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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
117
38-POS
Board 19
Negative Mechanotaxis of iPS Cells Observed on Microelastically-Patterned Hydrogels
Satoru Kidoaki
, Kenta Mizumoto.
Kyushu University, Fukuoka, Japan.
Feeder-free dissociating culture of iPS cells has been required for stable and easier supply of
them for further clinical applications. One of the problems with the dissociating culture is that
iPS cells undergo apoptosis not only due to the loss of cell-cell adhesion but also depending on
the quality and strength of cell-substrate adhesion. To clarify the optimized physicochemical
conditions for the dissociating culture of iPS cells, we have scrutinized the effect of laminin-
density and stiffness of the hydrogel gel surfaces on proliferation activity of iPS cells. Laminin
511-E8 fragments were chemically-fixed onto photocrosslinked-gelatin gels through water-
soluble carbodiimide-NHS condensation reaction. Laminin-density and elasticity were changed
by regulating feed concentration of laminin in the reaction and photoirradiation conditions,
respectively. As for the effect of laminin density, proliferation of iPS cells was attained over the
feed concentration of laminin of 0.3 mg/ml. Concerning the effect of stiffness of gel surface,
significant difference in proliferation activity was not observed for the elasticity conditions
between several kPa and 100 kPa. On the other hand, packing density of iPS cells in the
proliferating colonies became significantly higher on the gels with lower elasticity. To check
actual responses of iPS cells for elasticity of culture hydrogels, time-lapse observation of iPS
cells was performed on the microelastically-patterned gel with 400 μm-wide square hard
domains (270 kPa) in softer surroundings (10 kPa). Interestingly, iPS cells preferred to and
transferred into soft region to form cluster to survive and proliferate on the hydrogel surfaces.
i.e.,iPS cells exhibit biased movement toward softer region. These observations suggest that in
the case of iPS cells, negative mechanotaxis toward softer region occurs to inhibit apoptosis
induced by the lack of cell-cell adhesions.