Transcription Factor‐Based Gene Therapy Enables Functional Repair of Rat Following Chronic Ischemic Stroke

Objective: In vivo transcription factor (TF) ‐mediated gene therapy through astrocyte‐to‐neuron (AtN) conversion has shown therapeutic effects on rodent and non‐human primate cortical ischemic injury in the subacute phase. However, in the clinic, subcortical regions including striatum as well as white matter are vulnerable regions of stroke, with millions of patients beyond subacute phase. In this study, we investigate whether TF‐mediated AtN conversion therapy can be extended to treat chronic‐phase ischemic stroke involving subcortical regions (e.g., striatum) and white matter, beyond cortical injuries. Methods: Rat middle cerebral artery occlusion (MCAO)‐like models were established to induce broad ischemic injuries including cortical and striatal regions. Then multiple rounds of TF‐mediated gene therapy treatments through adeno‐associated virus (AAV) system to cover the large‐scaled infarct areas were conducted in the chronic phase of the stroke models. Magnetic resonance imaging (MRI), [18F] FDG‐PET/CT, behavioral tests, immunohistochemistry and bulk‐RNA seq were applied to evaluate the AtN conversion, tissue repair and functional recovery. Results: Our results revealed that administrated in the chronic phase of ischemic stroke, TF‐mediated gene therapy can efficiently regenerate new neurons in both cortical and striatal regions, and promote tissue repair in both grey and white matter. Compared with single round of AAV administration, multiple rounds of treatment regenerated more neurons and led to a significant functional recovery. Conclusions: Our study demonstrates that TF‐mediated gene therapy has a broad therapeutic time window and can be applied multiple rounds to treat severe ischemic stroke, making it an attractive therapeutic intervention in the chronic phase after stroke, when current approaches are largely ineffective.