Urbanek K et al. (2005) Cardiac stem cells possess growth factor-receptor systems that after activation regenerate the infarcted myocardium, improving ventricular function and long-term survival. Circ Res 97: 663–673

Growth factors can activate cardiac stem cells in mice with infarcted hearts, leading to regeneration of the myocardium, US researchers have shown.

The human heart has been found to harbor cardiac stem cells and early committed cells (CSCs–ECCs). Researchers have, therefore, been trying to promote the survival and proliferation of these cells. Urbanek et al. investigated whether a combination of insulin-like growth factor 1 (IGF1) and hepatocyte growth factor (HGF) could stimulate migration and growth of cardiac stem cells.

The researchers identified replicating CSCs–ECCs in the atrioventricular groove of the mouse heart and labeled these cells using enhanced green fluorescence protein. Mice with infarcted myocardial tissue were then treated with IGF1 and HGF and the degree of death, survival and growth of CSCs–ECCs were evaluated by confocal microscopy at regular time points over 4 months.

Sixteen days after growth-factor treatment, new myocardium-containing arterioles, capillaries and contractile myocytes had developed at the site of infarction. Although the area of ischemic heart tissue was generally larger in growth-factor-treated mice than in controls, the former had a higher chance of survival as the newly formed myocardium led to improved ventricular function.

These findings show that CSCs–ECCs can respond to local administration of IGF1 and HGF by migrating to sites of ischemic injury and developing into functional myocardial tissue.