Organ Shortages, Stem-Cell Discoveries and Xenotransplantation to be highlighted at International Transplantation Meeting
Over 2000 medical professionals from 50 countries will converge on the Windy City to discuss scientific advances and policy trends in the field of transplantation. Called TRANSPLANT 2000, the meeting is the first partnership of The American Society of Transplant Surgeons (ASTS), the American Society of Transplantation (AST) and their memberships of physicians, surgeons, scientists, nurses, organ procurement personnel and pharmacists.
Clinicians and researchers will present nearly 1,200 findings on a wide variety of issues including: pediatric transplantation; organ shortages; emerging technologies; new surgical techniques; status of immunosuppression; stem-cell discoveries; progress in transplant tolerance, infections and complications; as well as advances in xenotransplantation and immunobiology.
TRANSPLANT 2000 will feature major developments of interest to the public as well as to medical professionals. Among them are:
- Mandatory Liver Sharing Benefits Sickest at Expense of Others: Increasing the distribution area for donated organs cut waiting time for acute cases, but likely at the expense of healthier patients on the waiting list. (Abstract #3, Embargoed for release Sunday, May 14, 2:00 pm CST)
- New Test Predicts Rejection in Heart and Liver Transplants: A study with heart recipients and liver recipients suggests doctors may be able to predict organ rejection days or even weeks before symptoms appear. (Abstract #358, Embargoed for release Monday, May 15, 11:00 am CST)
- Blood-Pressure Drug Reduces Transplant-Related Cancers in Mice: An animal study shows common anti-hypertensive drugs lower the number of tumor growths associated with two immunosuppressive drugs that many transplant patients must take for life. (Abstract #1075, Embargoed for release Tuesday, May 16 noon CST)
- Children with Live-Donor Livers Grow Better: A successful liver transplant from a living related donor rather than a cadaver helps juvenile recipients grow significantly better. (Abstract #1102, Embargoed for release Wednesday, May 17, 9 am CST)
- Diabetics Need No Insulin after Islet Transplantation: A Canadian research team has developed a protocol demonstrated in eight patients with type 1 diabetes who need neither insulin nor steroid immunosuppressives after pancreatic islet transplantation. (Abstract #1105, Embargoed for release Wednesday, May 17, 9 am CST)
Tip Sheet -- TRANSPLANT 2000
Report Highlights of TRANSPLANT 2000
In joining forces for the first time at a national meeting, the American Society of Transplant Surgeons and the American Society of Transplantation are poised to present an unprecedented range and quality of scientific exchange in the field. Some of the major stories at TRANSPLANT 2000 include:
Mandatory Liver Sharing Benefits Sickest at Expense of Others: Increasing the geographical size of the pool from which patients can obtain a new liver cuts the waiting time for the most acute cases nearly in half, researchers at the University of Tennessee, Memphis, have found. But because of the scarcity of donor livers, explained study leader Dr. Santiago R. Vera, the benefits of this policy -- called mandatory liver sharing -- are likely offset by increased deaths among less acute patients, who now must wait longer for a new liver. Vera and his team changed the status I distribution area from individual districts (of an average 2.8 million people each) to a five-state region in the Mid-Atlantic. Over the next 15 months, the average wait for the 73 status I, or acute, patients dropped from five to three days. While 21 status I patients died before a new liver became available, 132 patients farther down the waiting list also died. In fact, Vera found the odds of dying while waiting for a new liver were highest for status IIb: 40 percent of 261 patients during the study period, in contrast to 27 percent (status I), 33 percent (18 status IIa patients) and 9 percent (331 status III patients). "This study demonstrates that whenever you transplant a liver, some other patient always dies," Vera said. "Instead of trying to change distribution areas, we need to promote liver donation and alternative transplant techniques." ("One Year of Status I Mandatory Liver Sharing: The UNOS Region 11 Experience," abstract #3, plenary session I, Sunday 14 May 8:45am.)
New Test Predicts Rejection in Heart and Liver Transplants: A study conducted with 55 heart recipients and 14 liver recipients suggests doctors may be able to predict organ rejection days or even weeks before symptoms appear. Dr. Nicole Suciu-Foca of New York's Columbia University explained tests that can signal impending graft damage -- not just diagnose it -- can buy valuable treatment time. Suciu-Foca, who is lead author, joined her group with Raffaello Cortesini and colleagues at the University of Rome, Italy to develop the test and apply it in a clinical setting. The test itself is two-fold, she said: one part measures the immune system's readiness to attack the new organ and the other its ability to suppress the attack. Suciu-Foca's team monitored the patients over a period of one to 24 weeks after transplantation. The researchers cultured cells of the host immune system in the laboratory either in the presence of peptides that correspond to donor HLA-DR (human leukocyte antigen) displayed by host immune cells or in the presence of donor cells. They found that when the number of a patient's reactive T-helper or T-cytotoxic cells was high, so was his or her chance of developing organ rejection in seven to 13 days. Conversely, the presence of reactive T-suppressor cells indicated host acceptance of the new organ out to 10 to 14 weeks. ("Evaluation of Allospecific T Helper, T Cytotoxic and T Suppressor Cells in Transplant Recipients," abstract #358, plenary session II, Monday 15 May 8:30am.)
