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1. Big Organs for Little Kids
“Because of the chronic shortage of organs for children, we’ve had to get creative,” says Carlos Esquivel, MD, PhD. He was one of the first surgeons to tailor a liver from a deceased adult donor by dividing it into two viable parts for two patients — one child and one adult.
Esquivel and his colleagues were also among the first to successfully transplant part of a liver from a living adult donor to a child. Amazingly, the transplanted portion grows to normal size as the child grows, and the adult donor’s liver also grows back to its original size.
Parent donors are able to pass along some immunity to their children, so kidney transplant patients under age 2 often receive a new organ from their mother or father. At Packard Children’s, the average parent-child kidney graft lasts more than 20 years. With a better understanding of the mechanisms of rejection, and the advent of better immunosuppression strategies, rates of kidney survival are expected to increase.
Thirty years ago, few pediatric hospitals transplanted livers from donors whose blood type didn’t match the child’s. Today, doctors at Packard Children’s regularly perform non-matching liver transplants in even the youngest patients. The ability to cross blood types shortens the time children have to wait for a transplant.
In a small child, the blood vessels involved in liver and kidney transplants are so tiny that surgeons must use sutures unable to be seen with the naked eye. For young patients receiving adult kidneys, doctors at Packard Children’s also pioneered an aggressive fluid replacement technique to increase their blood flow. In addition to absolute surgical precision, the transplant team provides comprehensive care to children before and after transplant to ensure the best possible outcomes. Today at Packard Children’s, the survival rate of liver transplant patients under age 2 is nearly 100 percent, and even newborns are saved through transplant surgeries.
In reaction to previous transplants, blood transfusions, or vaccinations, many children who need kidney transplants have highly sensitized immune systems that would attack their new organs. Packard Children’s is one of the few hospitals offering care for children who are considered “untransplantable”. One treatment, plasmapheresis, removes antibodies likely to attack a kidney from a donor with a different blood type. Lab tests developed at Stanford can also determine if a patient has specific antibodies that can be eliminated by intravenous immunoglobulin infusions.
Packard Children’s is one of the few pediatric hospitals that perform multi-organ transplants, including liver-kidney, liver-heart, liver-intestine, and the first pediatric liver-double lung transplant. “One advantage of being treated in this hospital is that we have so many transplant specialists on site,” says Esquivel.
Kenneth Cox, MD, professor of pediatric gastroenterology, and other researchers are developing innovative therapies that prevent the need for some transplants. In 1993, Cox discovered that an antibiotic called vancomycin was helpful in treating not only bacterial infections, but a rare liver and colon disease called primary sclerosing cholangitis. Previously, transplant had been the only way to combat the disease. Additionally, post-doctoral fellow Rebecca Berquist McKenzie, MD, is developing a new protocol for treating children with liver failure caused by acute hepatitis. To date, nine children with immune-mediated hepatitis have been treated. More than half are now hepatitis-free and have fully functioning livers, thus avoiding the need for a transplant.
For decades, children with kidney transplants received steroids to prevent organ rejection. However, the chronic use of steroids often led to serious complications, such as hip dysplasia, arthritis, diabetes, infections, and a variety of metabolic conditions. In the 1990s, physicians at Packard Children’s took the bold step of discontinuing steroid treatment for post-transplant patients. At the time, the idea was considered high risk, but rejection rates were shown to be low, and patients were spared the steroids’ side effects. Today, the steroid-free protocol is becoming the standard of care for pediatric kidney transplants worldwide.
Too much immune-suppressing medication can trigger deadly infections such as the Epstein-Barr virus, which can cause cancer of the white blood cells, or the BK virus, which destroys transplanted kidneys. With support from the National Institutes of Health and private donors, researchers are seeking to better understand the viruses, identify high-risk patients, and eliminate the risk of these dangerous infections.
Someday, liver stem cells may be used as an alternative to a liver transplant. Although ambitious, the goal is to use an infusion of liver stem cells as a supportive therapy in children with acute fulminant hepatitis until their own liver recovers, or as a bridge to transplant. In children with metabolic disorders that cause the liver to produce brain damaging toxins, stem cell therapy may be an effective and less invasive treatment than replacing the entire liver. “Right now, if one gene is defective, we have to replace the entire liver,” Esquivel says. “For those children who need transplants, our teams are ready for them. But at the same time, we are also committed to finding treatments that help our patients avoid transplants if possible.”
This article appeared in the Lucile Packard Children’s News publication in Fall 2013.