Xenopus retinal regeneration is full of surprises: activation of 3 types of stem-like cells and generation of a retinal organoid in vivo.
Xenopus retinal regeneration is full of surprises: activation of 3 types of stem-like cells and generation of a retinal organoid in vivo The study focuses on the variability in regenerative abilities across different animal species and, more specifically, explores the diverse modalities involved in retinal repair. In this context, Parain et al. have characterized a novel retinal degenerative model in Xenopus based on neurotoxic damage induced by CoCl2 intraocular injections. They showed that three different cellular sources could concomitantly be recruited for retinal regeneration: ciliary marginal zone (CMZ) stem cells, retinal pigmented epithelial (RPE) cells, or Müller glia. Remarkably, the RPE undergoes reprogramming and self-organizes, as an in vivo organoid, into a mini-retina on top of the original one. Although this is quite spectacular in terms of tissue regeneration, it makes the restoration of vision very unlikely. Surprisingly, the data also highlight that Müller glia cells regenerate several types of neurons, but not cones, despite being the most affected cell type in this injury paradigm. Finally, the data reveal that X. tropicalis, whose retinal regeneration was previously thought to primarily rely on the stem cells from the CMZ, can also effectively reactivate its Müller cells and undergo RPE reprogramming in the context of CoCl2-induced neurotoxicity.
Altogether, these findings highlight the critical role of the injury paradigm in determining the activation of different stem-like cell populations in Xenopus and reveal that regeneration occurs without a bias towards lost cells.
Regeneration from three cellular sources and ectopic mini-retina formation upon neurotoxic retinal degeneration in Xenopus. Karine Parain, Albert Chesneau, Morgane Locker, Caroline Borday, Muriel Perron