Investigating the Immunomodulatory Impact of Wharton's Jelly Mesenchymal Stem Cells (WJ-MSCs) on Cobalt Chloride (CoCl2)-Induced Damage to HK-2 Cells

Background: End stage renal diseases (ESRD) are usually caused by chronic kidney diseases (CKD) and renal dysfunction. Hypoxia, induced by reduced oxygen delivery, plays a crucial role in kidney damage by triggering inflammation, oxidative stress, mitochondrial dysfunction, and DNA damage. Studies indicate that hypoxia-inducible factor 1α (HIF-1α) regulates metabolic remodeling in renal tubular epithelial cells (RTECs) and promotes interstitial fibrosis. Promising results have been shown with the use of mesenchymal stem cells (MSCs) in CKD models, such as reducing oxidative stress, improving mitochondrial function, and decreasing inflammation. Interferon-gamma (IFN-γ) has been found to enhance MSCs' therapeutic effects on renal fibrosis, which is closely related to renal hypoxia, though the mechanisms remain unclear. This study aims to investigate whether IFN-γ primed Wharton’s Jelly-MSCs (IFNγ-MSCs) can protect HK-2 cells, human proximal tubule epithelial cells, from hypoxia-induced damage. We generated a hypoxic environment with CoCl2 and treated HK-2 cells with IFNγ-MSCs to explore their potential protective effects against kidney injury. Methods: The differentiation ability and cell surface marker profile of WJ-MSCs were confirmed. We mimicked hypoxia in HK-2 cells using CoCl2 and pretreated them with conditioned media from IFNγ-MSCs to assess the efficacy of MSCs against cell injury. Cell viability was measured using Cell Counting Kit-8. Gene and protein expressions related to hypoxia, oxidative stress, and apoptosis were evaluated via RT-qPCR and western blot. Mitochondrial ROS production and membrane potential were detected using MitoSOX and MitoTracker, respectively. Results: Our findings indicated that CoCl2 effectively induced cytotoxicity in HK-2 cells and upregulated genes and proteins associated with hypoxia, oxidative stress, and apoptosis. IFNγ-MSCs alleviated CoCl2-induced apoptosis in HK-2 cells by suppressing the Bax/Bcl-2 ratio. Additionally, IFNγ-MSCs downregulated the gene expressions of BNIP3, NIX, NRF2, HO1, and iNOS, as well as the protein expressions of HIF-1α, Nrf-2, and HO-1. These results suggest that IFNγ-MSCs might reverse hypoxia and reduce oxidative stress, thereby protecting HK-2 cells from apoptosis. Conclusion: In summary, our findings suggest that IFNγ-MSCs can alleviate CoCl2-induced HK-2 cells injury by reducing oxidative stress and reversing hypoxia.