Human stem cells may help treat heart failure: Study

Scientists have employed human stem cells to restore heart function in monkeys, a breakthrough that may pave the way to remedy heart failure in humans as well.

Published in the journal Nature Biotechnology, the research could make it possible to tackle heart failure, one of the leading causes of death in the world.

"The cells form new muscle that integrates into the heart so that it pumps vigourously again. In some animals the cells returned the hearts' functioning to better than 90 per cent of normal," said Charles Murry, a professor at the University of Washington in the US.

Heart failure is usually a result of heart muscles' death due to heart attacks.

The damaged heart muscles are usually replaced by a scar tissue which does not contract, making the heart weaker. This curtails blood supply and oxygen to the heart, culminating in heart failure.

The researchers induced experimental heart attacks in macaque monkeys, which were chosen because of their similarities with human beings in terms of heart size and general physiology.

The experimental heart attacks reduced the hearts' left ventricular ejection fractions - a measure of how much blood the heart pumps per beat - from about 65 per cent to 40 per cent, enough to put the animals into heart failure.

The researchers then took heart stem cells that they had grown from human embryo and injected them into and around the young scar tissue.

Each animal received roughly 750 million of these human embryonic stem cell-derived cardiomyocytes - muscle cells of the heart.

Researchers found that the ejection fraction of the treated monkeys over a span of three months, rose gradually from the previously recorded 40 per cent to 66 per cent, which is the normal fraction.

On studying the monkeys' hearts, the researchers found that human heart cells had created new muscle tissue in the damaged scar tissue, eventually forming mature heart cells.

"The goal of the research is to develop a treatment that could be given to people shortly after a heart attack to prevent heart failure. Because heart cells are long-lived there should be no need for additional treatments, Murry said.

The transplanted stem cells would also be genetically altered to reduce the risk of immune rejection, which often complicates organ transplantation, according to the researchers.

"What we hope to do is create a 'one-and-done' treatment with frozen 'off-the-shelf' cells that, like O-negative blood, can go into any recipient with only moderate immune suppression," Murry said.