GFP Adeno-associated virus(AAV Serotype 6)

Genomic screened homeobox 1 (Gsx1 or Gsh1), a neurogenic transcription factor required for the generation of excitatory and inhibitory interneurons during spinal cord development. In adult mice, lentivirus (LV)-mediated expression of Gsx1 promotes neural regeneration and functional locomotor recovery in a mouse model of lateral hemisection spinal cord injury (SCI). LV delivery approaches are clinically unsafe due to insertional mutagenesis of host DNA. Here, researchers found that adeno-associated virus serotype 6 (AAV6) preferentially infects neural stem/progenitor cells (NSPCs) in the injured spinal cord. Using a rat contusive SCI model, researchers demonstrated that AAV6-mediated expression of Gsx1 promoted neurogenesis, increased the number of neuroblasts/immature neurons, restored excitatory/inhibitory neuronal balance and serotonergic neuronal activity through the lesion core, and promoted locomotor functional recovery. These findings support the preferential targeting of AAV6 to NSPCs for gene delivery and confirm that Gsx1 is effective in a clinically relevant rat model of contusion SCI.

Here, researchers studied the effects of Gsx1 on reactive gliosis and glial scar formation at 14 days post-injury (14 dpi) and 56 dpi. The distribution of GFAP signal at 14 dpi was most evident in undamaged neural tissue near the lesion site, and astrocytes were significantly elongated and began to form glial scars (Figure 1a). AAV6-Gsx1 reduced reactive gliosis (GFAP/total cells) compared with AAV6-GFP control at 14 dpi (Figure 1b). The CS56 signal distribution at 56 dpi was diffuse, occurring most densely at the scar border at the edge of the lesion core but spreading 2 mm anterior/caudal to the lesion (Figure 1c). AAV6-Gsx1 reduced CSPG deposition compared with the AAV6-GFP control at 56 dpi (Figure 1d). GFAP distribution formed a clear dense border around the injury site, and the diffuse signal spread to 0.5–1 mm from the injury scar border (Figure 1e). AAV6-Gsx1 also reduced glial scar border astrocyte density compared with AAV6-GFP controls at 56 dpi (Figure 1f). Interestingly, LV-Gsx1-GFP did not significantly reduce reactive gliosis at 14 dpi (Figure 1b), CSPGs (Figure 1d) and astrocyte density (Figure 1f) at 56 dpi compared with the AAV6-GFP control, however displayed a trend toward glial scar reduction. These results indicate that AAV6-Gsx1 reduces astrocyte populations during reactive gliosis and scar border maturation.

Figure 1. Gsx1 reduces reactive gliosis and glial scar formation in subacute and chronic SCI. (Finkel Z, et al., 2024)