January 13, 2008
Beating Rat And Pig Hearts Created In Laboratory

Scientists used the extracellular matrix from dead animal hearts to organize growth of cells into a functioning heart shape. Wild.

MINNEAPOLIS / ST. PAUL (January, 13 2008) – University of Minnesota researchers have created a beating heart in the laboratory.

By using a process called whole organ decellularization, scientists from the University of Minnesota Center for Cardiovascular Repair grew functioning heart tissue by taking dead rat and pig hearts and reseeding them with a mixture of live cells. The research will be published online in the January 13 issue of Nature Medicine.

“The idea would be to develop transplantable blood vessels or whole organs that are made from your own cells,” said Doris Taylor, Ph.D., director of the Center for Cardiovascular Repair, Medtronic Bakken professor of medicine and physiology, and principal investigator of the research.

Lots of people have dodgy hearts that need replacement.

Nearly 5 million people live with heart failure, and about 550,000 new cases are diagnosed each year in the United States. Approximately 50,000 United States patients die annually waiting for a donor heart.

While there have been advances in generating heart tissue in the lab, creating an entire 3-dimensional scaffold that mimics the complex cardiac architecture and intricacies, has always been a mystery, Taylor said.

It seems decellularization may be a solution – essentially using nature’s platform to create a bioartifical heart, she said.

The problem with decellularization is that you need a dead heart to start with. But perhaps studies on the extracellular matrix will lead to ways to make a purely synthetic extracellular matrix.

Decellularization is the process of removing all of the cells from an organ – in this case an animal cadaver heart – leaving only the extracellular matrix, the framework between the cells, intact.

After successfully removing all of the cells from both rat and pig hearts, researchers injected them with a mixture of progenitor cells that came from neonatal or newborn rat hearts and placed the structure in a sterile setting in the lab to grow.

The results were very promising, Taylor said. Four days after seeding the decellularized heart scaffolds with the heart cells, contractions were observed. Eight days later, the hearts were pumping.

Growth of replacement hearts, as great as it would be, is not the ideal way to solve heart disease. Better to be able to send in gene therapy and/or cell therapy to repair the existing heart while it still beats. But even once such treatments become available some will still need replacement hearts due to sudden trauma.

Share |      Randall Parker, 2008 January 13 11:26 PM  Biotech Organ Replacement

Monica Hogue said at January 14, 2008 3:58 AM:

Your last paragraph makes a good point, Mr. Parker. In many instances, the existing heart scaffold is acceptable for stem cell replenishment. In hypertrophic cardiomyopathy or in case of significant aneurysm the scaffold can be badly stretched and compromised. Gene Tx and stem cells will not work then without surgical modification.

The research described above is rather sketchy. Basically they are saying that developing the fibrous scaffold is too difficult, so they have to use dead animal hearts and decellularize them. That's better than walking around hooked up to a rolling machine or a huge battery pack. Pig heart scaffold free of porcine cells and repopulated by the person's own stem cells might work quite well. The process would take some time, however. Not for emergencies.

Brock said at January 14, 2008 12:14 PM:

It only took eight days to go from decullarization of dead-heart to pumping away of new-heart? If (as Monica suggests) you can seed a pig's heart scaffold with human cells, we're probably talking about a 2 week turnaround time on harvesting skin cells, turning them into ESC's, seeding a (freshly harvested) heart scaffold, and transplant surgery. Bang: your heart, brand new. (Note that 8 days may work for a rat-sized heart, but a longer period for a human-sized one; but whatever. If it takes 2 weeks instead that's still awesome).

Replacement obviously won't work in the brain, and something less traumatic would obviously be preferable to full-on transplant surgery, but this is huge. If they can keep you alive on a respirator / blood-pump / artificial heart for that time period anyone should be able to "make it".

Michael G.R. said at January 14, 2008 2:39 PM:

This is certainly good news.

I'm more excited about where this will lead to than what they have done so far. Certainly a step in the right direction.

Randall Parker said at January 14, 2008 7:36 PM:

Monica Hogue,

Doesn't hypertrophic cardiomyopathy take years to develop? Given the right sorts of cells and perhaps gene therapy shouldn't it be possible to intervene and do repairs before the original scaffolding becomes too stretched?

Some types of heart disease could be stopped and reversed in early stages. The longer it develops the harder to do repairs without doing much riskier reshaping.

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