Using tissue-engineering, researchers from the Children's Hospital Boston have taken preliminary steps to produce electrically conductive tissue for the heart using the patient's own cells. If the approach, which showed promising results in rat models, succeeds in humans, this could replace the use of heart pacemakers, particularly in infants born with complete heart block.

Myoblasts, or muscle precursor cells, were collected from rat skeletal muscles, seeded on collagen.

The cells distributed themselves evenly in the tissue and oriented themselves in the same direction. Tested in the laboratory, the engineered tissue started beating when stimulated electrically, and its muscle cells produced proteins called connexins that channel ions from cell to cell, connecting the cells electrically.


When the engineered tissue was implanted into rats, between the right atrium and right ventricle, the implanted cells integrated with the surrounding heart tissue and electrically coupled to neighboring heart cells. Optical mapping of the heart showed that in nearly a third of the hearts, the engineered tissue had established an electrical conduction pathway, which disappeared when the implants were destroyed. The implants remained functional through the animals' lifespan (about 3 years).

Researchers say that using myoblasts from skeletal muscle is particularly advantageous for infants and newborns. Further research are planned to create tissue-engineered grafts that behave more like a natural atriventricular node.
Results will be published in the July issue of the American Journal of Pathology. For an overview, see the news release from the Children's Hospital.