LED Low-Level Light Photomodulation for Reversal of Photoaging

Robert A. Weiss1, Roy G. Geronemus2, and David H. McDaniel3

Maryland Laser Skin & Vein Institute, Hunt Valley, MD, USA 2New York University Medical Center, New York, NY, USA 3Eastern Virginia Medical School, Virginia Beach, VA, USA

12.1 Introduction

12.1.1 Photomodulation

Photorejuvenation is a greatly sought after treatment for restoring photodamaged skin, but the vocabulary used to describe it is often varied and confusing. Photorejuvenation refers to a process which utilizes light energy sources to reverse or structurally repair sun-induced changes over time. This skin degeneration, or photoaging, is compounded by environ­mental damage to the skin from smoking, pollutants, and other insults, causing free radical

Gurpreet S. Ahluwalia (ed.), Cosmetic Applications of Laser and Light-Based Systems, 271-280,

© 2009 William Andrew Inc.

formation. Nonablative photorejuvenation refers to the controlled use of thermal energy to accomplish skin rejuvenation without disturbance of the overlying epidermis. Nonablative modalities include primarily intense pulsed light (IPL), but other visible wavelengths are used as well, including pulsed dye laser (PDL) and 532 nm green light (KTP laser) [1]. Vari­ous infrared wavelengths with deeper penetration are used for remodeling dermal collagen in all skin types, regardless of pigmentation, and these wavelengths include 1064, 1320, 1450, and 1540 nm [2,3]. All these devices entail thermal injury, either by heating the dermis to stimulate fibroblast proliferation, or by heating blood vessels for photocoagulation [4-6]

A radical change in this concept is the theory of photomodulation. Light emitting diode (LED) photomodulation is a novel approach to photoaging and remains the only category of nonthermal light treatments designed to regulate the activity of cells rather than invoke thermal wound-healing mechanisms[7,8]. This incurs far less risk for patients than other light modalities. The first written report on using photomodulation for facial wrinkles was by McDaniel and his group in 2002 [9].

Photomodulation evolved from the use of LED and low-energy light therapy (LILT) use for stimulating the growth of plant cells [10]. The notion that cell activity can be up – or down-regulated by low-energy light had been entertained in the past, but consistent or impressive results had been lacking [11,12]. Some promise had been shown with wound healing for oral mucositis [12]. Wavelengths examined earlier included a 670 nm LED array [12], a 660 nm array [13], and higher infrared wavelengths [14]. Fluence and duration of exposure were varied in these studies, with high energy required for modest results [12].

To investigate LED light for modulating skin properties, a model of fibroblast culture was utilized in conjunction with clinical testing. Particular packets of energy with specific wavelengths combined with using a very specific propriety pulse sequencing “code” were found to up-regulate Collagen I synthesis in fibroblast culture using RT-PCR to measure collagen I [9]. The up-regulation of fibroblast collagen synthesis correlated with the clini­cal observation of increased dermal collagen on treated human skin biopsies [15]. Both in the fibroblast and clinical model, collagen synthesis was accompanied by the reduction of matrix metalloproteinases (MMP), in particular, MMP-1 or collagenases being greatly reduced with exposure to 590 nm/870 nm low-energy light. This novel concept of using very low energy and narrow-band light with specific pulse code sequences and durations was termed LED photomodulation [9]. The device which utilizes pulsed code sequences of LED light to induce photomodulation is Gentlewaves® (LightBioScience, LLC, Virginia Beach, VA).