Transplantation of human umbilical mesenchymal stromal cells attenuates heart failure progression in a rat model

Myocardial infarction (MI), mainly caused by coronary artery occlusion, remains a leading cause of death worldwide. Although many patients survive after emergency treatment, chronic MI often develops, underscoring the need for effective therapies. This study evaluated the therapeutic potential of human umbilical mesenchymal stromal cells (HUMSCs) in a rat model with chronic MI. MI was induced by permanent ligation of the left anterior descending artery. Seven days post-ligation, 4×10⁶ HUMSCs were transplanted into the peri-infarct myocardium, while an additional 2.5×10⁷ HUMSCs were introduced into the mediastinal space around the ligation site. Successful model establishment was confirmed by elevated cardiac biomarkers and characteristic electrocardiographic changes. Echocardiography and magnetic resonance imaging demonstrated significant impairments in myocardial strain dynamics, reduced ejection fraction, and diminished fractional shortening, all of which improved following HUMSC transplantation. The transplantation also reduced macrophage infiltration, increased M2 macrophage polarization, suppressed fibroblast activation, attenuated fibrosis, and promoted angiogenesis, ultimately preserving cardiomyocytes and improving cardiac function. The transplanted HUMSCs were detected in rat's myocardium without differentiating into cardiomyocytes or endothelial cells. These findings suggest that adequate HUMSC transplantation offers a promising therapy to attenuate progression of chronic MI or heart failure.