Abstract
The role of extracellular vesicles (EVs) as signal mediators has been described in many biological fields. How many EVs are needed to deliver the desired physiological signal is yet unclear. Using a normal trabecular meshwork (NTM) cell culture exposed to non‐pigmented ciliary epithelium (NPCE)–derived EVs, a relevant model for studying the human ocular drainage system, we addressed the EVs dose–response effects on the Wnt signaling. The objective of the study was to investigate the dosing effects of NPCE‐derived EVs on TM Wnt signaling. EVs were isolated by PEG 8000 method from NPCE and RPE cells (used as controls) conditioned media. Concentrations were determined by Tunable Resistive Pulse Sensing method. Various exosomes concentration were incubated with TM cells, for the determination of mRNA (β‐Catenin, Axin2 and LEF1) and protein (β‐Catenin, GSK‐3β) expression using real‐time quantitative PCR and Western blot, respectively. Exposure of NTM cells for 8 hrs to low EVs concentrations was associated with a significant decreased expression of β‐Catenin, GSK‐3β, as opposed to exposure to high exosomal concentrations. Pro‐MMP9 and MMP9 activities were significantly enhanced in NTM cells treated with high EV concentrations of (X10) as compared to low EV concentrations of either NPCE‐ or RPE‐derived EVs and to untreated control. Our data support the concept that EVs biological effects are concentration‐dependent at their target site. Specifically in the present study, we described a general dose–response at the gene and MMPs activity and a different dose–response regarding key canonical Wnt proteins expression.
Highlights
extracellular vesicles (EVs) are nanoscale secreted membrane vesicles, derived from the luminal membrane of multivesicular bodies (MVBs)
A possible pathway of communication between non-pigmented ciliary epithelium (NPCE) cells and normal trabecular meshwork (NTM) cells in the drainage system of the eye is by uptake of EVs by the target cells [12]
EVs secreted from NPCE cells are assumed to be released to the ocular anterior and posterior chambers, through the aqueous humour, and enter into NTM cells [13]
Summary
EVs are nanoscale secreted membrane vesicles, derived from the luminal membrane of multivesicular bodies (MVBs). Following the fusion of the MVBs with the cell membrane, these vesicles are released to the extracellular medium [1]. It is well accepted that beyond the classical secretory and exocytic pathways, EVs in general and exosomes in particular play an important role in cell:cell communications [3]. EVs function in normal physiology maintaining general homeostasis, and are part of the cell response under disease pathogenesis. Researchers have successfully demonstrated the ability of EVs to manipulate recipient cells in close and distant tissues by the delivery of their biological cargo [4]. EVs are capable to deliver biological messages by releasing active ligands from their surface or adhere and activate the recipient cells receptors [5]
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