Design of pH and Thermal Sensitive Hydrogels for Catheter Based Minimally Invasive Heart Surgery

A family of injectable and pH-sensitive hydrogels was developed to deliver cardiosphere-derived progenitor cells (CPCs) to infarcted heart by a minimally invasive approach. The hydrogels were based on N-isopropylacrylamide (NIPAM), propylacrylic acid (PAA) and hydroxyethyl methacrylate-poly(trimethylene carbonate) (HEMAPTMC). The hydrogels were injectable at physiological pH (7.4), but quickly gelled at pH similar to that in the infarct heart (6.5~6.8). This makes it possible to inject the hydrogels through catheters used for heart injection, and ensure sufficient cell retention after delivery. The hydrogels are also biocompatible. No significant cell death was observed. Furthermore, gel mechan-ical properties can be tuned to mimic the biomechanics of native heart muscle by alternat-ing molar ratio of NIPAM, PAA and HEMAPTMC. These results demonstrate that the developed hydrogels can potentially be used to deliver cells using minimally invasive approach.