Effect of melatonin‐induced exosomes on proregenerative and antifibrotic pathways involved in corneal scarring

Abstract

Aims/Purpose: Melatonin is a time‐and‐concentration dependent pro and antiinflammatory agent that also regulates cell proliferation, migration, angiogenesis, fibrosis, and extracellular matrix synthesis. This study aims to assess the effect of exosomes obtained from melatonin‐treated human limbal mesenchymal stem cells (hLMSCs) on naive hLMSCs and ascertain their influence on antifibrotic and proregenerative pathways involved in corneal scarring.Methods: hLMSCs were harvested from the eye bank of Eskişehir Osmangazi University Hospital and were subsequently isolated and characterized. We then treated hLMSCs (Mel‐treated hLMSCs) with varying concentrations of melatonin followed by isolation and characterization of the procured exosomes. These exosomes were added to enrich cell culture media of naïve hLMSCs (Mel‐exo‐treated hLMSCs) to examine their antifibrotic and proregenerative effects. The expression of miR155, miR29 Transforming Growth Factor Beta 1 (TGFβ1), TGFβ3, Peroxisome Proliferator‐Activated Receptor Gamma (PPARγ), and Alpha‐Smooth Muscle Actin (α‐SMA) miRNA and genes were compared between Mel‐treated hLMSCs and Mel‐exo‐treated hLMSCs by using Real‐Time PCR.Results: TGFβ3 expression increased dramatically in response to Mel‐exo, while the increase in TGFβ1 expression was only minimal in correlation with levels of miR155 expression. Likewise, PPARγ expression was increased while an inhibition was observed in α‐SMA expression and miR29 expression in Mel‐exo‐treated hLMSCs compared to Mel‐treated hLMSCs.Conclusions: Melatonin treatment of hLMSCs resulted in expression of exosomes that could drive naïve hLMSCs in favour of antifibrotic and proregenerative effects as evidenced by higher TGFβ3 and PPARγ expressions and inhibition of α‐SMA. This approach could prove beneficial in cornea and ocular surface tissue engineering applications.The authors acknowledge the support from Eskisehir Osmangazi University, Scientific Research Projects (Grant ID: TOA‐2022‐2458).