An injectable ice “slurry” may selectively reduce unwanted fat, according to research in pigs published in Plastic & Reconstructive Surgery.

The findings are out of the same Massachusetts General Hospital (MGH) laboratory that invented cryolipolysis and gave us CoolSculpting.

The ice slurry contains a sterile solution of normal saline and glycerol plus approximately 20 percent to 40 percent small ice particles. It can be injected directly into fat deposits via a hypodermic needle, causing the adipocytes to crystallize and die. The fat is eliminated gradually as it is with other fat-reduction techniques and technologies.

When the slurry was injected into pigs, there was a 55 percent reduction in fat thickness compared to that of pigs injected with the same but melted ice solution. The amount of fat loss correlated with the total volume of ice injected, the researchers report. Moreover, there was no damage to skin or muscle at the injection site, and no systemic side effects or abnormalities seen.

Unlike topical cooling which necessitates applicators, slurry injection can target fat tissue at essentially any depth and any site that can be accessed by a needle or catheter.

“Physiological ice slurry injection is a promising new strategy for selective and nonsurgical fat removal,” conclude the researchers who were led by Lilit Garibyan, MD, PhD, an investigator in the Wellman Center for Photomedicine at MGH and the Department of Dermatology at Harvard Medical School in Boston.

Further studies in humans are needed before any firm conclusion can be drawn about ice slurries and fat reduction, says Peter Henderson, MD, Assistant Professor of plastic and reconstructive surgery at the Icahn School of Medicine at Mount Sinai in New York City. “There is 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.“ Dr. Henderson was not involved in the new study.

Other questions remain, he adds. “One concern I have is not only how long-lasting the effect is, but also what the fat and overlying skin look like in the long term as the amount of surrounding fat increases or decreases with normal aging and weight fluctuations,” he says. “The second concern is how precise the location and extent of 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 that is removed to be more specific, as an excessive or uneven fat removal could lead to an unsatisfactory result.”