UC Berkeley researchers study fat cells, obesity prevention in mice

Kore Chan/Senior Staff

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Campus researchers have found a way to lower blood glucose levels and reduce weight gain in mice through the injection of heat-generating fat cells.

By converting white fat — which stores excess nutrients for later use — into energy-burning beige fat and transplanting it into mice, researchers were able to raise the core body temperature of mice in cold environments. According to the researchers, this process may later be adapted to humans to facilitate weight loss and prevent obesity.

Beige fat, which has a higher mitochondrial concentration, forms within white fat tissue after extreme exposure to cold. According to the study, cold temperatures can increase activity in these cells, which then burn calories in order to create heat.

The study, which began three years ago, represents tests of the process “in just about every context,” according to Kevin Tharp, lead author and a doctoral student in the department of nutritional sciences and toxicology. He said that all the materials used were already FDA approved.

According to Tharp, the injection of beige fat cells creates more metabolically active tissues that activate core temperature by breaking down fat and sugar to conduct heat. But Tharp said the effects of the experiment persist for only about a month.

“First and foremost, this is proof of the principle that beige fat is capable of reducing the effects of obesity,” he said. “It’s a really elegant bioengineering principle.”

Kevin Healy, campus professor of materials science and bioengineering, said future research will be directed at trying to keep the cells alive longer and attempting to find more robust matrix conditions. Healy helped in the research by recommending materials for conducting the study.

Tharp said his team initially tested the effect of directly transplanting heat-generating fat between mice over the course of five to six months. When the team discovered no significant results, it made its own cells.

Using isolated white-fat-derived stem cells, the fat was embedded in an optimized hydrogel matrix that the researchers created. The matrix was used to change characteristics of the cells to convert them into beige fat cells.

Fat cells were removed from the mice in a process that Tharp equated to liposuction. After the fat was modified, it was injected back into the mice using a noninvasive technique, according to Tharp.

“This process is totally innocuous — the fact that we can modify these fat cells allows us to create something that is biodegradable and bioactive,” he said.

The study was funded by the National Institutes of Health and the American Diabetes Association, both of which will not be able to fund research for adapting the process for humans, according to Tharp. He said that until further funding is found, the researchers will continue to experiment with mice.

Contact Robert Tooke and Trevor Greenan at [email protected].