An injectable capillary-like microstructured alginate hydrogel improves left ventricular function after myocardial infarction in rats.

Background: A new post-myocardial infarction (MI) therapy is injection of high-water-content polymeric biomaterial gels (hydrogels) into damaged myocardium to modulate cardiac negative remodeling and preserve heart function.

Methods: We investigated the therapeutic potential of a novel gelatinized alginate hydrogel with a unique microstructure of uniform capillary-like channels (termed Capgel). Shortly (48h) after induced anterior MI, Sprague Dawley rats received intramyocardial injection of Capgel directly into the antero-septal wall at the infarct border zone (n=12) or no injection (n=10, controls). Echocardiograms were performed at 48h (week 0) and 4weeks (week 4) to evaluate left ventricular function.

Results: Echocardiograms showed 27% improvement of left ventricular systolic function over time with gel injection: fractional shortening increased from 26±3% at week 0 to 33±2% at week 4 (p=0.001). Capgel was present at the injection site after 4weeks, but was minimal at 8weeks. The remaining gel was heavily populated by CD68(+) macrophages with CD206(+) clusters and blood vessels. An in vitro experiment was performed to assess Angiotensin-(1-7) released from Capgel. Angiotensin-(1-7) was released from the Capgel in a sustained manner for 90days.

Conclusions: Use of Capgel, a degradable, bioactive hydrogel composed of gelatinized capillary-alginate gel, appears safe for intramyocardial injection, is associated with improved left ventricular function after MI in rats, and may provide a long-term supply of Angiotensin-(1-7).