**5. Conclusions**

In the present study, cardiomyocytes differentiated from the hiPSCs were cultured on PET textiles, and their structural properties, expression of the cardiac specific genes, and calcium handling properties were assessed. Based on the results, culturing hiPSC-CMs on the PET textiles improved their structural properties, such as elongation and sarcomere orientation, as well as improved the expression of the sarcomeric genes such as *TNNT2*. However, no statistically significant changes in the expression of the genes encoding cardiac ion channels or in the calcium handling properties of the hiPS-CMs were observed, and only minor changes were observed in their functionality as suggested by Ca2+ transients.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/1996-1944/12/11/1805/s1, Figure S1: Immunostaining of hiPS-CMs on different coating materials, Figure S2: The expression levels of the genes coding cardiac ion channels, Table S1: Data describing the structural maturation state of the hiPS-CMs with the tested coating materials.

**Author Contributions:** Conceptualization, M.P.-M., J.K., M.K., and K.A.-S.; Data curation, M.P.-M.; Funding acquisition, M.K., and K.A.-S.; Investigation, M.P.-M., M.H., R.-P.P., T.M., A.J., E.T., and J.K.; Methodology, M.P.-M.; Project administration, M.P.-M., M.K., and K.A.-S.; Resources, E.T.; Supervision, M.P.-M., M.K., and K.A.-S.; Visualization, M.H.; Writing—original draft, M.P.-M., M.H., and R.-P.P.; Writing—review & editing, M.P.-M., J.K., M.K., and K.A.-S.

**Funding:** This research was funded by Business Finland, Päivikki and Sakari Sohlberg foundation, Pirkanmaa Regional Fund of the Finnish Cultural Foundation, the Finnish Foundation for Cardiovascular Research, Academy of Finland and Pirkanmaa Hospital District.

**Acknowledgments:** The authors acknowledge Henna Lappi and Markus Haponen for their technical expertise with the stem cell cultures and cardiac differentiation, as well as Kirsikka Stenlund for the design of the weave pattern. The authors acknowledge the Tampere facility of Electrophysiological Measurement, Tampere Imaging Facility (TIF), Tampere iPSC core facility and the Tampere CellTech Laboratories for their service.

**Conflicts of Interest:** The authors declare no conflict of interest.
