Skin responses to fractional photothermolysis
Version of Record online: 3 JAN 2006
Copyright © 2006 Wiley-Liss, Inc.
Lasers in Surgery and Medicine
Special Issue: Dermatologic Laser Surgery
Volume 38, Issue 2, pages 142–149, February 2006
How to Cite
Laubach, H.-J., Tannous, Z., Anderson, R. R. and Manstein, D. (2006), Skin responses to fractional photothermolysis. Lasers Surg. Med., 38: 142–149. doi: 10.1002/lsm.20254
- Issue online: 21 FEB 2006
- Version of Record online: 3 JAN 2006
- Manuscript Accepted: 15 SEP 2005
- ablative resurfacing;
- confocal microscopy;
- fractional resurfacing;
- fractional photothermolysis;
- in vivo;
- melanin shuttle;
- microscopic epidermal necrotic debris, MEND;
- Microthermal zones, MTZ;
- non-ablative resurfacing;
- non-ablative remodeling;
- skin rejuvenation
Background and Objective
Fractional photothermolysis (FP) is a new concept using arrays of microscopic thermal damage patterns to stimulate a therapeutic response. We analyzed epidermal and dermal response to FP with the aim of correlating histological and clinical response.
Study Design/Materials and Methods
Twelve subjects received a single treatment with a prototype diode laser emitting at a wavelength of 1,500 nm, delivering 5 mJ per microscopic treatment zone (MTZ), and a density of 1,600 MTZs/cm2 on the forearm. Biopsies were procured over a period of 3 months. The biopsies were analyzed by two blinded dermatopathologists using hematoxylin and eosin (Hematoxylin and Eosin Stain), Elastica von Gieson, nitro-blue-tetrazolium-chloride (NBTC) viability, and immunohistochemistry stains. Furthermore, the treatment sites were evaluated in vivo by confocal microscopy.
Results and Discussion
Twenty-four hours after fractional photothermolysis, the continuity of the epidermal basal cell layer is restored. Complete epidermal regeneration is obtained 7 days after the treatment. Microscopic epidermal necrotic debris (MENDs) are seen as early as 1 day after FP. MENDs contain melanin pigment, and are shed from the epidermis within 7 days. Evidence of increased collagen III production is shown with immunohistochemistry (IHC) staining 7 days after FP. IHC for heat shock protein 70 (HSP 70) shows the expression of HSP 1 day after FP, and IHC for alpha smooth muscle actin shows the presence of myofibroblasts 7 days after FP. These findings are concordant with the induction of a wound healing response by FP. There is no evidence of residual dermal fibrosis 3 months after treatment.
A single treatment with fractional photothermolysis induces a wound healing response in the dermis. A mechanism for the precise removal of epidermal melanin is described, in which MENDs act as a melanin shuttle. Lasers Surg. Med. 38:142–149, 2006. © 2006 Wiley-Liss, Inc.