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Diabetes and the stem cell promise

The search for a cure, or even a less-complicated treatment, is still on a long road to its goal.

November 07, 2011|By Eryn Brown, Los Angeles Times

"We have not regenerated the intricate mechanisms that regulate the levels of secretions," says Matthias Hebrok, director of the UC San Francisco Diabetes Center. "Beta cells are like a Porsche — an amazing, calibrated machine. What we've made is more like a Volkswagen Beetle."

Another major problem facing a cure in humans is the issue of autoimmunity — the problem that causes Type 1 diabetes in the first place. "Even if we are able to generate beta cells from stem cells, if you put them into a patient with Type 1 diabetes, they'll be eliminated quickly, because the immune system is primed to destroy those cells," Hebrok says.

Currently, physicians combat autoimmune responses with anti-rejection drugs. In the future, immunologists hope to figure out ways to specifically interfere with the interaction of the immune system and beta cells.

Another approach to the autoimmune problem is being tested by ViaCyte. The company is working on an embryonic stem cell-based therapy that will enclose beta-cell precursors inside a membrane envelope, then implant them under a diabetic patient's skin. The pouch will allow insulin to flow out of it, into a patient's bloodstream, but won't allow cells of the immune system to get in and attack the implant (or allow rogue cancers from the transplant, should they arise, to escape into the recipient's body).

Finally, diabetes researchers face the same challenges as any other scientists working with stem cells: They need to figure out how to produce large numbers of the beta cells and make sure they're safe and stable.

Over the long term, the best solution would probably be to study how stem cells generate beta cells to figure out how to teach a patient's body to regrow islets for itself from stem cells, and possibly even other types of cells, already in the body, Firpo says. "We could have stem cell therapies that don't actually involve a stem cell being transplanted into a person."

Weir, Firpo and Hebrok all say they can't predict when stem cell therapies for diabetes might become available.

Hebrok adds that he isn't discouraged, though. "To be honest, I think we're amazingly fast. When I started in 1996, we really had no idea" how to produce beta cells, he says. "What we've learned in the past decade and a half is truly amazing."

Still, the pace of progress can seem unbearably slow to some. The soonest ViaCyte's technology would begin human trials would be 2013. Other proposed cures won't be ready for testing until even further in the future.

"There was too much hype for this type of technology. There are no shortcuts in this kind of research," says Dr. Camillo Ricordi, an islet cell transplantation expert at the University of Miami Diabetes Research Institute.

"Next century, when you look back at it, two decades won't seem like much. But for those affected right now, every month is too long."

eryn.brown@latimes.com

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