BOULDER, Colo. -- "What do you say to somebody who saves your life?"

It's a question John Steele has asked for close to two years and one he'll have the opportunity to answer on Friday when he meets Colorado senior defensive end Derek McCartney. That afternoon, on the eve of McCartney's final Buffaloes home game, there will be a family reunion of sorts. Steele will meet the man whose DNA and A-positive blood type he now shares, and whose cells live in his body, keeping him alive through a transplant that saved his life.

"In a million years," Steele said, "I would have never guessed who it was."

Steele and McCartney were a mystery match, brought together by cancer, "Be The Match" by The National Marrow Donor Program, modern medicine and the generosity of the human spirit. According to domestic transplant protocol, a year had to pass before they could even know each other's identity.

Not that Steele didn't try.

On the night of March 3, 2016, Steele and his wife, Andie, sat in a hospital room, checking flights. They knew that sometime that evening, a container of peripheral blood stem cells that could save his life would arrive at Omaha's Eppley Airfield. John and Andie's knowledge of the donor was limited: American male. So, to pass the time while they waited, they became flight-tracking detectives and tried to guess where the donor was from and let their imagination run wild on who he might be.

"They get a lot of it from the Chicago area," John said, "and Virginia, where the Naval bases are, because they've got a lot of young guys who are donors."

Early that morning, McCartney, the grandson of Hall of Fame Buffaloes coach Bill McCartney, arrived at a Bonfils Blood Center on the east side of Denver. He received his fifth and final set of hormone injections, and then large, bore IVs were inserted in each of his arms. For the next five hours, McCartney lay on a chair watching movies as stem cells were extracted. Like the Steeles, McCartney knew little about the person on the other end of the transplant: An American male in his 60s with leukemia. That was it.

"It's hard to really understand the gravity," McCartney said. "I don't really think I understood it when I was doing it, how important it really was."

This spring, they began communicating. In Steele's first email, he asked the 23-year-old McCartney, "How does it feel to have a 64-year-old son?"

Emails formed an easy friendship, but there was still one last step. When Colorado offered to fly the Steeles out for Saturday's game, it was the chance to add the final touch of thanking McCartney in person. That's something the Steeles have been thinking about even before they were sitting in that hospital room, tracking planes.

"The day we found out there was a donor, that's all we could think about," Andie Steele said. "How do you thank that person? You can't believe somebody would do that, who doesn't even know you."

'You are indeed a lifesaver'

As Steele recovered from the transplant and his health started to improve, a different kind of anxiety built inside. He wanted to know who had given him a second chance at life. So did his family, friends and co-workers.

Steele would bug his oncologist's assistant about when he could find out. She always told him: one year.

John and Andie Steele just celebrated their 44th anniversary on June 2 and are looking forward to many more thanks to Derek McCartney's bone marrow donation. "There aren't enough words to let them know how much it meant," Andie said. Courtesy of Ryan Steele

In March, both Steele and McCartney signed consent forms to release their information. Steele received McCartney's name, age, place of residence and email. Thanks to the internet, he quickly learned a lot: McCartney's football roots, the accolades he received and a young man whose life included both triumph and tragedy. It was tougher for McCartney to learn about Steele.

"He's not in the news," McCartney said.

On March 27, McCartney received an email.

Good evening Derek:

Before I say anything else, THANK YOU from me and my family.

The first few emails were short and cordial. Each man asked if he could reveal the other's identity to family and friends. Steele noted an award McCartney had received from the Fellowship of Christian Athletes, writing: You are indeed a lifesaver.

After a few exchanges, Steele opened up: I suppose you would like to know who your DNA is now supporting.

He wrote about his life and family. How he and Andie, both Omaha natives, had been married nearly 44 years. How they have two sons: Ryan, a chemistry professor at the University of Utah; and Jeremy, a warehouse supervisor in Texas. How he had spent the past 23 years working for the Nebraska Supreme Court's Counsel for Discipline office, which investigates and prosecutes ethical complaints against attorneys.

