Islet Cell Xenotransplantation: Where Is It Now?

In most areas of diabetes research, you don’t hear much until there’s a big breakthrough of some sort. And then it goes dark again.

That’s what happened several years ago on the then-hot topic of xenotransplantation, or the sourcing of islet cells for transplants. Some studies were launched using porcine cells and the press had a field day with headlines like “pig sushi diabetes trial.” Since then? Nada.

But recently, a New Zealand-based company called Living Cell Technologies (LCT) announced positive results from a human clinical trial involving this type of research. Albeit the trial was tiny (only 14 patients), but it still seemed worthwhile to take a closer look at the potential of these unusual islet cells and what’s been going on lately.

LCT has only worked with a couple-dozen patients over the course of all its trials, so it’s hardly ready for prime time. But the results are looking promising. In September, in a summary of their Phase I/IIa trials, LCT says that the transplantation of its product DIABECELL, a implantable encapsulated pouch of porcine islet cells, was well-received by patients. It demonstrated a reduction in hypoglycemia, significantly reduced daily insulin, and some patients already saw a drop in A1C.

Zee-no What?

Pronounced “ZEE-no-transplantation,” the method takes the cells from another species (“xeno” means foreign) and transplants them into humans. As noted, in diabetes, researchers are using porcine islet cells. Yep — the Miss Piggy variety. As with any transplanted islet cell, immunosuppressant drugs or technology (like a pouch) are necessary to stop the body from rejecting the new cells.

The benefits of using porcine islet cells is that there are simply a lot more of them and they work just like human insulin. Veterans of diabetes might remember animal insulin, which was made from cows and pigs. Same concept, just with the islet cells this time.

Access to enough islet cells is arguably the biggest reason why islet cell transplants aren’t performed more often. With only about 7,000 cadaver pancreases available each year, there simply aren’t enough human islet cells. Porcine islet cells offer a possible route.

Low-Risk Pigs

Despite having already used animal insulin, actual transplantation of animal tissue into humans makes some people — especially the medical community — a little nervous. That didn’t stop Living Cell Technology from pursuing the process. Beginning in 2007, with Phase I/II research done in Russia, LCT has developed DIABECELL, which is designed to secrete insulin without being attacked by the immune system.

“Medical professionals take a very cautious approach to everything because human lives are at stake,” explains Dr. Leonard Bloksberg, LCT’s Business Development Manager. “When xenotransplantation was introduced, it wasn’t actually considered dangerous, but it was considered risky because the rule in medicine is that if you don’t know something, then it’s considered risky until you do. Scientists around the world have spent the last few decades studying the risks. We have identified what they are and what safety measures are needed.”

How does LCT make sure their pigs are kosher for transplantation?

Bloksberg explains that LCT has their own herd of disease-free pigs, and they have received internationally certified testing facility to monitor the pigs. He also explains that there are extensive clinical trials to demonstrate that the porcine islets cells are disease-free and without risk.

“So far our DIABECELL product is passing with flying colors (not to be confused with flying pigs) as a safe and effective product for treating diabetes,” Bloksburg says.

Treatment or Cure?

Some might also find it noteworthy that in a recent report by the Juvenile Diabetes Cure Alliance, DIABECELL is one of only five lines of research that the self-proclaimed donor watchdog on cure research describes as “adequate” in moving toward a “practical cure” for diabetes. Of course, we have to keep in mind that this research was done in only 14 (!) patients, so there are a lot more studies that need to be done and opinions may vary on just what the “cure” end-goal is anyhow…

But stepping back: Can DIABECELL be considered a possible cure for diabetes? Bloksberg thinks it will, but at this point, most patients still require some insulin because LCT is still working out on how many islet cells need to be transplanted into an individual. He says, “The idea of a ‘cure’ can be a subjective target and it is clearly our goal. We are confident we will get there, but the current version of our DIABECELL product does not meet all the criteria of a complete cure in the current early stages.”

LCT has conducted its research in its home country of New Zealand, and also in Russia and most recently in Argentina, but what does the United States think about xenotransplantation?

Xenotransplantation research actually is taking place right here in the United States, prominently at the Schulze Diabetes Institute of the Diabetes Research Institute, with research being led by Dr. Bernhard Hering. Last fall, he spoke at TEDxDelMar, a TED event focused on diabetes, and you can watch his presentation here. Because of the way clinical research is regulated in the U.S., his research isn’t being conducted in humans, but his work has shown that porcine islet cells can be used effectively in primates (monkeys).

Similar to LCT’s facility, the U.S. has their own medical-grade herd of pigs, known as the Spring Point Project. This is a facility in western Wisconsin where pigs are raised in a protected fashion specifically so that they can be used in islet xenotransplantation research.

So although restrictions and guidelines in the United States might slow the research down, we’re certainly not out of the game!

As for LCT, they continue to conduct trials, completing Phase II and beginning Phase III next year. Bloksberg explains that they’d like to get DIABECELL into the clinic as soon as possible, while also completing regulatory requirements so that more patients from around the world can participate.

“The USA has some cultural issues with some of the technologies we use, so the process is taking a little longer there,” he said. “That said, so far the FDA is very favorably impressed with the safety and quality of our work and we are confident that we will get the approvals in the USA when the time comes.”

When exactly that time will come is not clear.

Meanwhile, despite all the potential of this pig cell methodology, I still have one burning question: what will the vegetarians do?!