Neoplastic Stromal Cells of Intracranial Hemangioblastomas Disclose Pericyte-derived Mesenchymal Stromal Cells-like Phenotype

Background: Stromal cells (SCs) of hemangioblastomas (HBs) have been regarded as true neoplastic components, but their ontogeny remains unclear. Convincing evidence suggests that embryonic mesenchymal cells may be the cells of origin of HBs. The aim of the present study was to investigate the immunophenotypic characteristics of neoplastic SCs using a set of markers against endothelial cells (ECs), vascular smooth muscle cells (vSMCs), mesenchymal stoma! cells (MSCs), and pericytes. Methods: Intracranial HBs (n=46), angiolipoma (n=9), and pyogenic granuloma (n=11) were retrieved and the immunophenotypic profile of SCs was determined by immune stainings. Results: The MIB-1 labeling index was significantly higher in SCs compared to that of ECs and vSMCs, regardless of the type of lesion. The neoplastic SCs of HBs consistently expressed both MSC and pericyte markers, but did not express markers of ECs and vSMCs. Double immunofluorescent staining demonstrated that the neoplastic SCs of HBs expressing MSC or pericyte markers directly abutted onto the ECs of capillaries/venules. Conclusions: The results suggest that the neoplastic SCs of HBs share the immunophenotypic profile and distribution with those of pericyte-derived MSCs. Thus, HBs might originate from a distinctive population of perk cyte-derived MSCs in the central nervous system.