A preclinical study testing "Focused multiple laser beams," a new concept of irradiation with the 1064-nm Nd:YAG laser for skin rejuvenation.
BACKGROUND
In order to avoid epidermal heat damage, we developed a novel irradiation method termed "Focused multiple laser beams (FMLB)," which allows long-pulse neodymium:yttrium aluminum garnet (Nd:YAG) laser beams to be irradiated from several directions in a concentric fashion followed by focusing into the dermis without epidermal damage. This study aimed to assess whether FMLB achieves the desired dermal improvement without epidermal damage.


METHODS
The dorsal skin of New Zealand White rabbits was irradiated with FMLB. Macroscopic and histological analyses were performed after 1 hour and 1, 2, 3 and 4 weeks. Real-time PCR analysis of type I and III collagen expression was performed at two and four weeks.


RESULTS
Control groups exhibited skin ulcers which were healed with scar formation whereas FMLB groups remained intact macroscopically. Histologically, FMLB group showed increase in dermal thickness at four weeks while the epidermis remained intact. Real-time PCR demonstrated that both type I and III collagen increased at two weeks but decreased at four weeks.


CONCLUSIONS
FMLB can deliver the target laser energy to the dermis without significantly affecting the epidermis.
a Department of Plastic and Reconstructive Surgery , Juntendo University School of Medicine , Tokyo , Japan.
Masatoshi
M
Horiguchi
b Miyata Plastic Surgery & Skin Clinic , Tokyo , Japan.
Nariaki
N
Miyata
a Department of Plastic and Reconstructive Surgery , Juntendo University School of Medicine , Tokyo , Japan.
Hiroshi
H
Mizuno
D000535:Aluminum; D000818:Animals; D024042:Collagen Type I / Q000528:radiation effects; D024061:Collagen Type III / Q000528:radiation effects; D004817:Epidermis / Q000528:radiation effects*; D005260:Female; D053844:Lasers, Solid-State / Q000009:adverse effects*; D011817:Rabbits; D060888:Real-Time Polymerase Chain Reaction; D012060:Rejuvenation; D012867:Skin / Q000528:radiation effects*; D015595:Skin Aging; D015019:Yttrium
D024042:Collagen Type I; D024061:Collagen Type III; C503779:yttrium-aluminum-garnet; D015019:Yttrium; D000535:Aluminum
Non-ablative laser; real-time PCR; silver impregnation staining; type I collagen; type III collagen