Hair Loss Research

Erbium YAG Laser-assisted Hair Regrowth

A large proportion of the population is at some time affected by androgenic alopecia. Current therapies consisting of minoxidil or finasteride are often the first choices for treatment. These regimens are limited by their efficacy, side-effect profiles, and often lengthy treatment courses. Low-level laser/light has shown to be relatively effective and safe for the treatment of hair loss, and a number of products are currently available to consumers. Recently, fractional lasers have been examined as treatment options for androgenic alopecia. The mechanism of action of these minimally invasive resurfacing procedures is thought to be 2-fold. First, the microscopic injuries created by these treatments may induce a favorable wound healing environment that triggers hair growth. Alternatively, disruption of the stratum corneum allows for the improved transdermal passage of well-established therapeutic drugs to the hair roots.

The non-ablative Er glass laser (1,550 nm) has a chromophore of water and works to a depth of 0.4–2.0 mm, causing thermal injury without tissue destruction. The benefits of non-ablative lasers over fractional lasers are the reduction of downtime and less hypopigmentation. We have identified 4 original studies that have used the non-ablative Er glass laser for the treatment of alopecia.

In 2011, Kim et al.25 published the pooled results of a mouse and human subject study, marking the first use of fractional lasers for hair regrowth. Murine study results showed that the higher energy, densities, and treatment frequencies were more efficacious for anagen induction. Using these results, the authors initiated a human split-scalp study enrolling 20 male Korean patients with AGA.25 Measurements of hair density and growth rate were significantly improved in the treatment sides as compared with controls. Hair density began to decline 1 month posttreatment, showing that like medical treatment, the effects of laser treatment are transient. They were able to see an increase in the Wnt-5a and β-catenin signals, further supporting the role of these pathways in LAHR. A study by Wu et al.23 on 140 female mice helped to determine appropriate energy settings for safety and hair regrowth. The group determined that settings above a certain density and/or energy caused scar formation and wound contracture, and induction of anagen phase occurred most rapidly at settings just below this threshold.

In the first study examining the use of fractional lasers on female pattern hair loss, Lee et al.24 published a prospective trial of 28 pre- and postmenopausal Korean women. The mean baseline hair density and hair shaft diameter improved after treatment, with none showing progression of disease. The Er glass laser in conjunction with topical finasteride and hair growth factors has also been shown to be effective in 4 cases of patients with recalcitrant AGA.21 This series is the only reported use of nonablative Er glass laser in conjunction with topical medications, and the only topical 5α-reductase study to be performed in conjunction with LAHR to date.

Preliminary evidence suggests that fractional laser therapies have a positive effect on hair regrowth; however, most of the literature is limited to case reports, and small prospective and retrospective series. Further studies, in the form of well-designed randomized controlled trials, are necessary to evaluate the efficacy, safety, and optimal treatment courses.


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