Thrombospondin 1‐induced exosomal proteins attenuate hypoxia‐induced paraptosis in corneal epithelial cells and promote wound healing

Abstract

Thrombospondin‐1 (TSP1) is involved in corneal wound healing caused by chemical injury. Herein, we examined the effects of TSP1 on hypoxia‐induced damages and wound‐healing activity in human corneal epithelial (HCE) cells. Exosomal protein expression was determined using liquid chromatography‐tandem mass spectrometry, and HCE cell migration and motility were examined through wound‐healing assay and time‐lapse microscopy. Reestablishment of cell junctions by TSP1 was assessed through confocal microscopy and 3D image reconstruction. Our results show that CoCl2‐induced hypoxia promoted HCE cell death by paraptosis. TSP1 protected these cells against paraptosis by attenuating mitochondrial membrane potential depletion, swelling and dilation of endoplasmic reticulum and mitochondria, and mitochondrial fission. Exosomes isolated from HCE cells treated with TSP1 contained wound healing‐associated proteins that were taken up by HCE cells to promote tissue remodeling and repair. TSP1 protected HCE cells against hypoxia‐induced damages and inhibited paraptosis progression by promoting cell migration, cell‐cell adhesion, and extracellular matrix remodeling. These findings indicate that TSP1 ameliorates hypoxia‐induced paraptosis in HCE cells and promotes wound healing and remodeling by regulating exosomal protein expression. TSP1 may, therefore, play important roles in the treatment of hypoxia‐associated corneal diseases.

Extracellular Vesicles in Corneal Fibrosis/Scarring

“…More recently, our laboratory found that epithelial-EVs released by corneal epithelial cells encapsulate provision matrix proteins that triggers corneal fibroblast to myofibroblast differentiation, while also contributing to elevated contractility, proliferation, and migration [ 20 ]. In a similar study, it was shown corneal epithelial-EVs have the capacity to influence the transdifferentiation of human conjunctival and corneal epithelial cells [ 124 ], or EVs pre-treated with thrombospondin-1 promoted tissue remodeling and repair [ 125 ]. More recently, our study examined the paracrine crosstalk from the corneal stromal (keratocytes, fibroblasts, and myofibroblasts) EVs and how they influence corneal epithelial wound healing [ 23 ].…”

Recent Advancements in Molecular Therapeutics for Corneal Scar Treatment

“…They were subjected to the same hypoxic stress encountered in corneal wound healing. Exosomes with TSP-1 as a cargo protein decrease paraptosis (apoptosis caused by hypoxic conditions) [ 57 ]. EVs derived from human placenta mesenchymal stem cells were used to treat alkali-burned mouse corneas.…”

Corneal Epithelial Stem Cells–Physiology, Pathophysiology and Therapeutic Options

“…[ 290 ]. Another study reported that thrombospondin-1 ameliorated hypoxia-induced paraptosis and promoted wound healing and remodeling by regulating exosomal protein expression in human corneal epithelial cells [ 291 ]. However, exosomes derived from antigen presenting cells, such as dendritic cells and B lymphocytes, can carry major histocompatibility complex class I and II molecules on the surface, which can induce stronger antigen-specific immune responses [ 292 ].…”