Effect of Methyl Mercury on the Cerebellar Cortex of Rats and the Possible Neuroprotective Role of Mesenchymal Stem Cells Conditioned Medium. Histological and Immunohistochemical Study

BACKGROUND: Methyl mercury (Me Hg) is an environmental toxin associated with many serious neurological disorders. Conditioned Medium (CM) derived from Mesenchymal Stem Cells (MSCs) is a novel promising approach for the treatment of nervous system damage and various diseases. OBJECTIVE: The aim of this research is to assess the consequence of Me Hg on the rats’ cerebellar cortex and the potential neuroprotective effect of MSCs – CM. MATERIALS AND METHODS: Forty adult male albino rats were divided into four groups: Group I: control rats; Group II: Me Hg chloride treated rats; Group III: Me Hg chloride and DMEM treated rats; Group IV: CM treated rats after injection with Me Hg chloride. Cerebellar specimens were taken and handled for histological and immunohistochemical techniques. Morphometrical studies and statistical analysis were performed. RESULTS: Groups II and III showed various changes such as neuronal degeneration and apoptosis. The mean number of Purkinje cells was significantly decreased (P<0.01), while Glial Fibrillary Acidic Protein (GFAP) immunostaining was significantly increased (P<0.01) in the neuroglial cells. Ultrastructural examination showed thinning and apparent decrease in the number of myelinated nerve axons. Shrunken Purkinje cells were observed with irregular nuclei, heterogenous cytoplasm, and disrupted mitochondria. Group IV showed improvement of the histological and electron microscopic changes defined in groups II and III. CONCLUSION: Me Hg exposure led to degenerative changes on cerebellar cortex. MSCs – CM is a very promising approach and has neuroprotective effects.