U.S. scientists have successfully grown bladders in a lab from tissue samples and implanted them into patients with failing bladders.
It's the first time an organ has been mostly replaced with one engineered in a laboratory from a patient's own cells, the researchers say. Previously, only connective tissue, such as bone or cartilage, and patches of skin have been grown and implanted this way.
The researchers, whose work is in Monday's early online publication of the journal The Lancet, say such "regenerative medicine" could one day lead to a solution for the shortage of donor organs.
Patients receiving organs engineered from their own cells wouldn't have to take anti-rejection drugs, as they do after receiving donor organs.
Dr. Anthony Atala, the lead researcher, started the work at Children's Hospital in Boston in 1999. Now at Wake Forest University in North Carolina, Atala and his team used immature bladder cells, called progenitor cells, to create the new bladders.
The research patients were young people four to 19 years old who had congenital birth defects, leaving them with poor bladder function. The walls of their bladders were not flexible enough, leading to high pressure in their kidneys and possible damage to them.
All the patients were candidates for a 100-year-old procedure to repair their bladders using tissue from the intestines.
Starting at the cell level
The procedure to create a replacement bladder begins with a CT scan of the patient to determine what shape the organ should take. Scientists next take a small patch of tissue from the patient's ailing bladder, and separate the muscle cells on the outside and the lining cells on the inside.
They then build an artificial scaffold out of biodegradable material, based on the computerized image data from the CT scan. The cells are grown in a culture and then layered onto the bladder-shaped scaffold.
The bladder takes about eight weeks to grow. Surgeons suture the new bladder to the patient's original bladder, and the scaffold eventually degrades inside the patient's body.
Atala's team implanted the first grown bladder at Children's Hospital, but wanted to make sure it would work before attempting other procedures. Doctors performed six more surgeries and followed the progress of each patient for two years.
Their research showed the engineered bladders worked as well as bladders repaired using the old method with intestine tissue without its side effects.
Working with a 'blank slate'
Atala is now working with stem cells, "blank slate" cells that can develop into any cell in the body, to create blood vessels, kidneys, hearts, livers and nerves. Scientists stress that building more complex tissues and organs this way will likely prove more difficult.
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Dr. Steve Chung, a urologist who wrote a commentary for The Lancet, said replacing an entire bladder, rather than grafting it onto an existing one, may pose problems with the connection blood vessels, ureter tubes and nerves.
The Children's Hospital has licensed the technology to a new company called Tengion.
Tengion's chief financial officer told Reuters the company would be seeking Food and Drug Administration approval for clinical trials of the new bladders.