Monday, September 27, 2010
Individuals that develop liver failure often die before a suitable donor can be found or before the damaged liver can heal on its own. There is no artificial liver comparable to the dialysis machine for kidney failure. But using a specially develop pig liver outside the body to cleanse the person’s blood of noxious compounds is a possibility. There have been some positive results using a normal or a genetically modified pig liver for such “extracorporeal” perfusion until a donor organ is available or until the patient’s liver recovers on its own.
Progress has also been made with genetically modified insulin-producing pancreas islet cells for treating diabetes. One approach is to place the transplanted islet cells into a “capsule” that allows insulin to exit out and nutrients like glucose to enter in yet keeps immune cells that would destroy the islet cells at bay outside the capsule.
Further progress in xenotransplantation is likely but there are significant barriers to success. Genetic modification of the pig is possible but it is not yet clear all of the modifications that will be necessary. Concurrently, work is progressing to develop immune modulation with drugs just as is done to suppress the immune system with human to human organ transplants. Further development of encapsulation may aide the process, especially with islet cell transplantation for diabetes.
Despite all of the progress to date, the barriers to success are very real and only time will tell if xenotransplantation will become a truly viable path to organ replacement
Wednesday, September 22, 2010
Today the only option for more organs available for transplant is to encourage more individuals to pre-certify their desire for organ donation should they die in a traffic or other accident.
But another approach, still in the future but gaining traction, is to use organs from an animal – known as xenotransplantation.
Most efforts in xenotransplantation focus on the pig, in part because the organs are near to the same size as humans and the physiology is similar. Very real progress has been made in recent years. The steps required to make this approach effective include genetic modification of the pig so that the human immune system will no longer “reject” the transplanted organ. This has included removing the genes that produce the most important pig carbohydrate antigen that human immune cells recognize. Another step has been to add genes that create certain protective proteins in the complement regulatory system (another part of the body’s mechanism to eradicate “foreign” materials like bacteria, viruses or a cancer.) So far, these steps have been major advances but not sufficient so further efforts will be necessary in order for say, a pig heart or kidney to be successfully transplanted into a primate and eventually into a human. But the progress is real, exciting and promising. Stay tuned.
Tuesday, September 14, 2010
Monday, September 13, 2010
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).