Cognitive studies and a direct cell reprogramming protocol for the aging rat brain

LÓPEZ-LEÓN MICAELA; MOREL, GUSTAVO RAMÓN; URIARTE, MAIA; LEHMANN, MARIANNE; GOYA, RODOLFO GUSTAVO

Vancouver

Congreso; 9th Annual Canadian Neuroscience Meeting; 2015

IBRO-Canadian Society for Neuroscience

We use the aging rat (AR) as a model of age-related cognitive decline and plan to use cell reprogramming as a restorative intervention in the hippocampus of AR. We assessed the extent of spatial memory (SM) impairment in 26 months (old) and 29-32 months old (senile) as compared to 4-6 months old (young) female rats as well as the age-related histopathological changes in their dorsal hippocampus. Age changes in SM performance were assessed with a simplified version of the Barnes maze test. We employed two probe trials, one and five days after training, in order to evaluate ?short-term? and ?middle-term? SM. The results revealed that old rats perform better than senile rats in acquisition trials and young rats perform better than both aging groups. Morphological analysis of the dorsal hippocampus showed a marked decrease (94-97%) in doublecortin neuron number in the dentate gyrus in both aging groups and a 40% reduction in vimentin-positive glial cell number in the hilus in the senile but not in the old group. It has been recently demonstrated that transient induction of the four pluripotency genes, Oct4, Sox2, Klf4, and c-Myc (the Yamanaka genes), followed by appropriate signalling inputs, can efficiently transdifferentiate fibroblasts into functional neural stem/progenitor cells (NPC). We report the ongoing construction of a helper-dependent recombinant adenovector for the simultaneous expression of hGFP and the pluripotency genes Oct4, Sox2, Klf4 and c-Myc, all under the control of a bidirectional Tet-Off regulatable promoter. This vector will be used to implement direct cell reprogramming in a non-integrative fashion. We describe the direct reprogramming protocol to be used to convert fibroblasts into NPC, to be subsequently used for experimental cell therapy studies in the hippocampus of aging rats. We conclude that the decline in cognitive performance that occurs in AR is paralleled by a marked reduction in neurogenesis. Regenerative medicine is a promising approach to reverse these changes.