Physical Properties of Poly (N-isopropylacrylamide) Hydrogel Promote its Effects on Cardiac Protection after Myocardial Infarction

Abstract

Objective: Studies have demonstrated the protective effects of biomaterials against myocardial infarction (MI), but the relationship between their physical characteristics and their function is incompletely understood. This study investigated such relationships for a hydrogel preparation. Methods: Two types of poly(N-isopropylacrylamide) (PNIPAAm) hydrogel with different degradation times (Gel A and Gel B) were synthesized. In vivo hydrogel formation and maintenance were observed and confirmed in mice. The solutions were also injected into the infarct area immediately after MI induction in rats. Results: PNIPAAm hydrogel exhibited a three-dimensional structure resembling native extracellular matrix (ECM). Compared with phosphate-buffered saline, Gel A and Gel B increased contractility of isolated infarcted myocardium, reduced collagen deposition, increased neovascularization, inhibited left ventricle expansion and improved cardiac function. Myocardial contractility was greater with Gel B than with Gel A. Conclusions: Intra -myocardial injection of PNIPAAm hydrogel provides structural support and some functional repair of damaged ECM, suggesting that it might be useful for cardiac tissue engineering.