Senescence-Induced Lipidome Alterations in Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) show great promise as a clinical treatment for a variety of diseases, but their susceptibility to senescence during culture reduces the therapeutic potential and limits cell expansion. In this study, we explored how MSC lipid metabolism is altered in culture over time using ultrahigh-performance liquid chromatography mass spectrometry. The proportion of cells with senescence-associated β-galactosidase (SA-β-gal) activity was evaluated during 12 days of culture expansion of MSCs from two human donors. Lipid profiles were evaluated in parallel using exact mass and tandem mass spectrometry spectral database matching to generate 237 unique lipid annotations. Lipid abundance generally increased across most lipid classes over serial culture; however, many changes were heterogeneous between donors. Despite donor differences, 12 lipids, including 4 triglycerides (TG), provided discrimination between cultures with less than 10% SA-β-gal+, those with 10-20% SA-β-gal+, and greater than 20% SA-β-gal+ senescence proportion regardless of donor. More specifically, TG composed of long-chain, highly unsaturated fatty acids was strongly associated with higher MSC senescence. These changes in bulk lipid profiles may inform future strategies to monitor early culture senescence during the expansion of MSCs.