Abstract TP254: Reduction Of Behavior Deficits Following Delivery Of Sox2 To Stroke Rats Using Mixed-Surface PAMAM Dendrimer Nanomolecules

A major drawback of current stroke treatment strategies (such as the use of tPA) includes time sensitivity to achieve maximum therapeutic efficacy. Alternative treatments include less time-sensitive approaches and utilize in vivo reprogramming of resident reactive astrocytes to repopulate the lost neurons in sufficient numbers. In this study, we tested whether a transcription factor, hSOX2, when expressed under a glial cell-specific GFAP promoter, could sufficiently reprogram astrocytes in and around the infarct to enhance their differentiation into neurons. To achieve delivery of the hSOX2 gene, we utilize PAMAM dendrimers, which are nanomolecules with a well-established capacity of delivering drugs/ large biomolecules to the brain across the BBB and confer intrinsic anti-inflammatory properties. Dendrimers are comprised of an interior dendritic structure with modifiable sizes, and an exterior surface with functional surface groups. The G4 PAMAM dendrimers used in this study has 10% of the surface covered with amine groups and 90% of the surface covered with hydroxyl groups (G4-90/10). These dendrimers are less toxic and readily form complexes with plasmids up to 14 kb in size (dendriplex) and successfully deliver cargo in vitro and in vivo . Four days following stroke inductions in Sprague Dawley rats via MCAo, the hSOX2 dendriplex was injected into the ipsilateral corpus callosum. A battery of behavior tests, such as cylinder and ladder tasks, were used to assess motor abilities of the treated and untreated stroked and sham-operated control rats. Moreover, the animals underwent In vivo Imaging System to confirm the presence of dendriplex in the brain. Five weeks following the injections, the brains were collected and processed, using immunohistochemistry, to detect the complex and measure the amount of hSOX2 gene expression. The size of the brain infarct was measured using the conventional H&E staining. Our results indicated that the dendrimers were able to deliver the hSOX2 gene to the stroke brain and this significantly reduced motor deficits, relative to untreated stroked rats. These results indicated that PAMAM dendrimers effectively deliver genes into the brain and that the hSOX2 gene can successfully reduce motor deficits following stroke.