In-depth analysis of pH-dependent mechanisms of electromechanical reshaping of rabbit nasal septal cartilage

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.

Electrochemical Therapy of In Vivo Rabbit Cutaneous Tissue

OBJECTIVES

To examine the acid-base and histological changes in in vivo rabbit cutaneous tissue after electrochemical therapy.

STUDY DESIGN

In vivo rabbit tissue study.

METHODS

The shaved skin on the backs of female Oryctolagus cuniculi were assigned to treatments with or without tumescence with normal saline. Two platinum-needle electrodes were inserted into each treatment area and connected to a direct current (DC) power supply. Voltage (3-5 V) was varied and applied for 5 minutes. The wound-healing process was monitored via digital photography and ultrasonography until euthanasia at day 29. Treatment areas were biopsied, and specimens were sectioned through a sagittal midline across both electrode insertion sites. Samples were then evaluated utilizing light microscopy (hematoxylin and eosin, Masson's Trichrome, and Picrosirius red).

RESULTS

Treatment sites developed mild inflammation that dissipated at lower voltages or became scabs at higher voltages. Ultrasonography demonstrated acoustic shadowing with spatial spread that increased with increasing voltage application. The 4- and 5-V sites treated with saline had localized areas of increased tissue density at day 29. Although specimens treated with 3 V did not look significantly different from control tissue, 4- and 5-V samples with and without saline tumescence had finer, less-organized collagen fibers and increased presence of fibrocytes and inflammatory infiltrates.

CONCLUSIONS

Electrochemical therapy caused localized injury to in vivo rabbit cutaneous tissue, prompting regenerative wound repair. With future development, this technology may offer precise, low-cost rejuvenation to restore the functionality and appearance of dermal scars and keloids.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:E2196-E2203, 2021.

Electrochemical treatment of ex vivo human abdominal skin and potential use in scar management: A pilot study

INTRODUCTION

Scar treatments aim to address pathologic collagen deposition; however, they can be expensive or difficult to control. Electrochemical therapy (ECT) offers a simple alternative treatment. The purpose of this study is to examine the acid-base and histological changes in ex vivo human abdominal skin following ECT.

METHODS

Forty-two ex vivo human panniculus tissue sections collected from six individuals were tumesced with normal saline. ECT was performed by inserting two platinum needle electrodes connected to a DC power supply into each specimen. Voltage was varied (3-6 V) and applied for 5 minutes. Each specimen was sectioned across both electrode insertion sites and immediately stained with pH sensitive dye. The width of dye color change for each dosimetry pair was calculated. Hematoxylin and eosin staining was used to evaluate samples.

RESULTS AND DISCUSSION

ECT caused a spatially localised and dose-dependent increased area of acidic and basic pH around the anode and cathode, respectively. A significantly greater mean width of pH change was generated at the cathode compared to the anode in all treatment groups. Histological evaluation displayed broad condensation and hyalinisation of dermal collagen.

CONCLUSION

ECT triggered dermal pH alterations and changed the underlying structural framework of the specimen. This technology may serve as a low-cost, minimally invasive local soft-tissue remodeling technique with potential application in scar management.

LEVEL OF EVIDENCE

5.

LAY SUMMARY

Electrochemical therapy is a novel treatment that causes spatially selective dermal injury in areas of interest. This study measures the effects of electrochemical therapy when applied to abdominal skin. Electrochemical therapy appears to have beneficial effects by causing a highly localised reduction in collagen content or local softening of tissue, which is consistent with other studies on scar therapies, including chemexfoliation, radiofrequency technologies, and lasers. However, electrochemical therapy can be performed at a fraction of the costs of these aforementioned modalities.

