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.