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    Scientists revive dead heart

    Scientists revive dead heart - News - Scientists revive dead heart

    'Bioartificial' organ grown from new injected cells hailed by researchers as future hope for humans

    January 14, 2008
    Sheryl Ubelacker
    The Canadian Press

    Researchers have brought a dead animal heart back to life in the lab by repopulating it with healthy cells, a feat they believe may someday allow them to grow new hearts and other organs for people desperate for transplants.

    In a paper published online yesterday in Nature Medicine, researchers at the University of Minnesota describe the process of revitalizing the heart of a euthanized lab rat, which begins with washing out the interior cells to leave just the outer shell of the organ.

    The scientists then injected the empty sac with heart cells from newborn rats. Within days, the cells had multiplied to flesh out the heart, which began beating on its own.

    "We've taken organs from cadavers, removed all the cells, put cells back in and been able to reanimate what was previously a dead organ," said molecular biologist Doris Taylor, director of the Center for Cardiovascular Repair at the University of Minnesota.

    "What that means, we hope, is that one day if you need a new organ, we'll be able to take your cells, transplant them into this framework or scaffold and build you an organ that works for you," she said.

    "We're not there yet, but we hope this opens a new door."

    Taylor's team has created these "bioartificial" organs with hearts from dozens of rats and close to a dozen pigs, using a special detergent to destroy and clear out the dead cells, while leaving the outer structure intact.

    What surprised and delighted the researchers was what happened once they injected the baby rat cells into the empty sac of the heart.

    "The cells began to reorganize in the wall of that heart," she said. "The ones that were going to make blood vessels moved to the spot where the blood vessels had been and relined the blood vessels, and the ones that were going to make muscle lined up in the wall and started to make new muscle.

    "And what it says is a couple of things. It says that this scaffold has a lot more information than we thought and that the cells know how to respond to that in some way."

    Co-investigator Dr. Harald Ott, a former research associate at the Minnesota cardiovascular repair centre, who is now at Massachusetts General Hospital, said the research team used "nature's own building blocks to build a new organ.

    "When we saw the first contractions, we were speechless."

    The researchers believe new hearts could be built for people waiting for a transplant, either using the shell of a human cadaver heart or pig heart injected with the person's own stem cells. Their hope is that those stem cells would also grow to replace the outer sac, thereby preventing rejection by the body.

    Taylor believes the process could be used to generate other organs – from the liver and lungs to the pancreas and kidneys.

    Dr. Peter Liu, a cardiologist and scientist at Toronto General Hospital's Peter Munk Cardiac Centre, hailed the research as a huge step toward solving the shortage of donor organs.

    But he said the heart is an easier organ to revitalize because its functions are simpler. The pancreas, for example, includes specialized insulin-producing cells, while the kidneys contain various cellular structures to filter waste from the body.

    "To have all those things work out beautifully with each other is a higher-level challenge," said Liu, who was not involved in the work.

    And Dr. Marc Ruel, director of cardiac surgery lab research at the Heart Institute at the University of Ottawa, called the work a "really important breakthrough."

    But he cautioned there are still many obstacles to overcome before the technique could be applied to humans.

    What's clear, Taylor said, is that thousands of people are dying each year while waiting for donor organs that are in short supply – and she doubts that growing whole new organs from scratch in the lab using a person's stem cells alone is feasible in the foreseeable future.

    Her team's ultimate goal would be to take a human cadaver or pig heart and infuse it with stem cells from the bone marrow, muscle or heart of a person with heart failure and "grow a heart that matched your body."

    She's aware that some people may be uncomfortable with the idea of using an organ from another species. But the donor organ shortage may leave no choice.

    "Clearly if a pig scaffold works, it would provide almost unlimited scaffolds for kidney, liver, heart, lung, pancreas, you name it."