PT - JOURNAL ARTICLE AU - Phillip, Jude M. AU - Zamponi, Nahuel AU - Phillip, Madonna P. AU - Daya, Jena AU - McGovern, Shaun AU - Williams, Wadsworth AU - Tschudi, Katherine AU - Jayatilaka, Hasini AU - Wu, Pei-Hsun AU - Walston, Jeremy AU - Wirtz, Denis TI - Fractional re-distribution among cell motility states during ageing AID - 10.1101/2020.04.29.069286 DP - 2020 Jan 01 TA - bioRxiv PG - 2020.04.29.069286 4099 - http://biorxiv.org/content/early/2020/05/01/2020.04.29.069286.short 4100 - http://biorxiv.org/content/early/2020/05/01/2020.04.29.069286.full AB - Ageing in humans is associated with a decreased capacity to regulate cell physiology. Cellular properties, such as cell morphology and cell mechanics, encode ageing information and as a result can be used as robust ageing biomarkers. Using a panel of dermal fibroblasts derived from healthy donors spanning a wide age range, we observe an age-related reduction in average cell motility, which we show is not due to the decreased motility of all cells, but results from fractional re-distribution among motility states. By taking advantage of the single-cell nature of our motility data, we show that cells can be classified based on spatial and activity patterns that define age-dependent motility states. These findings highlight an important feature of ageing cells shown by the decrease in the heterogeneity of cell movement in older adults, that potentially offer new mechanistic insights into the ageing process and avenues for novel biomarker development.Competing Interest StatementThe authors have declared no competing interest.MSD6Mean-squared displacements at time lag equal to 6 minutesMSD60Mean-squared displacement at time lag equal to 60 minutesPpPersistence time along the primary axis of migrationPnpPersistence time along the secondary axis of migrationPRWPersistence random walkAPRWAnisotropic persistence random walkMean-squared displacement (MSD)the average displacement of a cell per unit time lag (dt), which is a multiple of the time step. The MSD is a common measure of random movements of cells.Autocorrelation function of velocity (ACF)is a measure of the correlation in cell velocities per unit time lag (dt). Higher values of the ACF typically indicate that cells are more persistent in their movement.Angular velocity magnitudeis a measure of the magnitude of average cell velocities evaluated at different orientations after re-alignment along the primary axis of migration. This reveals the degree of anisotropy of cell velocities. If the velocity profile is isotropic (circular), as is typical in cases of persistent random walks, the average magnitude of the velocity is equally likely in all directions. However, if the velocity is anisotropic, as seen for cells from young donors, the average velocity along the primary axis is significantly higher that along other axes of movements.Spatial clusters (Pn)Motility clusters defined based on the eight motility parameters defined using the APRW modelActivity clusters (ACn)Motility clusters defined by the 1D displacement profiles of single cells that define the temporal motility patternsShannon entropy (S)A surrogate measurement of cellular heterogeneity based on the number of states and the abundances of cells within each stateSP6Average speed computed at a 6-min time lag SP60Average speed computed at a 60-min time lag DpDiffusivity along the primary axis of migration (motility coefficient) DnpDiffusivity along the secondary axis of migration (motility coefficient) DtotTotal diffusivity, equal to the sum of diffusivities along the primary and secondary axes of migration Psi (ϕ)Anisotropy (spatial persistence), equal to the ratio of the diffusivities in the primary and secondary axes of migration Trainslength of time steps within the normalized activity profile per cells having a value greater than or equal to one standard deviation above the baseline.Lagslength of time steps within the normalized activity profile per cells having a value less than one standard deviation above the baseline.