Speaking from a wheelchair that granted him the luxury of independent movement, Matt Nagle downplayed the suggestion that it took courage to let neuroscientists use his body as laboratory.
"I'm not brave at all," he told the Globe a little more than a year ago. The experiments, he said, might prove beneficial for others who are paralyzed. "I was happy I could help; it was very humbling to be able to do that."
Where he saw humility, others saw heroism. Mr. Nagle was paralyzed from the shoulders down six years ago when he went to help friends in a brawl and was stabbed in the neck. Refusing to accept that he would never walk again or breathe without a ventilator, he volunteered for experimental treatments. Sensors and electrodes implanted in his body allowed him to operate a robotic hand, play computer games, and, at last, breathe on his own.
On July 16, a day after his weekly trip home to Weymouth for Sunday dinner with his family, Mr. Nagle slipped into a coma and was diagnosed with sepsis, an infection that affects the entire body. He died Monday in Good Samaritan Medical Center in Brockton.
At 27, Mr. Nagle was a veteran of two kinds of groundbreaking treatments designed to improve the lives of those who are paralyzed. A few years ago, he volunteered to be the first human subject for BrainGate, and a tiny sensor was implanted in his head. The chip picked up electrical brain signals and transmitted them to computer software, which allowed him to move a cursor through the power of thought.
Dr. Jon Mukand, a researcher at Sargent Rehabilitation Center in Warwick, R.I., was the principal investigator for the BrainGate trial and was so impressed with Mr. Nagle that he is working on a book, tentatively titled, "At Knifepoint: Brain Implant, Stem Cells, and Matthew Nagle's Quest for Recovery."
"Matt was a brave pioneer who knew that he was in a terrible position, but struggled against his condition as much as he could," Mukand said. "He wanted to try to do everything possible to take advantage of the latest research, not only for himself, but for everyone else with severe disabilities.
"He really felt that by being the first person to have the BrainGate, he would make a contribution to others. I think, most importantly, he gave them hope."
"God uses some people's bodies to show what life can be like," Mr. Nagle told the Globe in October 2004 while demonstrating what he could do with a computer.
Mr. Nagle took part in treatments with the same intensity he had brought to the football field at Weymouth High School, where he set a record his senior year by making 33 unassisted tackles.
"There's that little bit of a fire that you need to be able to draw on at crunch time, and he had it," said Ross Tortora, who had been Mr. Nagle's football coach.
"Matty was always out there trying," said his father, Patrick. "He always said, 'If it doesn't help me, it'll help someone else.' "
The BrainGate chip was later removed, and electrodes were implanted to stimulate the diaphragm, allowing Mr. Nagle to breathe without a ventilator and direct his wheelchair with puffs of breath.
"He used to say: 'You know what, there's a lot of us in chairs. If we all do a little, maybe we can make it a lot,' " his father said.
Matthew R. Nagle was born in Cambridge, the younger of two brothers, and lived in Weymouth. A talented athlete, he was eager to compete long before he grew to 6 feet, 2 inches tall. When he was a boy, the cutoff weight for a football league was 55 pounds and he weighed 53.
"So Matty's got rocks in his pockets to get in, and the coach put his toe on the back of the scale and smiled," his father said. "And Matty says, 'I'm in, I'm in!' "
At Weymouth High School his senior year, Mr. Nagle played several positions and usually was outweighed by opponents.
"To me, he was what high school athletics are all about," Tortora said. "He was not the biggest kid on the field, he was not the fastest kid on the field, but he was able to maximize his talents. He did that through hard work, through being an incredibly coachable kid, and through being an intense competitor."
That kind of drive was displayed after the night of July 3, 2001, when Mr. Nagle was out with friends and a fight broke out.
"One of his buddies was at the bottom of the pile," his father said. "Matty ran down like he was playing football and started throwing people off."
Nicholas Cirignano is serving nine to 10 years in prison for stabbing Mr. Nagle in the neck that night.
"He died right there on the beach, and the paramedics brought him back," Patrick Nagle said.
When he regained consciousness days later, Mr. Nagle made it clear he planned to defy the predictions of doctors. "I don't care if I have to use a cane. I'm going to walk. I'm going to do this," he told the Globe in 2004. "I know God has a plan for me."
At home, his brother, Michael, built ramps and made adjustments to accommodate a wheelchair for visits. At New England Sinai Hospital and Rehabilitation Center in Stoughton, where he lived, Mr. Nagle impressed the medical staff and friends with his resilience.
"If I was paralyzed and my friends came in and told their stories and they're moving and they're sparky, I'd be jealous," said Mike Romig of Boston, a friend since childhood and a football teammate. "His eyes would open up and he'd smile and say, 'How are you doing?' He was more interested in you and what you're doing. I said to him, 'Matty, I couldn't do what you're doing for a year.' "
On July 16, Mr. Nagle sat outside the family's Weymouth home with his mother, Ellen, and the two spoke at length.
"They had to be out there for two hours," his father said. "And Ellen said, 'He told me how much he loved us.' I think he was ready to move on, and we didn't know -- or we didn't want to know."
The next day, he slipped into a coma. When tests showed brain activity had stopped, Mr. Nagle's mother held him as the machines were disconnected and he died.
He had told his mother that he wanted to donate his organs. In death, his father said, Mr. Nagle's heart, eyes, liver, and skin are "going to make someone else happy, give someone else a better life."
"He was a hero in the full sense of the word, and that's why I use the word 'Quest' in the title of my book," Mukand said. "It really was a quest for him. You think back to the typical hero, the knight and the Holy Grail. Matthew was looking for the Holy Grail, wherever he might find it."
A funeral Mass will be said at noon Saturday in St. Francis Xavier Church in South Weymouth. Burial plans are pending.