it is being touted as the solution from 1995!
and we are no where near implementation.
Focusing on an Artificial Pancreas
For decades, medical scientists have dreamed of a technology that would end insulin-dependent diabetics’ daily need for needles to inject insulin and the endless pinpricks to draw blood for glucose monitoring. That dream took hold of Tejal Desai when she was a Whitaker Graduate Fellow at the University of California, Berkeley. Despite warnings that it was too difficult and she might not graduate, Desai set out to create an artificial pancreas, a small, implantable device containing live pancreas cells.
Scientists have tried to develop an artificial pancreas, among other organs, since the 1970s. One challenge to this approach is keeping the insulin-producing pancreas cells, or islets of Langerhans, alive while protecting them from the body’s natural immune system. At the same time, the islet cells must respond to changing glucose levels and release the needed insulin.
Desai saw that many of the challenges could be overcome with the right container, one that allows only nutrients, waste products, and insulin to pass through while barring harmful antibodies from entering. She built a small capsule employing micromachining techniques, similar to the technology used to make silicon computer chips, which allowed her to etch each pore merely a billionth of a meter wide in a paper-thin silicon membrane. That gave her control over pore number, location and size—enough to allow the small-sized glucose, insulin and oxygen to pass through while blocking immune components, which are larger. After filling a capsule with islet cells, she demonstrated its short-term effectiveness in diabetic rats.
“There are far-reaching applications of microtechnology and nanotechnology that seem sort of distant,” says Desai, “but this is something that has a real application in diabetes or other diseases. It’s a nice example of the convergence of cell science and material science and true biomedical engineering technology.”
Desai not only surprised the doubters; in 1999 she became the first Whitaker Graduate Fellow to earn a Whitaker Research Grant. The support helped her refine the device before handing the idea to a private company, iMEDD, in Columbus, Ohio, which was granted a license to the technology.
“We’re improving it toward more of a pharmaceutical product,” says Carl Grove, president of iMEDD. The company has enhanced the initial design—two silicon wafers glued together with islet cells between—with such improvements as a port to replenish the cells and a more reliable titanium housing. The new device, about the size of a half-dollar, is being tested in rats.
While iMEDD performs most of the scale-up work, Desai continues to do the basic science. One area of special focus aims at inducing capillaries to grow around the device, or vascularization. Improved vascularization gets insulin to the rest of the body faster and increases the transport of nutrients, especially oxygen. “You want a blood supply to be as close as possible to the isolated device,” says Desai, now an associate professor of biomedical engineering at Boston University. But there is a trade-off, she warns; too many capillaries could induce an inflammatory response.
Increasing the oxygen available to cells is one of the main hurdles, not only to an artificial pancreas, but to all artificial organs. “I think success is still going to rely on getting enough oxygen into the device, whether through vascularization or some other means. That is truly going to be a stumbling block.”
A block, she says, not a barrier. “I think we can do it short term, but the question is, how long can it really go? A permanent implant, of course, would be ideal, the Holy Grail. But I think even a two-year viability would be great.”
Desai received a Whitaker Foundation Biomedical Engineering Research Grant in 1999 for research toward a bioartificial pancreas and a Graduate Fellowship in 1995.
Annual Report 2003
© The Whitaker Foundation
1700 N. Moore St. #2200
Arlington VA 22209
No comments:
Post a Comment