Electrochemical Lipolysis Induces Adipocyte Death and Fat Necrosis: In Vivo Pilot Study in Pigs.

BACKGROUND: Current minimally invasive fat reduction modalities use equipment that can cost thousands of U.S. dollars. Electrochemical lipolysis (ECLL), using low-cost battery and electrodes (approximately $10), creates acid/base within fat (width, approximately 3 mm), damaging adipocytes. Longitudinal effects of ECLL have not been studied. In this pilot study, the authors hypothesize that in vivo ECLL induces fat necrosis, decreases adipocyte number/viability, and forms lipid droplets. METHODS: Two female Yorkshire pigs (50 to 60 kg) received ECLL. In pig 1, 10 sites received ECLL, and 10 sites were untreated. In pig 2, 12 sites received ECLL and 12 sites were untreated. For ECLL, two electrodes were inserted into dorsal subcutaneous fat and direct current was applied for 5 minutes. Adverse effects of excessive pain, bleeding, infection, and agitation were monitored. Histology, live-dead (calcein, Hoechst, ethidium homodimer-1), and morphology (Bodipy and Hoechst) assays were performed on day 0 and postprocedure days 1, 2, 7, 14 (pig 1 and pig 2), and 28 (pig 2). Average particle area, fluorescence signal areas, and adipocytes and lipid droplet numbers were compared. RESULTS: No adverse effects occurred. Live-dead assays showed adipocyte death on the anode on days 0 to 7 and the cathode on days 1 to 2 (not significant). Bodipy showed significant adipocyte loss at all sites ( P < 0.001) and lipid droplet formation at the cathode site on day 2 ( P = 0.0046). Histology revealed fat necrosis with significant increases in average particle area at the anode and cathode sites by day 14 (+277.3% change compared with untreated, P < 0.0001; +143.4%, P < 0.0001) and day 28 (+498.6%, P < 0.0001; +354.5%, P < 0.0001). CONCLUSIONS: In vivo ECLL induces fat necrosis in pigs. Further studies are needed to evaluate volumetric fat reduction. CLINICAL RELEVANCE STATEMENT: In vivo ECLL induces adipocyte death and fat necrosis. ECLL has the potential to be utilized in body fat contouring.

Exploring feedback-controlled versus open-circuit electrochemical lipolysis in ex vivo and in vivo porcine fat: A feasibility study.

OBJECTIVES: Minimally invasive fat sculpting techniques are becoming more widespread with the development of office-based devices and therapies. Electrochemical lipolysis (ECLL) is a needle-based technology that uses direct current (DC) to electrolyze tissue water creating acid and base in situ. In turn, fat is saponified and adipocyte cell membrane lysis occurs. The electrolysis of water can be accomplished using a simple open-loop circuit (V-ECLL) or by incorporating a feedback control circuit using a potentiostat (P-ECLL). A potentiostat utilizes an operational amplifier with negative feedback to allow users to precisely control voltage at specific electrodes. To date, the variation between the two approaches has not been studied. The aim of this study was to assess current and charge transfer variation and lipolytic effect created by the two approaches in an in vivo porcine model. METHODS: Charge transfer measurements from ex vivo V-ECLL and P-ECLL treated porcine skin and fat were recorded at -1 V P-ECLL, -2 V P-ECLL, -3 V P-ECLL, and -5 V V-ECLL each for 5 min to guide dosimetry parameters for in vivo studies. In follow-up in vivo studies, a sedated female Yorkshire pig was treated with both V-ECLL and P-ECLL across the dorsal surface over a range of dosimetry parameters, including -1.5 V P-ECLL, -2.5 V P-ECLL, -3.5 V P-ECLL, and 5 V V-ECLL each treated for 5 min. Serial biopsies were performed at baseline before treatment, 1, 2, 7, 14, and 28 days after treatment. Tissue was examined using fluorescence microscopy and histology to compare the effects of the two ECLL approaches. RESULTS: Both V-ECLL and P-ECLL treatments induced in-vivo fat necrosis evident by adipocyte membrane lysis, adipocyte denuclearization, and an acute inflammatory response across a 28-day longitudinal study. However, -1.5 V P-ECLL produced a smaller spatial necrotic effect compared to 5 V V-ECLL. In addition, 5 V V-ECLL produced a comparable necrotic effect to that of -2.5 V and -3.5 V P-ECLL. CONCLUSIONS: V-ECLL and P-ECLL at the aforementioned dosimetry parameters both achieved fat necrosis by adipocyte membrane lysis and denuclearization. The -2.5 V and -3.5 V P-ECLL treatments created spatially similar fat necrotic effects when compared to the 5 V V-ECLL treatment. Quantitatively, total charge transfer between dosimetry parameters suggests that -2.5 V P-ECLL and 5 V V-ECLL produce comparable electrochemical reactions. Such findings suggest that a low-voltage closed-loop potentiostat-based system is capable of inducing fat necrosis to a similar extent compared to that of a higher voltage direct current system.