Effects of electromechanical reshaping on mechanical behavior of exvivo bovine tendon

BACKGROUND

Electromechanical reshaping is a novel, minimally invasive means to induce mechanical changes in connective tissues, and has the potential to be utilized in lieu of current orthopedic therapies that involve tendons and ligaments. Electromechanical reshaping delivers an electrical current to tissues while under mechanical deformation, causing in situ redox changes that produce reliably controlled and spatially limited mechanical and structural changes. In this study, we examine the feasibility of altering Young's modulus and inducing a shape deformation using an ex vivo bovine Achilles tendon model.

METHODS

Tendon was mechanically deformed in two different modes: (1) elongation to assess for tensile modulus and (2) compression to assess for compressive modulus. Electromechanical reshaping was applied to tendon specimens via flat plate platinum electrodes (6 V, 3 min) while simultaneously under mechanical strain for 15 min.

FINDINGS

In elongation mode, post-electromechanical reshaping samples demonstrated a significant decrease in Young's modulus compared to pretreatment samples (66.02 and 45.12 MPa, respectively, p < 0.0049). In compression mode, posttreatment samples illustrated a significant shape change, with an increase in diameter (10.62 to 11.36 mm, p < 0.05) and decrease in thickness (4.13 to 3.62 mm, p < 0.05).

INTERPRETATION

Results demonstrated a tissue softening effect without lengthening deformation during elongation, and a shortening effect without compromising compressive stiffness during compression. Electromechanical reshaping's reliable, low-cost, and efficacious methodology in inducing mechanical and structural connective tissue modifications illustrates a potential for future alternative orthopedic applications. Future studies will optimize and refine electromechanical reshaping to address clinically relevant geometries and methods such as needle techniques.

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.

Characterization of Injury Induced by Routine Surgical Manipulations of Nasal Septal Cartilage

Importance

This study characterizes and compares common surgical manipulations' effects on septal cartilage to understand their implications for rhinoplasty outcomes based on cell viability and cartilage health.

Objective

To illustrate distinct differences in the impact of various surgical manipulations on septal cartilage in an in vitro septal cartilage model. A secondary objective is to better understand the chondrocyte's response to injury as well as how alterations in the extracellular matrix correspond to chondrocyte viability.

Design, Setting, and Participants

In this bench-top in vitro porcine model using juvenile bovine septal cartilage from bovine snouts, easily obtainable septal cartilage was used to generate large numbers of homogenous cartilage specimens. Quantitative outcomes at early and late time points were cell viability, cell stress, matrix loss, and qualitative assessment through histologic examination. The study was performed at a single academic tertiary care research hospital.

Interventions

Four common surgical manipulations were contrasted with a control group: crushed cartilage, scored cartilage, diced cartilage, and shaved cartilage.

Main Outcomes and Measures

Following the manipulation of the cartilage, the quantitative outcomes were glycosaminoglycan release to the media, lactate dehydrogenase release to the media, and cell death analysis through apoptosis staining. The qualitative outcomes were histologic staining of the manipulated cartilage with safranin-O/fast green stain to identify proteoglycan loss.

Results

The crushing followed by shaving manipulations were the most damaging as indicated by increased levels of lactate dehydrogenase release, glycosaminoglycans loss, and cell death. Matrix loss did not increase until after 48 hours postinjury. Furthermore, chondrocyte death was seen early after injury and accelerated to the late time point, day 9, in all manipulations. Conversely, cell stress was found to be greater at 48 hours postinjury, which then declined to the late time point, day 9.

Conclusions and Relevance

The crushing manipulation followed by shaving and then dicing were the most destructive methods of cartilage manipulation relative to control specimens. Collectively, these outcomes demonstrate the range of injury which occurs with all septal cartilage manipulations and can inform rhinoplasty practice to use the least damaging effective surgical manipulation to obtain the desired outcome.

Level of Evidence

NA.

The biophysical effects of localized electrochemical therapy on porcine skin

BACKGROUND

Minimally-invasive methods to treat scars address a common pathway of altering collagen structure, leading to collagen remodeling.

