An optimized animal model of lysolecithin induced demyelination in optic nerve; more feasible, more reproducible, promising for studying the progressive forms of multiple sclerosis

Background: Multiple Sclerosis (MS) is a demyelinating disease leading to long-term neurological deficit due to unsuccessful remyelination and axonal loss. Currently, there are no satisfactory treatments for progressive MS somewhat due to the lack of an adequate animal model for studying the mechanisms of disease progression and screening new drugs. New method: Lysolecithin (LPC) or agarose-gel loaded LPC (AL-LPC) were applied to mouse optic nerve behind the globe via a minor surgery. Agarose loading was used to achieve longer time of LPC exposure and subsequently long-lasting demyelination. Results: The lesion sites characterized by luxol fast blue (LFB), FluoroMyelin, Bielschowsky?s staining, and immunostaining showed extensive demyelination and axonal damage. The loss of Retinal ganglion cells (RGCs) in the corresponding retinal layer was shown by immunostaining and H&E staining. Visual evoked potential (VEP) recordings showed a significant increase in the latency of the P1 wave and a decrease in the amplitude of the P1N1 wave. Comparison with existing methods: The new approach with a very minor surgery seems to be more feasible and reproducible compared to stereotaxic LPC injection to optic chiasm. Our data revealed prolonged demyelination, axonal degeneration and RGCs loss in both AL-LPC and LPC groups; however, these pathologies were more extensive in the AL-LPC group. Conclusion: The optimized model provides a longer demyelination time frame and axonal damage followed by RGC degeneration; which is of exceptional interest in investigating axonal degeneration mechanisms and screening the new drugs for progressive MS.