Subcutaneous Fat Reduction with Injected Ice Slurry

Large area fractional laser treatment of mouse skin increases energy expenditure

Fractional laser (FL) treatment is a common dermatologic procedure that generates arrays of microscopic treatment zones separated by intact tissue, promoting fast wound healing. Using a mouse model, we introduced a large area fractional laser treatment (LAFLT) method to study metabolic effects. Using two laser modalities, ablative FL (AFL) and non-ablative FL (NAFL), and exposing different percentages of mice's total body surface area (TBSA), we followed changes in metabolic parameters in real time using metabolic cages. Additionally, body composition, markers of inflammation, neurohormonal signaling, and browning of adipocytes were investigated. LAFLT, especially in high TBSA groups, had specific metabolic effects such as significantly increased average daily energy expenditure, increased fat mass loss, systemic browning of adipocytes, and inflammatory states, without compromising other organs. The ability of LAFLT to stimulate metabolism in a controlled way could develop into a promising therapeutic treatment to induce positive metabolic changes that replace or augment systemic drugs.

Assessment of the Efficacy of Cryolipolysis on Abdominal Fat Deposits: A Prospective Study

BACKGROUND

Cryolipolysis is a non-invasive and efficacious procedure for body contouring. The effectiveness of cryolipolysis has been demonstrated on multiple areas of the body, but on a limited number of subjects. The aim of this study is to demonstrate the effectiveness and the safety of cryolipolysis in the lower abdomen adipose tissue thickness reduction.

METHODS

A prospective study on 60 healthy women was carried out using CryoSlim Hybrid device. Each patient underwent two cryolipolysis sessions centered on the abdominal area. The primary endpoint was to decrease the thickness of the abdominal fat deposits. The change in the abdominal circumference and the thickness of the subcutaneous fat layer were assessed. Patient satisfaction and tolerance of the procedure were also taken into account.

RESULTS

A significant reduction of the abdominal circumference and subcutaneous fat layer thickness was observed. The mean decrease in abdominal circumference was 2.10 cm (3.1%) 3 months after the procedure and 4.03 cm (5.8%) 6 months after the procedure. The mean decrease in fat layer thickness was 1.25 cm (43.81%) 3 months after the procedure and 1.61 cm (41.73%) 6 months after the procedure. No major adverse events were noted. All patients were very satisfied, and minimal pain was reported.

CONCLUSIONS

Cryolipolysis is an effective technique to treat abdominal localized fat deposits. No major adverse events have been described for this procedure. Our promising results should encourage further studies aimed at optimizing the efficacy of the procedure without a considerable increase in the risks.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266 .

Cryolipolysis: The future of cryolipolysis

BACKGROUND

Cryolipolysis has revolutionized the field of cosmetic dermatology as a nonsurgical procedure, utilizing controlled cooling to selectively destroy fat cells.

AIMS AND METHODS

This review article will focus on the future prospects of cryolipolysis, considering advancements in current technology as well as innovations that hold promise for the future. We will explore emerging trends in cryolipolysis, considering novel applicator designs, combination therapies, an innovative injectable treatment approach, and the evolving role of this technology in the field of cosmetic dermatology.

CONCLUSION

The future holds promise for advances in cryolipolysis using both the noninvasive topical cooling approach and the novel injectable ice-slurry technology.

Selective reduction of visceral adipose tissue with injectable ice slurry

Reduction in visceral adipose tissue (VAT) mass reduces body weight and metabolic disease risk in obese patients. However surgical removal of VAT is highly invasive and thus not clinically feasible. We developed an injectable ice slurry for selective reduction of adipose tissue through cryolipolysis. The aim of this study was to investigate safety, feasibility and mechanism of ice slurry-induced cryolipolysis of VAT. Perigonadal VAT in diet-induced obese mice and rats was subjected to slurry or sham treatment. Body weight and blood chemistry were monitored for 56 days post-treatment. Histological analysis and molecular studies were performed to elucidate mechanisms of fat reduction. Treatment of VAT was well tolerated in all animals. Slurry induced adipocyte cell death via selective cryolipolysis; significant weight loss was noted at day 21 post-treatment. RNA sequencing from treated VAT samples showed increased expression of genes involved in inflammation, immune response, collagen biosynthesis and wound healing, and decreased expression of adipokines. This study demonstrates that slurry treatment is safe and effective in inducing cryolipolysis of VAT and subsequent weight loss in mice. Ice slurry is promising as a minimally-invasive treatment to reduce visceral adipose tissue.

