WASHINGTON, April 3 (Xinhua) -- U.S. scientists have successfully rebuilt the bladders in seven young patients with lab-cultured tissue grown from their own cells, making a breakthrough in regenerative medicine.

A doctor at the Institute for Regenerative Medicine at Wake Forest University School of Medicine dips a specially constructed biodegradable mold, shaped like a bladder, and seeded with human bladder cells, into a growth solution at Wake Forest Uinversity in Winston-Salem, N.C., March 30. (AP)

    This is the first time a complex human organ was lab-grown and transplanted. The transplants were performed on seven patients, aged between 4 and 19 years old, who had poor bladder function dueto a myelomeningocele (a congenital anomaly). The first operation was done in 1999, and the results weren't announced until the last transplant had worked for years.

    The research team at the Children's Hospital in Boston reported long-term success of the seven transplant cases online Tuesday in The Lancet medical journal.

    "This suggests that regenerative medicine may one day be a solution to the shortage of donor organs in this country for those needing transplants," said lead researcher Dr. Anthony Atala, who is now with the Wake Forest University in North Carolina.

    The traditional bladder reconstructive surgery usually involves tissue grafts from a section of the small intestine or stomach. The use of such tissue segments, however, has been associated with many complications.

    Atala's team investigated an alternative approach using engineered bladders grown from patients' own cells. They obtained a bladder biopsy from each patient, from which they grew muscle cells and special bladder cells (urothelial cells) in the lab. The cells were then placed onto a specially designed bladder-shaped scaffold and left to grow for seven to eight weeks. The researchers surgically attached the engineered bladder to the patient's own bladder and followed progress for two to five years.

    Researchers reported that the rebuilt bladders were up to threetimes more elastic and better at holding urine. The transplants reduced leaking from the bladders of the study participants, in all of whom kidney function was preserved. The patients must still empty their bladders regularly with a tube.

    "The implanted composite engineered bladders showed improved functional parameters that were durable over a period of years. Although follow-up longer than 5 years is reported, additional studies will be needed before this procedure can be used widely," Dr. Atala added. Enditem