Background: Cardiovascular disease and myocardial infarction are associated with high mortality and morbidity and a more effective treatment remains a major clinical need. The intramyocardial injection of biomaterials has been investigated as a potential treatment for heart failure by providing mechanical support to the myocardium and reducing stress on cardiomyocytes. Another treatment approach that has been explored is therapeutic angiogenesis that requires careful spatiotemporal control of angiogenic drug delivery. An injectable sulfonated reversible thermal gel composed of a polyurea conjugated with poly(N-isopropylacrylamide) and sulfonate groups has been developed for intramyocardial injection with angiogenic factors for the protection of cardiac function after a myocardial infarction.
Results: The thermal gel allowed for the sustained, localized release of VEGF in vivo with intramyocardial injection after two weeks. A myocardial infarction reperfusion injury model was used to evaluate therapeutic benefits to cardiac function and vascularization. Echocardiography presented improved cardiac function, infarct size and ventricular wall thinning were reduced, and immunohistochemistry showed improved vascularization with thermal gel injections. The thermal gel alone showed cardioprotective and vascularization properties, and slightly improved further with the additional delivery of VEGF. An inflammatory response evaluation demonstrated the infiltration of macrophages due to the myocardial infarction was more significant compared to the foreign body inflammatory response to the thermal gel. Detecting DNA fragments of apoptotic cells also demonstrated potential anti-apoptotic effects of the thermal gel.
Conclusion: The intramyocardial injection of the sulfonated reversible thermal gel has cardioprotective and vascularization properties for the treatment of myocardial infarction.
Keywords: Heparin-mimicking; Intramyocardial biomaterial injection; Reversible thermal gel; Spatiotemporal release; Sulfonation; Therapeutic angiogenesis.