Nerve Growth Factor Receptor Expression in Heterotransplanted Vestibular Schwannoma in Athymic Nude Mice

Nerve growth factor (NGF) has the potential to induce cellular differentiation in various neoplastic and non-neoplastic cell lines. the purpose of the present study was to determine by immunohistochemistry: the presence/distribution of nerve growth factor receptor (NGFr), cellular proliferation expressed by Ki-67, and intratumoral vascularization visualized by the endothelial marker CD 31, in a series of 61 human vestibular schwannoma heterotransplants in athymic nude mice. the immunohistochemical results were correlated to the observed macroscopic growth in 22 heterotransplants (36%) with obvious macroscopic growth, versus 39 heterotransplants (64%) that were stationary or regressed. the positive immunore-activity to NGFr, number of Ki-67 positive nuclei and number of intratumoral vessels were significantly higher in the 22 (36%) growing heterotransplants than in the 39 heterotransplants (64%), which were stationary or regressed (p < 0.00005, p =0.046, p < 0.00001). NGFr was statistically related to the vascularity of the heterotransplants expressed by CD 31 (p < 0.00001). No significant relation was observed between NGFr and the proliferation, as estimated by Ki-67. the results revealed that the macroscopic growth of VS in athymic nude mice was associated with strong positive expression of NGFr, high cellular proliferation expressed by Ki-67 and vivid neovascularization expressed by CD 31. the possible clinical applicability of the achieved results is discussed.