Tuesday, June 18, 2002
By Michael Perry
SYDNEY (Reuters) - Australian scientists have used stem cells to grow an organ in mice critical to the immune system, saying the technique could be used to restore the human immune system in HIV/AIDS and cancer patients.
"We are very confident that this work will be able to progress to humans within the next 3 to 5 years," said Jason Gill from Monash University Medical School in Melbourne.
Gill and fellow researcher Richard Boyd said on Tuesday they had discovered a "small population of cells that can generate a complete and functional thymus."
The thymus, a small lymphoid organ situated in the neck, is critical in generating cells vital to the immune system, including infection-fighting T-cells.
But the thymus' ability to generate T-cells is dramatically reduced by aging, viruses, chemotherapy or genetic abnormalities. By the age of 20 the thymus, the only organ which produces T-cells, is down to 1% functionality.
HIV/AIDS patients suffer life-threatening infections because their immune system is destroyed as the deadly virus kills large numbers of T-cells. Chemotherapy and radiation therapy also destroys large quantities of the infection-fighting cells.
"Hence the need to replace the thymus in people with the virus or undergoing chemo," said Boyd.
Gill and Boyd, whose research was published on Tuesday in the journal Nature Immunology, said they had grown thymus organs in several mice and believed the same could be achieved in humans as the immune systems were strikingly similar.
Boyd told Reuters they had discovered that epithelium stem cells injected into mice attracted haemopoetic (red blood cell-producing) stem cells and converted them into infection fighting T-cells.
"Once you have those handles, the stem cells of both epithelium and the T-cells, then you can rebuild a thymus the way you want it to be," Boyd said.
"You can use gene therapy to make the whole thing resistant to HIV infection, we may even be able to make a thymus that is resistant to chemotherapy," he said.
Boyd said the thymus, about the size of a fingernail or pea, was grown in mice by simply injecting the epithelium stem cells under the skin. Once a thymus was grown it could be transplanted into position, he said.
To date there had been limited success with thymus transplants as they
are invariably rejected by the recipient.
Copyright 2002 Reuters