BENEFITS/APPLICATIONS

 

Despite the possible risks of xenotransplantation, many patients and researchers alike see this as the only viable hope for the 4,000 who die each year awaiting organs. Polls in the United States indicate that as many as 75 percent of those surveyed would find xenotransplantation acceptable (and this figure is certain to increase with successful advances in the technology).

Some have adopted a middle-of-the-road position. Although whole organ transplants are still viewed by many as too experimental, simpler non-vascularized grafts (islets, skin, etc.) have a proven track record. They are far easier to transplant, do not involve the need for immunosuppressive drugs (as the grafts are not directly connected to the recipient's blood stream), and have minimized chances of infection. While such xenotransplants are not the lifesavers organ transplants are, they do have the potential of improving the lifestyles of millions of people (diabetics, burn victims, etc).

Furthermore, most of these miminal-risk xenotransplants would involve tissue from pigs, which are among the least riskiest and controversial of donor animals. Hundreds of years of human and pig interaction (in everything from butchery to skin grafts) has not resulted in a single case of retroviral infection; neither have any of the experimental trials in which pig tissue was introduced into other animal species. As a further safeguard, pigs can be bred in specific-pathogen-free environments that would optimize the safety to recipient patients. Lastly, the use of pigs rarely invokes the ethical controversy that surrounds the use of non-human primates. Apparently, most people are indifferent to the use of a species that is regularly slaughtered for meat.

Thus, for both its possibilities and realities alike, research into xenotransplantation continues. The economic implications of xenotransplantation are still difficult to predict. The cost of organs from SPF pigs will initially be high, then most likely lower as the market stabilizes. There are also unknown factors regarding the costs of immunosuppressants and possible lifelong patient monitoring. Nonetheless, xenotransplantation is a field that American industry seems to find worth pursuing, and it continues to pour much effort in that respect.

 

INVOLVED COMPANIES/LABORATORIES

PPL Therapeutics and ProBio America

Working on applying cloning technology to pigs.

 

Imutran Ltd. and Novartis

Developed transgenic pigs that incorporate genes for the complement inhibitory proteins DAF, MCP, and CD59.

 

Circe biomedical

Making medical products that incorporate animal cells for the treatment of liver diseases and of diabetes.

 

Cell Genesys and Hoechst

Designed T-cell therapy to stimulate the immune system in fighting viral infections and cancer.

 

Alexion Pharmaceuticals and US Surgical

Created dual-acting fusion gene that incorporates the functional domains of two genes coding for the complement inhibitors DAF and CD59.

 

VivoRx

Demonstrated that microencapsulated islet cells could work in humans using human islets protected inside microcapsules.

 

La Jolla Pharmaceuticals

Designed therapeutics that suppress production of disease-causing antibodies without affecting protective functions of immune system.

 

Nextran and Baxter Healthcare Corp.

Creating transgenic pigs incorporating human genes that code for complementary inhibitory proteins.

Source: The Organisation for Economic Co-Operation and Development