The promotion of myocardial repair by the sequential delivery of IGF-1 and HGF from an injectable alginate biomaterial in a model of acute myocardial infarction.

Proper spatio-temporal delivery of multiple therapeutic proteins represents a major challenge in therapy strategies aimed at inducing myocardial regeneration after myocardial infarction (MI). We hypothesized that the dual delivery of insulin-like growth factor-1 (IGF-1) and hepatocyte growth factor (HGF) by injectable affinity-binding alginate biomaterial would maximize their therapeutic effects, leading to a more favorable course of tissue restoration after acute MI. A sequential release of IGF-1 followed by HGF was attained from affinity-binding alginate biomaterial, which also protected the proteins from proteolysis (shown by mass spectroscopy). The released factors retained bioactivity, as judged by their capability to activate their respective signaling pathways and to prevent cardiomyocyte apoptosis in vitro. In a rat model of acute MI, an intramyocardial injection of the dual IGF-1/HGF affinity-bound alginate biomaterial preserved scar thickness, attenuated infarct expansion and reduced scar fibrosis after 4 weeks, concomitantly with increased angiogenesis and mature blood vessel formation at the infarct. Furthermore, this treatment prevented cell apoptosis, induced cardiomyocyte cell cycle re-entry and increased the incidence of GATA-4-positive cell clusters. The dual delivery of IGF-1 and HGF from affinity-binding alginate biomaterial represents a useful strategy to treat MI. It showed a marked therapeutic efficacy at various tissue levels, as well as potential to induce endogenous regeneration of cardiac muscle.