Real or mimic?

New Delhi, Jan. 13: Starting with a dead heart stripped of all its cells, scientists have for the first time created a beating heart that faithfully mimics the original organ in a laboratory.

The feat announced today by biomedical researchers in the US involved experiments on rat hearts. But scientists hope to refine the technique to grow entire organs as spare parts for humans.

The researchers at the University of Minnesota removed cells from dead rat hearts using detergents, leaving behind a basic heart scaffold made up of connective fibres and tissues. Then they reseeded them with living cells from newborn rats, allowing them to grow on the scaffold into full beating hearts.

The new hearts began to contract within four days and began to show pumping action eight days after seeding. The findings will appear in the journal Nature Medicine tomorrow.

“We took nature’s own building blocks to build a new organ,” said Harald Ott, a team member at the Massachusetts General Hospital in Boston. “When we first saw the contractions, we were speechless.”

The scientists have also applied the decellularisation process on other organs such as the liver, lung and the kidney as well as on pig hearts, which are comparable in size and complexity to human hearts.

“It opens a door to the notion that you can make any organ — kidney, liver, lung or pancreas. You name it and we hope we can make it,” said Doris Taylor, a senior team member at the University of Minnesota.

But scientists cautioned that there were several hurdles before the technique could be used to produce organs for human transplantation.

Researchers point out that the performance of these bioartificial hearts has not yet been demonstrated in animals. “We need to see what happens when these artificial hearts are placed in a recipient animal,” said Anita Thomas, a scientist at the Australian Institute of Bioengineering and Nanotechnology, University of Queensland.

The raw material to seed the scaffolds is also likely to be a problem. The US researchers had to inject the decellularised scaffold with 50 to 75 million cells that had been obtained from 100 rat hearts.

“There is a long way to go for all of us in terms of where we go to get the cells that ultimately would make a real human heart. We can’t just get access to 100 other hearts as they have done here,” said Wayne Morrison, the director of the Institute of Microsurgery in Melbourne.

This technique would also cause rejection because they are made from someone else’s hearts. “We need another source of cells to be able to repopulate the heart,” Morrison said.

Stem cells, which have the potential to turn into any type of cell in the body, are likely to be good candidates as seed cells. “Our goal is to use a patient's own stem cells to build a new heart,” Taylor said.

The scientists hope such bioartificial organs will provide an alternative to organ transplantation procedures. According to one estimate, about 22 million people worldwide suffer from heart failure alone.