Effects of non‐invasive, 1,210 nm laser exposure on adipose tissue: Results of a human pilot study

Abstract

Laser radiation (1,210 nm) has been previously shown to be capable of selective photothermolysis of adipose tissue in vitro when applied non-invasively. The objective of this pilot study was to evaluate the in vivo effects of this laser in human subjects. Twenty-four adult subjects were exposed non-invasively on the abdomen to a 1,210 nm laser at fluences of 70, 80, and 90 J/cm(2), with a 10 mm spot size, 5 seconds pre-cooling, and 3 seconds exposure duration delivered with parallel contact cooling. There was an impairment of the skin-cooling device during the study. Exposure and control sites were biopsied at either 1-3 days or 4-7 weeks. Tissue was processed for nitroblue tetrazolium chloride (NBTC) staining, a marker for thermal damage, and hematoxylin and eosin (H&E) staining. Laser exposures were painful, requiring local anesthesia in most subjects, but otherwise well tolerated. At 1-3 days after exposure, there was a fluence-dependent loss of NBTC staining in the fat and dermis. In 2 of 14 subjects (2 of 42 exposure sites) evaluated at 1-3 days after exposure, epidermal damage was noted within a small portion of the test site, likely due to impaired contact cooling. At 4-7 weeks, lipomembranous changes of the fat were seen in 89% of test sites and 33% of control sites. This in vivo study shows histologic evidence of laser-induced damage of fat. With further development, this might become a useful treatment for disorders involving the fat and/or lower dermis.