Injectable ice slurry for reducing pericardial adipose tissue

OBJECTIVES

Excess pericardial adipose tissue (PAT) is associated with a higher risk of cardiovascular diseases. Currently, available methods for reducing PAT volume include weight loss through diet and exercise, weight loss with medications, and bariatric surgery. However, these methods are all limited by low patient compliance to maintain the results. We have developed an injectable ice slurry that could selectively target and reduce subcutaneous adipose tissue volume. The aim of this study was to investigate the feasibility and safety of using injectable slurry to selectively reduce PAT volume in a preclinical large animal model.

METHODS

PAT in Yucatan swine was injected with slurry or room temperature control solution. All animals were imaged with baseline chest computed tomography (CT) before slurry injection and at 2 months after injection to quantify PAT volume. Specimens from injected and noninjected PAT were harvested for histology.

RESULTS

Slurry treatment of PAT was well tolerated in all animals. Slurry-induced selective cryolipolysis in treated PAT. CT imaging showed decrease in PAT volume in treated area at 8 weeks posttreatment compared to baseline, that was significantly different from control solution treated group (median [range]: -29.66 [-35.07 to -27.92]% vs. -1.50 [-11.69 to 8.69]% in control animals respectively, p < 0.05).

CONCLUSIONS

This study demonstrated that slurry injection into PAT is feasible in a large animal model. Slurry injection was safe and effective in inducing selective cryolipolysis in PAT and reducing PAT volume. Slurry reduction of PAT could potentially serve as a novel treatment for cardiovascular diseases.

Potential treatment modalities for suprapubic adiposity and pubic contouring

Excess suprapubic adiposity can have negative consequences for patients, including concerns related to physical comfort, sexual function, hygiene, and esthetics. Historically, treatment options for pubic contouring have been limited to surgical methods. The purpose of this article is to review the literature investigating the use of minimally invasive fat reduction treatments for suprapubic adiposity including cryolipolysis, injection lipolysis, radiofrequency, and ultrasound. A thorough search of the PubMed database was conducted to search for studies evaluating the use of cryolipolysis, injection lipolysis, radiofrequency, and ultrasound for suprapubic adiposity. The literature search did not yield any publications that evaluated the use of cryolipolysis, injection lipolysis, radiofrequency, or ultrasound for treatment of suprapubic adiposity. Minimally invasive treatments for fat reduction, including cryolipolysis, injection lipolysis, radiofrequency, and ultrasound, have clinically demonstrated safety and efficacy in various anatomic locations. However, clinical studies evaluating these procedures for suprapubic adiposity are noticeably absent. These options may confer benefits such as decreased recovery time, risk, and cost to patients. Future clinical studies evaluating these potential treatment modalities for suprapubic fat reduction are warranted.

Total ice content and lipid saturation determine adipose tissue cryolipolysis by injection of ice-slurry

OBJECTIVES

Cryolipolysis uses tissue cooling to solidify lipids, preferentially damaging lipid-rich cells. Topical cooling is popular for the reduction of local subcutaneous fat. Injection of biocompatible ice-slurry is a recently introduced alternative. We developed and verified a quantitative model that simulates the heat exchange and phase changes involved, offering insights into ice-slurry injection for treating subcutaneous fat.

METHODS

Finite element method was used to model the spatial and temporal progression of heat transfer between adipose tissue and injected ice-slurry, estimating dose-response relationships between properties of the slurry and size of tissue affected by cryolipolysis. Phase changes of both slurry and adipose tissue lipids were considered. An in vivo swine model was used to validate the numerical solutions. Oils with different lipid compositions were exposed to ice-slurry in vitro to evaluate the effects of lipid freezing temperature. Microscopy and nuclear magnetic resonance (NMR) were performed to detect lipid phase changes.

