Pluripotent Stem Cell-Engineered Cell Sheets Reassembled with Defined Cardiovascular Populations Ameliorate Reduction in Infarct Heart Function Through Cardiomyocyte-Mediated Neovascularization

Abstract

Although stem cell therapy is a promising strategy for cardiac restoration, the heterogeneity of transplanted cells has been hampering the precise understanding of the cellular and molecular mechanisms. Previously, we established a cardiovascular cell differentiation system from mouse pluripotent stem cells, in which cardiomyocytes (CMs), endothelial cells (ECs), and mural cells (MCs) can be systematically induced and purified. Combining this with cell sheet technology, we generated cardiac tissue sheets reassembled with defined cardiovascular populations. Here, we show the potentials and mechanisms of cardiac tissue sheet transplantation in cardiac function after myocardial infarction (MI). Transplantation of the cardiac tissue sheet to a rat MI model showed significant and sustained improvement of systolic function accompanied by neovascularization. Reduction of the infarct wall thinning and fibrotic length indicated the attenuation of left ventricular remodeling. Cell tracing with species-specific fluorescent in situ hybridization after transplantation revealed a relatively early loss of transplanted cells and an increase in endogenous neovascularization in the proximity of the graft, suggesting an indirect angiogenic effect of cardiac tissue sheets rather than direct CM contributions. We prospectively dissected the functional mechanisms with cell type-controlled sheet analyses. Sheet CMs were the main source of vascular endothelial growth factor. Transplantation of sheets lacking CMs resulted in the disappearance of neovascularization and subsequent functional improvement, indicating that the beneficial effects of the sheet were achieved by sheet CMs. ECs and MCs enhanced the sheet functions and structural integration. Supplying CMs to ischemic regions with cellular interaction could be a strategic key in future cardiac cell therapy.

Exploiting human iPS cell-derived cardiovascular cell populations toward cardiac regenerative therapy

“…We have previously reported that the coexistence of mouse ES cell-derived vascular cells and CMs within a cell sheet structure enhances its tissue function, for example by incrementing the production of angiogenic factors and enhancing the stability of the construct. This indicates that the simultaneous transplantation of CMs and vascular cells may further enhance their therapeutic effect [18] . We attempted to simultaneously induce ECs and MCs (which surround endothelial cell layers to support the vascular structure in native vasculature) along with CMs by modifying the CM induction method from hiPSCs described above.…”

“…Cardiovascular cell types, namely cardiomyocytes (CMs), endothelial cells (ECs), and vascular mural cells (MCs; pericytes) [17] , can be systematically induced and purified with this system. We have also reported a transplantation experiment of a three-layered cardiac tissue sheet bioengineered with mouse ESC-derived defined cardiovascular cell populations onto the infarcted heart [18] . In this study, we demonstrated increased tissue neovascularization together with a prominent attenuation of cardiac remodeling leading to an improvement in cardiac function.…”

Future Prospects for Regenerated Heart Using Induced Pluripotent Stem Cells

“…However, Masumoto et al (23) reported that the functional recovery with cardiac cell sheets was mainly due to cytokine effects, and not cardiac contraction. In addition, CMs in the cell sheets were gone one month after engraftment, and sheets comprising more than three layers are susceptible of necrosis.…”

Myocardial Reprogramming Medicine: The Development, Application, and Challenge of Induced Pluripotent Stem Cells

“…A cardiac tissue sheet reassembled with defined cardiovascular populations (including purified hiPSC-derived cardiomyocytes and New Journal of Science ECs) was implanted in an animal MI model which showed significant and sustained improvement of cardiac function accompanied by neovascularization [193,194]. In our studies, a tricell omentum patch (seeded with iPSC-derived cardiomyocytes, ECs, and MEFs) was created and implanted into mice resulting in significantly higher cell engraftment accompanied by angiomyogenesis in the infarcted area and improvement in heart function [195,196].…”