Last updated at 08:53 12 February 2007

Women have grown their own breast implants through pioneering stem cell treatment, it emerged yesterday.

Scientists harvested the stem cells from the women's own fat and encouraged them to form breast tissue.

They say the result gives a more natural look than many of the synthetic implants used by showbusiness stars like Pamela Anderson.

The Japanese teams have carried out trials on dozens of women and say they have had no problems.

They say the treatment will be routinely available from plastic surgeons within five years.

British surgeons said yesterday they were convinced by the technique and found it "appealing".

Stem cells can turn into different tissues in the body and this technique involves taking them from fat.

Dr Kotaro Yoshimura of the University of Tokyo and his team then mix these with general fat cells and inject them back into patients' breasts.

The hope is the stem cells will lead to the formation of new fat cells and coax blood vessels to grow into new breast tissue and nurture it.

The technique was first used in 2004 and since another 38 women have been treated without any major side effects.

The long-term effectiveness has not yet been demonstrated fully, however, and further tests are needed.

To date the technique can boost breast size by only half as much as existing synthetic implants, and slender patients may not have enough fat to spare.

However Dr Yoshimura believes the effect is more natural-looking and should avoid any problems such as the leaking which occurred with older silicone implants.

Doctors can already use fat to create "natural implants", but they can shrink over time because of a lack of blood supply.

The new technique aims to overcome this problem.

Dr Yoshimura said: "I believe that within five years my procedure will be available as plastic surgery and that it will prove very popular."

Similar work is being carried out in the U.S. Dr Jeremy Mao told the American Association for the Advancement of Science conference in Washington in 2005 that using stem cells could eliminate the need for extra surgery and produce long-lasting and more shapely implants.

In his tests, scientists at the University of Illinois turned stem cells into fatproducing, or adipose, cells which were put into plastic moulds to create different shapes and sizes of implants.

These were grown in the laboratory and then placed under the skin of laboratory mice.

They were removed four weeks later and found to be still the same shape and size.

Some British plastic surgeons have expressed an interest in using the new technique.

Venkat Ramakrishnan, a specialist in plastic and reconstructive surgery at Mid Essex Hospital Services NHS Trust said: "I'm newly convinced.

"A lot more people have to use it and prove it, but it does seem to have something to it."

Eva Weller-Mithoff, a consultant at Canniesburn Hospital in Glasgow, said the technique could be particularly beneficial to cancer patients who have a mastectomy.

"The most distressing effect of radiotherapy is that the blood vessels shrivel up," she said.

"Stem cells can differentiate into new blood vessels which could mean that more fat cells will survive."