His research takes aim at deafness
Zheng-Yi Chen might be the only iPod owner in Boston who does not plug in his earphones and turn up the music when he gets on the subway.
Chen, to be frank, doesn't like noise. He knows what the inner ear looks like, and how fragile it is, and how, when we lose our hearing, it's forever. And so, when he rides the Red Line to his tiny office at Massachusetts General Hospital, Chen goes without his music, unwilling to crank up the volume enough so he can hear it inside the squealing train car.
Turns out, your mother was right: You could lose your hearing if that music you listen to is too loud. Chen, an assistant professor of neurology at Harvard Medical School, has seen it happen in mice, and he believes he's watching it happen every weekday, song by downloaded song, on the T.
This news may not endear Chen to his fellow commuters, but his work restoring hearing loss has brought hope to people across the world. Chen, 42, is looking for a way for the inner ear to regenerate auditory hair cells, the microscopic bundles that conduct sound in the inner ear. What he has found has made him a very popular man among people who ask: Will I ever hear again?
''Science is really up and down. It takes unexpected turns. We really don't know how long it's going to take," Chen said. ''The only thing I can say is we're making progress much faster than before."
Hair cells, typically, are scattered across the cochlea in the inner ear, detecting sounds that the brain then perceives as words, conversations, or music. There are only about 35,000 of them, Chen said, far less than the cells that can be found in a fingertip. And unlike skin cells, which when damaged regenerate, hair cells have just one life cycle.
When they die due to disease, or old age, or even noise, Chen said, they're gone. ''That's it."
But Chen's research, which was recently honored by Scientific American as some of the most groundbreaking of 2005, shows that hair cells may be able to grow again if researchers can unlock their potential to grow back. Early studies, conducted by Chen and published earlier this year, show that hair cells do grow back when researchers knock out a gene called retinoblastoma.
And that's why he has become so popular, getting phone calls and e-mails from people all over the world. In one e-mail, written by the father of a deaf child in Chile, Chen was invited to be their houseguest.
''Rest in my pais," or country, the father wrote.
It's humbling to Chen, whose parents wanted him to be a medical doctor. Chen was always more interested in the science behind the medicine. But he wanted his work to have practical uses for real people.
He studied Norrie disease, a rare disorder that leads to blindness and deafness, and soon found himself more and more interested in the goings-on of the inner ear.
''It's an extremely beautiful system, the inner ear," he said, ''the intricacies, how it functions."
He began to focus on the hair cells, and now, he said, the next challenge is to figure out just how researchers can inactivate the retinoblastoma gene in the ears of deaf mice.
''We have deaf mice downstairs," Chen said recently from his office. ''Many deaf mice."
It won't be easy to help them, Chen admitted, and he tells those who write him not to wait for some overnight breakthrough. That may not come, he said, for years, maybe a decade, who knows?
But he hopes that one day his work will help people, maybe even someone who once grooved to their iPod sitting next to him on the train.
''I do feel responsibility somehow," he said. ''If my work, in any way, can contribute to the health of people, or improve people's hearing, then I'll be really happy. I don't really care about anything else."
Home: Born and raised in Chengdu, China, now living in Somerville.
Family: His wife, Dr. Elisabeth Battinelli, is doing a fellowship in hematology-oncology at Beth Israel Deaconess Medical Center. Their daughter, Sofia, is 20 months old.
Education: Earned a bachelor's degree in genetics from Sichuan University in China in 1984 and a doctorate in human genetics eight years later from Oxford University, England.
Living in silence: Chen doesn't have any close family members who are deaf. But while working with Norrie disease in the early 1990s, he met families whose children could not see or hear and has not forgotten them. ''When you see a family with this kind of child -- can you imagine how devastated they are? They have to take care of these children for the rest of their lives."
Our future deafness: As we live longer, more and more people will suffer from hearing loss. These days, Chen pointed out, people have, on average, 20 years longer than recent ancestors to lose their hearing, meaning the problem is likely going to get worse before it gets better.
His science: Auditory hair cells conduct hearing in our inner ears, vibrating with sound that our brains then translate into words or music. These cells, unlike others in the body, do not regenerate when they die. But Chen, and others, are looking for ways to help them proliferate again, giving the hearing-impaired a chance to hear again.
