  We perform a detailed analysis of the migratory motion of human embryonic
stem cells in two-dimensions, both when isolated and in close proximity to
another cell, recorded with time-lapse microscopic imaging. We show that
isolated cells tend to perform an unusual locally anisotropic walk, moving
backwards and forwards along a preferred local direction correlated over a
timescale of around 50 minutes and aligned with the axis of the cell
elongation. Increasing elongation of the cell shape is associated with
increased instantaneous migration speed. We also show that two cells in close
proximity tend to move in the same direction, with the average separation of 70
um or less and the correlation length of around 25 um, a typical cell diameter.
These results can be used as a basis for the mathematical modelling of the
formation of clonal hESC colonies.
