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Heart Tissue Is Grown From Rat Cells

Posted on: Tuesday, 14 December 2004, 12:00 CST

CAMBRIDGE -- Researchers at the Massachusetts Institute of Technology have used rat cells to grow dime-sized swatches of heart tissue that twitch like a beating heart when an electrical current passes through.

The researchers are now trying to patch ailing rodent hearts with the tissue in hopes that it works like a kind of cardiac bandage. If successful, it raises the possibility that human hearts could one day be repaired with tissue grown in the laboratory.

The Boston Globe reported that the MIT findings mark the first time that scientists have successfully used an electrical current to produce dense heart tissue that beats in a rhythm mimicking a live animal's heart.

Heart cells must be densely packed to communicate with each other. The electrical signal functions like an orchestra conductor, telling those cells how to align and work together.

Heart specialists and scientists from the expanding field of tissue engineering described the MIT research as a significant advance. But they noted it's a long way from research in rodents to successful treatment in humans.

"We'd all like to be able to grow a patch and put it onto the patient and reanimate what has become dysfunctional tissue in the heart," said William Wagner, a University of Pittsburgh researcher who is also working to develop a cardiac patch. "That's the dream. This research from MIT looks like it's an important advance in our ability to get something that functionally approaches cardiac tissue."

The MIT team's findings appeared Monday in the online edition of the Proceedings of the National Academy of Sciences.

The treatment tries to address a fundamental problem in patients with heart failure - a lot of the cells have died or aren't working well, said Dr. Donald Baim, a cardiologist at Brigham and Women's Hospital.

"And just like brain cells, the heart cells don't replenish themselves," he said

The MIT team, led by chemical engineer Gordana Vunjak-Novakovic, took heart tissue from a day-old rat and incubated it in a brew of enzymes, breaking it down into its constituent cells.

"This is a little, teeny, tiny rat," Vunjak-Novakovic said. "We do this because these young cells are still able to undergo changes. Old heart cells do not work."

The heart cells were then placed on a three-dimensional scaffold made of collagen and bathed in nutrients and gases designed to help the cells knit themselves into a single piece of tissue. The scaffold was necessary to help form the structure of the tissue.

The MIT scientists decided on a novel approach that involved using a pacemaker to generate electrical signals like those in a developing heart that help cells communicate.

Eight days after the experiment began, the MIT scientists had a piece of tissue remarkably like that in an actual heart. It was also beating in synchrony, just as a heart would inside a rodent.

"We are trying to create an environment that mimics as well as possible the actual development of a heart," Vunjak-Novakovic said. "We can never do it as well as Mother Nature, but it is good enough. We like to call it a patch for a broken heart."

The patches now being implanted in rats are designed, Vunjak-Novakovic said, as a sort of resurfacing project. The scientists hope the laboratory-grown tissue will adhere to the rodent hearts and work in concert with the existing healthy muscle.

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Massachusetts Institute of Technology (MIT)

Source: Associated Press/AP Online

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