An eye scanner that Boston University Medical
School developed can detect molecular aging in people. The new technique
provides an accurate measure of age-related damage and could, one day, play a
role in routine clinical practice.
Everyone ages, but not in the same way. Two
people of exactly the same age may be in very different states of health.
In other words, chronological age and biological age are
different. But while chronological age is very easy to measure, biological age
is more difficult to assess.
Although scientists know that there is wide variation in the
processes of aging — for example, in the deterioration of cells and tissues —
among individuals, there is currently no universally accepted measure of
biological aging.
In a new study that appears in The Journals of Gerontology: Series A, researchers led by Boston University Medical School
describe a tool that could fill this gap.
The researchers have developed a new eye scanner that detects
molecular signatures of aging in the lens and is entirely noninvasive. Doctors
could use it clinically to assess an individual’s aging process and then
suggest personalized interventions.
The eyes have it
The dearth of tools to assess aging accurately puts a limit on
scientific understanding, senior author of the paper Dr. Lee E. Goldstein
explains.
“The absence of clinical tools and metrics to quantitatively
evaluate how each person is aging at the molecular level represents a major
impediment to understanding aging and maximizing health throughout life.”
To address this, Dr. Goldstein and a team of investigators from
institutions including Boston Children’s Hospital and Harvard Medical School
looked to the eye.
The eyes are a good measure of aging because they contain cells
that are generated in the fetus and not replaced. This means that the cells
that a person is born with remain with them for life.
These cells are called primary fiber cells, and they occur in
the lens, which focuses light onto the back of the eye. Incidentally, these
cells also contain the highest concentration of protein in the human body.
Importantly, these proteins do not regenerate, so they
accumulate damage throughout life. This damage could provide a molecular readout
of the aging process. As Dr. Goldstein puts it, the lens proteins provide a
“permanent record” of a person’s life history.
Decoding
the molecular record
To decode this molecular information, the researchers used a
technique called quasi-elastic light scattering, or QLS, which uses lasers to
measure the size of particles.
The technique works because the molecular damage that occurs to
lens proteins over time causes the proteins to change shape and stick together.
This aggregation of altered proteins changes the scattering of light in a way
that QLS can detect.
The team first tested the technique in isolated lens proteins
that they had incubated in a test tube for different lengths of time — up to
almost a year — to mimic the way these proteins would age in people aged 12,
30, and 53. They found that, over time, the molecular signature of the proteins
changed as they expected and that this was detectable using the QLS scanner.
They then tested the scanner, which the Food and Drug
Administration (FDA) have deemed a “nonsignificant risk device,” in a trial of
34 people aged between 5 and 61. Impressively, the scanner was able to detect
the same age-related changes that the researchers saw in the lab.
Precision medicine
Although further testing is necessary, the authors say that
these results support the use of the scanner to track molecular aging in
people.
They state that the tool could work in a similar fashion to
other clinical biomarkers, such as brain imaging for Alzheimer’s disease and blood tests for diabetes.
“[E]ye scanning
technology that probes lens protein affords a rapid, noninvasive, objective
technique for direct measurement of molecular aging that can be easily,
quickly, and safely implemented at the point of care. Such a metric affords
potential for precision medical care across the lifespan.”
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