Surgical Corner. Evaluation of the Wound Healing Response After Deep Dermal Heating by Fractional Micro-needle Radiofrequency Device: Animal Study

September 2013 | Volume 12 | Issue 9 | Original Article | 1044 | Copyright © September 2013

So Dug Lim MD PhD,a Un-Cheol Yeo MD PhD,b,c Il-Hwan Kim MD PhD,d
Chong Won Choi MD,cand Won-Serk Kim MD PhDc

aDepartment of Pathology, Konkuk University School of Medicine and Konkuk University Medical Center, Seoul, Korea
bS&U Dermatologic Clinic, Seoul, Korea
cDepartment of Dermatology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
dDepartment of Dermatology College of Medicine Korea University, Korea

Abstract
BACKGROUND: Fractional Radiofrequency Microneedles (FRM) are minimally invasive devices that use inserting bipolar radiofrequency for deep dermal heating, has been introduced. We investigated the tissue response after FRM according to different energy levels in porcine skin.
METHODS: Porcine back skin was used in the study. A FRM device was composed of 49 insulated needles. Needles were vertically inserted with 1.5mm depth and four different energy levels were used to examine wound healing response chronologically. Histologic evaluation was done by hematoxylin & eosin (H&E) and heat shock proteins (HSP) 47 staining for immediately after, 2 days after, 14 days after, 28 days after and 10 weeks after the procedure. RT-PCR was done for various cytokines including HSP47, HSP72, metalloproteinase (MMP), and extracellular matrix (ECM) proteins.
RESULTS: FRM treatment generated a thermally coagulated zone localized in the reticular dermis, without damaging the epidermis. The coagulation necrosis zone in H&E staining was replaced by new collagen tissue over 10 weeks. RT-PCR studies revealed an increase in HSP, MMPs, and ECM proteins. In the high energy level procedure, an increased number of fibroblasts were found.
CONCLUSION: FRM treatment induced a dermal remodeling process including neocollagenesis in the deep dermis. From this result, FRM is expected to provide a good and positive efficacy for skin rejuvenation.

J Drugs Dermatol. 2013;12(9):1044-1049.

INTRODUCTION

Various methods have been utilized to rejuvenate aged skin, skin laxity, and facial rhytides. Ablative laser resurfacing had been the gold standard dermatologic approach for facial rejuvenation.1-3 Although the ablative laser resurfacing is highly effective, the risk of unwanted side effects was high and the postoperative recovery period was too long.4,5 Non-ablative skin resurfacing was introduced in an effort to minimize healing time and patient discomfort,6,7 but the post-treatment effects were unsatisfactory. To overcome the limitations of both ablative and non-ablative laser resurfacing, fractional resurfacing was developed.8-10 However, the conventional fractional laser system used the epidermis as energy channels but the risk for epidermal burn and hyperpigmentation could not be avoided, and it was impossible to deliver high energy exclusively deep in the dermis.11,12
Recently, fractional radiofrequency microneedles (FRM) were introduced for skin rejuvenation.12-14 By delivering electric energy by using minimally a invasive bipolar radiofrequency microneedle device, it can create thermal damage in deep dermis. In this study, we studied the wound healing response in porcine subjects after the FRM procedure using histologic, immunohistochemical, and molecular techniques.

METHODS

Animal Study Using FRM System

The FRM system (INTRAcel; Jeisys, Seoul, Korea) delivered bipolar RF energy directly within the dermis via 49 micro-needle electrodes in 1cm2 area. The micro-needles electrodes were nonconductive except for the tip to protect the epidermis. Needle length can be chosen (0.5mm, 0.8mm, 1.5mm, 2.0mm) for