Laser melts harmful fat

Infrared laser light could be used to treat conditions such as acne, cellulite and even clogged arteries by melting fatty material without damaging surrounding tissue, a US research team has claimed.

The team of medics and engineers from the Wellman Center for Photomedicine at Massachusetts General Hospital, Harvard Medical School and the US Department of Energy's Thomas Jefferson National Accelerator Facility (Jefferson Lab) conducted the first part of the study using human fat obtained from surgically discarded normal tissue. Based on a fat absorption spectrum, tissue was exposed to a range of wavelengths of infrared laser light using the Free-Electron Laser facility at Jefferson Lab.

The researchers measured how selected wavelengths heated the fat and compared the result to a similar experiment conducted with pure water. At most infrared wavelengths, water is more efficiently heated by infrared light. However, the researchers found three wavelengths - 915, 1210 and 1720 nm - where fat was more efficiently heated than water.

The researchers then exposed pig skin-and-fat tissue samples to free-electron laser infrared light at wavelengths of 1210 and 1720 nm. They found that the 1210 nm wavelength preferentially heated pig fat up to 1 cm deep, without damaging the overlying skin. At 1210 nm, laser-induced heating of fat was more than twice that of the overlying skin; at 1720 nm, it was about 1.7 times that of skin.

Rox Anderson, a dermatologist and lead author on the study, said the results provide a proof of principle for the use of selective photothermolysis, selectively heating tissues with light, for several potential medical applications. He highlighted the potential for using lasers to target sebaceous glands.

"The root cause of acne is a lipid-rich gland, the sebaceous gland, which sits a few millimetres below the surface of the skin," said Anderson. "We want to be able to selectively target the sebaceous gland, and this research shows that if we can build lasers at this region of the spectrum, we may be able to do that."

Dr. Anderson also envisions that laser treatments could emerge for other medical conditions involving lipid-rich tissues, such as atherosclerosis, which causes heart disease and stroke. Fatty plaques form in arteries, rupture, and kill millions of people each year. A selective treatment that stabilises lipid plaques could be much better than previous attempts at laser treatment for heart disease.