TRANsCre-DIONE transdifferentiates scar-forming reactive astrocytes into functional motor neurons

Abstract

In spinal cord injury (SCI), the scar-forming reactive astrocytes with upregulated glial fibrillary acidic protein (GFAP) proliferate aberrantly near the injury site, representing a potential cellular source for transdifferentiation into neurons to replenish dead neurons. However, the conventional use of GFAP promoter to target reactive astrocytes has two inherent problems: inadvertent conversion of normal astrocytes and low efficiency due to progressive weakening of promoter activity during transdifferentiation. Here, we present TRANsCre-DIONE, a dual-promoter split-Cre system combining GFAP and Lcn2 regulatory elements with Cre-dependent Neurog2 expression under the EF1α promoter, enabling selective targeting of scar-forming reactive astrocytes. This approach achieved 87% conversion efficiency and 96% specificity in vivo. After SCI, TRANsCre-DIONE caused transdifferentiation into Isl1-positive and ChAT-positive motor neurons, reduced astrogliosis, enhanced regeneration in surrounding cells, and a significant motor recovery. These findings suggest that TRANsCre-DIONE enables efficient and selective astrocyte-to-neuron conversion and represents a promising strategy for SCI repair. Spinal cord injuries often lead to irreversible neuronal damage and limited treatment options, primarily focussing on symptom management. This study explores a novel approach to neuronal regeneration by transdifferentiating reactive astrocytes into neurons using a genetic tool called TRANsCre-DIONE. The method uses a split-Cre system with specific promoters to target reactive astrocytes, expressing the transcription factor Neurog2 to induce neuronal conversion. The study demonstrates that this approach can effectively convert reactive astrocytes into functional neurons in both mouse and monkey models, significantly improving motor function in spinal cord injury models. The findings highlight the potential of Neurog2 to generate region-specific neurons, such as GABAergic neurons in the striatum and motor neurons in the spinal cord, without tumorigenic risks. This research suggests a promising direction for future therapies targeting neuronal regeneration in spinal cord injuries and other neurodegenerative conditions. "This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author."