Clinical and histological effects of weakly focused high-frequency ultrasounds on human subcutaneous adipose tissue

Introduction: Lipo-reductive ultrasound devices are commonly used for non-invasive body sculpting purposes because they can achieve clinically appreciable subcutaneous fat pad reduction and are safe and well tolerated by patients. Objective: This study aims to evaluate the morphological changes induced on the different cell components of human skin as a result of weakly focused high-frequency ultrasound. Methods: Full-thickness skin samples exposed or not to ultrasound ex vivo, and skin biopsies from patients pre-treated or not with ultrasound before lipo-reductive surgery, were analyzed to evaluate possible morphological changes of adipocytes. Adipocyte apoptosis and triglyceride release were also assayed. Clinical evaluation of the effects of repeated ultrasound treatment vs. sham-treatment was also performed. Results: Compared with the control samples, ultrasound treatment induced an appreciable reduction in adipocyte size, the appearance of plasma membrane micropores and triglyceride release, without appreciable changes in microvascular, stromal and epidermal components, and in the number of apoptotic adipocytes. Clinically, the ultrasound treatment resulted in a time-dependent significant reduction of abdominal fat. Conclusions: This study supports the safety and efficacy of trans-cutaneous weakly focused high-frequency ultrasounds for localized fat reduction, and provides experimental evidence for a possible mechanism of action.