A Focused Monopolar Radiofrequency Causes Apoptosis: A Porcine Model

Abstract

Background: The purpose of this study was to demonstrate the effect of monopolar, focused radiofrequency (RF) with embedded cooling on subcutaneous skin structures. Specifically, the study was to prove that the monopolar RF with cooling can selectively heat fat, causing disintegration of adipocytes and programmed cell death (apoptosis) of the subcutaneous fat cells. Methods: A non-invasive monopolar RF device with cooling (Exilis Elite, BTL Industries, Framingham, MA) was used to reduce abdominal fat in a porcine model. The study was done on 3 Vietnamese pigs in a certified veterinary facility. The treatment was delivered to an area the size of 20 x 10cm. The treatment duration was 11 minutes, 30 seconds. Biopsy samples were taken before the first treatment, 1 hour post each treatment, as well as 8 and 20 hours post each treatment. Programmed cell death (apoptosis) was monitored using the TUNEL method. The temperature was measured on the skin surface by an infrared thermal imager and built-in IR thermometer, and by an internal probe inserted into various depths of the subcutaneous layer. The internal probe placement was monitored by diagnostic ultrasound examination. Results: The temperature in the treated adipose tissue was higher compared to the skin surface temperature. The average temperature gradient observed was 3.1 degrees C. Due to the temperature gradient the skin surface remained intact, while subcutaneous layers showed significant changes. The TUNEL method proved large-scale apoptosis of fat cells after each treatment. The apoptotic index increased from 7% before the first treatment to an average of 53.4%, 39.6%, 40.2%, and 44.7% respectively for each treatment. In the three-month follow up the apoptotic index dropped back to 11.7%. Histology, blood biochemistry and hematology samples showed mild to no signs of inflammation in the treated area. Conclusion: The study has shown that use of monopolar, focused radiofrequency can induce substantial apoptotic process in a porcine model. The data suggests that the monopolar, focused radiofrequency device can be used for reduction of fat and body shaping.