But LaMattina figures five to 10 years might be about right for human studies of his specialty, the liver.
"I'm an optimist," he adds. "You have to be an optimist in this job."
Michael Rubinkam in Lewisburg, Pa., and Allen Breed in Winston-Salem, N.C., contributed to this story.
Ott lab: http://ottlab.mgh.harvard.edu/
Atala lab: http://www.wakehealth.edu/WFIRM/
Malcolm Ritter can be followed at http://twitter.com/malcolmritter
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