Netrin-1 ameliorates myocardial infarction-induced myocardial injury: mechanisms of action in rats and diabetic mice.

Netrin-1 is typically known as a neuronal guidance factor. Studies have reported the proangiogenic, antiapoptotic, and antiinflammatory properties of Netrin-1. A critical role for Netrin-1 in ischemic organ damage, myocardial infarction (MI) in particular, has also been demonstrated, making Netrin-1 a potential therapeutic target for the treatment of cardiovascular diseases (CVDs). Mesenchymal stem cells (MSCs) have shown promising therapeutic efficacy in preclinical studies. However, limited clinical success was observed, mainly due to poor MSC survival. Given the reported beneficial impact of Netrin-1 in tissue repair and cell survival, we examined the effects of Netrin-1 in MSC therapy against MI-induced ischemic cardiac injury in rats and type 2 diabetic (T2D) mice. MSCs were isolated and Netrin-1-expressing MSCs were obtained by transduction with a Netrin-1-encoding retroviral vector. The Netrin-1-MSCs were then delivered intramyocardially to the infarct sites of rats and T2D mice with MI. Thirty days after MSC implantation, changes at the infarct area, level of collagen deposition, and cardiac hypertrophy were assessed. Molecular mechanisms underlying the effects of Netrin-1 were also investigated. Attenuated MI-induced myocardial dysfunction was observed after Netrin-1-MSC treatment. Protective effects of the Netrin-1-MSCs were attributable primarily to better MSC survival and migration, which is mediated by Netrin-1-induced phosphorylation of p44/42 mitogen-activated protein kinase. Netrin-1-stimulated nitric oxide production was also responsible, which could promote neovessel formation and progenitor cell mobilization in vivo. We report a protective role for Netrin-1 against MI-induced ischemic injuries, reinstating its promising potential as a therapeutic target for CVDs and, more importantly, for patients with CVD with coexisting diabetes.