Cell-scale curvature is a key regulator of cell migration, yet its quantitative effects and underlying mechanisms remain elusive. Here, we combine controlled in vitro experiments with a phenomenological theoretical framework to investigate the migration of fibroblasts (NIH3T3) and epithelial cells (MCF10A) on the inner concave surfaces of polydimethylsiloxane microcylinders across a wide range of cell-scale curvatures (∼0.01 per micrometer). We find that migration persistence positively correlates with mean speed across all curvatures, consistent with the universal speed-persistence coupling relation previously observed for cells migrating on 1D and 2D planar substrates, as well as for cells embedded in 3D environments. Cell migration inside microcylinders is stochastic and anisotropic, as quantified by the nematic order parameter, and exhibits a biphasic dependence on curvature. At small curvatures, cells remain fully adhered to the surface, with anisotropy and speed both increasing while persistence decreases. When curvature exceeds a threshold of approximately 1/75 per micrometer, cells detach by forming stress-fiber chords, leading to reduced anisotropy and speed but increased persistence. This adhered-to-chord transition is followed by a shift in preferred orientation: migration initially favors the lateral direction and progressively aligns toward the axis at larger curvatures. These findings demonstrate that cells can actively reorient their stress fibers and migration in response to local cell-scale curvature sensed by the entire cell, even on cylindrical surfaces with constant mean curvature and vanishing Gaussian curvature. A modified persistent random walk model, incorporating persistent randomness and curvature-dependent directionality via bending and adhesion energetics, quantitatively captures these behaviors and predicts the transition threshold in close agreement with experiments. Together, this work establishes a quantitative framework for biphasic, curvature-dependent migration and provides new insight into how local geometry regulates mesenchymal motility.
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