OBJECTIVE

In this study, we employed in situ redox chemistry to create focal pH gradients in skin, altering dermal collagen, in a process we refer to as electrochemical therapy (ECT). The effects of ECT to induce biochemical and structural changes in ex vivo porcine skin were examined.

METHODS

During ECT, two platinum electrodes were inserted into fresh porcine skin, and following saline injection, an electrical potential was applied. pH mapping, high frequency ultrasonography, and two photon excitation microscopy and second harmonic generation (SHG) microscopy were used to evaluate treatment effects. Findings were correlated with histology.

RESULTS

Following ECT, pH mapping depicted acid and base production at anode and cathode sites respectively, with increasing voltage and application time. Gas formation during ECT was observed with ultrasonography. Anode sites showed significant loss of SHG signal, while cathode sites showed disorganized collagen structure with fewer fibrils emitting an attainable signal. Histologically, collagen denaturation at both sites was confirmed.

CONCLUSION

We demonstrated the production of in situ acid and base in skin occurring via ECT. The effects chemically and precisely alter collagen structure through denaturation, giving insight on the potential of ECT as a simple, low-cost, and minimally-invasive means to remodel skin and treat scars.

Optimal Electromechanical Reshaping of the Auricular Ear and Long-term Outcomes in an In Vivo Rabbit Model

IMPORTANCE

The prominent ear is a common external ear anomaly that is usually corrected through surgery. Electromechanical reshaping (EMR) may provide the means to reshape cartilage through the use of direct current (in milliamperes) applied percutaneously with needle electrodes and thus to reduce reliance on open surgery.

OBJECTIVE

To determine the long-term outcomes (shape change, cell viability, and histology) of a more refined EMR voltage and time settings for reshaping rabbit auricle.

DESIGN, SETTING, AND SUBJECTS

The intact ears of 14 New Zealand white rabbits were divided into 2 groups. Group 1 received 4 V for 5 minutes (5 ears), 5 V for 4 minutes (5 ears), or no voltage for 5 minutes (control; 4 ears). Group 2 received an adjusted treatment of 4 V for 4 minutes (7 ears) or 5 V for 3 minutes (7 ears). A custom mold with platinum electrodes was used to bend the pinna and to perform EMR. Pinnae were splinted for 6 months along the region of the bend. Rabbits were killed humanely and the ears were harvested the day after splint removal. Data were collected from March 14, 2013, to July 8, 2014, and analyzed from August 29, 2013, to March 1, 2015.

MAIN OUTCOMES AND MEASURES

Bend angle and mechanical behavior via palpation were recorded through photography and videography. Tissue was sectioned for histologic examination and confocal microscopy to assess changes to microscopic structure and cell viability.

RESULTS

Rabbits ranged in age from 6 to 8 months and weighed 3.8 to 4.0 g. The mean (SD) bend angles were 81° (45°) for the controls and, in the 5 EMR groups, 72° (29°) for 4 V for 4 minutes, 101° (19°) for 4 V for 5 minutes, 78° (18°) for 5 V for 3 minutes, and 126° (21°) for 5 V for 4 minutes. At 5 V, an increase in application time from 3 to 4 minutes provided significant shape change (78° [18°] and 126° [21°], respectively; P = .003). Pinnae stained with hematoxylin-eosin displayed localized areas of cell injury and fibrosis in and around electrode insertion sites. This circumferential zone of injury (range, 1.3-2.1 mm) corresponded to absence of red florescence on the cell viability assay.

CONCLUSIONS AND RELEVANCE

In this in vivo study, EMR produces shape changes in the intact pinnae of rabbits. A short application of 4 V or 5 V can achieve adequate reshaping of the pinnae. Tissue injury around the electrodes is modest in spatial distribution. This study provides a more optimal set of EMR variables and a critical step toward evaluation of EMR in clinical trials.

LEVEL OF EVIDENCE

NA.