RESULTS

A ball of granular ice was deposited at the injection site in subcutaneous fat. Total injected ice content determines both the effective cooling region of tissue, and the duration of tissue cooling. Water's high latent heat of fusion enables tissue cooling long after slurry injection. Slurry temperature affects the rate of tissue cooling. In swine, when 30 ml slurry injection at -3.5°C was compared to 15 ml slurry injection at -4.8°C (both with the same total ice content), the latter led to almost twice faster tissue cooling. NMR showed a large decrease in diffusion upon lipid crystallization; saturated lipids with higher freezing temperatures were more susceptible to solidification after ice-slurry injection.

CONCLUSIONS

Total injected ice content determines both the volume of tissue treated by cryolipolysis and the cooling duration after slurry injection, while slurry temperature affects the cooling rate. Lipid saturation, which varies with diet and anatomic location, also has an important influence.

Fast-acting and injectable cryoneurolysis device

Cryoneurolysis is an opioid-sparing therapy for long-lasting and reversible reduction of pain. We developed a nerve-selective method for cryoneurolysis by local injection of ice-slurry (- 5 to - 6 °C) that induced decrease in nocifensive response starting from about a week after treatment and lasting up to 8 weeks. In this study, we test the hypothesis that injection of colder slurry leads to faster onset of analgesia. Colder slurry (- 9ºC) was injected around the rat sciatic nerve to induce cryoneurolysis. Hematoxylin and Eosin (H&E) staining was used to examine histologic effects on surrounding tissues. Coherent anti-Stokes Raman scattering (CARS) microscopy was used to study effects on myelin sheaths. Functional tests were used to assess changes in sensory and motor function in the treated hind paw. No inflammation or scarring was detected in surrounding skin and muscle tissues at day 7 post slurry injection. Functional tests showed rapid onset reduction in mechanical pain sensitivity starting from day 1 and lasting up to day 98. CARS imaging demonstrated disintegration of myelin sheaths post treatment followed by complete recovery of nerve structure by day 140. In this study we showed that colder slurry (- 9 °C) produces more rapid onset and longer duration of analgesia, while remaining nerve-selective.

Safety and feasibility of selective tongue fat reduction with injected ice-slurry

Objectives

There is growing evidence that excess adipose tissue within the head and neck contributes to obstructive sleep apnea (OSA), particularly in obese patients. This subset of the population is often difficult to treat with surgical therapies. We theorized that a novel, transcervical method of injectable cryoablation using ice-slurry can achieve low temperatures without causing neurovascular damage or airway distress in a swine model.

Methods

Four Yorkshire pigs were injected with ice-slurry comprised of normal saline and 10% glycerol cooled to -6°C via a transcervical, ultrasound guided approach. Direct laryngoscopy was used to confirm accurate placement of the slurry. Thermocouple placement at the needle-tip was used to measure temperatures at injection site. Swine were monitored for clinical signs of tongue necrosis and airway edema for 2 months, and then euthanized. Twelve biopsy samples from the base of the tongue were collected for histology. These were assessed for presence of tissue damage, inflammation and collagen formation by a blinded board-certified pathologist.

Results

Tongue tissue temperature below 10°C was achieved for 13.5 ± 1.1 min. Minimum tissue temperature was -4 ± 0.6°C. There was no clinical or pathological evidence of tongue damage to include damage to the lingual nerve or artery. There was some histologic evidence of new collagen formation in areas of the tongue.

Conclusions

Transcervical ultrasound-guided ice-slurry injection is feasible, well-tolerated at temperatures previously shown to be capable of selectively targeting adipose tissue in the base of the tongue in a preclinical swine model, without causing neurovascular damage or airway distress when properly injected.

Injection Cryolipolysis: First-in-human Study

Background

Injection cryolipolysis using an ice slurry has been hypothesized to be a novel method of reducing fat. The present first-in-human pilot study aims to investigate the feasibility, safety, and tolerability of ice slurry injection into human subcutaneous fat.

Methods

Preabdominoplasty subjects were recruited. Baseline measurements and serial follow-up visits following a single ice slurry injection procedure into tissue to be excised during abdominoplasty were performed. Melted ice slurry injection was used as control. Feasibility using standard injection techniques was assessed. Thermal imaging was used to determine cooling efficacy. Safety was assessed by adverse event monitoring. Tolerability was assessed by subject-reported pain score. Histology and ultrasound were monitored for structural changes associated with cryolipolysis.

