PV-1 expression could distinguish the subset of caveolae-presenting telocytes that are endothelial progenitors

Telocytes (TCs) are stromal cells with characteristic long, thin and moniliform prolongations termed telopodes. They were formerly termed interstitial Cajal-like cells. A characteristic set of markers to identify TCs in light microscopy has not been established until now. Transmission electron microscopy (TEM) is a better tool for identifying TCs. Telocytes display caveolae and can express caveolin-1. On the other hand, endothelial cells (ECs) as well as endothelial progenitor cells (EPCs) have caveolae. Recent evidence suggests that a subset of TCs are in fact EPCs. The distinction of this progenitor subset of TCs can be easily made by a specific set of ultrastructure markers, as follows. Caveolae of endothelial cells present stomatal diaphragms (SDs). The plasmalemma vesicle-associated protein-1 (PV-1), which is identical with the Pathologische Anatomie Leiden endothelium (PAL-E), is specifically identifying the ECs SDs of caveolae. We therefore raise the reasonable hypothesis that the EPCs subset of caveolae-presenting TCs could be accurately identified, without exploration in TEM, by the positive expression of PV-1 or PAL-E in the SDs.