Role of endothelial cells and angiogenesis in cardiomyocyte survival under ischemic stress in a 3D spheroid model

Abstract

Introduction

Endothelial cells play a crucial role in the function of the majority of tissues in the body, including cardiac tissue. Their ability to regulate angiogenesis, inflammation, and vascular remodeling makes them essential for cardiac tissue homeostasis and repair. Numerous studies support the idea that the inclusion of endothelial cells in 3D cardiac tissue models could significantly enhance cardiomyocyte survival and overall tissue function.

Objective

The present study aimed to generate cardiac spheroids using cardiomyocytes and fibroblasts, with or without endothelial cells, to investigate the potential of endothelial cells in protecting cardiac spheroids from ischemic stress.

Method

Cardiac spheroid was generated using human primary cardiac fibroblasts, human primary endothelial cells and human cardiomyocytes derived from induced pluripotent stem cells, at a ratio of 1.5:1.5:7, in a spindle-shaped plate. As a control, cardiac spheroid without endothelial cells were also generated. The spheroids were then exposed to an ischemic stress model developed in the laboratory, which combines hypoxia, nutrient deprivation and inflammatory stresses.

Results

The spheroids were analyzed 3 days after exposure to ischemic stress. The presence of endothelial cells not only enhanced cardiomyocyte survival, as evidenced by TUNEL staining, but also improved the structural organization of contractile proteins. Furthermore, the presence of endothelial cells in the spheroid protected the contractile function of cardiomyocytes against ischemic stress. Importantly, treatment with the angiogenesis inhibitor, angiostatin, reversed both the functional and structural improvements induced by endothelial cells, highlighting their essential role in preserving cardiomyocyte integrity under stress.

Conclusion

In conclusion, the presence of endothelial cells in the cardiac spheroids provides essential structural and functional support to cardiomyocytes. More importantly, our results suggest that the 3D organization of endothelial cells and angiogenesis are key factors driving the observed improvements.