Electrochemolipolysis of Human Adipose Tissue.

Importance: Body fat contouring procedures have increasingly grown in popularity over the years. As such, there is a need for inexpensive, minimally invasive, and simple fat reduction/contouring technique. Objective: To examine the acid-base and histological changes in ex vivo human adipose tissue after electrochemolipolysis (ECL). Design, Setting, and Participants: Panniculus tissue specimens obtained after abdominoplasty procedures were tumesced with normal saline. Two platinum needle electrodes were inserted into each sample and connected to a DC power supply. Voltage (3-6 V) was varied and applied for 5 min. Specimens were sectioned through a sagittal midline across both electrode insertion sites and immediately stained with pH-sensitive dye. A numerical algorithm was used to calculate the area of the dye color change for each dosimetry pair. Samples were also evaluated utilizing light microscopy (hematoxylin and eosin). An ex vivo human adipose tissue model was used for evaluating the effects of ECL. Results: Acidic and basic pH was appreciated surrounding the anode and cathode insertion sites, respectively. The effect was spatially localized and dose dependent. Statistical analysis of these data showed no significant difference between the mean area of the pH disturbance generated at the anode compared with the cathode at 3 V for 5 min (6.04 mm2 vs. 2.95 mm2, p = 0.40, 95% CI -4.8 to 11). A significantly greater area of pH disruption was generated at the cathode versus the anode in groups 4 V for 5 min (14.7 mm2 vs. 5.00 mm2, p = 0.032, 95% CI 0.93-19), 5 V for 5 min (15.5 mm2 vs. 6.72 mm2, p = 0.019, 95% CI 1.6-16), and 6 V for 5 min (22.5 mm2 vs. 10.0 mm2, p = 0.047, 95% CI 0.22-25). Acute structural changes in adipocytes were observed in all specimens. Vascular damage with adjacent adipocyte necrosis was prominent at the cathode site in group 6 V for 5 min. Conclusions and Relevance: ECL at the studied dosimetry parameters induced acid and base changes in human adipose tissue, suggesting its potential use in nonsurgical fat reduction as an ultralow cost alternative to current lipolytic devices and pharmaceuticals. Level of Evidence: NA.

Confocal Shear Wave Acoustic Radiation Force Optical Coherence Elastography for Imaging and Quantification of the In Vivo Posterior Eye.

Retinal diseases, such as age-related macular degeneration (AMD), are the leading cause of blindness in the elderly population. Since no known cures are currently present, it is crucial to diagnose the condition in its early stages so that disease progression is monitored. Recent advances show that the mechanical elasticity of the posterior eye changes with the onset of AMD. In this work, we present a quantitative method of mapping the mechanical elasticity of the posterior eye using confocal shear wave acoustic radiation force optical coherence elastography (SW-ARF-OCE). This technique has been developed and validated with both an ex-vivo porcine tissue model and a customized in-vivo rabbit model, which both showed the quantified elasticity variations between different layers. This study verifies the feasibility of using this technology for the quantification and diagnosis of retinal diseases from the in-vivo posterior eye.

In Vivo Elasticity Mapping of Posterior Ocular Layers Using Acoustic Radiation Force Optical Coherence Elastography.

Purpose: We used acoustic radiation force optical coherence elastography (ARF-OCE) to map out the elasticity of retinal layers in healthy and diseased in vivo rabbit models for the first time. Methods: A healthy rabbit eye was proptosed and imaged using ARF-OCE, by measuring the tissue deformation after an acoustic force is applied. A diseased retinal inflammation model was used to observe the contrast before and after disease formation. Retinal histologic analysis was performed to identify layers of the retina corresponding with the optical images. Results: The general trend of the retinal layer elasticity is increasing stiffness from the ganglion side to the photoreceptor side, with the stiffest layer being the sclera. In a healthy rabbit model, the mechanical properties varied from 3 to 16 kPa for the five layers that were identified via optical imaging and histology (3.09 ± 0.46, 3.82 ± 0.88, 4.53 ± 0.74, 6.59 ± 2.27, 16.11 ± 5.13 kPa). In the diseased model, we have induced optical damage in a live rabbit and observed a change in the stiffness trend in its retina. Conclusions: High sensitivity elasticity maps can be obtained using the ARF-OCE system to differentiate different retinal layers. Subtle changes in the mechanical properties during the onset of diseases, such as retinal degeneration, can be measured and aid in early clinical diagnosis. This study validates our imaging system for the characterization of retinal elasticity for the detection of retinal diseases in vivo.

