It's the only grafting procedure using bi-layered, engineered skin derived from living human cells to be approved by the US Food and Drug Administration. If doctors have their way, it will be also be the most prevalent one.

The method, known as Apligraf, is currently cleared only for use in the treatment of venous leg ulcers, but doctors say the product is so much like real human skin that they want to use it to treat other conditions, such as burns, diabetic foot ulcers, and sites where skin cancer has been removed.

Apligraf, developed by Organogenesis in Canton, Massachusetts, was approved in May 1998 for venous leg ulcers. Vericose veins and venous hypertension can lead to skin ulcerations – the most common type of wound in elderly patients. Doctors use Apligraf to heal these serious wounds that previously would have required amputation.

"The last time there was a significant advance in wound care for venous leg ulcers, the US was at war with Spain," said Organogenesis spokeswoman Carole Hausner.

"You can't compare [Apligraf] with anything else because there's nothing else like this available," said Anna Falabella, a wound-care specialist at the University of Miami School of Medicine. "It's a human skin equivalent: It contains living cells, it's readily available, it doesn't contain cells that induce acute clinical rejection."

Organogenesis will present findings on Apligraf's use with burn patients at a scientific meeting next month, Hausner said. The company has also completed enrollment for a study to prove Apligraf's efficacy with diabetic foot ulcers.

A regular graft is not always possible if, for example, a patient has damaged skin or doesn't have extra skin available. Tissue-engineered skin is what doctors call off the shelf. It eliminates another painful wound elsewhere on the body, as well as time in the operating room "harvesting" the patient's own skin.

The tissue-engineered skin is derived from post-circumcision human neonatal foreskin. According to a special report in the December issue of the Journal of the American Academy of Dermatology, the cells of one foreskin can be expanded to an area the size of five to six football fields and generate 250,000 skin products.

The mother of the newborn must be tested for infectious disease and give permission for doctors to use the foreskin of her newborn.

"Usually, if you do a graft from another person, the organ contains antigens that are rejected," Falabella said. "But this doesn't have the types of cells that induce rejection."

Similar products contain some human proteins along with synthetic cells and act as temporary wound covering. Others are comprised mostly of bovine collagen, contain just one layer of skin, or are harvested from the patient's own cells, which are grown at a lab and returned to the patient.

Apligraf is natural, permanent, contains both layers of the skin, and can be received within 24 hours of ordering, Hausner said. "People call their products 'skin' when most scientists wouldn't call it skin."

The combination of the human cells with bovine collagen create a product that, unlike other tissue-engineered skin, has both a dermis and epidermis, Hausner said.

"There's a reason the skin has a dermis and epidermis," she said. "Evolution got it right – they're used to working together as a team."

Research shows that certain growth factors are only produced by the epidermis, some by the dermis only, and others are produced only by the combination of both layers, Hausner said.

Apligraf is designed to be a permanent replacement of human skin. But researchers suspect it might actually induce the growth of the patient's own skin and is eventually replaced by it – what doctors call a "silent rejection."

"It's not known for sure what happens in the long term but it's thought that maybe the graft is eventually replaced by the host cells," said Falabella, who is conducting a study to find out.

Either way, doctors say the product is encouraging the skin to heal unlike anything else used before.

Besides chronic wounds and skin diseases, doctors believe tissue engineering could also be used for tattoo removal and to rejuvenate aging skin.