Scientists plan market in spare body parts

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The Independent Online
Replacement body parts could be available to order from the medical laboratories of the 21st century. Scientists have already grown human skin, cartilage, bone and liver outside the body and heart muscle is next on the list. Our Health Editor reports on a new medical frontier.

The world's first human skin grown entirely in the laboratory could herald a new era in transplant surgery, a scientist claimed yesterday. Instead of relying on organs taken from other bodies doctors may soon be able to harvest specially grown replacements.

The aim is to overcome the shortage of donor organs by farming human tissue which would be grown for specific purposes. The first example, human skin called Dermagraft launched yesterday, is grown on a biodegradeable mesh that dissolves once the transplant is complete and is specially designed for the treatment of foot ulcers suffered by diabetics.

Stem cells taken from the foreskins of newly circumcised boys are used to seed the mesh and the skin grows over two weeks in an incubator that mimics conditions in the womb. Dr Gail Naughton, inventor of the technique known as tissue engineering, said it was already being used to grow other body parts, including whole bones and living joints, incorporating bone and cartilage together.

Knee joints had been successfully transplanted into rabbits and sheep said Dr Naughton, president of Advanced Tissue Sciences, a biotechnology company based in California. The first human trials involving laboratory grown cartilage are to begin in the United States and the United Kingdom next year.

She said there was a "world-wide need" for replacements for ligaments damaged in sports injuries but no living tissue was available for transplant. It could, however, be grown in the laboratory. The long-term aim is that hip and knee replacements using artificial materials will be consigned to history and living joints inserted instead. "This is not science fiction. Physiological transplants replacing the plastic and metal currently used will happen some day."

The difficulties of growing human cells in the laboratory had been overcome by studying the normal growth process. She described the mesh on which the tissue is grown as a "scaffold" and the process of tissue engineering as similar to building with bricks and mortar. It required tight control of temperature, oxygen, nutrition and waste removal.

"In nine months in the womb a human develops from one cell to a fully grown foetus. By looking at the growing environment and what the cells need we have been able to mimic the state in the womb. The only thing that limits transplant surgery is the availability of tissue and organs. Here we have the ability to grow tissue in the laboratory from starter cells that have been highly tested."

One cell bank taken from a single foreskin was enough to produce 5 million squares of Dermagraft skin. It has been used in 2,000 implants in the US and the UK with no adverse reactions.

The product, developed with Smith and Nephew, the pharmaceutical company, was designed for the treatment of foot ulcers, but there was "no reason" why it should not be used to heal wounds, improve a scar, or bring a youthful look to the middle-aged, Dr Naughton said.

"It could be used to repair wrinkles. Collagen from cows has been tried but how much better to use human baby collagen," she said.

Each piece of Dermagraft is only 200 microns thick, a fraction of the thickness of human skin, and costs pounds 250. Eight implants are required to build up a full thickness allowing time for blood vessels to grow into the structure between each piece as it is constructed.

It does not trigger the powerful immune response found with normal skin because it does not include the Langerhans cells that give the skin its immunogenicity.

Livers had been grown for up to six months in culture and had made the right proteins and enzymes.

Transplanting them was difficult because they needed a complex blood supply and they died before it could be established. Patients would also have to be treated with immunosuppressive drugs to prevent rejection.

Heart muscle was "not difficult to grow at all", and a laboratory-produced version might one day be used to replace a patch of a diseased heart. Kidneys, however, were highly complex organs and were unlikely ever to be produced in the same way.

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