Cell biologist Douglas Cowan, PhD, and his team have engineered tissue capable of passing electrical signals from the upper to the lower chambers of the heart in rats, potentially taking on the role of the defective atrioventricular (AV) node in complete heart block. The AV node synchronizes the beats of the heart’s atria and ventricles. Without it, the heart can’t pump blood efficiently.
One in 22,000 babies is born with complete heart block each year.
A normal infant’s heart beats 120 to 180 beats per minute, while that of a baby with comlpete heart block may beat as slowly as 40 to 80 beats per minute. Present treatment involves implantation of a pacemaker, but pacemakers fail over time and must be surgically replaced regularly. With a life expectancy of 70, a baby with complete heart block is likely to require 12 surgical procedures.
Cowan’s team isolated muscle precursor cells called myoblasts and “seeded” them onto a collagen scaffolding, creating living tissue that could be implanted in the heart. In laboratory experiments with rats, the cells took on the properties of AV node cells, beating when electrically stimulated. Additionally, the muscle cells produced proteins called connexins that channel ions from cell to cell, connecting the cells electrically.
“The advantage of using myoblasts is that they can be taken from skeletal muscle rather than the heart itself, which will be important for newborns whose hearts are so tiny they cannot spare any tissue for a biopsy,” Cowan says.
“We have a ways to go,” he adds, “but if we can show that this works in humans, it will improve the quality of life for tens of thousands of babies.”
Source: Children’s Hospital Boston
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