Effect of Sei and Fin whale Müller glia in the survival and neurite growth of RGCs in vitro

Abstract

AbstractPurposeMüller cells are crucial in retinal homeostasis. In zebrafish and lower vertebrates, spontaneous retinal regeneration was observed. In the mammalian retina, there is no such evidence. However, recent studies have been demonstrated that Müller cells promote the survival and the neurite outgrowth of RGCs in vitro. Here, the effect of Müller cells from two of the largest mammals in the world, Fin and Sei whales, was analyzed on RGCs survival and neurite outgrowth.MethodsThe retinas of beached Balaenoptera physalus and Balaenoptera borealis whales, 24 hr post‐mortem, were studied. Cultures of Müller cells were grown and, once whale Müller cells reached confluence, adult rat RGCs were seeded on Müller cells. The cells were cultured during six days. The number and length of the neurites of the RGCs were quantified. The conditioned media (CM) from whale Müller cells was analysed by mass spectrometry to identify and quantify proteins. Results were compared to the CM from pig Müller cells. NELL2, SEMA3F, CD56, NRCAM, OGN and PEDF were selected as candidate factors to promote neurite outgrowth and tested in pure rat RGCs cultures.ResultsRGCs survival increased 60% when cultured with whale Müller cells. The length of the neurites (>200 μm) increased 90% and the length of the longest neurites (>1000 μm) increased more than 500%. Proteomic analysis from whale Müller cells CM showed that the function of the 10% of the most represented proteins detected was related to neurite outgrowth, compared to only 2% of the proteins in pig CM. The selected proteins induced an increase in the percentage of RGCs with long neurites (>200 μm) and an increase of 200% in RGCs with very long neurites (>1000 μm).ConclusionsWhale Müller cells increase RGCs neurite growth, suggesting that whale Müller cells secrete a combination of neurotrophic factors promoting regeneration of RGCs. Besides, the selected proteins from the CM increase neurite outgrowth, confirming the capacity of the factors secreted by whale Müller cells to regenerate RGCs.Supported by ELKARTEK (KK‐2019/00086), MINECO‐Retos (PID2019‐111139RB‐I00) Grupos UPV/EHU (GIU2018/50).