|UIC's Jose Oberholzer|
Researchers have been experimenting with islet cell transplantation as a possible cure for Type 1 diabetes for decades. These insulin-producing cells are destroyed by Type 1 diabetes, but various transplant methods that worked in animals--including using tiny capsules to deliver the cells in a way that guards against an immune response--have failed to make the grade in humans.
Now a team at the University of Illinois in Chicago, though, says that they've successfully tested larger capsules, or spheres, in mice, and found that they could avoid the hurdles that tripped up earlier attempts.
The problem with the tiny spheres that were used in the past to deliver islet cells, which were 0.1 to 1 millimeter in diameter, is that scar tissue would form around them, preventing the nutrients and oxygen needed by the cell to produce insulin from getting inside. But the team found that if you made the spheres larger, 1.5 millimeters or larger in diameter, using different biocompatible material and inserted them into mouse models, they could maintain blood sugar levels for 180 days--several times longer than the smaller spheres accomplished.
"This changes everything--this finding completely overturns what we thought about the biocompatibility of implantable spheres," said Dr. Jose Oberholzer, chief of transplantation surgery and director of cell and pancreas transplantation at the University of Illinois Hospital & Health Sciences System and an author on the paper. "We always thought very small spheres were necessary for encapsulating cells, in order to minimize the diffusion distance for insulin to reach the bloodstream. But we now know that these small spheres are actually not nearly as biocompatible as larger spheres."
The next step for the team, which includes researchers from MIT, is to try this approach in clinical trials.
"We have pegged encapsulated islet cells as a cure for type 1 diabetes for so long--but trials always end with the capsules engulfed in scar tissue and the cells dying," Oberholzer added. "If we can get around this simply by increasing the size of the capsules, then we may have a viable cure for type 1 diabetes within reach.
- here's the release