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 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.
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.
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.”
– Dr. Lee E. Goldstein
Doctors could eventually use the tool in routine clinical practice to provide an individual measure of molecular aging and perhaps even help identify interventions to extend the healthy period of a person’s lifespan.
