After a heart attack, scar tissue that can’t contract or transmit electrical signals usually replaces dead cardiac muscle, resulting in chronic heart failure. A heart patch could conceivably be implanted over dead muscle and provide more strength for contractions as well as a path for electrical signals.
A cardiac patch large enough to cover the affected tissue and as strong and electrically active as native tissue was engineered at Duke University. Human pluripotent stem cells are injected into a support structure and supplied with nutrients and growth factors. The stem cells differentiate into cardiomyocytes and other types of tissues, which are then embedded at specific ratios in a jelly-like substance to self-organize and grow into functioning tissue.
Rocking the containers of cells proved key to the development of effective patch structures. “It turns out that rocking the samples to bathe and splash them to improve nutrient delivery is extremely important,” said biomedical engineering doctoral student Illia Shadrin. “We obtained three-to-five times better results with the rocking cultures compared to our static samples.”
Previous patches were one- and four square centimeters, but with the improved culture technique the researchers were able to grow a patch of 16 square centimeter size and five to eight cells thick. The material resembled native cardiac tissue in structure and was fully functional both electrically and mechanically.
The patches maintained their function and became vascularized and integrated with native tissues after implantation onto rodent hearts.
This research is published in Nature Communications.