Body sculpting by nonsurgical fat removal may become an even more common cosmetic procedure than it already is, thanks to an experimental technique that homes in on subcutaneous fat with an icy injectable slurry.
Researchers at Massachusetts General Hospital in Boston report promising results from studies in swine using a biocompatible mix of ice, saline, and glycol injected at adipose tissue sites for selective fat removal.
They report a gradual reduction in the thickness of fat tissue of as much as 54.5% (± 5.9%) at slurry-targeted sites compared with 2.6% (± 0.9%) at control sites injected with a melted slurry (P < .001). Moreover, they observed a dose-response effect, with fat loss correlating to the total volume of ice injected. No scarring or damage to surrounding tissue occurred. The research was published online January 7 in Plastic and Reconstructive Surgery. "Our data shows that the slurry is safe, selective for adipose tissue, and leads to long-lasting or permanent loss of adipose tissue and the amount of fat loss correlates with total slurry ice volume," write Lilit Garibyan, MD, PhD, a dermatologist at the hospital's Wellman Center for Photomedicine and an assistant professor of dermatology at Harvard Medical School, and colleagues. "Slurry injection can be done in office under local or no anesthesia and it will take seconds to inject. The effect also appears to be long lasting or permanent." The researchers previously developed the topical cooling method of fat reduction known commercially as CoolSculpting, a procedure that takes almost an hour in the office. Dose Response They injected varying slurry mixes of 30 mL or 15 mL and 20% or 40% ice content into the subcutaneous fat of young female pigs aged 3 to 6 months and weighing 52 to 85 kg. Control animals received injections of melted slurry. Animals were assessed before injection and monitored periodically with ultrasound imaging for as long as 8 weeks. The injections produced no systemic side effects or abnormalities in blood chemistry, including liver function and lipid profile, at day 3 and weeks 2, 4, and 8. The greatest fat loss of almost 55% was seen in the 30 mL/40% group. In other groups treated with either 15mL of slurry with 40% ice content or 30 mL of slurry with 20% ice content, fat thickness reduction was less: 25.3% compared with 16.7% (P < .05 and P < .001, respectively). Slurries with ice contents of 40% and 20% achieved average temperatures of –4.8°C and –3.5°C, respectively. The corresponding volumes of fat loss in the three treatment groups were 2.6 cm3, 1.0 cm3, and 0.7 cm3. "These dose-response studies highlight the importance of total ice volume for the biologic effect of the slurry, rather than the volume of slurry," the authors write. "Injected ice volume is the major determinant of how much adipose tissue will be lost." Garibyan told Medscape Medical News that slurry recipients might initially feel quite cold at first as the subcutaneous temperature drops, "but at about plus 4°C the nerves stop firing." Cooling could also have a collateral metabolic effect, she added, in that some studies have shown that cooling can convert white fat to brown fat, thereby increasing energy expenditure. According to the investigators, ice slurry injection has the potential to become a "transformative and a minimally-invasive fat removal modality for body contouring." It has the capacity to target any volume of adipose tissue at any anatomic location. Human trials are expected to get underway soon, Garibyan said. Further studies in humans are clearly needed, Peter Henderson, MD, MBA, an assistant professor of plastic surgery at Icahn School of Medicine at Mount Sinai in New York City, stressed. "But there's a high likelihood that the same effect that was seen in pigs will be seen in humans. And if that proves to be true, then this technology has the potential to drastically change how excess and unwanted fat is treated throughout the body." Henderson pointed to several concerns, however, including the longevity of the treatment effects and the long-term appearance of the fat and overlying skin as the surrounding fat increases or decreases with normal aging and weight fluctuations. Another issue is how precise the location and extent of the fat reduction would be. "It is one thing to decrease fat in general, but especially in more nuanced parts of the body like the face and neck we would ideally like the amount of fat removed to be more specific, as an excessive or uneven fat removal could lead to an unsatisfactory result," said Henderson, who was not associated with the research. Obesity medicine specialist Fatima Cody Stanford, MD, MPH, MPA, also of Massachusetts General but not involved in the study, also sounded a warning. "This study was done in swine so we have to be a bit cautious about translating the conclusion that this procedure will likely lead to long-term fat loss to humans," she told Medscape Medical News. "And with cosmetic procedures, we don't often see sustained long-term results with anything that claims to remove fat tissue. Fat has memory — it knows where it was, so you can take it away today but it knows it was there and it can grow back — and sometimes even in areas where it hadn't been deposited before." In addition, Stanford said, owing to the multifactorial complexities of obesogenesis and fat regulation in the human body, especially in the current obesogenic environment of the United States, significant long-term changes with this single treatment are not likely to occur. "I don't think this is the Holy Grail." This research was supported by various funds. Lead author Garibyan and several study coauthors are inventors with patents owned by Massachusetts General Hospital and received part of a licensing fee. Coauthor Emilia Javorsky works for Arctic Fox Biomedical, which has licensed the patent for commercial development. Henderson and Stanford have disclosed no relevant financial relationships. Plast Reconstr Surg. Published online January 7, 2020. 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