No more lying about your age: Scientists can now gauge skin's true age with new laser technique

Dec 13, 2012
This series of harmonic generation microscopy images shows the skin cells of a 24-year-old subject at increasing depths, ranging from the outermost layer of skin (a) to approximately 300 millionths of a meter deep (f). The magenta areas, generated from third harmonics, show skin cells and their nuclei. The green areas, generated from second harmonics, show fibers made of the protein collagen. Credit: Biomedical Optics Express

Wrinkles, dryness, and a translucent and fragile appearance are hallmarks of old skin, caused by the natural aging of skin cells. But while most of us can recognize the signs of lost youth when we peer into the mirror each morning, scientists do not have a standardized way to measure the extent of age damage in skin. Now a group of Taiwanese researchers has used a specialized microscope to peer harmlessly beneath the skin surface to measure natural age-related changes in the sizes of skin cells. The results, which are published in the Optical Society's (OSA) open-access journal Biomedical Optics Express, can be used to study the general phenomenon of skin aging and may help provide an index for measuring the effectiveness of 'anti-aging' skin products.

In the study, Chi-Kuang Sun, a distinguished professor at National Taiwan University and chief director of the university's Molecular Imaging Center, along with medical researcher and dermatologist Yi-Hua Liao and colleagues, evaluated 52 subjects ranging in age from 19 to 79 years old. The researchers focused a brief burst of light into the of the subjects' inner forearms, an area that is generally protected from , which accelerates natural aging. The beam penetrated to a depth of about 300 millionths of a meter, or approximately where the epidermis (the upper layer of skin) and the (the lower layer) meet.

The researchers used a technique known as microscopy (HGM), which has previously been used to study developing embryos. In the procedure, a concentrated beam of photons is sent into a material. The photons naturally oscillate at a particular frequency, and as they interact with the material, they generate "harmonics" – vibrations that are multiples of the original frequency, which are characteristic of the material structure and properties. For example, the second harmonic is twice the original frequency and the third harmonic is three times the original frequency. In an imaging system, harmonics can reveal different structures at very high resolution. In their study, the team scanned for reflected second and third harmonic photons, and from those measurements, produced a high-resolution 3-D map of the tissue that revealed structures within the .

This shows images of basal keratinocytes, the most common cells in the outermost layer of skin. The images were taken of the forearms of a 24-year-old (a), a 47-year-old (b), a 59-year-old (c) and a 69-year-old (d). Compared to the skin cells of the youngest volunteers, the skin cells in older subjects were larger, more irregular in shape, and showed spaces between cells, as indicated by the white arrows in images b-d. Credit: Biomedical Optics Express

Natural aging, the scanning showed, caused a significant increase in the overall size of cells known as basal keratinocytes – the most common cells in the outermost layer of skin – as well as in the sizes of their nuclei. However, other types of skin cells, known as granular cells, did not show a similar pattern. Thus, says Sun, the relative changes in the two types of cells can serve as an index for scoring natural or "intrinsic" skin aging –the aging of skin caused by programmed developmental or genetic factors.

"No one has ever seen through a person's skin to determine his or her age from their skin," says Sun. "Our finding serves as a potential index for skin age."

A skin age index would provide a standardized, quantitative scale that could be used rate the true "age" of skin, from young (less age-related damage) to old (more -related damage). The scale could give doctors another tool to monitor the overall health of skin—by investigating whether the skin of certain individuals or populations ages faster or slower than average, tracking the aging of an individual's skin over time, or testing how effective anti-aging treatments are at slowing the rate of skin aging.

This shows images of granular skin cells, a type of cell found near the top of the outermost layer of skin, for a 24-year-old (a), a 47-year-old (b), a 59-year-old (c) and a 69-year-old (d). In contrast to the irregularities that developed in the basal cells of older subjects, the images of granular cells revealed no significant correlation between age and size or shape of the cells. Credit: Biomedical Optics Express

Intrinsic, or chronological, aging is different from extrinsic aging, which is caused primarily by sun exposure. "There are a lot of extrinsic factors that can accelerate the aging process, such as smoking, ultraviolet light, and stress," says Sun. The researchers found that the extent of extrinsic skin aging in their study subjects varied depending on occupation, personal habits, and skin type, but because the researchers looked at skin on the sun-protected inner forearm, their findings provide a measure of the primarily genetically-based intrinsic skin aging.

"This could provide an index for someone who cares about the health of their skin and might also provide a test-bed for measuring the effectiveness of 'anti-aging' skin products," Sun says. "Of course," he and Liao joke, "you could set an HGM scanner at the entrance to a bar, so you can know whether a person is over 21 years old and permitted for entry."

Explore further: Yellowstone's thermal springs—their colors unveiled

More information: "Determination of chronological aging parameters in epidermal keratinocytes by in vivo harmonic generation microscopy," Biomedical Optics Express, Vol. 4, Issue 1, pp. 77-88 (2012).

Related Stories

Cancer-causing skin damage is done when young

May 10, 2012

With high UV levels continuing in Queensland this autumn, young people are at risk of suffering the worst skin damage they will receive during their lifetime, research from Queensland University of Technology (QUT) has found.

Skin ages differently for men, women

Oct 06, 2006

Researchers at Germany's Friedrich Schiller University, using an experimental measuring device, suggest that men's and women's skin age at different rates.

Another new wrinkle in treating skin aging

Jun 05, 2008

Topical applications of a naturally occurring fat molecule have the potential to slow down skin aging, whether through natural causes or damage, researchers report.

Recommended for you

Controlling core switching in Pac-man disks

Dec 24, 2014

Magnetic vortices in thin films can encode information in the perpendicular magnetization pointing up or down relative to the vortex core. These binary states could be useful for non-volatile data storage ...

World's most complex crystal simulated

Dec 24, 2014

The most complicated crystal structure ever produced in a computer simulation has been achieved by researchers at the University of Michigan. They say the findings help demonstrate how complexity can emerge ...

Atoms queue up for quantum computer networks

Dec 24, 2014

In order to develop future quantum computer networks, it is necessary to hold a known number of atoms and read them without them disappearing. To do this, researchers from the Niels Bohr Institute have developed ...

New video supports radiation dosimetry audits

Dec 23, 2014

The National Physical Laboratory (NPL), working with the National Radiotherapy Trials Quality Assurance Group, has produced a video guide to support physicists participating in radiation dosimetry audits.

Ultrasounds dance the 'moonwalk' in new metamaterial

Dec 23, 2014

Metamaterials have extraordinary properties when it comes to diverting and controlling waves, especially sound and light: for instance, they can make an object invisible, or increase the resolving power of ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Mike_Massen
not rated yet Jan 13, 2013
Brilliant approach however, given that many westerners are below their recommended daily intake of metals such as Copper & Molybdenum, I wonder how these scans translate since Elastin, a major component of skin, is a copper based protein and copper enzymes are present in the growth cycle of skin and in immune system signalling to varying degrees ?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.