In vivo experience with natural scaffolds for myocardial infarction: the times they are a-changin’
The conductive polymer polypyrrole was blended with alginate to investigate its potential in tissue engineering applications. This study showed that increasing the polypyrrole content altered the macroscopic structural morphology of the polymer blend scaffold, but did not alter the overall conductivity of the polymer blend, which was 10(-2)S/cm(2). Culturing of human umbilical vein endothelial cells on the polymer blend scaffolds showed that addition of polypyrrole mediated cell attachment to the polymer scaffold. However, cell proliferation was dependent on the polypyrrole content with 0.025% v/v polypyrrole giving the best results. Using an ischemia-reperfusion rat myocardial infarction model, local injection of 0.025% polypyrrole in alginate polymer blend into the infarct zone yielded significantly higher levels of arteriogenesis at 5 weeks post-treatment when compared with the saline control group and the alginate only treatment group. In addition, this alginate-polypyrrole polymer blend significantly enhanced infiltration of myofibroblasts into the infarct area when compared with the control group. The results of this study highlight the potential clinical benefit of using this alginate-polypyrrole polymer blend as an injectable scaffold to repair ischemic myocardium after myocardial infarction.