When John Davis' kidney began failing in January, his girlfriend's mother decided to donate one of her kidneys to help save his life. That the two weren't actually a "match" — meaning Davis' body would never accept her kidney — didn't matter.

In a groundbreaking program at Johns Hopkins Hospital that is as much about nationwide networking as it is medical innovation, kidney transplants are being arranged not through isolated pairings of patient and donor, but through longer and longer chains of individuals who don't even know each other.

Gone are the days when a donor might be discounted for not being a match with the specific patient, doctors say. Another patient in Hopkins' network might be a match, and perhaps that patient also brought a willing donor to the mix, facilitating a successive chain of matches until everyone in the chain is paired up.

Many donor-patient matches are found in pools that reach well beyond individual circles of family and friends. They are identified by complicated computer algorithms scanning the characteristics of patients and donors across the country.

"John's kidney came from Salt Lake City, from an 'altruistic' donor. They never met," said Dr. Robert Montgomery, director of Hopkins' Comprehensive Transplant Center and Davis' surgeon. "And then John's intended donor is going to give to someone else and continue the chain."

"She graciously stepped up," Davis, 28, said of his donor, Deborah Kocsis, 58, on a recent morning as they sat with family members around his hospital bed, days after the two underwent surgery to facilitate the swap.

Nearly 100,000 people are on a national waiting list for kidneys, out of just over 121,000 waiting for all organs, according to the United Network for Organ Sharing (UNOS), a private nonprofit that manages the nation's organ transplant system under a contract with the federal government.

This year, through Sept. 30, there were 12,584 kidney transplants in the country and 370 in Maryland, 177 of which were at Hopkins and 193 at the University of Maryland Medical Center, according to UNOS data.

Without a willing, living donor, people can wait for a kidney from a deceased donor for years, facing dialysis, other painful side effects of chronic disease and organ failure and, eventually, death.

However, UNOS is facilitating a national Kidney Paired Donation Pilot Program to allow all willing donors to give, even if they aren't a match with their own loved ones. The program works with dozens of hospitals across the country to find participants, including several that coordinate their own pairings, like Hopkins.

The program removes patients with living donors from the national waiting list, in favor of pairing them with other donors and recipients who have compatible blood and tissue types and aren't likely to reject the organs.

"There are so many incompatible donors, but their organs are perfectly suitable for someone. It seemed logical to try and address the needs of recipients who have their own donor," said Dr. Christie Thomas, chair of UNOS' living donor committee and a professor of medicine at the University of Iowa. "Every kidney donated is someone coming off the waiting list."

Paired donations "allow us to honor the wishes of the donors to help their loved ones," Thomas said.

Hopkins, which now finds pairings often, including with the University of Maryland Medical Center, was a pioneer in the concept of a chain, he said.

Rhode Island Hospital performed the nation's first paired transplants, involving two donors and two recipients, in 2000. But the "domino" idea was sparked, Montgomery said, with the arrival at Hopkins in 2003 of an "altruistic" donor, a woman from the Midwest who wanted to donate a kidney but didn't have a specific recipient in mind. The hospital performed its first triple swap that year.

The idea grew from there. Today, many chains still begin with an altruistic donor, and UNOS is running algorithms every couple of weeks to find matches wherever they may be around the country.

"We're constantly checking for matches," Thomas said.

Some modern chains of patients and donors can surpass 20 people, and one involving 60 people began in late 2011 — lines of compassion and selflessness that Davis' father, also named John Davis, calls "tremendous."

"Your heart starts to pound, and every once in a while you get tears in your eyes. It's just an amazing thing," the elder Davis said. "You just can't believe it happens, but it does."

Davis and his family, from the Pocono Mountains in Pennsylvania, have experience with the process. The younger Davis' recent transplant was his second. His first was when he was in eighth grade.

His oldest sister, Diana Davis, 33, has had three kidney transplants, the most recent on New Year's 2012, also at Hopkins. His older sister Lauren Lehman, 31, had her first kidney transplant at Hopkins in August 2010.

All three siblings have nephronophthisis, a recessive genetic disorder of the kidneys that leads to renal failure. It's usually spotted in children — Diana and John were diagnosed as youngsters, the family said — but can also come in adult-onset form. Lauren was diagnosed with the latter.

The family had thought the gene spared Lauren, an elementary music teacher. When she was diagnosed, they were blindsided.

"The train backed up and hit us again," her father said.

"A kick in the head" is how her brother described it.

Diana's first two donated kidneys were both from deceased donors, as was John's first. Kidneys from deceased donors don't last as long as those from live donors. Even kidneys from live donors typically fail after a couple of decades, and subsequent surgeries become more complicated.

For their most recent transplants, each came to Hopkins with a living donor willing to give. None were a match with the donor they arrived with, but they all were able to take advantage of the paired donor program.

In John Davis' hospital room at Hopkins recently, he cracked jokes with visitors, including his parents, John and Ann Davis; his sisters Diana and Lauren; Lauren's husband, Darrell Lehman; his girlfriend, Rebecca Kocsis; and her mother — his donor, Deborah Kocsis.

Deborah Kocsis said she felt "relieved." Before the surgery, many friends had a hard time understanding what she was doing. She told them she was giving a kidney so that her daughter's boyfriend would receive one, but that he wouldn't be getting her kidney. People didn't seem to grasp the concept, she said.

But she did.

"I was asked by my creator to do this; I said, 'Yes,'" she said. "It's as simple as that, or as difficult as that."

Diana's most recent donor was a woman who read about the family's story in a Rotary International newsletter.

Lauren's donor was a man, Jim Kintz, who goes to her church, though she actually received the kidney from Marie Brett through a chain of pairings. During Lauren's wedding reception last year, she stopped to call Kintz and Brett up on stage.

"That's how important it is to us," said Ann Davis of the generosity of the people who have made Diana, John and Lauren's transplants possible.

All three siblings say they are excited about staying healthy, thanks in part to the pairing program. They hope none will need another transplant for some time to come.

"We'll never stop going to hospitals, we'll never stop going to clinics," John said. "But that's just part of our lives."

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