He detailed his cancer story. The diagnosis of acute lymphoblastic leukemia on Dec. 11, 2014; the rounds of chemo that followed; how he debated having a transplant; how his brother emerged as the first potential donor, and then McCartney. He described how he spent 13 days in the hospital after the transplant, returned home and then slept about 23 hours a day for the next month. Steele returned to work in June and hasn't stopped since, thanks to you, he wrote.

Steele's note ended with: That is probably enough for now. I have a drain to unclog. One of the many things I have not been allowed to do for 2 years. Take care.

"I remember getting the first one from him, and I was like, 'Whoa, this is crazy. I'm actually talking to this guy. It's so cool,'" McCartney said. "It made it more real. It showed how much of an impact it actually made. People kept saying, 'You're saving a life, you're saving a life.' And I was like, 'Yeah,' but it just didn't feel as real until then."

McCartney responded, telling Steele about his own family: his famous grandfather, his mother, Kristy, and brother, T.C. He wrote about being in graduate school, where he was researching the effects of travel on Pac-12 athletes, and his excitement about an upcoming trip to Hollywood for Pac-12 media days. McCartney ended his email with: I will continue to pray for you.

A perfect match

Last year, 81 college football teams participated in "Get In The Game. Save A Life" program, which partners with Be The Match. Doctors use non-relatives in 70 percent of transplants, and the best donors are men between 18 and 44. Get In The Game has a match rate of one in every 187 potential donors, more than twice the national average.

Mike MacIntyre led registration drives for three years at San Jose State, which generated several matches. The Buffaloes head coach brought the program to Colorado in 2013, which has held marrow drives every year since and generated six matches (five from that first year, including McCartney). Players register to be donors and go around campus encouraging others to sign up. It requires only paperwork and a cheek swab DNA test.

MacIntyre also had a personal connection. As a Dallas Cowboys assistant, he had registered to be a stem cell donor, matched with a recipient who had leukemia and began pre-transplant screening.

"I went all the way down the wire," MacIntyre said. "I was going the next day to give blood, but the [patient] didn't make it."

McCartney signed up at Colorado's first Be The Match event in 2013.

"I knew it wasn't likely I would ever get picked," he said.

Derek McCartney, who has 41 tackles and three sacks this season, is well-known for his big heart, so his becoming a donor just fit. "Derek's the type of guy that everybody goes, 'Of course,'" CU coach Mike MacIntyre said. "It wasn't a surprise at all." Ric Tapia/Icon Sportswire

In January 2016, McCartney's cell phone buzzed from an unknown number. He normally would have forwarded the call to voicemail, but for some reason, he answered. He was told he had matched with a leukemia patient -- a perfect 8-of-8 match -- and asked if he still would be willing to donate.

Spring football was about six weeks away. There was a chance Derek would miss time after the transplant.

"You have to think about this," Kristy McCartney recalled telling her son. "I was concerned about him. I don't think he heard anything I said. He said, 'Mom, I'm going to do it.' He didn't hesitate. He's always had a tender heart for other people."

MacIntyre was thrilled. If one of his players needs to miss practices, even games, to donate, MacIntyre would never object.

"It's more important to save a life than play a football game," MacIntyre said. "If that's your dad or your mom or your daughter or your sister or your brother and you matched and you were in the middle of something, you'd do it. They said, 'Derek's a match,' and I said, 'When's he going?' I would hope all of our young men would do that, and I think all of them would, but Derek's the type of guy that everybody goes, 'Of course.'

"It wasn't a surprise at all."

'I kind of just thought it would work'

In the summer of 2015, Steele faced a decision: monthly chemo, which could control his cancer but had few long-term guarantees, or a stem cell transplant, which could cure him but also posed risks.

"I knew how lousy I felt from the chemo," Steele said. "I thought if there's a chance I might be able to get some quality of life back, I wanted to go for it."

