Transdifferentiation, a Potential Mechanism for Covering Vascular Grafts Grown Within Recipient’s Peritoneal Cavity With Endothelial-Like Cells

Monocytes/Macrophages Cooperate with Progenitor Cells during Neovascularization and Tissue Repair

“…This pertains to the often mentioned but poorly documented propensity of adult MC/Mph to behave like endothelium, supposedly via trans-differentiation. 17,24,81 Alternatively, this could be a case of vascular mimicry, similar to that undergone by cancer cells or other cell types, 22,82 thought to be at the foundation of a more general process of functional adaptation. 83 However, we cannot exclude the possibility of cell fusion, another proposed mechanism that would explain the appearance of mixed phenotypes among different classes of cells.…”

“…Nevertheless, the specific steps of this conversion in vivo are yet unknown. Many examples of vascular mimicry were recently described, including tumor cells, 22 epithelial cells, 23 mesothelial cells, 24 or cytotropho-blasts, 25 all functioning in an endothelial capacity in various physiological or pathological settings. The potential of selected subpopulations of circulating or bone marrow-derived mononuclear cells to (trans-)differentiate into cells of various lineages 26,27 led recently to a hot debate of the plasticity of stem cells, along with the very notion of stemness.…”

Role of monocytes and macrophages in angiogenesis

“…These situations involving a pre-existent vascular "tube" and non-endothelial cells which cover it and adopt endothelial functions, suggest an alternative mechanism of vasculogenesis. Recently it was discussed in the literature another instance where MC/Mph participating in the foreign body reaction apparently acquire endothelial-like properties upon exposure to the blood [130,131].…”

Angiogenesis, l'enfant terrible of vascular biology is coming to age

“…An even closer look to the actual phenotypes of cells inserting in an intimal position revealed that they are not always endothelial, but also -depending on the conditiontumoral, fetal, inflammatory or even epithelial origin [20]. This surprising cellular plasticity of the endothelial phenotype stretched the minds of researchers over a wide range of notions, from "vascular mimicry" [21] to transdifferentiation [22]. How otherwise to explain for example the presence of monocytes in functional lymphatics [23] and in capillaries [24], or of dendritic-like cells in tumor microvessels [25]?…”