PDGFRβ+ perivascular progenitor cells in tumours regulate pericyte differentiation and vascular survival

The microvasculature consists of endothelial cells and their surrounding pericytes. Few studies on the regulatory mechanisms of tumour angiogenesis have focused on pericytes. Here we report the identification of tumour- derived PDGFR beta(+) ( platelet- derived growth factor receptor beta) progenitor perivascular cells ( PPCs) that have the ability to differentiate into pericytes and regulate vessel stability and vascular survival in tumours. A subset of PDGFR beta(+) PPCs is recruited from bone marrow to perivascular sites in tumours. Specific inhibition of PDGFR beta signalling eliminates PDGFR beta(+) PPCs and mature pericytes around tumour vessels, leading to vascular hyperdilation and endothelial cell apoptosis in pancreatic islet tumours of transgenic Rip1Tag2 mice.