Biophysical, Molecular and Proteomic profiling of Human Retinal Organoids derived Exosomes

Extracellular vesicles (EVs) are phospholipid bilayer-bound particles released by cells that play a role in cell-cell communication, signal transduction, and extracellular matrix remodeling. There is a growing interest in EVs for ocular applications as therapeutics, biomarkers, and drug delivery vehicles. EVs secreted from mesenchymal stem cells (MSCs) have shown to provide therapeutic benefits in ocular conditions. However, very little is known about the properties of bioreactors cultured-3D human retinal organoids secreted EVs. This study provides a comprehensive morphological, nanomechanical, molecular, and proteomic characterization of retinal organoid EVs and compares it with human umbilical cord (hUC) MSCs. Nanoparticle tracking analysis indicated the average size of EV as 100–250 nm. Atomic force microscopy showed that retinal organoid EVs are softer and rougher than the hUCMSC EVs. Gene expression analysis by qPCR showed a high expression of exosome biogenesis genes in late retinal organoids derived EVs (>120 days). Immunoblot analysis showed highly expressed exosomal markers Alix, CD63, Flotillin-2, HRS and Hsp70 in late retinal organoids compared to early retinal organoids EVs (<120 days). Protein profiling of retinal organoid EVs displayed a higher differential expression of retinal function-related proteins and EV biogenesis/marker proteins than hUCMSC EVs, implicating that the use of retinal organoid EVs may have a superior therapeutic effect on retinal disorders. This study adds supplementary knowledge on the properties of EVs secreted by retinal organoids and suggests their potential use in the diagnostic and therapeutic treatments for ocular diseases. ### Competing Interest Statement The authors have declared no competing interest.