Formation of new lymphatic vessels in glioma: An immunohistochemical analysis.

We investigated the distribution and formation of new lymphatic vessels in gliomas. Specimens from seven glioma cases were analyzed by immunohistochemical staining for CD34, lymphatic endothelial hyaluronic acid receptor 1 (LYVE-1), prospero-related homeobox 1 (Prox1), nestin, and hypoxia-inducible factor 1α (HIF-1α). Three types of vessels were observed in glioma specimens: LYVE-1+ lymphatic vessels, CD34+ blood vessels, and LYVE-1+ /CD34+ blood vessels. Prox1+ /LYVE-1+ cells were distributed in some lymphatic vessels as well as among vascular endothelial cells and glioma cells. Nestin+ cells were scattered throughout the gliomas, and some lymphatic cells also expressed nestin. HIF-1α+ Prox1+ cells were widely distributed within the glioma specimens. The present immunohistochemical analysis revealed upregulation of Prox1 and HIF-1α in some glioma tissues as well as the differentiation of nestin+ tumor stem cells into LYVE-1+ lymphatic vessels.