[tt] scienceblog: living rat heart made by taking cells out of dead rat's heart and pumping in neonatal progenitor cells

[Alejandro Dubrovsky]

(
http://www.scienceblog.com/cms/researchers-create-beating-heart-lab-15218.html
)

Researchers create beating heart in lab
Submitted by BJS on Sun, 2008-01-13 12:13. Topic:

 * bioscience and medicine

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.

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.

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.

“Take a section of this ‘new heart’ and slice it, and cells are back in
there,” Taylor said. “The cells have many of the markers we associate
with the heart and seem to know how to behave like heart tissue.”

“We just took nature’s own building blocks to build a new organ,” said
Harald C. Ott, M.D., co-investigator of the study and a former research
associate in the center for cardiovascular repair, who now works at
Massachusetts General Hospital. “When we saw the first contractions we
were speechless.”

Researchers are optimistic this discovery could help increase the donor
organ pool.

In general, the supply of donor organs is limited and once a heart is
transplanted, individuals face life-long immunosuppression, often
trading heart failure for high blood pressure, diabetes, and kidney
failure, Taylor said.

Researchers hope that the decellularization process could be used to
make new donor organs. Because a new heart could be filled with the
recipient’s cells, researchers hypothesize it’s much less likely to be
rejected by the body. And once placed in the recipient, in theory the
heart would be nourished, regulated, and regenerated similar to the
heart that it replaced.

“We used immature heart cells in this version, as a proof of concept. We
pretty much figured heart cells in a heart matrix had to work,” Taylor
said. “Going forward, our goal is to use a patient’s stem cells to build
a new heart.”

Although heart repair was the first goal during research,
decellularization shows promising potential to change how scientists
think about engineering organs, Taylor said. “It opens a door to this
notion that you can make any organ: kidney, liver, lung, pancreas – you
name it and we hope we can make it,” she said.

http://www.umn.edu