Characterization of 9L glioma model of the Wistar rat

The aim of our study was to develop and characterize solid brain tumors in Wistar rats, which could be used in investigations concerning the molecular mechanisms that lay beneath the genesis of the gliomas as well as in the testing of curative potentials of various therapeutics. The tumors were induced by intracerebral inoculation of 9L glioma cells and characterized by morphometrical, histological and immunohistochemical analysis after 7, 14 and 21 postimplantation days. Immunohistochemical characterization included detection of the nuclear antigene Ki-67 as the proliferative cell marker, GFAP as a tracer of reactive gliosis surrounding the tumor mass, and CD4/CD8 and ED1 antigens, as markers of the immunological response. Our results showed that after 7 days all experimental animals developed solid, well-circumcised tumors, which were clearly separated from the surrounding brain tissue. Tumors showed progressive growth from the 7th to the 21st day despite the observed immunological response starting after 14 days. Histologically tumors were hypercellular with neovascularization and necrosis. These results indicate that reproducible morphometric evaluation can be performed on 9L tumors growing in immunocompetent Wistar rats, enabling its use as an animal tumor model for the evaluation of various therapeutic approaches.