Comparative Cytotoxic Effects of Ethanol, Methanol, and DMSO on Mesenchymal Stem Cell Viability and Apoptosis

Organic solvents are widely used in biomedical and stem cell research; however, their concentration-dependent cytotoxicity can compromise assay reliability and cell-based applications. This study comparatively evaluated the effects of ethanol, methanol, and dimethyl sulfoxide (DMSO) on umbilical cord mesenchymal stem cell (UCMSC) viability and apoptosis after 24 h exposure. UCMSCs were treated with each solvent at 0, 0.5, 1, 2, and 5% (v/v), and cell viability was determined using the MTT assay. Half-maximal inhibitory concentration (IC50) values were estimated from mean concentration-response data. Apoptosis and necrosis were assessed at 2% solvent concentration using Annexin V-FITC/propidium iodide staining and flow cytometry. All tested solvents reduced UCMSC viability in a concentration-dependent manner. Methanol produced the greatest cytotoxicity, reducing viability to 19.8 ± 2.6% at 5%, followed by ethanol (40.4 ± 3.0%) and DMSO (59.4 ± 3.0%). The estimated IC50 values were 2.41% for methanol and 4.02% for ethanol, whereas DMSO did not reach 50% inhibition within the tested range (>5%). At 2%, methanol induced the highest apoptotic fraction (34.9 ± 3.1%), followed by ethanol (25.9 ± 3.8%) and DMSO (18.7 ± 2.8%). Necrotic fractions remained lower than apoptotic fractions across all solvent-treated groups. These findings indicate that methanol is the most cytotoxic of the three tested solvents under the present conditions and that apoptosis is the major cell death pattern after short-term exposure. Careful solvent selection and concentration optimization are therefore essential for reliable MSC-based experiments.