Chemerin and NPC2 produced from iPSC-derived Müller glial cells promote retinal ganglion cell regeneration

Müller glial cells (MGCs), non-neuronal retinal cells, have a role in supporting retinal ganglion cells (RGCs) and are a potential therapeutic target for retinal nerve diseases such as glaucoma. Here we analyzed the characteristics of induced MGCs (iMGCs) differentiated from human induced pluripotent stem cells (hiPSCs) and investigated the therapeutic potential of proteins secreted by iMGCs. Early developmental iMGCs were generated from hiPSCs. RNA-sequencing was performed on iMGCs, and the gene expressions were compared with those of human primary MGCs (pMGCs). Chemerin and NPC2, proteins identified from the conditioned medium of iPSC-derived retinal organoid, were added to iPSC-derived optic vesicles to evaluate their effects on RGC axon elongation. Chemerin and NPC2 produced from iMGCs were quantified using ELISA. Each protein was added to rat RGC transplantation to retinal explants, and the number of RGC with neurite was counted. Finally, chemerin and NPC2 were added to rat primary retinal cells under hypoxia/reoxygenation conditions, and the number of survived RGCs was counted. Transcriptome analysis of early-stage iMGCs showed common characteristics with pMGCs. Chemerin and NPC2 were found to promote RGC axon elongation and confirmed to be secreted from iMGCs. Furthermore, the addition of these proteins increased the number of RGCs with neurites in ex vivo transplantation and inhibited RGC death under hypoxia/reoxygenation conditions. This study demonstrated that chemerin and NPC2 were secreted from iMGCs and promoted RGC survival and axon elongation. These proteins may be future drug candidates for retinal regeneration.