Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Poster Abstracts

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.

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