The bladders were grown from patients' own cells
US scientists have successfully implanted bladders grown in the laboratory from patients' own cells into people with bladder disease.
The researchers, from North Carolina's Wake Forest University, have carried out seven transplants, and in some the organ is working well years later.
The achievement, details of which have been published online by The Lancet, is being described as a "milestone".
The team is now working to grow organs including hearts using the technique.
Bladder disease can raise pressure in the bladder leading to kidney problems.
It is usually treated by reconstructive surgery but this can lead to complications.
Standard reconstructive surgery uses tissue grafts from a section of the small intestine or stomach to build up the damaged bladder.
The technique has been shown to protect kidney function and ease problems with incontinence.
But because the intestine is designed to absorb nutrients and a bladder is designed to excrete, patients who have the procedure are prone to problems such as osteoporosis, increased risk of cancer and kidney stone formation.
The Wake Forest team identified seven young patients with a congenital condition called myelomeningocele which causes a weak bladder.
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They took a bladder biopsy from each patient and isolated muscle cells and special bladder cells called urothelial cells, which they grew 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 up to five years.
They found that bladder function improved without any of the ill-effects associated with the technique using bowel tissue.
The researchers are now working to grow 20 different tissues and organs in the lab, including blood vessels and hearts.
Kaitlyne McNamara was born with a diseased bladder, and underwent surgery to implant a lab-grown replacement
She said: "Since I have had the bladder I have not had the accidents, so I don't have to worry about people making fun of me because of that."
Lead researcher Dr Anthony Atala said: "This is one small step in our ability to go forward in replacing damaged tissues and organs.
"It is rewarding when you can see the improved quality of life in these patients.
"We wanted to go slowly and carefully and make sure we did it the right way.
"This is a small, limited experience, but it has enough follow-up to show us that tissue engineering is a viable tool that will allow us to tackle problems of similar magnitude."
In a commentary, Dr Steve Chung, of the Advanced Urology Institute of Illinois, described the work as a "milestone".
He said it could prove to be particularly useful for people with bladder cancer.
However, he warned that longer term follow-up was needed to ensure the technique was safe and effective.
Dr Richard Horton, editor of The Lancet, the journal which published details of the new research, said the science of growing organs was still at an early stage.
But he added: "This is a milestone. A lot more work needs to go into this, but over the next ten years or so we are going to see a revolution in transplantation."