Transplant Advance for Type 1 Diabetes: Report
Used in single patient, special chamber may allow implantation of insulin-producing cells without rejection
The device was implanted into a 63-year-old man, who'd had type 1 diabetes for 54 years. He was of average weight, and didn't have any serious complications from his diabetes.
Blood tests for a substance called C-peptide showed he wasn't producing any of his own insulin. C-peptide is a byproduct of insulin production, and is often used to measure the success of diabetes treatments in research settings. If C-peptide levels rise, it means insulin production has risen.
The transplant recipient had modest increases in his C-peptide levels, and the levels of C-peptide and insulin rose rapidly in response to an injection of glucose (a form of sugar). Over time, his long-term blood sugar control improved slightly, and his need for insulin decreased, though not to the point where he didn't need insulin injections.
What was remarkable, however, was that after 10 months, there were no signs that the immune system was aware of the new cells. There were no signs of possible rejection of the new cells, and no signs that the immune system initiated an attack on the new islet cells.
The transplant only contained about half the amount of islet cells normally transplanted. "We only had a limited number of beta cells available from this one pancreas," explained Block, a distinguished professor of urologic research and clinical director of the Endocrine Polypeptide and Cancer Institute at the Veterans Affairs Medical Center Research Service, in Miami.
The limited availability of islet cells for transplant has been another barrier to more widespread use of islet cell transplantation. Block said that the device used in this study could help with that problem as well.
"The reality of this device, since the device protects the incorporated islet cells from immune attack, is that it doesn't really matter if you use human or porcine (pig) islets. Going to xenotransplantation could be a future step that would enable an unlimited number of islet cells that produce human-like insulin," he said.
Xenotransplantation is any procedure that transplants cells, tissues or organs from an animal into a human, according to the U.S. Food and Drug Administration.
A diabetes expert not connected with the study called the finding "exciting."
"They've clearly shown the ability to maintain some function without immunosuppression," said Julia Greenstein, vice president for cure therapies at JDRF (formerly the Juvenile Diabetes Research Foundation).
But, she added, "It's a study of one patient, and the level of C-peptide wasn't enough to significantly impact the clinical situation of the recipient. The goal of transplantation is normal [blood sugar levels] or insulin independence." Neither of those goals was met in this study."
"This study is one early step on the way to developing a practical approach to providing islet function for a person with type 1 diabetes," Greenstein said.