His older brother, Steve, volunteered to donate. Relatives are preferred donors, especially full siblings, who have about a 25 percent chance to match. Initial tests showed Steve could donate, but eventually, doctors found a protein in his blood that could cause problems for Steele. In December 2015, Steve was ruled out and a search began in the national donor database.

As Steele passed one year since diagnosis, his health fluctuated. One day, he painted the house. The next, he couldn't get out of bed. He needed occasional transfusions to boost his blood counts.

The initial search yielded seven strong candidates, which shrunk to four after Dr. Lori Maness, the transplant physician from Nebraska Medicine who oversaw Steele, requested additional tests. Eventually, only McCartney and one other person remained. On Feb. 8, 2016, McCartney was confirmed.

"Whoa," McCartney thought to himself, "this is wild."

He had questions: How painful is it? What were the effects of the filgrastim injections, a hormone that stimulates the production of blood-forming cells? He had never donated blood before the transplant -- he's no fan of needles. Rose Caro, his coordinator at Bonfils, guided him through every step.

Because of McCartney's size, he received high doses of filgrastim in the four days leading up to the transplant. He struggled to sleep, as his sternum and back throbbed.

"That was the hardest part, the most uncomfortable part," he said, "but that's nothing for me in how it helped John."

On transplant day, McCartney watched "Gridiron Gang" and another movie as his blood was drawn from one arm and sent into a machine, which separated the stem cells and then filtered blood back through his other arm. Wearing a black Colorado T-shirt and sweats, he sat as still as possible, not even taking a bathroom break.

He produced nearly double the amount of stem cells Maness requested for Steele.

"To see him sitting there, smiling," said Andie, who saw pictures and video of McCartney's donation, "who could be smiling while having to go through that? It's inspirational."

A volunteer courier took McCartney's cells -- about a liter of material -- to Omaha. As the Steeles waited, Ryan and his wife, Sally, Skyped in from Utah. They made Steele a "0th birthday cupcake," as he prepared to start a new phase of life.

At around 1 a.m. on March 4, McCartney's stem cells entered Steele's body during an hour-long procedure. Steele began a difficult recovery, as his energy was sapped for months. Maness said transplants for patients Steele's age and with his leukemia type work only 30 to 40 percent of the time.

John Steele underwent the transplant on March 4, 2016. While transplants for patients his age and with his leukemia type work only 30 to 40 percent of the time, his prognosis now is "excellent," according to Dr. Lori Maness, Steele's transplant physician. Courtesy of the Steele family

Most donors fully recover after a few days, but McCartney wasn't so fortunate. In the coming weeks, he would contract both pneumonia and mononucleosis, likely a result of a weakened immune system from the donation. After participating in Colorado's first few practices, he was shut down for the spring.

"I experienced [recovery] the worst," he said, "and I would do it again."

Like Steele, McCartney knew stem cell transplants were not guaranteed to succeed. Steele's body ultimately had to accept McCartney's cells.

"I kind of just thought it would work," McCartney said. "I was thinking positively."

'He's got a little Buffalo blood running through him now'

John Steele rates his college football interest as a "5 out of 10," which, in Nebraska, equates to 1 out of 10. His football career ended at a junior high tryout, when he was knocked out during a drill and the coach suggested he try another sport (he moved on to track and cross country).

Yet as a proud Nebraskan, he follows the Huskers, so he knew of Bill McCartney, whose Colorado teams had several epic, Big 8 clashes with Big Red.

On a family trip home from Minneapolis in the 1990s, Steele caught the Colorado radio broadcast of a Bill McCartney-led CU team playing Nebraska. In emails to Derek, he occasionally brought up football: It looks like you still have a year of eligibility AND the Big Red D-line could use you AND we have a great College of Medicine [wink emoji].

The Colorado-Nebraska connection resonated more with Steele's brother and his family, all huge Husker fans. Those on the Colorado side loved it, too.

