Neuroprotective Impact of Müller Glia-Derived Microvesicles on Retinal Ganglion Cells Under High Pressure Conditions

Abstract

Purpose : The partnership between glial cells and neurons is crucial for maintaining inner retinal homeostasis, and any disruptions may lead to the death of retinal ganglion cells (RGCs). Müller Glia (MG) have the ability to shield against the excitotoxic effects of glutamate and promote the survival and neuritogenesis of RGCs. This support is triggered by anatomical interactions but also through the secretion of factors and it is possible that extracellular vesicles (EVs), particularly microvesicles (MVs), play a significant role in this interaction. These vesicles contain bioactive molecules that induce functional changes when internalized by recipient cells. The main objective is to elucidate the role of MG-derived MVs in the survival of RGCs under conditions of high pressure (HP).

Methods : Primary cultures of MG and RGCs were subjected to HP to simulate elevated intraocular pressure. Primary MG were cultured under atmospheric (control) pressure, and conditioned media (CM) was collected. Subsequently MVs were isolated from MG-derived CM through low-speed ultracentrifugation. The contained proteins in MVs were also characterized by mass spectrometry. Primary RGC cultures were then exposed to HP in the presence of MVs to assess cell survival. The impact of MG-derived MVs on rat retinas was evaluated 15 days after intravitreal injection of MG-derived MVs in an in vivo glaucoma model.

Results : Under HP conditions, the survival of RGCs decreases to 21.64±3.87%, whereas MG-derived MVs were found to significantly elevate the number of viable RGCs to 80.20±6.80%, reaching levels comparable to those in control cultures (100±6.58%). Proteomic analysis of the MVs revealed the enrichment of specific proteins that directly contribute to the survival and adaptability of neurons. This neuroprotective impact was validated in an in vivo glaucoma model, preventing the death of RGCs, increasing RGCs survival from 57.45±2.01% to 86.61±5.44%, compared to the contralateral eye (100±3.24%) as the control condition.

Conclusions : The results clearly indicate that MVs derived from MG can shield RGCs when exposed to HP, underscoring the significance of MVs within the secretome of MG for RGCs survival. The specific emphasis on understanding the interactions between MG and RGCs, given their potential therapeutic implications, emerges as a pivotal strategy to prevent neurodegenerative diseases like glaucoma.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.