Reversing Aging:
Not as Crazy as You Think
Harvard
researchers find a new compound that can make old cells young again
What makes
cells age? Wear and tear, yes. But biologically, says, Dr. David Sinclair,
professor of genetics at Harvard Medical School, it’s lack of oxygen that
signals cells that it’s their time to go. Without oxygen, the energy engines
known as the mitochondria become less efficient at turning physiological fuel
like glucose into the energy that the cells need to function. Eventually, they
shut down.
But in a
paper published in the journal Cell, Sinclair and his colleagues describe for
the first time a compound naturally made by young cells that was able to revive
older cells and make them energetic and youthful again. In an experiment in
mice, the team found that giving older mice a chemical called NAD for just one
week made 2-year-old-mice tissue resemble that of 6-month-old mice (in human
years, that would be akin to a 60-year-old’s cells becoming more like those
belonging to a 20-year-old).
As mammals
age, says Sinclair, levels of NAD drop by 50%; with less of the compound, the
communication between the cell and its mitochondrial energy source also
falters, and the cell becomes vulnerable to common aging assaults —
inflammation, muscle wasting and slower metabolism. By tricking the cell into
thinking it’s young again, with adequate amounts of NAD, aging can
theoretically be reversed. “When we give the molecule, the cells think oxygen
levels are normal and everything revs back up again,” Sinclair says.
While NAD
may be a key to the fountain of youth, Sinclair, who also investigated the
anti-aging effects of the red-wine compound resveratrol, isn’t ready to say
that the chemical could lead to immortal cells. “I wouldn’t take it that far,”
he says. “What makes reversing aging interesting is that it could buy more time
than we are currently looking at.”
His next
step is to put NAD in the drinking water of his mice, and see if they take
longer to develop the typical chronic diseases linked to aging, such as
inflammation, muscle wasting, cancer and diabetes. The pathway may become an
important target for cancer researchers as well, since tumors typically grow in
low-oxygen conditions and are more common in older patients.
Because NAD
is a naturally occurring compound that simply declines with age, Sinclair is
optimistic that boosting its levels in people won’t have as many significant
adverse effects as introducing an entirely new compound might. “If a body is
slowly falling apart and losing the ability to regulate itself effectively, we
can get it back on track to what it was in its 20s and 30s,” he says.
At least
that’s the hope.
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