WASHINGTON: For the first time, scientists have grown a human organ from patients' own cells to transplant back into their bodies.

The breakthrough was pioneered by US doctors who developed bladders in the laboratory and are now using their techniques to work on doing the same for 20 kinds of tissues and organs, including blood vessels and hearts.

With tissues grown from their own cells, patients don't face the risk of rejection as they do with ordinary transplants and wouldn't have to live with the fear that a donor might not be found.

"This is one small step in our ability to go forward in replacing damaged tissues and organs," Anthony Atala, who led the research, said on Monday in announcing the development.

Atala developed the procedure for patients born with spina bifida, a birth defect in which their spines were not enclosed and that impaired their bladder functions.

The traditional treatment is to replace the bladder with one formed from part of the intestine, but because the intestine absorbs nutrients and the bladder excretes, the procedure can lead to its own host of problems, including kidney stones, osteoporosis and a higher cancer risk.

So Atala began work in 1990 on an alternative that led to the transplants in seven patients from 4 to 19 years old that he reported in the Lancet medical journal.

Atala, who began his work at Boston Children's Hospital before moving to the Wake Forest University School of Medicine in North Carolina, reported that he and his team of researchers removed a small portion of the patients' bladders, extracted cells from the biopsies and began using those cells to grow more like them in Petri dishes. The cells were then placed on a mould shaped like a bladder to grow further.

In seven to eight weeks after the biopsy, the engineered bladders were then sewn onto the patients' original bladders, and a few weeks after the surgery, the engineered organs had grown into normal-sized bladders and had begun functioning, the researchers said.

The first transplant was done in 1999, and the team said the engineered bladders have functioned as well as bladders reconstructed with intestinal tissue but without the side effects.

The procedure relieved pressure within the bladder, which can cause kidney damage, and improved the patients' incontinence, they said.

Researchers reported that the rebuilt bladders were up to three times more elastic and better at holding urine.

"We have shown that regenerative-medicine techniques can be used to generate functional bladders that are durable," Atala said. "This suggests that regenerative medicine may one day be a solution to the shortage of donor organs."

Atala said that further study is needed before the techniques could be put into wide use, but additional clinical trials were scheduled for this year.

(China Daily 04/05/2006 page1)