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  • The conductive function of biopolymer corrects myocardial scar conduction blockage and resynchronizes contraction to prevent heart failure.

The conductive function of biopolymer corrects myocardial scar conduction blockage and resynchronizes contraction to prevent heart failure.

Biomaterials (2020-08-12)
Sheng He, Jun Wu, Shu-Hong Li, Li Wang, Yu Sun, Jun Xie, Daniel Ramnath, Richard D Weisel, Terrence M Yau, Hsing-Wen Sung, Ren-Ke Li
ABSTRACT

Myocardial fibrosis, resulting from ischemic injury, increases tissue resistivity in the infarct area, which impedes heart synchronous electrical propagation. The uneven conduction between myocardium and fibrotic tissue leads to dys-synchronous contraction, which progresses towards ventricular dysfunction. We synthesized a conductive poly-pyrrole-chitosan hydrogel (PPY-CHI), and investigated its capabilities in improving electrical propagation in fibrotic tissue, as well as resynchronizing cardiac contraction to preserve cardiac function. In an in vitro fibrotic scar model, conductivity increased in proportion to the amount of PPY-CHI hydrogel added. To elucidate the mechanism of interaction between myocardial ionic changes and electrical current, an equivalent circuit model was used, which showed that PPY-CHI resistance was 10 times lower, and latency time 5 times shorter, compared to controls. Using a rat myocardial infarction (MI) model, PPY-CHI was injected into fibrotic tissue 7 days post MI. There, PPY-CHI reduced tissue resistance by 30%, improved electrical conduction across the fibrotic scar by 33%, enhanced field potential amplitudes by 2 times, and resynchronized cardiac contraction. PPY-CHI hydrogel also preserved cardiac function at 3 months, and reduced susceptibility to arrhythmia by 30% post-MI. These data demonstrated that the conductive PPY-CHI hydrogel reduced fibrotic scar resistivity, and enhanced electrical conduction, to synchronize cardiac contraction.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Chitosan, low molecular weight
Sigma-Aldrich
Glutaraldehyde solution, Grade II, 25% in H2O
Sigma-Aldrich
Pyrrole, reagent grade, 98%
Sigma-Aldrich
Iron(III) chloride hexahydrate, ACS reagent, 97%
Sigma-Aldrich
β-Glycerophosphate disodium salt hydrate, BioUltra, suitable for cell culture, suitable for plant cell culture, ≥99% (titration)