Visualizing radiofrequency-skin interaction using multiphoton microscopy in vivo.
BACKGROUND
Redundant skin laxity is a major feature of aging. Recently, radiofrequency has been introduced for nonablative tissue tightening by volumetric heating of the deep dermis. Despite the wide range of application based on this therapy, the effect of this technique on tissue and the subsequent tissue remodeling have not been investigated in detail.


OBJECTIVE
Our objective is to evaluate the potential of non-linear optics, including multiphoton autofluorescence and second harmonic generation (SHG) microscopy, as a non-invasive imaging modality for the real-time study of radiofrequency-tissue interaction.


METHODS
Electro-optical synergy device (ELOS) was used as the radiofrequency source in this study. The back skin of nude mouse was irradiated with radiofrequency at different passes. We evaluated the effect on skin immediately and 1 month after treatment with multiphoton microscopy.


RESULTS
Corresponding histology was performed for comparison. We found that SHG is negatively correlated to radiofrequency passes, which means that collagen structural disruption happens immediately after thermal damage. After 1 month of collagen remodeling, SHG signals increased above baseline, indicating that collagen regeneration has occurred. Our findings may explain mechanism of nonablative skin tightening and were supported by histological examinations.


CONCLUSIONS
Our work showed that monitoring the dermal heating status of RF and following up the detailed process of tissue reaction can be imaged and quantified with multiphoton microscopy non-invasively in vivo.
Department of Dermatology, Far Eastern Memorial Hospital, Taipei, Taiwan. tsaitsunghua@yahoo.com.tw
Tsung-Hua
TH
Tsai
Sung-Jan
SJ
Lin
Woan-Ruoh
WR
Lee
Chun-Chin
CC
Wang
Chih-Ting
CT
Hsu
Thomas
T
Chu
Chen-Yuan
CY
Dong
D000818:Animals; D003094:Collagen / Q000378:metabolism; D006358:Hot Temperature; D054023:Lasers, Semiconductor / Q000009:adverse effects; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D036641:Microscopy, Fluorescence, Multiphoton; D012867:Skin / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D013997:Time Factors
D003094:Collagen