Results

A single injection of ice slurry was feasible and sufficient to cool adipose below the target temperature (10C). There were no serious adverse events. The most common adverse events were bruising and erythema. The mean pain score for ice slurry-injected sites was 1.9/10 and 1.3/10 in control injection sites. Evidence of cryolipolysis was observed on ultrasound and tissue histology in ice slurry-injected sites.

Conclusions

Ice slurry injections are feasible, with an observed safety and tolerability profile comparable to topical cryolipolysis. The ice slurry can cool tissue to induce cryolipolysis, as observed by thermal imaging, ultrasound, and tissue histology, and is selective for ice-injected sites. No significant changes were observed in control sites. The ice slurry may be a promising candidate to enable more precise, effective, and customizable aesthetic fat reduction that warrants further investigation.

Acute Renal Failure following Novel Subcutaneous Fat Reduction with Injected Ice Slurry

A new fat-freezing injection may pose significant health risks. Subcutaneous injection of partially frozen normal saline and glycerol has been shown to significantly reduce adipose tissue. This article reports the first human case and adverse reactions following this new procedure.

Facial Fat Fitness: A New Paradigm to Understand Facial Aging and Aesthetics

Traditionally, facial adipose tissue has been perceived and treated as a homogenous volume-occupying subcutaneous depot. However, recent research from across disciplines is converging to reveal a far more anatomically organized and functionally dynamic role of facial adipose tissue. In this narrative review, we will discuss new insights into adipocyte function and facial adipose anatomy that have far-reaching implications for the practice of aesthetic facial plastic surgery. These concepts are synthesized into a "facial fat fitness" model which can be used to explain clinical observations in facial aging and aesthetic surgery. Fat fitness relates to the quality of facial adipose tissue, as opposed to quantity, and describes whether adipose tissue is in a predominantly healthy hyperplastic or unhealthy hypertrophic state. Fat fitness is modulated by lifestyle factors, and may be impacted positively or negatively by facial aesthetic treatments. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Dermal Adipose Tissue Secretes HGF to Promote Human Hair Growth and Pigmentation

Hair follicles (HFs) are immersed within dermal white adipose tissue (dWAT), yet human adipocyte‒HF communication remains unexplored. Therefore, we investigated how perifollicular adipocytes affect the physiology of human anagen scalp HFs. Quantitative immunohistomorphometry, X-ray microcomputed tomography, and transmission electron microscopy showed that the number and size of perifollicular adipocytes declined during anagen‒catagen transition, whereas fluorescence-lifetime imaging revealed increased lipid oxidation in adipocytes surrounding the bulge and/or sub-bulge region. Ex vivo, dWAT tendentially promoted hair shaft production, and significantly stimulated hair matrix keratinocyte proliferation and HF pigmentation. Both dWAT pericytes and PREF1/DLK1⁺ adipocyte progenitors secreted HGF during human HF‒dWAT co-culture, for which the c-Met receptor was expressed in the hair matrix and dermal papilla. These effects were reproduced using recombinant HGF and abrogated by an HGF-neutralizing antibody. Laser-capture microdissection‒based microarray analysis of the hair matrix showed that dWAT-derived HGF upregulated keratin (K) genes (K27, K73, K75, K84, K86) and TCHH. Mechanistically, HGF stimulated Wnt/β-catenin activity in the human hair matrix (increased AXIN2, LEF1) by upregulating WNT6 and WNT10B, and inhibiting SFRP1 in the dermal papilla. Our study demonstrates that dWAT regulates human hair growth and pigmentation through HGF secretion, and thus identifies dWAT and HGF as important novel molecular and cellular targets for therapeutic intervention in human hair growth and pigmentation disorders.

