Effects of polarized macrophages on the in vitro gene expression after Co-Culture of human pluripotent stem cell-derived cardiomyocytes

Abstract A promising approach to rescue cardiac function after a myocardial infarction (MI) is to apply an engineered heart tissue (EHT) onto the infarcted area. After the onset of MI, a dynamic inflammatory environment develops comprising of the temporal recruitment of macrophages (Mϕs), and their interactions with the cells of the damaged myocardium. There is limited knowledge about the interactions between this inflammatory environment and the cells that could potentially be used to create an EHT, such as pluripotent stem cell derived-cardiomyocytes. In the present study, a cell-based system was used to study the in vitro interactions between lipopolysaccharide (LPS) and interferon-gamma (IFNγ)-activated Mϕs, and interleukin 4 (IL4) and interleukin 13 (IL13)-activated Mϕs and human embryonic stem cell-derived cardiomyocytes (hESC-CMs). Using a co-culture system, gene expression profiles of key markers of both the Mϕs and the hESC-CMs were obtained, as well as the protein secretion. Additionally, the effects of Mϕ polarizing cytokines on hESC-CMs with or without the presence of Mϕs were studied. Mϕs co-cultured with hESC-CMs showed no significant changes in their gene expression profile after two days in culture. hESC-CMs, however, were noted to have an overall decrease in expression of cardiac-related genes upon exposure to both Mϕ subtypes in co-culture. Gene expression of Bone morphogenetic protein-2 (BMP2), Bone morphogenetic protein-4 (BMP4) and GATA-binding protein-4 (GATA4) were also affected by Mϕ exposure and by inflammatory signals such as LPS and IFNγ. This study represents an important step towards the design of advanced in vitro testing platforms to further study the effect of Mϕs and inflammatory signals on EHTs in vitro.