Blood-Pressure Drug Reduces Transplant-Related Cancers in Mice: An animal study shows common anti-hypertensive drugs lower the number of tumor growths associated with cyclosporin A (CsA) and FK506, immunosuppressive drugs that many transplant patients must take for life. Dr. Manikkam Suthanthiran of Weill Medical College of Cornell University, New York, explained that organ recipients tend to have more aggressive as well as a higher incidence of cancers. Last year, Suthanthiran and colleagues reported that CsA induces a signal protein called TGF-beta1, which can promote cancer progression. "Because it's also known that angiotensin II can stimulate TGF-beta1, we then thought it might be worth blocking the angiotensin II system," he said. For this study, Suthanthiran and colleagues tested a drug called losartan, which treats hypertension by blocking the angiotensin II receptor. Injecting immune-deficient mice with human bladder-cancer cells, for example, caused an average 25 tumors to metastisize in their lungs. Adding CsA increased that number to 58. Adding CsA and losartan, however, reduced the pulmonary metastases to 16. FK506 also increased metastases and the anti-hypertensive drug enalapril reduced them. "These results clearly need to be evaluated in a clinical setting, but 80 percent of transplant patients have hypertension anyway," he said. "These drugs might have twin benefits, blood-pressure control and prevention of tumor progression." ("Angiotensin II Receptor Blockade: A Novel Strategy to Prevent Immunosuppressant Associated Cancer Progression," abstract #1075, concurrent session 46, Tuesday 16 May 4:00 pm.)
Children with Live-Donor Livers Grow Better: Infants and children who receive a successful transplant of liver tissue from a live donor, such as a parent, grow significantly better than those whose new liver comes from a cadaver, according to a study conducted at the University of Chicago. Dr. Puneet Gupta and colleagues followed 74 children, all born with livers missing the ducts to excrete bile, for three years after transplantation. Thirty-two patients received a piece of living-related liver at an average 1.1 years of age. Forty-two others were placed on donor waiting lists and received a cadaveric transplant at an average 1.9 years of age. All children exhibited similar growth retardation before transplantation. Those who received a live donation -- usually the left lateral segment, about 15 percent of the adult liver‹grew immediately. However, the cadaveric-transplant group did not experience growth spurts until an average one year after transplantation, and never caught up. Pinpointing the reason among several possibilities is the group's next focus of research, Gupta said. For example, live-donor transplants can occur as soon as indicated by patient prognosis, while the increasing age and deteriorating condition of those waiting for a cadaver donation may harm long-term outcome. A live donation, with minimum transport time, may yield a healthier liver. Gupta also suggests immunocompatibility may be more important with liver transplants than previously thought. Finally, children whose livers come from an unrelated cadaver may be less sensitive to growth hormone. ("Growth Benefits of Living Donor Transplantation," abstract #1102, plenary session IV, Wednesday 17 May 8:00am.)
Diabetics Need No Insulin after Islet Transplantation: Eight adult Canadians with type 1, or juvenile-onset, diabetes no longer require insulin after receiving pancreatic islet transplantations from physicians with the University of Alberta, Edmonton. Nor do they require steroids to prevent their immune systems from attacking the new tissue, said lead investigator Dr. James Shapiro. He and his team developed the new drug protocol. Shapiro explained the process begins with Jonathan Lakey, who oversees the extraction of cadaveric pancreatic tissue to purify the islets (insulin-secreting cells whose destruction by the diabetic's own immune system originally caused the disease). Patients receive the new islets via injection into their portal veins. The Alberta group administers currently available immunosuppressive drugs in a new way to block T-cell activation and proliferation without introducing steroids and their difficult side effects. Shapiro said each of the eight patients (29 to 53 years of age; diabetics for 18 to 50 years) are now "totally off insulin" after an average of two islet transplants. Even more important, he added, each exhibits "complete control" of hemoglobin A1C, a marker in red blood cells that signals damage from high blood-sugar levels. Only very mild, occasional side effects have been noted. Other project goals include lowering the number of required injections (and thus donors) and further minimizing the drug regimen. ("Insulin Independence after Solitary Islet Transplantation in Type 1 Diabetic Patients Using Steroid-Free Immunosuppression," abstract #1105, plenary session IV, Wednesday 17 May 8:30 am.)
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Press Room: Parlor B
May 14-18, 2000
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