MIAMI - Kimberly Lindsey marvels that her 3-year-old son Merrick doesn't need his 10 medications anymore and she can let him frolic on the playground among the germs that lurk there.
Two years ago, Merrick's liver suddenly shut down. Normally, Merrick would have needed a full liver transplant to survive, which would have required a lifetime on drugs to suppress his immune system. That would have kept his body from rejecting his new organ, but the drugs would have also increased his susceptibility to infections and possibly damaged his kidneys.
Instead, Merrick underwent a rare and once virtually abandoned operation where a partial donor liver is attached to a recipient's failing liver temporarily. The hope is that the patient's liver will regenerate and the patients can be taken off the toxic drugs after the donor liver wastes away or, if necessary, is surgically removed.
Seven children have received the operation at the University of Miami/Jackson Memorial Medical Center - the only U.S. facility believed to be regularly performing the surgery. Four of them are now off immunosuppressants and a fifth is close.
The procedure was first tried in the mid-1990s, but U.S. doctors decided the benefit wasn't worth the higher rate of complications and mortality. Even at Jackson, a patient who received the transplant in 1998 had to stay at the hospital for three months because bile was leaking from the place the liver had been cut. Ultimately, his liver recovered and he was taken off the anti-rejection drugs.
But surgeons in England, France and Japan continued to do the procedure, and in several cases had favorable results. Jackson's Dr. Tomoaki Kato was encouraged by reports out of Europe and wanted to try the procedure again. He has performed six partial transplants since 2005; all have survived.
It's 'time to revisit the procedure,' said Kato, the hospital's director of pediatric liver and gastrointestinal transplant program. 'There's a great benefit for the children and the technology has developed so much.'
Still, some surgeons say they will stick with the traditional transplant until they see more proof that the partial transplant is safe. The partial transplant can take more than 10 hours, twice as long as the standard liver transplant surgery, and is more complicated, increasing the risk. After the surgery, patients then have to undergo multiple biopsies to see if their own liver is regenerating.
Dr. Charles Miller, director of liver transplantation at the Cleveland Clinic, said what concerns surgeons 'is that you're taking a very sick patient and, in most cases, you would rather do the simplest operation.'
The liver, which cleans toxins from the blood, is unique among the body's organs in its ability to regenerate, making the procedure possible. In some cases, the liver can recover from acute, or sudden, failure on its own. But if the liver doesn't recover fast enough, patients can suffer brain damage from the toxins if they don't get a transplant.
For Lindsey, the decision to go with the potentially more risky partial transplant for Merrick was easy. Either road was going to be difficult, she said, and at least with the partial transplant, Merrick had a chance to regain the use of his own liver.
A little more than a year after the operation, Merrick's liver had regenerated enough to make Kato comfortable taking him off his last immunosuppressant drug. His transplanted liver is shrinking and may eventually disappear.
'I can sit here and say my son is off. He's off everything,' Lindsey said. 'What they did was a true miracle.'
Because the operation is so rare, organizations like the United Network for Organ Sharing and the American Liver Foundation do not track the number of partial transplants performed or have guidelines on it specifically beyond what's required normally.
Kato has created his own rough guidelines for partial transplants. The patients have been children, since their livers tend to have better rejuvenating abilities than adult patients, and their diagnosis has been acute liver failure. Chronic liver problems, like hepatitis or cancer, would not be resolved with this procedure.
Using this criteria, the number of patients who could benefit from this procedure is limited. Almost 400 people received transplants for acute liver failure in 2006, about a fifth of them children, according to data from the Organ Procurement and Transplantation Network.
Because the transplant was approved in the '90s, it is not considered experimental and is covered by insurance companies. Kato said the cost is roughly the same as traditional transplants. He also noted the long-term health care savings: After patients get off immunosuppressants, they save thousands of dollars a year in drug costs.
And while the Miami patients received livers from deceased donors, the surgery could be performed using a live donor, like a parent, if necessary and the blood type and other factors are compatible.
The University of Chicago's Dr. Donald Jensen said that although the procedure is promising, at this point, he would still want his child to have a standard liver transplant.
Jensen, director of the Center for Liver Disease at the University of Chicago and a liver foundation board member, said some of the partial transplant's safety and long-term management issues still need to be worked out.
In particular, Jensen said he would like pioneering centers like Miami to flesh out: how to select patients, the best way to withdraw immunosuppressants and how to deal with complications. Some of Kato's patients have needed a second surgery to take out the transplanted part because it became inflamed after immunosuppressants were halted.
And some patients have yet to get off immunosuppressants.
Yailin Nunez's 2-year-old son Jonathan was the sixth patient to undergo the procedure at Miami. Of all the patients, his liver has shown the least recovery more than 20 months later, even compared to a boy who had the operation this summer.
'I still have faith my son's liver's going to regenerate... It's just taking a little longer,' Nunez said through tears. 'And if it doesn't, it's OK... We're given the chance and I've met other moms who weren't given the chance.'
Brenner Logan's parents are praying the toss up goes in their favor. In August, the 2-year-old became the latest partial transplant patient at Miami.
His liver is already showing signs of recovery, but Kato's short-term goal is to keep the transplanted liver healthy in case Brenner's original liver doesn't make a comeback. In February, a decision could be made to take Brenner off immunosuppressants.
Brenner's mother, Kristen Logan, is cautiously optimistic. After her son's surgery she met one of the patients whose liver had recovered.
'You think, 'Wow. This could be my son,' Logan said. 'You begin to have so much more hope for the future.'