UC Berkeley team says brown fat implants may effectively tackle obesity

A team of scientists at UC Berkeley has developed a technique that utilizes the protective effects of brown fat--which may potentially lead to a new approach to manage obesity, diabetes and other metabolic disorders.

Kevin Tharp

The study was led by Kevin Tharp, a PhD student in the department of Nutritional Sciences and Toxicology, and was published in the journal Diabetes.

The UC Berkeley team designed a hydrogel as a scaffold with stem cells that have the ability to form brown-fat tissue. Since white fat is typically associated with obesity and stores excess energy, the long held hypothesis is that while white fat can exacerbate obesity brown fat on the other hand burns calories due to its heat generating nature.

Over the last 10 years there has been an explosion in the knowledge of brown fat, both at the cell biological level and at the clinical level. It's known that the metabolic activity is lower in obese individuals, however therapies targeting either white or brown fat have been lacking. The obesity market is difficult to enter since there is more stringency in the side-effect profile for obesity-drugs, a disease that is not immediately life threatening as compared with terminal diseases like cancers.

"What is truly exciting about this system is its potential to provide plentiful supplies of brown fat for therapeutic purposes", says Tharp. "The implant is made from stem cells that reside in white fat, which could be made from tissue obtained through liposuction".

Other than the energy storing white fat, there are two other types of fat tissue that promote energy metabolism--namely brown fat found during fetal development (and recently in adults albeit at smaller amounts) and beige fat which has brown-like behaviour and is formed within white fat after exposure to cold stimuli among others.

The researchers looked at increasing brown-like beige fat without the need for lowering the temperature. They created a tightly woven 3-D mesh in a hydrogel containing water, hyaluronic acid (combining with water to thicken the gel) and short protein sequences associated with brown-fat growth and function. After injecting the mixture before it thickened into mice from the same genetic background.

They initially observed an increase in core body temperature of up to half a degree Celsius warmer regardless of the outside temperature in the injected mice compared to a control group. The number of injected cells also correlated with a greater effect on their temperature.

Next they put the experimental mice on a high-fat diet and after three weeks the mice with the injected beige fat gained half as much weight and had lower levels of blood glucose and circulating fatty acids compared with control mice.

"This is a feasibility study, but the results were very encouraging," said Andreas Stahl who was the senior author of the study. "It is the first time an optimized 3-D environment has been created to stimulate the growth of brown-like fat. Given the negative health effects of obesity research into the role of brown fat should continue to see if these findings would be effective in humans."

- here's the release

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