"He's got a little Buffalo blood running through him now!" MacIntyre said.

"For me to have it happen to somebody in Nebraska, it just makes my heart happy," Bill McCartney said. "You can't help it. I'm a big Nebraska fan. I've always admired Tom Osborne and what they did there back in the day when I coached. I just think it's ironic. More than a coincidence."

Steele tracks all of Derek McCartney's games, noting his strong performance last week against Arizona State. Ryan still marvels at how the 6-foot-3, 240-pound McCartney -- "physically speaking, the polar opposite of my father" -- gave a man 6 inches shorter and 50 pounds lighter a lifeline.

"As a Nebraska guy, you kind of grew up hating Colorado," Ryan said, "but thinking back on it, we're pretty thankful he gave us a fifth down."

A meeting years in the making

It takes two weeks for doctors to tell if the donor's cells are entering the recipient's marrow and starting to produce blood. The first 100 days post-transplant are critical, as doctors want to see mostly the donor's blood cells, platelets, plasma and marrow in the recipient's body. About a month after Steele's transplant, he had a blood test that showed more than 95 percent of his cells came from McCartney. His daily pill count dropped from a high of 22 down to five. He didn't develop acute graft versus host disease, in which donor cells attack the recipient's body -- in severe cases causing death -- although he did develop some lesser cases of it on his leg and mouth that he's receiving treatment for still. He returned to work in June.

The Steele family -- from left, Jeremy, Darcy, Andie, John, Sally and Ryan -- appreciate the CU-Nebraska connection at play here. "As a Nebraska guy, you kind of grew up hating Colorado," Ryan said, "but ... we're pretty thankful he gave us a fifth down." Courtesy of Ryan Steele

Although his energy fluctuates, his prognosis is "excellent," according to Maness.

"We're still within the first couple of years from transplant," she said, "so that's a big-time point, to make it two years without relapsing. Five years is another big-time point. But for the most part, he's doing great."

This summer, Ryan and John went fishing -- John's favorite pastime -- at Fremont Lakes, where John and Andie met when he was 19 and she was 16. They married two years later and celebrated their 44th anniversary June 2.

"He's basically the same wonderful, kind person he's always been," Andie said. "It's been very hard on him, and he still never complains about anything. It's so funny, it doesn't matter how many years you have, you always want more.

"Thanks to Derek, we have a better chance."

There's work left to ensure more stories end up like John Steele's. While white patients are more than 70 percent likely to find perfect, 8-of-8 matches with unrelated donors, the numbers are much lower for African-Americans (19 percent) and for those of Asian or Hispanic descent.

It's why marrow drives on college campuses are so significant. The odds of a mixed-raced donor like McCartney matching up with Steele was pretty rare, according to Caro. "It was a bit of a surprise," Maness said.

"It's a great understanding that we're all the same. We've all got the same heart, we've got the same organs, we've got the same bodies, we've got the same souls," MacIntyre said. "It's really cool that we're all human, and none of that [racial stuff] matters."

Since March, Steele and McCartney have exchanged emails and a few text messages. They have yet to speak on the phone. Steele, always mindful of McCartney's schedule, doesn't want to bombard him.

But on Friday, the two will meet, and neither is exactly sure what he'll say. Steele will be joined by Andie, Ryan and Sally for the weekend. They will ride Colorado's team bus to the Pearl Street Stampede pep rally and will be at Folsom Field as McCartney and his teammates take on USC.

"I am really nervous, I know I'm going to blubber all over the place," Andie said. "We're so impressed with the kind of person he is. How do you express that appreciation? There aren't enough words to let them know how much it meant."

Added Ryan: "Other than 'thank you' about a million times."

McCartney looks forward to meeting Steele and wants to be in more frequent contact going forward. They share a link that neither will ever take for granted.

"It's really cool," McCartney said, "that life brought us together."