Quantified elasticity mapping of retinal layers using synchronized acoustic radiation force optical coherence elastography.

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly (over the age of 60 years) in western countries. In the early stages of the disease, structural changes may be subtle and cannot be detected. Recently it has been postulated that the mechanical properties of the retina may change with the onset of AMD. In this manuscript, we present a novel, non-invasive means that utilizes synchronized acoustic radiation force optical coherence elastography (ARF-OCE) to measure and estimate the elasticity of cadaver porcine retina. Both regions near the optic nerve and in the peripheral retina were studied. An acoustic force is exerted on the tissue for excitation and the resulting tissue vibrations, often in the nanometer scale, are detected with high-resolution optical methods. Segmentation has been performed to isolate individual layers and the Young's modulus has been estimated for each. The results have been successfully compared and mapped to corresponding histological results using H&E staining. Finally, 64 elastograms of the retina were analyzed, as well as the elastic properties, with stiffness ranging from 1.3 to 25.9 kPa in the ganglion to the photoreceptor sides respectively. ARF-OCE allows for the elasticity mapping of anatomical retinal layers. This imaging approach needs further evaluation but has the potential to allow physicians to gain a better understanding of the elasticity of retinal layers in retinal diseases such as AMD.

Miniature probe for mapping mechanical properties of vascular lesions using acoustic radiation force optical coherence elastography.

Cardiovascular diseases are the leading cause of fatalities in the United States. Atherosclerotic plaques are one of the primary complications that can lead to strokes and heart attacks if left untreated. It is essential to diagnose the disease early and distinguish vulnerable plaques from harmless ones. Many methods focus on the structural or molecular properties of plaques. Mechanical properties have been shown to change drastically when abnormalities develop in arterial tissue. We report the development of an acoustic radiation force optical coherence elastography (ARF-OCE) system that uses an integrated miniature ultrasound and optical coherence tomography (OCT) probe to map the relative elasticity of vascular tissues. We demonstrate the capability of the miniature probe to map the biomechanical properties in phantom and human cadaver carotid arteries.

Association of Electrochemical Therapy With Optical, Mechanical, and Acoustic Impedance Properties of Porcine Skin.

IMPORTANCE: The classic management of burn scars and other injuries to the skin has largely relied on soft-tissue transfer to resurface damaged tissue with local tissue transfer or skin graft placement. In situ generation of electrochemical reactions using needle electrodes and an application of current may be a new approach to treat scars and skin. OBJECTIVE: To examine the changes in optical, mechanical, and acoustic impedance properties in porcine skin after electrochemical therapy. DESIGN, SETTING, AND PARTICIPANTS: This preclinical pilot study, performed from August 1, 2015, to November 1, 2016, investigated the effects of localized pH-driven electrochemical therapy of ex vivo porcine skin using 24 skin samples. Platinum-plated needle electrodes were inserted into fresh porcine skin samples. A DC power supply provided a voltage of 4 to 5 V with a 3-minute application time. Specimens were analyzed using optical coherence tomography, optical coherence elastography, and ultrasonography. Ultrasonography was performed under 3 conditions (n = 2 per condition), optical coherence tomography was performed under 2 conditions (n = 2 per condition), and optical coherence elastography was performed under 2 conditions (n = 2 per condition). The remaining samples were used for the positive and negative control groups (n = 10). EXPOSURES: Platinum-plated needle electrodes were inserted into fresh porcine skin samples. A DC power supply provided a voltage of 4 to 5 V with a 3-minute application. MAIN OUTCOMES AND MEASURES: Tissue softening was observed at the anode and cathode sites as a result of electrochemical modification. Volumetric changes were noted using each optical and acoustic technique. RESULTS: A total of 24 ex vivo porcine skin samples were used for this pilot study. Optical coherence tomography measured spatial distribution of superficial tissue changes around each electrode site. At 4 V for 3 minutes, a total volumetric effect of 0.47 mm3 was found at the anode site and 0.51 mm3 at the cathode site. For 5 V for 3 minutes, a total volumetric effect of 0.85 mm3 was found at the anode site and 1.05 mm3 at the cathode site. CONCLUSIONS AND RELEVANCE: Electrochemical therapy is a low-cost technique that is on par with the costs of suture and scalpel. The use of electrochemical therapy to create mechanical and physiologic changes in tissue has the potential to locally remodel the soft-tissue matrix, which ultimately may lead to an inexpensive scar treatment or skin rejuvenation therapy. LEVEL OF EVIDENCE: NA.

