  Apparent tissue surface tension allows the quantification of cell-cell
cohesion and was reported to be a powerful indicator for the cellular
rearrangements that take place during embryonic development or for cancer
progression. The measurement is realized with a parallel compression plate
tensiometer using the capillary laws. Although it was introduced more than a
decade ago, it is based on various geometrical or physical approximations.
Surprisingly, these approximations have never been tested. Using a novel
tensiometer, we compare the two currently used methods to measure tissue
surface tension and propose a third one, based on a local polynomial fit (LPF)
of the profile of compressed droplets or cell aggregates. We show the
importance of measuring the contact angle between the plate and the
drop/aggregate to obtain real accurate measurement of surface tension when
applying existing methods. We can suspect that many reported values of surface
tension are greatly affected because of not handling this parameter properly.
We show then the benefit of using the newly introduced LPF method, which is not
dependent on this parameter. These findings are confirmed by generating
numerically compressed droplet profiles and testing the robustness and the
sensitivity to errors of the different methods.
