The impact of timing and injury mode on induced neurogenesis in the adult mammalian retina.

Regeneration of neurons has important implications for human health, and the retina provides an accessible system to study the potential of replacing neurons following injury. In previous work, we generated transgenic mice in which neurogenic transcription factors were expressed in Müller glia (MG) and showed that they stimulated neurogenesis following inner retinal damage. It was unknown, however, whether the timing or mode of injury mattered in this process. Here, we explored these parameters on induced neurogenesis from MG and show that MG expressing Ascl1 will generate new bipolar neurons with similar efficiency irrespective of injury mode or timing. However, MG that express Ascl1-Atoh1 produce a new type of retinal ganglion-like cell after outer retinal damage, which is absent with inner retinal damage. Our data suggest that although cell fate is primarily dictated by neurogenic transcription factors, the inflammatory state of MG relative to injury can influence the outcome of induced neurogenesis.

A multiplexed, single-cell sequencing screen identifies compounds that increase neurogenic reprogramming of murine Muller glia.

Retinal degeneration in mammals causes permanent loss of vision, due to an inability to regenerate naturally. Some non-mammalian vertebrates show robust regeneration, via Muller glia (MG). We have recently made significant progress in stimulating adult mouse MG to regenerate functional neurons by transgenic expression of the proneural transcription factor Ascl1. While these results showed that MG can serve as an endogenous source of neuronal replacement, the efficacy of this process is limited. With the goal of improving this in mammals, we designed a small molecule screen using sci-Plex, a method to multiplex up to thousands of single nucleus RNA-seq conditions into a single experiment. We used this technology to screen a library of 92 compounds, identified, and validated two that promote neurogenesis in vivo. Our results demonstrate that high-throughput single-cell molecular profiling can substantially improve the discovery process for molecules and pathways that can stimulate neural regeneration and further demonstrate the potential for this approach to restore vision in patients with retinal disease.