Mesenchymal stem cells inhibited chronic myeloid leukemia cells in vitro, correlating with oxidative stress.

BACKGROUND: Chronic myeloid leukemia (CML) originates from bone marrow, and its progression to blast crisis phase is a primary cause of poor prognosis in patients. Investigating its underlying mechanisms may help improve patient survival. METHODS: Optical microscopy and Cell Counting Kit-8 assays were utilized to observe and assess the viability of K562 cells (human cells derived from CML) treated with or without mesenchymal stem cell (MSC)-conditioned medium. Flow cytometry was employed to assess apoptosis and cell cycle changes. Intracellular reactive oxygen species (ROS) were assessed utilizing a 2’,7’-dichlorofluorescin diacetate probe. Antioxidant enzymes (total superoxide dismutase [T-SOD], catalase [CAT], glutathione peroxidase [GSH-Px]) and malondialdehyde (MDA), a marker of lipid peroxidation and oxidative stress, were measured using relevant assay kits. Western blotting was performed to evaluate inflammation-related proteins (nuclear factor erythroid 2-related factor 2 [Nrf2], inhibitor of nuclear factor kappa B alpha [IκBα]), and reverse transcription quantitative polymerase chain reaction (RT-qPCR) was utilized to assess expression of inflammatory cytokines (interleukin [IL]-6, IL-1β, IL-4, IL-10). All experiments were repeated three times, and the data were presented in mean form. Welch t-test was used to compare the treatment group and the control group. RESULTS: Compared with K562 cells without MSC-conditioned medium treatment, those cultured with MSC-conditioned medium exhibited significantly inhibited proliferation. The K562 cells treated with MSC-conditioned medium showed increased apoptosis compared with untreated cells (11.34% vs. 2.93%, P<0.0001) and cell cycle arrest (17.54% vs. 11.00%, P = 0.0007). Additionally, the K562 cell group with MSC-conditioned medium treatment elevated intracellular ROS levels (9.34% vs. 2.43%, P = 0.0002) in K562 cells. Oxidative stress factor analysis revealed decreased T-SOD (3.82 vs. 6.89, P = 0.0023), CAT (21.43 vs. 34.36, P = 0.0025), and GSH-Px (3.42 vs. 6.88, P = 0.0088) levels alongside increased MDA (6.29 vs. 3.30, P = 0.0009) in K562 cell group with MSC-conditioned medium treatment. Inflammatory protein assessment demonstrated reduced Nrf2 (0.46 vs. 1.00, P = 0.0017) and IκBα (0.71 vs. 1.00, P = 0.0002) levels in the K562 cell group with MSC-conditioned medium treatment. IL-6 (2.14 vs. 1.00, P<0.0001) and IL-1β (2.21 vs. 1.00, P<0.0001) were upregulated, whereas IL-4 (0.52 vs. 1.00, P<0.0001) and IL-10 (0.39 vs. 1.00, P<0.0001) were downregulated. CONCLUSION: MSC-conditioned medium inhibited K562 cell growth concomitant with increased oxidative stress and altered inflammatory responses.