Scientists create beating animal heart in lab; could help organ shortage

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http://ca.news./s/capress/080113/health/health_rebuilding_hearts

By Sheryl Ubelacker, The Canadian Press

TORONTO - 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 Sunday in Nature Medicine, researchers at

the University of Minnesota describe the process of revitalizing the

heart of a euthanized laboratory 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 , 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 from

Minneapolis-St. .

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

'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.

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. "

" I think it's the first proof of principle that we can actually get

the stem cells to become functional contractile cardiac cells that

will actually generate a blood pressure, " said Ruel, who was not

involved in the research. " And this had never been shown before. "

But he cautioned there are still many obstacles to overcome before the

technique could be applied to humans. For one, the bioartificial heart

was beating at a rate far slower than what is normal for an adult rat.

As well, the problem of the body rejecting the " foreign " heart may

mean patients would still need to take anti-rejection drugs.

" It's still not something that's going to be done in two years, " he

said. " But it's certainly a huge step forward and it gives a lot of hope. "

believes the process could be used to generate other organs -

from the liver and lungs to the pancreas and kidneys.

Dr. Liu, a cardiologist and scientist at Toronto General

Hospital's Munk Cardiac Centre, hailed the research as a huge

step towards 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 also was not involved in the

work. " So the heart is, I think, the easier starting point. "

What's clear, 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, " she

said. " It clearly means that more organs could be available. "

" If pig becomes the shortest route to a heart that works, that's the

route we'll take ... My bottom line is to try to make a difference in

the lives of people with disease, and if this gets us there, great. "