Fig. 1. Global decrease in ensemble cell motility with increasing age.

A Age-dependent mean-squared displacements (MSD) of dermal fibroblasts with color code indicating the age of the donor (blue-to-red), an exponent alpha of 1 denotes pure diffusion. B Age-dependent probability functions of cell displacements at time lags equal to 6 min (dashed lines) and 60 min (solid lines). C Auto-correlation function of velocities (ACF) measured at 3 min time lags. D Angular velocity magnitudes as a function of the donor age, “circular” denotes similar likelihood for all angles and “ellipsoidal” indicating a polarization of cell movements along primary axis of migration. Color coding in B also applies to C, D. E Heatmap showing the magnitude of the correlation between motility parameters (z-score normalized) and age. Dendrogram branches indicate unsupervised hierarchical clustering with ward linkages of the cityblock distances of parameters. Red-to-green signifies low-to-high Pearson correlation coefficient. These parameters include total diffusion (Dtot), diffusion along the primary and secondary axes of cell movements (Dp and Dnp), measure of the spatial persistence—anisotropy of the cell movements (ϕ), persistence time of cell motion along the primary and secondary axes of cell movements (Pp and Pnp), average cell speed at time lags of 6 and 60 min (S6 and S60), and the MSD measured at time lags of 6 and 60 min (MSD6 and MSD60). F Heatmap showing the magnitude of cross correlations of motility parameters across all cells for all ages, range of Pearson correlation coefficients = 0.39–0.94. G Cell migration patterns and trajectories for primary dermal fibroblasts collected from healthy donors with ages spanning 2–92 years. Top panels show origin-centered trajectories for all cells per age; bottom panels show a grid of x–y trajectories for 25 randomly selected cells per age. The number of tracked cells per sample is indicated in the upper left corner of the plot.