Friday, October 15, 2010
Encapsulated Pig Islet Cells For Diabetes Type 1 – A Trial
“Intraperitoneal islet transplantation has the potential to ameliorate type 1 diabetes mellitus and avert the long-term consequences of chronic diabetes which cannot be achieved by conventional insulin treatment.
As donor human islets are not available in sufficient numbers, porcine islets are the best alternative source as they are recognised as the most physiologically compatible xenogeneic insulin-producing cells. Although the use of pig-derived cells raises the risk of xenotic infections, this can be minimised by obtaining cells from designated pathogen-free (DPF) animals bred in isolation and monitored to be free of specified pathogens. The worldwide experience to date in more than 200 patients who have received transplants of pig tissue has not demonstrated evidence of transmitted xenotic infections.
As animal-derived tissues have to be protected from immune rejection when transplanted into humans, transplants are usually accompanied by immunosuppressive therapy. However, porcine islets are preferably transplanted without the use of immunosuppressive drugs which cause significant morbidity. To protect them from immune rejection, the islets can be encapsulated in alginate microcapsules which permit the inward passage of nutrients and glucose and the outward passage of insulin. Alginate-encapsulated porcine islets transplanted without immunosuppressive drugs have survived rejection for many months in animal studies, and have been retrieved from a diabetic patient over 9.5 years after intraperitoneal transplantation and shown to contain viable islets that stain positive for insulin.
DIABECELL® comprises neonatal porcine islets encapsulated in alginate microcapsules. DIABECELL® has been safely transplanted in healthy and diabetic mice, rats, rabbits, dogs and non-human primates. Following DIABECELL® transplants, the requirement for daily insulin was significantly reduced in diabetic rats and non-human primates.
The optimal dose and frequency of transplantation of the current DIABECELL® preparation for the treatment of type 1 diabetes in humans can only be determined in clinical trials. The intention of this phase I/IIa clinical trial is to obtain at least 52 weeks safety and preliminary efficacy data in type 1 diabetic patients following transplantation of a single low effective dose of DIABECELL® into the peritoneal cavity.”
The results of this study, still a few years off, will be of great interest to those whose diabetes is hard to control with standard insulin approaches.
Praise for Dr Schimpff
The craft of science writing requires skills that are arguably the most underestimated and misunderstood in the media world. Dumbing down all too often gets mistaken for clarity. Showmanship frequently masks a poor presentation of scientific issues. Factoids are paraded in lieu of ideas. Answers are marketed at the expense of searching questions. By contrast, Steve Schimpff provides a fine combination of enlightenment and reading satisfaction. As a medical scientist he brings his readers encyclopedic knowledge of his subject. As a teacher and as a medical ambassador to other disciplines he's learned how to explain medical breakthroughs without unnecessary jargon. As an advisor to policymakers he's acquired the knack of cutting directly to the practical effects, showing how advances in medical science affect the big lifestyle and economic questions that concern us all. But Schimpff's greatest strength as a writer is that he's a physician through and through, caring above all for the person. His engaging conversational style, insights and fascinating treasury of cutting-edge information leave both lay readers and medical professionals turning his pages. In his hands the impact of new medical technologies and discoveries becomes an engrossing story about what lies ahead for us in the 21st century: as healthy people, as patients of all ages, as children, as parents, as taxpayers, as both consumers and providers of health services. There can be few greater stories than the adventure of what awaits our minds, bodies, budgets, lifespans and societies as new technologies change our world. Schimpff tells it with passion, vision, sweep, intelligence and an urgency that none of us can ignore.
-- N.J. Slabbert, science writer, co-author of Innovation, The Key to Prosperity: Technology & America's Role in the 21st Century Global Economy (with Aris Melissaratos, director of technology enterprise at the John Hopkins University).