Combinatorial expression of critical Ca²⁺ handling proteins in human embryonic stem cell-derived cardiomyocytes

Abstract

The self-renewable human embryonic stem cells (hESCs) represent a potential unlimited ex vivo source of human cardiomyocytes that could be used for applications in disease modeling, cardiotoxicity screening, drug discovery, and cell-based therapies. The rise and decay of 〖Ca〗^(2+) during the excitation–contraction process is known as the 〖Ca〗^(2+) transient and a precise modulation of such transient plays an important part of the cardiomyocytes contractility. An array of 〖Ca〗^(2+)-handling proteins is responsible for the regulation of the 〖Ca〗^(2+) transient. Many of these proteins, are, however, sub-optimally expressed or even absent in hESC-CMs, comparing to normal adult CMs. Previous efforts made on the individual overexpression of 〖Ca〗^(2+)-handling proteins like Calsequestrin (CSQ), Phospholamban (PLB) and Sarcoplasmic Reticulum Calcium ATPase 2a (SERCA2a) showed positive maturation of 〖Ca〗^(2+) handling, but the effect of combinatorial overexpression of multiple 〖Ca〗^(2+)-handling proteins simultaneously in hESC-CMs have never been examined. In this work, I have taken a lentiviral-based transgenes delivery approach to try to simultaneously overexpress 3 critical 〖Ca〗^(2+) handling proteins (CSQ, PLB, SERCA2a) that are insufficiently expressed in hESC-CMs and subsequently examined the functional consequences following successful combinatorial overexpression. My results indicate that overexpressing 〖Ca〗^(2+) handling proteins can definitely cause to consequential phenotypic changes regarding the 〖Ca〗^(2+) handling of hESC-CMs but a carefully titration for an optimal combination of different proteins will be needed in order to fulfill an overall driven maturation of the 〖Ca〗^(2+) handling of hESC-CMs.