Modular Component Assembly Approach to Microtia Reconstruction

BACKGROUND

Current methods of microtia reconstruction include carving an auricular framework from the costal synchondrosis. This requires considerable skill and may create a substantial defect at the donor site.

OBJECTIVE

To present a modular component assembly (MCA) approach that minimizes the procedural difficulty with microtia repair and reduces the amount of cartilage to a single rib.

DESIGN, SETTING, AND PARTICIPANTS

Ex vivo study and survey. A single porcine rib was sectioned into multiple slices using a cartilage guillotine, cut into components outlined by 3-dimensional printed templates, and assembled into an auricular scaffold. Electromechanical reshaping was used to bend cartilage slices for creation of the helical rim. Chondrocyte viability was confirmed using confocal imaging. Ten surgeons reviewed the scaffold constructed with the MCA approach to evaluate aesthetics, stability, and clinical feasibility. The study was conducted from June 5 to December 18, 2014.

MAIN OUTCOMES AND MEASURES

The primary outcome was creation of a modular component assembly method that decreases the total amount of rib needed for scaffold construction, as well as overall scaffold acceptability. The surgeons provided their assessments through a Likert-scale survey, with responses ranging from 1 (disagree with the statement) to 5 (agree with the statement). Thus, a higher score represents that the surgeon agrees that the scaffold is structurally and aesthetically acceptable and feasible.

RESULTS

An auricular framework with projection and curvature was fashioned from 1 rib. The 10 surgeons who participated in the survey indicated that the MCA scaffold would meet minimal aesthetic and anatomic acceptability. When embedded under a covering, the region of the helix and antihelix of the scaffold scored significantly higher on the assessment survey than that of an embedded alloplast implant (mean [SD], 4.6 [0.97] vs 3.5 [1.27]; P = .007). Otherwise, no significant difference was found between the embedded MCA and alloplast implants (4.42 [0.48] vs 3.87 [0.41]; P = .13). Cartilage prepared with electromechanical reshaping was viable.

CONCLUSIONS AND RELEVANCE

This study demonstrates that 1 rib can be used to create an aesthetic and durable framework for microtia repair. Precise assembly and the ability to obtain thin, uniform slices of cartilage were essential. This cartilage-sparing MCA approach may be an alternative to classic techniques.

LEVEL OF EVIDENCE

NA.

Long-term in vivo electromechanical reshaping for auricular reconstruction in the New Zealand white rabbit model

OBJECTIVES/HYPOTHESIS

To demonstrate the dosimetry effect of electromechanical reshaping (EMR) on cartilage shape change, structural integrity, cellular viability, and remodeling of grafts in an in vivo long-term animal model.

STUDY DESIGN

Animal study.

METHODS

A subperichondrial cartilaginous defect was created within the base of the pinna of 31 New Zealand white rabbits. Autologous costal cartilage grafts were electromechanically reshaped to resemble the rabbit auricular base framework and mechanically secured into the pinna base defect. Forty-nine costal cartilage specimens (four control and 45 experimental) successfully underwent EMR using a paired set of voltage-time combinations and survived for 6 or 12 weeks. Shape change was measured, and specimens were analyzed using digital imaging, tissue histology, and confocal microscopy with LIVE-DEAD viability assays.

RESULTS

Shape change was proportional to charge transfer in all experimental specimens (P < .01) and increased with voltage. All experimental specimens contoured to the auricular base. Focal cartilage degeneration and fibrosis was observed where needle electrodes were inserted, ranging from 2.2 to 3.9 mm. The response to injury increased with increasing charge transfer and survival duration.

CONCLUSIONS

EMR results in appropriate shape change in cartilage grafts with chondrocyte injury highly localized. These studies suggest that elements of auricular reconstruction may be feasible using EMR. Extended survival periods and further optimization of voltage-time pairs are necessary to evaluate the long-term effects and shape-change potential of EMR.

LEVELS OF EVIDENCE

NA.