Application for drug evaluation of human-induced pluripotent stem cell-derived cardiomyocytes cultured by anisotropic orientation

Human-induced pluripotent stem cell-derived cells (hiPSC) are expected to have applications in the fields of regenerative medicine and drug discovery. Due to the recent trend of reducing or eliminating animal testing, hiPSC is also expanded to use as the alternative method for animal testing. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) are especially effective as an alternative assay of human cardiomyocytes which are not easily available. hiPS-CMs are, however, considered immature, hence the maturation of hiPS-CMs is an important issue for proper assessment of drug response. To induce maturation of hiPS-CMs, various methods have been developed, including long-term culturing, three-dimensional (3D) tissue engineering, mechanical loading, electrical stimulation, modulation of substrate stiffness, and treatment with neurohormonal factors. In these context, we attempted an anisotropic orientation culture, in which the cultured cells are aligned in one orientation resembling in vivo cardiomyocytes. Culture substrate for anisotropic orientation culture was developed by applying our original nanofabrication technology (CellArray-Heart™, Oji Holdings Corporation), and the alignment and maturation of hiPS-CMs were evaluated with the culture substrate. The hiPS-CMs cultured in anisotropic orientation on CellArray-Heart™ showed elongated morphology and unidirectional contraction using cell motion vector analysis and increase of mRNA related to maturation of hiPS-CMs including KCNJ2, ATP2A2, and GJA1. Furthermore, in Ca²⁺ transient assay with isoproterenol (0.1 μM, 1 μM), the hiPS-CMs cultured in anisotropic orientation showed 1.5- to 2.4-fold change in beating rate and 1.1- to 1.4-fold change in amplitude, the parameters of contraction force, compared to hiPS-CMs treated with DMSO. The hiPS-CMs cultured in anisotropic orientation might have induced the expression of positive inotropy by beta-receptor stimulation. These results indicate the hiPS-CMs cultured in anisotropic orientation on CellArray-Heart™ are induced maturation and are suitable for drug evaluation.