Human glioblastoma cells display mesenchymal stem cell features and form intracranial tumors in immunocompetent rats.

Isolation of highly tumorigenic stem-like cells from human glioblastoma specimens and cell lines has been focusing on their neural stem cells properties or capacity to efflux fluorescent dyes. Here, we report that, under standard culture conditions, human glioblastoma cells of the U87MG cell line display a predominant mesenchymal phenotype and share some of the in vitro properties of mesenchymal stem cells. Moreover, these cells were capable of forming tumors in immunocompetent rats. Infiltrative intracranial tumors could be detected 15 to 30 days post-stereotaxic cell injection within the motor cortex. Tumors were comprised by pleomorphic and mitotically active cells and displayed necrotic and hemorrhagic foci, which are common features of human glioblastomas. This rather unexpected in vivo tumorigenesis in the absence of immune suppression more closely mimics the physiological milieu encountered by tumor cells and could be explored as a xenograft orthotopic model of human glioblastomas to address new therapeutic approaches, particularly those involving immune effector mechanisms.