DECEMBER 18, 2012 1:45 AM • BY MELISSA HEALY LOS ANGELES TIMES (MCT)
LOS ANGELES — Struggling with your weight? Here’s a future transplant list you might want to be on: Receive a donation of some brown fat from a lean, healthy individual, have it injected in or around your belly fat, and quickly see your metabolic function improve, your white-fat deposits make way for lean muscle and your bathroom scales show a downward trend.
That tantalizing prospect for fighting fat took a small step closer to reality last week with the publication of a study that found that, in chubby mice, at least, such a procedure worked.
The study, conducted at the Joslin Diabetes Center in Boston, explored whether it would be possible to boost a body’s stores of brown fat — the mitochondria-rich fat tissue that burns up lots of calories to keep us warm in cold weather — as an aid to weight loss.
The researchers sought to discover how a body would respond to the transplantation of brown fat from someone else’s body: Would it be rejected or converted into its unhealthy cousin, white fat? If it “took” inside its new host, the team wanted to know if it would behave as it does in those who are born with plentiful stores of it — helping the body burn more calories and clear the bloodstream of excess glucose.
The scientists took a tiny sample (either 0.1 gram or 0.4 grams) of brown fat tissue from the space between a mouse’s shoulders. They transplanted it into the abdominal cavity of 12-week-old mice that had been fattened with a high-fat, high-calorie diet, right on top of the animals’ own pad of abdominal fat. Two comparison groups of mice got “placebo” treatments: either transplants of a small glass bead or 0.1-gram of white fat.
Eight weeks after the brown fat was transplanted, it had insinuated itself into the fat tissue of its new host and gone to work: The animals’ glucose processing improved dramatically and responses to insulin improved too, even as it grew steadily worse in the two other groups.
By 12 weeks, the brown-fat recipients weighed less and burned more calories than the control mice, even though all groups were eating the same diet. Their total lean mass — muscles and bones — was unchanged.
The study was published last Monday in the Journal of Clinical Investigation.