesis and lymphangiogenesis.
- © 2011 by American Heart Association, Inc.