WEDNESDAY, Jan. 22, 2020 (HealthDay News) -- The Harvard-associated lab that created the "CoolSculpting" process of reducing fat says it's on the trail of the next advance in nonsurgical slimming.

CoolSculpting freezes fat cells by applying an ice-cold gel pad to the skin, causing cells to die off and either be flushed away or absorbed by the body, said lead researcher Dr. Lilit Garibyan, an investigator at the Wellman Center for Photomedicine at Massachusetts General Hospital in Boston.

Now her lab is trying to make that process even more effective by injecting an icy liquid slurry directly into fat deposits.

In tests with pigs, the injectable slurry containing 20% to 40% ice caused fat deposits to melt away over several weeks, researchers reported recently in the journal Plastic and Reconstructive Surgery.

The procedure is headed to human clinical trials next, and researchers hope to have it approved and on the market in a few years, Garibyan said.

The U.S. Food and Drug Administration approved CoolSculpting in 2008. Garibyan said it remains the only noninvasive technology the FDA has cleared to reduce and reshape fat deposits in the body.

The process works using a principle that you observe every time you open your refrigerator -- fats freeze at a lower temperature than water, she said.

Butter turns to liquid at warmer temperatures, but solidifies in the fridge, Garibyan said. Water remains liquid at warm or cool temperatures.

"Lipid-rich tissue is more sensitive to cold injury," Garibyan said. "You can get adipose or lipid-rich tissue to die, where nothing happens to water-rich surrounding tissue like skin or muscle."

If applying cold pads to the outside skin can cause fat cells to die, the researchers reasoned, then a very cold solution injected directly into a fat deposit might work even better.

A sterile solution of normal saline and glycerol is brought to near-freezing temperatures, then injected into fatty areas.

The solution caused fat cells to crystallize and die in test pigs, and fat deposits to shrink, researchers reported.

But it didn't harm any of the surrounding tissue, Garibyan added.

"When we inject this directly into muscle or skin, nothing happens. There's no significant injury. It would only be the fat tissue that's affected," she said.

This new process seems promising, but is more invasive than CoolSculpting and will need tests to prove its safety, said Dr. Charles Salzberg, chief of plastic and reconstructive surgery at Mount Sinai Hospital in New York City. He wasn't part of the research.

Salzberg said CoolSculpting is a very safe process, but often under-delivers in terms of expected fat reduction.

The newly developed injection "is a very positive thing and it could be a wonderful tool to get rid of localized fat, but it would have to be proven safe," Salzberg said. "You are injecting ice fluid into the patients. Do they have any problems?"

More information

Wake Forest Baptist Health has more about CoolSculpting.