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Diaphragms grown from stem cells, may cure birth defect

The lab-grown tissue was successfully transplanted into rats, but the process must be tested with larger animals before scientists attempt to do the same with human patients.

By Stephen Feller

STOCKHOLM, Sweden, Dec. 1 (UPI) -- Scientists in Sweden have engineered new diaphragm tissue in rats that regrows with the same functional mechanical properties as diaphragm muscle, according to a newly published study.

The researchers used donor tissue and stem cells from rats, using a method similar to recent experiments to regrow vocal cords and a rat arm.

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Malformations or holes in the diaphragm, which is important to swallowing and breathing, are found in 1 out of 2,500 newborns and cause extreme symptoms that are sometimes fatal.

Artificial patches are often used to repair the defects, but the patches don't grow or provide the chest contraction needed to help with breathing, making them a less than ideal solution.

"So far, attempts to grow and transplant such new tissues have been conducted in the relatively simple organs of the bladder, windpipe and esophagus," said Dr. Doris Taylor, Regenerative Medicine Research Director at the Texas Heart Institute, in a press release. "The diaphragm, with its need for constant muscle contraction and relaxation puts complex demands on any 3D scaffold; until now, no one knew whether it would be possible to engineer."

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The scientists started by taking diaphragm tissue from donor rats and removing living cells from it with chemical treatments, leaving behind an extracellular matrix -- the connective tissue giving organs their structure and mechanical properties. The remaining scaffolds are then seeded with bone-derived stem cells and transplanted into the rats.

Three weeks after the transplants, the rats were gaining weight and the new tissue was acting the same as native diaphragm tissue.

While researchers said the method would have to be tested in larger animals before trying it with humans, the success of the study with rats suggests they can cure diaphragm defects in children rather than fitting them with a temporary patch.

The method may also eventually be useful for regenerating heart tissue, they said, because of its similar requirements for contraction and relaxation each time it beats.

"This bioengineered muscle tissue is a truly exciting step in our journey towards regenerating whole and complex organs," said Dr. Paolo Macchiarini, Director of the Advanced Center for Regenerative Medicine at Karolinska Institutet. "You can see the muscle contracting and doing its job as well as any naturally-grown tissue -- there can be no argument that these replacements are truly regenerated, and the possibilities that this opens up for the future are enormous."

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The study is published in the journal Biomaterials.

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