Changes in the Heterogeneity of MSC Subpopulations During Replicative Senescence as Seen from Single-Cell Speed Measurements

Objective: To examine the distribution of motility metrics of human mesenchymal stem cells (MSCs) and immortalized cell line in long-term 2D culture. Methods: We used single-cell motility tracking to analyze changes in the motility metrics (average speed, distance, track length). The study compared three cell lines: two lines of MSCs that undergo replicative senescence (DF-2, MSCWJ-1), and a third line of immortalized fibroblast-like cells with an unlimited lifespan (XP12RO). Results and Discussion: The results revealed that replicative senescence in MSCs is associated with an alteration in the distribution of observed motility metrics, which is expressed as a change from a bimodal distribution in young cells to a unimodal distribution in old cells. The distribution of motility metrics in immortalized cells did not change throughout long-term cultivation. Conclusions: Subpopulation heterogeneity decreases as MSCs undergo replicative senescence.