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

## TL;DR

This study shows that gene therapy using transcription factors can repair brain damage from chronic stroke in rats, even when treatment starts late.

## Contribution

The study extends TF-based gene therapy to chronic-phase subcortical stroke and demonstrates functional recovery through multiple treatment rounds.

## Key findings

- Multiple rounds of TF-mediated gene therapy regenerate neurons in cortical and striatal regions during chronic stroke.
- The therapy promotes tissue repair in grey and white matter and reduces scar formation.
- Functional recovery is significantly improved compared to single treatment rounds.

## Abstract

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.

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.

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.

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.

Multiple rounds of transcription factor‐based gene therapy can efficiently regenerate neurons in a large‐scale rat ischemic stroke model in the chronic phase, rescue tissue atrophy, reduce scar formation, promote the recovery of neurovascular units, repair the white matter, and enhance functional recovery of the brain.