Environmental impact on direct neuronal reprogramming in vivo in the adult brain

Abstract

Direct reprogramming of non-neuronal cells to generate new neurons is a promising approach to repair damaged brains. Impact of the in vivo environment on neuronal reprogramming, however, is poorly understood. Here we show that regional differences and injury conditions have significant influence on the efficacy of reprogramming and subsequent survival of the newly generated neurons in the adult rodent brain. A combination of local exposure to growth factors and retrovirus-mediated overexpression of the neurogenic transcription factor Neurogenin2 can induce new neurons from non-neuronal cells in the adult neocortex and striatum where neuronal turnover is otherwise very limited. These two regions respond to growth factors and Neurogenin2 differently and instruct new neurons to exhibit distinct molecular phenotypes. Moreover, ischaemic insult differentially affects differentiation of new neurons in these regions. These results demonstrate strong environmental impact on direct neuronal reprogramming in vivo. A combination of growth factors and the transcription factor Neurogenin2 has been shown to enhance the production of new neurons from endogenous cells. Here Grandeet al.demonstrate in a rat brain injury model that these factors reprogramme non-neuronal cells into different neuronal phenotypes at distinct efficiencies depending on the environment the cells reside in.