Embryonic rat dorsal root ganglia organotypic culture: a reliable model to test neurotoxicity

Neurotoxicity is a common dose-limiting side-effect of several drugs. So far a validated test method to screen drugs neurotoxicity does not exist, therefore in this interdepartment study we have analyzed the effectiveness of a neurotoxicty assessment model. Drug neurotoxicity evaluation in this model is based on the ability of NGF exposed embryonic rat dorsal root ganglia (DRG) organotypic culture to grow neurite; in particular the interference of the under study neurotoxic compound with neurite elongation is analysed. The effectiveness and reproducibility of this model , even if commonly used to test drugs , has not yet been demonstrated. In order to assess the validity of this in vitro model, antineoplastic drugs known to be in clinical use and in animal models neurotoxic (paclitaxel and oxaliplatin) or not dangerous (cyclophosphamide and 5-Fluorouracil) have been tested. DRGs explanted from E15 rat embryos have been treated for 24h with drugs concentrations comparable to those achievable in vivo. The length of the longest neurite of each DRG has been measured by ImageJ program. Experiments have been performed by three different blinded researchers in two different laboratories. Mean and standard deviation of each experiment were obtained, subsequently the mean value and standard deviation of the three independent experiments for each researcher were calculated. Data obtained by the three researchers in two different laboratories resulted statistically comparable and no significant differences were detected (One Way Anova analysis of variance and Tukey post test; p<0.05). This interdepartment in vitro study, therefore, indicates that the DRG organotypic culture represents a reliable model to study drug neurotoxicity. The test method permits to make prediction of neurotoxic effects on humans because the concentrations tested are the same to which DRG are exposed during clinical use. This model will allow to reduce animal testing for screening of new drugs and to determine their range of neurotoxic concentrations in the earliest stage of preclinical investigation. Moreover, an overall significant refinement of preclinical modelling in anticancer drug discovery will be achieved. Supported by an unrestricted research grant from Banca del Monte di Lombardia