Campaign for Responsible Transplantation

Chances of Animal-To-Human Transplants Fade

Friday February 9 5:46 PM ET
By Richard Woodman

LONDON (Reuters Health) - Serious doubts about the prospects of successful animal-to-human organ transplants have been expressed by a Government expertadvisory committee.

Several companies, including the UK's PPL, Switzerland's Novartis and America's Biotransplant, are backing animal-to-human transplantation research in the hope that animal organs can alleviate the severe shortage of human donor organs available for transplantation.

But the chances of success may be receding, according to the annual report of the UK Xenotransplantation Regulatory Authority which was set up three years ago regulate this new field. Any transplant between different species is called xenotransplantation.

The report, published by the Department of Health on February 5th, notes that genetic modification of source animals to "knock out'' the generesponsible for rejection and the inclusion of new genes needed to controllater rejection--though promising--is still in the "very early stages.'' It adds that research in animals "do not yet provide substantive data that xenotransplanted organs are capable of sustaining life in humans.

Researchers have indicated that this is related more to the inability to optimise immunosuppressive regimes rather than the problems of physiology. Nevertheless the absence of data is a concern, not least because such data will only be obtained through further animal research.''

The report also voices concern that eliminating all possible risks of transferring diseases as a result of xenotransplantation is impossible atpresent.

"It seems therefore that the likelihood of whole-organ xenotransplantation--particularly for heart transplantation--being availablewithin a clinically worthwhile time frame may be starting to recede,'' the authors of the report conclude.

The report says greater progress has been made in the development of cell transplant therapies for conditions such as Parkinson's disease, Huntington's disease, stroke, epilepsy, spinal injury and diabetes.The authority has met several companies involved in this area, including Genzyme to discuss the firm's progress in xenotransplant cell therapies for Parkinson's disease, and the small UK firm Reneuron which is developing mouse and human neural stem cells for implantation into brains damaged by degenerative diseases.

The problem of rejection is less of a hurdle with this type of treatment,they say.