Acoustic Radiation Force Optical Coherence Elastography of Corneal Tissue.

We report on a real-time acoustic radiation force optical coherence elastography (ARF-OCE) system to map the relative elasticity of corneal tissue. A modulated ARF is used as excitation to vibrate the cornea while OCE serves as detection of tissue response. To show feasibility of detecting mechanical contrast using this method, we performed tissue-equivalent agarose phantom studies with inclusions of a different stiffness. We obtained 3-D elastograms of a healthy cornea and a highly cross-linked cornea. Finally we induced a stiffness change on a small portion of a cornea and observed the differences in displacement.

Imaging and characterizing shear wave and shear modulus under orthogonal acoustic radiation force excitation using OCT Doppler variance method.

We report on a novel acoustic radiation force orthogonal excitation optical coherence elastography (ARFOE-OCE) technique for imaging shear wave and quantifying shear modulus under orthogonal acoustic radiation force (ARF) excitation using the optical coherence tomography (OCT) Doppler variance method. The ARF perpendicular to the OCT beam is produced by a remote ultrasonic transducer. A shear wave induced by ARF excitation propagates parallel to the OCT beam. The OCT Doppler variance method, which is sensitive to the transverse vibration, is used to measure the ARF-induced vibration. For analysis of the shear modulus, the Doppler variance method is utilized to visualize shear wave propagation instead of Doppler OCT method, and the propagation velocity of the shear wave is measured at different depths of one location with the M scan. In order to quantify shear modulus beyond the OCT imaging depth, we move ARF to a deeper layer at a known step and measure the time delay of the shear wave propagating to the same OCT imaging depth. We also quantitatively map the shear modulus of a cross-section in a tissue-equivalent phantom after employing the B scan.

Long-range Fourier domain optical coherence tomography of the pediatric subglottis.

BACKGROUND: Acquired subglottic stenosis (SGS) most commonly results from prolonged endotracheal intubation and is a diagnostic challenge in the intubated child. At present, no imaging modality allows for in vivo characterization of subglottic microanatomy to identify early signs of acquired SGS while the child remains intubated. Fourier domain optical coherence tomography (FD-OCT) is a minimally invasive, light-based imaging modality which provides high resolution, three dimensional (3D) cross-sectional images of biological tissue. We used long-range FD-OCT to image the subglottis in intubated pediatric patients undergoing minor head and neck surgical procedures in the operating room. METHODS: A long-range FD-OCT system and rotary optical probes (1.2mm and 0.7mm outer diameters) were constructed. Forty-six pediatric patients (ages 2-16 years) undergoing minor upper airway surgery (e.g., tonsillectomy and adenoidectomy) were selected for intraoperative, trans-endotracheal tube FD-OCT of the subglottis. Images were analyzed for anatomical landmarks and subepithelial histology. Volumetric image sets were rendered into virtual 3D airway models in Mimics software. RESULTS: FD-OCT was performed on 46 patients (ages 2-16 years) with no complications. Gross airway contour was visible on all 46 data sets. Twenty (43%) high-quality data sets clearly demonstrated airway anatomy (e.g., tracheal rings, cricoid and vocal folds) and layered microanatomy of the mucosa (e.g., epithelium, basement membrane and lamina propria). The remaining 26 data sets were discarded due to artifact, high signal-to-noise ratio or missing data. 3D airway models were allowed for user-controlled manipulation and multiplanar airway slicing (e.g., sagittal, coronal) for visualization of OCT data at multiple anatomic levels simultaneously. CONCLUSIONS: Long-range FD-OCT produces high-resolution, 3D volumetric images of the pediatric subglottis. This technology offers a safe and practical means for in vivo evaluation of lower airway microanatomy in intubated pediatric patients. Ultimately, FD-OCT may be applied to serial monitoring of the neonatal subglottis in long-term intubated infants at risk for acquired SGS.