A preclinical study testing “Focused multiple laser beams,” a new concept of irradiation with the 1064-nm Nd:YAG laser for skin rejuvenation

ABSTRACT

Introduction: 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. Materials and 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.

KEYWORDS:

• Non-ablative laser
• real-time PCR
• silver impregnation staining
• type I collagen
• type III collagen

Financial disclosure

The authors have no financial interest to declare in relation to the content of this article.

Additional information

Notes on contributors

Masatoshi Horiguchi

Masatoshi Horiguchi: Study conception and design, collection and assembly of data, data analysis and interpretation, and manuscript writing. Nariaki Miyata: Conception and design, and data analysis and interpretation. Hiroshi Mizuno: Conception and design, financial support, data analysis and interpretation, and final approval of manuscript.

Nariaki Miyata

Masatoshi Horiguchi: Study conception and design, collection and assembly of data, data analysis and interpretation, and manuscript writing. Nariaki Miyata: Conception and design, and data analysis and interpretation. Hiroshi Mizuno: Conception and design, financial support, data analysis and interpretation, and final approval of manuscript.

Hiroshi Mizuno

Masatoshi Horiguchi: Study conception and design, collection and assembly of data, data analysis and interpretation, and manuscript writing. Nariaki Miyata: Conception and design, and data analysis and interpretation. Hiroshi Mizuno: Conception and design, financial support, data analysis and interpretation, and final approval of manuscript.