The effect of intravenous transplantation of adipose-derived stem cells on hippocampal neurogenesis after 6-hydroxydopamine induced injury

Released dopamine from dopaminergic neurons in the substantia nigra pars compacta affects dentate gyrus (DG) neurogenesis in the hippocampus (HPC). Damage to dopaminergic neurons in Parkinson's disease (PD) causes decreased neurogenesis in DG which results in memory impairment. This was an experimental laboratory study. We assessed the effect of intravenous transplantation of adipose-derived stem cells (ADSCs) on hippocampal neurogenesis after inducing injury by 6-OHDA (memory disability model of PD).We performed bilateral injections of 6-OHDA into substantia nigra (SNc) of male Wistar rats. First group of the rats received bilateral injections of 6-OHDA (6 µg) dissolved in 2µl saline. Second group received saline injections instead of neurotoxin (sham group). In the third group we transplanted the 3rd passage of ADSC cells which had been assessed for CD90 immunostaining (1×106 in 500 μl medium), via tail vein. The 4th group included injured rats which received an injection of the fluid of the culture media (500 µl) through tail vein. After treatment, rats were sacrificed. The brains of the rats were removed, fixed with 4% paraformaldehyde, dehydrated, embedded in paraffin and cut into 10μm thick slices. We stained the sections with cresyl violet and determined the density of neurons in DG, CA1, CA3. Statistical analysis was performed by one-way ANOVA and Tukey test. P≤ 0. 05 was considered significant. Neuron density in DG, CA1, CA3 showed significant decrease in the injured and medium treated groups compared to the sham group (P<0.00). All so we found a significant increase in neuron density in these regions in the cell group in comparison to the medium treated and injured groups (p<0.000). Intravenous injection of ADSCs protected hippocampal neurons from further damage in response to 6-OHDA.Therfore cell therapy can be a suitable method for the improvement of memory impairment in the patients with Parkinson's disease.