Exploring the role of Müller cells-derived exosomes in diabetic retinopathy

• Published in: Microvascular research Vol. 154; p. 104695
• Main Authors: Gad, Mohamed S., Elsherbiny, Nehal M., El-Bassouny, Dalia R., Omar, Nesreen M., Mahmoud, Safinaz M., Al-Shabrawey, Mohamed, Tawfik, Amany
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2024
• Subjects: Barrier function; Diabetic retinopathy; Endothelial cells; Exosomes; Müller cells; Diabetic retinopathy; Müller cells; Exosomes; Barrier function; Endothelial cells
• ISSN: 0026-2862; 1095-9319; 1095-9319
• DOI: 10.1016/j.mvr.2024.104695

Exosomes are nanosized vesicles that have been reported as cargo-delivering vehicles between cells. Müller cells play a crucial role in the pathogenesis of diabetic retinopathy (DR). Activated Müller cells in the diabetic retina mediate disruption of barrier integrity and neovascularization. Endothelial cells constitute the inner blood-retinal barrier (BRB). Herein, we aim to evaluate the effect of Müller cell-derived exosomes on endothelial cell viability and barrier function under normal and hyperglycemic conditions. Müller cell-derived exosomes were isolated and characterized using Western blotting, nanoparticle tracking, and electron microscopy. The uptake of Müller cells-derived exosomes by the human retinal endothelial cells (HRECs) was monitored by labeling exosomes with PKH67. Endothelial cell vitality after treatment by exosomes under normo- and hypoglycemic conditions was checked by MTT assay and Western blot for apoptotic proteins. The barrier function of HRECs was evaluated by analysis of ZO-1 and transcellular electrical resistance (TER) using ECIS. Additionally, intracellular Ca+2 in HRECs was assessed by spectrofluorimetry. Analysis of the isolated exosomes showed a non-significant change in the number of exosomes isolated from both normal and hyperglycemic condition media, however, the average size of exosomes isolated from the hyperglycemic group showed a significant rise when compared to that of the normoglycemic group. Müller cells derived exosomes from hyperglycemic condition media markedly reduced HRECs cell count, increased caspase-3 and Annexin V, decreased ZO-1 levels and TER, and increased intracellular Ca+ when compared to other groups. However, treatment of HRECs under hyperglycemia with normo-glycemic Müller cells-derived exosomes significantly decreased cell death, preserved cellular integrity and barrier function, and reduced intracellular Ca+2. Collectively, Müller cell-derived exosomes play a remarkable role in the pathological changes associated with hyperglycemia-induced inner barrier dysfunction in DR. Further in vivo research will help in understanding the role of exosomes as therapeutic targets and/or delivery systems for DR.