In vivo histological evaluation of a novel ablative fractional resurfacing device

Abstract

Background and Objectives: A novel carbon dioxide (CO 2 ) laser device employing ablative fractional resurfacing was tested on human skin in vivo for the first time. Study Design/Materials and Methods: An investigational 30 W, 10.6 mm CO 2 laser system was focused to a 1/e 2 spot size of 120 mm to generate an array of microscopic treatment zones (MTZ) in human forearm skin. A range of pulse energies between 5 and 40 mJ was tested and lesion dimensions were assessed histologically using hematoxylin & eosin. Wound healing of the MTZ's was assessed immediately-, 2-day, 7-day, 1-month, and 3-month post treatment. The role of heat shock proteins was examined by immunohistochemistry. Results: The investigational CO 2 laser system created a microscopic pattern of ablative and thermal injury in human skin. The epidermis and part of the dermis demonstrated columns of thermal coagulation that surrounded tapering ablative zones lined by a thin eschar layer. Changing the pulse energy from 5 to 30 mJ resulted in a greater than threefold increase in lesion depth and twofold increase in width. Expression of heat shock protein (hsp)72 was detected as early as 2 days post-treatment and diminished significantly by 3 months. In contrast, increased expression of hsp47 was first detected at 7 days and persisted at 3 months post-treatment. Conclusion: The thermal effects of a novel investigational ablative CO 2 laser system utilizing fractional resurfacing were characterized in human forearm skin. We confirmed our previous ex vivo findings and show for the first time invivo, that a controlled array of microscopic treatment zones of ablation and coagulation could be deposited in human skin by varying treatment pulse energy. Immunohistochemical studies of heat shock proteins revealed a persistent collagen remodeling response lasting at least 3 months. We successfully demonstrated the first in-vivo use of ablative fractional resurfacing (AFR TM ) treatment on human skin.

Long‐term efficacy of a fractional resurfacing device

“…The authors speculate that results seen at 3 months may be enhanced by persistent inflammatory changes and edema, a concept supported by the persistence of heat shock protein (HSP) 47 activity at the 3-month time point. HSP 47 is consistent with continued collagen synthesis and remodeling seen in previous histologic studies [3]. As with any procedure, results tend to fade over time due to relaxation of the tightening process and the natural progression of aging.…”

Fractional CO2 laser‐assisted drug delivery

“…The CO 2 laser penetrates approximately 20 mm, and the Er:YAG laser penetrates approximately 2 mm into tissue. Deep tissue holes are created by a dynamic laser tissue interaction in which water absorption coefficients and pulse widths are responsible for the formation of MTZ with different dimensions of ablation and thermal coagulation zones (TCZ) [5,6,37]. In our study, the TCZ surrounding each laser hole was about 70 mm thick.…”

“…Fractional ablative procedures are available with carbon dioxide laser (CO 2 laser, 10,600 nm) and erbium YAG laser (Er:YAG laser, 2,940 nm) [3][4][5]. The concept of AFR has so far been used for dermal remodeling in the treatment of photodamaged facial skin, rhytides, acneiform scarring, and burn scar remodeling [3,[6][7][8][9][10]. Theoretically, AFR may also facilitate penetration and distribution of topically applied drugs, since the ablated laser holes extend into dermis, thereby possibly acting as channels for drug uptake.…”

In vivo non‐invasive monitoring of collagen remodelling by two‐photon microscopy after micro‐ablative fractional laser resurfacing

“…In such a treatment, a significant amount of skin is completely ablated, giving rise to a long wound healing time with some related risks of persistent redness, infection, and scarring [9][10]. A possible way to overcome these side effects is represented by micro-ablative fractional laser resurfacing [11][12][13][14]. In this technique, skin is ablated only on raster scanned points, preventing the complete ablation of skin, and hence the long recovery time.…”