Purpose: Müller glia (MG) in the retina of Xenopus laevis (African clawed frog) reprogram to a transiently amplifying retinal progenitor state after an injury. These progenitors then give rise to new retinal neurons. In contrast, mammalian MG have a restricted neurogenic capacity and undergo reactive gliosis after injury. This study sought to establish MG cell lines from the regeneration-competent frog and the regeneration-deficient mouse.
Methods: MG were isolated from postnatal day 5 GLAST-CreERT; Rbfl/fl mice and from adult (3-5 years post-metamorphic) X laevis. Serial adherent subculture resulted in spontaneously immortalized cells and the establishment of two MG cell lines: murine retinal glia 17 (RG17) and Xenopus glia 69 (XG69). They were characterized for MG gene and protein expression by qPCR, immunostaining, and Western blot. Purinergic signaling was assessed with calcium imaging. Pharmacological perturbations with 2'-3'-O-(4-benzoylbenzoyl) adenosine 5'-triphosphate (BzATP) and KN-62 were performed on RG17 cells.
Results: RG17 and XG69 cells express several MG markers and retain purinergic signaling. Pharmacological perturbations of intracellular calcium responses with BzATP and KN-62 suggest that the ionotropic purinergic receptor P2X7 is present and functional in RG17 cells. Stimulation of XG69 cells with adenosine triphosphate-induced calcium responses in a dose-dependent manner.
Conclusions: We report the characterization of RG17 and XG69, two novel MG cell lines from species with significantly disparate retinal regenerative capabilities.
Translational relevance: RG17 and XG69 cell line models will aid comparative studies between species endowed with varied regenerative capacity and will facilitate the development of new cell-based strategies for treating retinal degenerative diseases.