MEDICAL scientists are growing the first living human hearts to be created in a laboratory.
They stripped the cells from the hearts of people who had died, leaving behind the organ's tough protein skeleton, known as a “ghost heart”.
The researchers seeded eight ghost hearts with living human stem cells, which successfully stuck to them and then, crucially, started turning into heart cells.
“The hearts are growing and we hope they will show signs of beating within the next week,” said Doris Taylor, a specialist in regenerative medicine at the University of Minnesota.
“There are many hurdles to overcome to generate a fully functional heart, but the hope is that it may one day be possible to grow entire organs for transplant.”
She revealed the research at the American College of Cardiology's annual meeting in New Orleans. It follows a series of successes by her team in growing beating animal hearts.
They include growing an entire beating rat's heart in the laboratory, which was reported in the journal Nature Medicine in 2008, and then a pig's heart. Again the organ grew and started beating.
The team has also taken the ghost hearts of rats and pigs and seeded them with human stem cells. Again the cells multiplied rapidly, colonised the structure and started to beat independently. The beating strength was up to 25 per cent that of a normal heart, but the fact that the hearts were beating at all was seen as a triumph.
Dr Taylor hopes that, in the long term, the technology can be applied to overcome two of the biggest obstacles to transplant surgery. One is the shortage of organ donors; the other is the more complex problem of rejection, where people lucky enough to get transplants still have to take drugs for the rest of their lives to prevent their own immune systems attacking the organ that has saved them.
Dr Taylor points out that there is no shortage of pigs from which to extract hearts if no human cadavers are available. Once such a heart has been stripped of pig cells and reseeded with human stem cells taken from a patient needing a new heart, there should be few rejections.
“We are a long way off creating a heart suitable for transplant, but the potential is clearly there," she said.
Regenerative science has seen a host of recent advances. Last year Laura Niklason, professor of biomedical engineering at Yale School of Medicine, Connecticut, published research in the journal Science describing how she had grown rat lungs in a laboratory using a similar technique to Dr Taylor's.
She then transplanted the artificial organs into living rats where they kept the creatures alive for up to two hours.
Last month Professor Shay Soker and colleagues at the Wake Forest Institute for Regenerative Medicine, North Carolina, described in the journal Hepatology how he had grown miniature “human” livers from the animal ones.
The researchers removed livers from mice, rats, ferrets, rabbits and pigs and then stripped them of their natural cells. Once cleansed, the livers were seeded with human foetal and other cells that multiplied and began functioning like normal human liver cells.
They wrote: “This technology may provide the necessary tools to produce the first fully functional bioengineered livers for organ transplantation and drug discovery.”
The Australian
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