Inhibition of VEGF-A expression in hypoxia-exposed fetal retinal microvascular endothelial cells by exosomes derived from human umbilical cord mesenchymal stem cells

: Objective: This study aimed to investigate the potential of human umbilical cord mesenchymal stem cell (hucMSC)-derived exosomes (hucMSC-Exos) in inhibiting hypoxia-induced cell hyper proliferation and overexpression of vascular endothelial growth factor A (VEGF-A) in immature human fetal retinal microvascular endothelial cells (hfRMECs). Methods: Exosomes were isolated from hucMSCs using cryogenic ultracentrifugation and characterized through various techniques, including transmission electron microscopy, nanoparticle tracking analysis, bicinchoninic acid assays, and western blotting. The hfRMECs were identi fi ed using von Willebrand factor (vWF) co-staining and divided into four groups: a control group cultured under normoxic condition, a hypoxic model group, a hypoxic group treated with low-concentration hucMSC-Exos (75 μ g/mL) and a hypoxic group treated with high-concentration hucMSC-Exos (100 μ g/mL). Cell viability and proliferation were assessed using Cell Counting Kit-8 (CCK-8) assay and EdU (5-ethynyl-2 ′ -deoxyuridine) assay respectively. Expression levels of VEGF-A were evaluated using RT-PCR, western blotting and immuno fl uorescence. Results: Hypoxia signi fi cantly increased hfRMECs ’ viability and proliferation by upregulating VEGF-A levels. The administration of hucMSC-Exos effectively reversed this response, with the high-concentration group exhibiting greater ef fi cacy compared to the low-concentration group. Conclusion: In conclusion, hucMSC-Exos can dose-dependently inhibit hypoxia-induced hyperproliferation and VEGF-A overexpression in immature fetal retinal microvascular endothelial cells.