March 19, 2012

Growing a blood vessel fro transplant inside your own body

Wall Street Journal - Doctors at Yale University here implanted in Angela's chest in August a bioabsorbable tube that is designed to dissolve over time. The tube was seeded with cells, including stem cells, that had been harvested from Angela's bone marrow. Since then, the doctors say, the tube has disappeared, leaving in its place a conduit produced by Angela's cells that functions like a normal blood vessel.

"We're making a blood vessel where there wasn't one," says Christopher Breuer, the Yale pediatric surgeon who led the 12-hour procedure to implant the device. "We're inducing regeneration."

Angela, who had little stamina before the operation, now has the energy of a regular kid. She is on several medications, but Dr. Breuer and her parents think she'll be able to start school in the fall.




Angela's condition, known as hypoplastic left heart syndrome, affects some 3,000 newborns in the U.S. each year. With just one ventricle, the babies can't deliver sufficient levels of oxygen to their organs and extremities, compromising their development and causing them to turn blue and suffer from a lack of energy. Without a surgical repair, says Dr. Breuer, 70% of them die before their first birthday.

Pediatric surgeons typically treat the condition with a series of operations called the Fontan procedure, designed to enable the heart to function without the missing ventricle. The last operation involves implanting a synthetic blood vessel made of Gore-Tex to reroute blood from the lower extremities directly to the lungs instead of through the heart. The device works, but it is prone to clotting, infection and in some cases, the need for additional surgery later in life as the child grows. The idea behind Dr. Breuer's project is that a natural conduit with the biology of a normal blood vessel would grow with the child and avoid or significantly reduce complications associated with a synthetic tube.

Angela's case "is a real milestone and broadly important for the field of tissue engineering," says Robert Langer, a researcher at Massachusetts Institute of Technology and a regenerative-medicine pioneer who isn't involved in the Yale initiative. "It gives you hope that when you combine cells with a scaffold and [put] them in the body, they will do the right thing."

Angela's heart defect was diagnosed in utero, when her mother Claudia was five months pregnant. She had her first operation when she was 5 days old, and another at 8 months

Development of the procedure has been painstaking. Dr. Breuer undertook four years of laboratory research after he joined Yale in 2003 before seeking approval from the U.S. Food and Drug Administration in 2007 to test the approach on patients. It took four more years and 3,000 pages of data before he got a greenlight. The study builds on the cases of 25 children and young adults successfully treated in Japan a decade ago with a similar approach.

Dr. Breuer, who holds several patents through Yale related to the technology, expects to implant a tissue-engineered blood vessel in a second patient soon as part of a six-patient study to test the safety of the procedure and determine whether the blood vessels actually grow in the body as a child gets bigger. The hope is that if these patients are treated without a hitch, the procedure may be available under a special FDA humanitarian device exemption, which would allow Yale to charge for it while conducting a larger study.

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