Ten‐eleven translocation methylcytosine dioxygenase 3‐loaded microspheres penetrate neurons in vitro causing active demethylation and neurite outgrowth

Epigenetic processes, such as DNA methylation and other chromatin modifications, are believed to be largely responsible for establishing a reduced capacity for growth in the mature nervous system. Ten‐eleven translocation methylcytosine dioxygenase 3 (Tet3)‐, a member of the Tet gene family, plays a crucial role in promoting injury‐induced DNA demethylation and expression of regeneration‐associated genes in the peripheral nervous system. Here, we encapsulate Tet3 protein within a clinically tolerated poly(lactide‐co‐glycolide) microsphere system. Next, we show that Tet3‐loaded microspheres are internalized into mHippoE‐18 embryonic hippocampal cells. We compare the outgrowth potential of Tet3 microspheres with that of commonly used nerve growth factor (NGF)‐loaded microspheres in an in vitro injury model. Tet3‐containing microspheres increased levels of nuclear 5‐hydroxymethylcytosine indicating active demethylation and outperformed NGF‐containing microspheres in measures of neurite outgrowth. Our results suggest that encapsulated demethylases may represent a novel avenue to treat nerve injuries.