Cryolipolysis-induced abdominal fat change: Split-body trials

Cryolipolysis has been considered as a noninvasive alternative to surgical procedures for reducing subcutaneous fat without affecting the surrounding tissues. However, no clinical trial has investigated changes in the abdominal fat tissue by 12 weeks after cryolipolysis. Therefore, in this split-body trial, we explored whether a single session of unilateral cryolipolysis could change visceral and subcutaneous adipose tissue over a period of 12 weeks. We compared the cross-sectional areas of the abdominal adipose tissue of 15 subjects (9 women; 38.3 [10.8] years) by computed tomography before and at 12 weeks after a single treatment of cryolipolysis to the left abdomen and used the right abdomen as untreated control. In addition, we measured participants' waist circumference, percentage of body fat (by bioelectrical impedance analysis) at baseline and at 6- and 12-weeks post-treatment. Single unilateral cryolipolysis tended to reduce the cross-sectional areas of visceral adipose tissue, by 8.4 cm2 (9.9%), the waist circumferences, and the percent body fat, by 2.8 cm2 (0.6%), overall. The cross-sectional area of visceral adipose tissues on the treated side significantly decreased, by 6.8 cm2 (15.6%; P = 0.003), and that of the untreated side tended to decrease by 1.2 cm2 (3.6%). Thus, a single unilateral session of noninvasive selective cryolipolysis can be considered as a safe and effective treatment for reduction of visceral adipose tissue over a period of 12 weeks, which should result in metabolic improvement.

Neural Selective Cryoneurolysis with Ice Slurry Injection in a Rat Model

BACKGROUND

Postoperative pain caused by trauma to nerves and tissue around the surgical site is a major problem. Perioperative steps to reduce postoperative pain include local anesthetics and opioids, the latter of which are addictive and have contributed to the opioid epidemic. Cryoneurolysis is a nonopioid and long-lasting treatment for reducing postoperative pain. However, current methods of cryoneurolysis are invasive, technically demanding, and are not tissue-selective. This project aims to determine whether ice slurry can be used as a novel, injectable, drug-free, and tissue-selective method of cryoneurolysis and resulting analgesia.

METHODS

The authors developed an injectable and selective method of cryoneurolysis using biocompatible ice slurry, using rat sciatic nerve to investigate the effect of slurry injection on the structure and function of the nerve. Sixty-two naïve, male Sprague-Dawley rats were used in this study. Advanced Coherent anti-Stokes Raman Scattering microscopy, light, and fluorescent microscopy imaging were used at baseline and at various time points after treatment for evaluation and quantification of myelin sheath and axon structural integrity. Validated motor and sensory testing were used for evaluating the sciatic nerve function in response to ice slurry treatment.

RESULTS

Ice slurry injection can selectively target the rat sciatic nerve. Being injectable, it can infiltrate around the nerve. The authors demonstrate that a single injection is safe and selective for reversibly disrupting the myelin sheaths and axon density, with complete structural recovery by day 112. This leads to decreased nocifensive function for up to 60 days, with complete recovery by day 112. There was up to median [interquartile range]: 68% [60 to 94%] reduction in mechanical pain response after treatment.

CONCLUSIONS

Ice slurry injection selectively targets the rat sciatic nerve, causing no damage to surrounding tissue. Injection of ice slurry around the rat sciatic nerve induced decreased nociceptive response from the baseline through neural selective cryoneurolysis.

Injectable slurry for selective destruction of neck adipose tissue in New Zealand obese mouse model

PURPOSE

Increased neck circumference is a major risk factor for obstructive sleep apnea (OSA). New data suggest that increased adipose tissue in the neck may be a contributory cause of OSA. The aim of this study was to investigate safety and efficacy of a recently developed injectable ice slurry in selective reduction of neck adipose tissue in a mouse model.

METHODS

We used the New Zealand obese mice that have increased volume of anterior neck fat, and are commonly used in OSA studies. MRI imaging was used to measure changes in fat tissue volume.

RESULTS

Thirty animals were used in this study. Volumetric measurements in MRI images showed thatchanges in anterior neck adipose tissue volume from baseline in treated mice was significantly different in comparison with the control group (-1.09/kg ± 0.33/kg vs 0.68/kg ± 0.37/kg; p < 0.01 by two-tailed Student's t test). Histological analysis of samples from the treated area of the neck did not show scarring or damage to the surrounding tissues.

CONCLUSIONS

Injection of ice slurry safely, effectively, and selectively reduces upper airway fat in New Zealand obese mice without scarring or damage to surrounding tissue. Our results suggest that slurry injection may be a novel and minimally invasive method of removing neck adipose tissue. This intervention should be further investigated to determine its suitability for treatment of OSA.