Mesenchymal stem cells rescue corneal epithelial cells from rotenone-induced mitochondrial damage via intercellular mitochondrial transfer

Abstract

PURPOSE: Our recent studies have demonstrated that direct mitochondrial transfer from mesenchymal stem cells (MSCs) can rescue damaged airway epithelial cells in lung disease. Hence, we hereby ask if mitochondrial (Mt) transfer of MSCs could repair mitochondrial dysfunction of rabbit corneal epithelial cells (RCECs). In order to examine the roles and mechanisms involved in mitochondrial transfer from MSCs to protect epithelial cells against mitochondrial damage, we demonstrated efficient Mt transfer from MSCs into RCECs via tunneling nanotubes (TNT), and examined the functional improvement and protection resulting from such Mt uptake in RCECs. METHODS: TNT formation of RCECs under rotenone (rot) induced Mt stress-induction was examined by light and fluorescence microscopy as well as scanning electron microscopy after co-cultivation with MSCs and control skin fibroblast cells (SFCs). To determine the function of the intercellular mitochondria transfer, we also studied the extracellular oxygen consumption rate (OCR) under similar stress conditions. RESULTS: Mitochondria from MSCs or SFCs were labeled with a lentivirus expressing Mt-specific green florescence protein (GFP), and RCECs were labeled with CellTrace blue prior to co-cultivation. The TNT-like structures that bridge MSCs and RCECs were detected by fluorescence microscopy as early as 2hrs after co-culture.<br /> Mt transfer peaked at 24hrs, and transfer rate was significantly higher in MSCs compared with control SCFs. Rotenone treatment also increased the transfer rate in MSC co-cultures. Under the same rotenone stress condition significant more RCECs obtain mitochondria when co-culture with MSCs compared with SFCs.<br /> Rot treated RCECs show an obvious reduction in the basal respiration and ATP production when compared with untreated cells. MSC co-culture rescues the stressed induced reduction of basal respiration and ATP production. CONCLUSIONS: Our observations indicate that MSCs can transfer mitochondria to rabbit corneal epithelial cells via TNT-like structures; Healthy mitochondria transferred from MSCs to RCECs via TNT-like structure could rescue mitochondria damaged RCECs. These results will support a novel MSC-based therapy to repair multiple ocular surface diseases caused by mitochondrial dysfunction.