for National Geographic News
The human body is remarkably adept at healing itself. Even when significant injuries cause people to lose chunks of their major organs, the tissues can fully regenerate.
Now doctors have harnessed the body's healing process to produce the first lab-grown organs for use in human patients.
The work, announced in today's online edition of the British medical journal The Lancet, involved implanting laboratory-grown bladders into children and teens with spina bifida.
Spina bifida is a birth defect that causes a host of medical problems, including kidney damage and incontinence due to poorly functioning bladders.
When surgery is needed, the traditional solution is to graft tissue from the patient's stomach or intestine onto the bladder. The same process can be used to "build" bladders for patients who have lost them due to bladder cancer.
"[Pieces of] intestines have been used for more than a hundred years," said Anthony Atala, director of the Institute for Regenerative Medicine at Wake Forest University School of Medicine in Winston-Salem, North Carolina.
But the intestine is designed to absorb nutrients, whereas the bladder is meant to prevent the reabsorption of waste products from urine.
"You can imagine the problems that ensue if you put in a tissue that is absorbing things it should be excreting," Atala said. "You wind up with chemical imbalances, increased infections, and increased cancer."
The laboratory-grown organs resolve this by using bladder tissue grown from healthy parts of the patients' own malfunctioning organs.
The procedure begins with a biopsy. "We took a small piece of the bladder, less than half the size of a postage stamp," Atala said.
His team separated the cells into two types: muscle cells, which form a layer on the outside of the bladder, and urothelial cells, which line its interior. These cell types were grown separately in a process called tissue culturing.
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