Sam Golas loves to drive combines and tractors around his family's farm north of Winnipeg, to swim in the sand pits, and in his downtime, to build Lego forts. When he was diagnosed with Type 1 diabetes at age 8, his family didn't want the disease to interfere with his active lifestyle.
His parents read everything they could about diabetes, which affects two million Canadians, and got Sam an insulin pump -- a tiny device worn in a belt that delivers fast-acting insulin into the body through a thin plastic tube.
Since diabetics produce very little or no insulin, they cannot metabolize glucose and must go to great lengths to try to keep their blood sugar on an even keel.
For Sam, the pump was an improvement over needles, but his family still had to test his blood sugar levels every two hours and worried constantly about the long-term damage the disease can cause: kidney failure, blindness and loss of limbs.
When the Golases heard about a transplant surgeon in Mexico City who had developed an innovative but highly controversial way to control diabetes, they jumped at the chance for Sam to try the experimental therapy.
Pioneered by Raphael Valdes, a prominent Mexican transplant surgeon, the treatment centres on a process known as xenotransplantation -- animal-to-human transplantation. He transplants insulin-producing islet cells cultivated from the pancreases of seven-day-old piglets into his diabetic patients.
Now Sam, and Teresa Hibbert, a Toronto teacher in her mid-50s and the only other international patient to undergo this treatment, find themselves in the middle of a highly unusual scientific controversy.
Dr. Valdes believes his treatment works, and has published results of transplanting porcine insulin in his adolescent patients in a peer-reviewed journal. Yet in an extraordinary vote of non-confidence, the International Xenotransplantation Society is calling for an end to his clinical trials, saying there isn't enough independent proof the treatment works.
For now, Dr. Valdes's patients are standing by him. Both Sam and Ms. Hibbert say their health has improved, and they require less insulin -- results replicated in 31 Mexican patients.
"There has been a dramatic improvement in Sam's lifestyle and in the control of his sugar levels," said Nathan Golas, who estimates his son needs 30 per cent less insulin.
Ms. Hibbert is also enthusiastic: "I can eat a croissant and my blood sugar levels do not go up and I don't have to inject as much insulin."
To his patients, the 57-year-old Dr. Valdes is a hero who pushes the boundaries of science and is ushering in a new era of hope.
But he has been forced to stop the trials at the Federico Gomez Children's Hospital in Mexico City while it and the National Committee for Bioethics review his results and the ethics of Dr. Valdes's study.
The International Xenotransplantation Society, a prestigious body of 300 scientists, has published a letter in the September issue of Xenotransplantation concluding that the information from Dr. Valdes's clinical trials was "insufficient to justify the use of children" as research subjects.
"IXA isn't some super-conservative group. We are the people most invested in seeing xenotransplantation succeed," said Dr. Megan Sykes, a Harvard Medical School professor who serves as the society's president. "But we understand the need for caution and we think it is dangerous when people raise public expectations for success falsely."
Critics say Dr. Valdes moved too quickly, skipping preclinical tests on primates, a crucial step in ensuring that the operation has the potential to succeed. The other overriding concern that stalks the field of xenotransplantation is the potentially catastrophic risk of cross-species transmission of animal infections.
