A NeuroD1 AAV-Based Gene Therapy for Functional Brain Repair after Ischemic Injury through In Vivo Astrocyte-to-Neuron Conversion

• Published in: Molecular therapy Vol. 28; no. 1; pp. 217 - 234
• Main Authors: Chen, Yu-Chen, Ma, Ning-Xin, Pei, Zi-Fei, Wu, Zheng, Do-Monte, Fabricio H., Keefe, Susan, Yellin, Emma, Chen, Miranda S., Yin, Jiu-Chao, Lee, Grace, Minier-Toribio, Angélica, Hu, Yi, Bai, Yu-Ting, Lee, Kathryn, Quirk, Gregory J., Chen, Gong
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 08-01-2020; Elsevier Limited; American Society of Gene & Cell Therapy
• Subjects: AAV; Action Potentials; Amino acids; Animals; Anterograde transport; astrocyte-to-neuron conversion; Astrocytes - metabolism; Axon guidance; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; Beta2 protein; Brain injury; Brain Ischemia - therapy; brain repair; Brain slice preparation; Cellular Reprogramming - genetics; Clinical trials; Cognitive ability; Dependovirus - genetics; Disease Models, Animal; fear conditioning learning; Gene therapy; Genetic Therapy - methods; Glial cells; Ischemia; ischemic injury; Male; Mice; Mice, Transgenic; Morphology; motor function; mRNA; Nerve Degeneration - therapy; NeuroD1; Neurogenesis; Neuroglia - metabolism; Neuronal-glial interactions; Neurons; Neurons - metabolism; Original; Performance evaluation; Rats; Rats, Sprague-Dawley; Retrograde transport; Stroke; Transcription factors; Traumatic brain injury; Treatment Outcome; astrocyte-to-neuron conversion; brain repair; AAV; ischemic injury; gene therapy; motor function; NeuroD1; fear conditioning learning
• ISSN: 1525-0016; 1525-0024
• DOI: 10.1016/j.ymthe.2019.09.003

Adult mammalian brains have largely lost neuroregeneration capability except for a few niches. Previous studies have converted glial cells into neurons, but the total number of neurons generated is limited and the therapeutic potential is unclear. Here, we demonstrate that NeuroD1-mediated in situ astrocyte-to-neuron conversion can regenerate a large number of functional new neurons after ischemic injury. Specifically, using NeuroD1 adeno-associated virus (AAV)-based gene therapy, we were able to regenerate one third of the total lost neurons caused by ischemic injury and simultaneously protect another one third of injured neurons, leading to a significant neuronal recovery. RNA sequencing and immunostaining confirmed neuronal recovery after cell conversion at both the mRNA level and protein level. Brain slice recordings found that the astrocyte-converted neurons showed robust action potentials and synaptic responses at 2 months after NeuroD1 expression. Anterograde and retrograde tracing revealed long-range axonal projections from astrocyte-converted neurons to their target regions in a time-dependent manner. Behavioral analyses showed a significant improvement of both motor and cognitive functions after cell conversion. Together, these results demonstrate that in vivo cell conversion technology through NeuroD1-based gene therapy can regenerate a large number of functional new neurons to restore lost neuronal functions after injury.
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After ischemic brain injury, many neurons die but surviving astrocytes become activated and proliferative. Using NeuroD1 AAV-based gene therapy, Chen and colleagues demonstrate robust neuroregeneration through direct astrocyte-to-neuron conversion and significantly improved functional recovery. This study provides a new paradigm for brain repair using in vivo cell conversion technology.