Scientists at Dana-Farber Cancer Institute have isolated a new type of energy-burning fat cell in adult humans which they say may have therapeutic potential for treating obesity.
Called "beige fat," the cells are found in scattered pea-sized deposits beneath the skin near the collarbone and along the spine in adult humans. Because this type of fat can burn off calories - rather than store them, as "white fat" cells do - beige fat cells might spawn new therapies for obesity and diabetes, according to researchers led by Bruce Spiegelman, PhD, of Dana-Farber.
Spiegelman is the senior author of a report scheduled for advance online publication on July 12 by the journal Cell. The print issue of Cell will publish on July 20.
The study found that beige fat is genetically distinct from "brown fat," which also burns calories to generate heat. Brown fat is found in small mammals and human infants, where it protects against harm from cold. White fat, on the other hand, stores calories, and excess white fat contributes to obesity.
Existence of this third type of fat (in addition to white and brown) had been proposed in a paper by Spiegelman's lab in 2008, but the Dana-Farber team is the first to isolate them and to determine their unique genetic profile. In the new report, Spiegelman's team, led by first author, Jun Wu, PhD, also found that beige cells are specifically targeted by the hormone irisin, which muscle cells express during exercise.
In 2009, three research groups reported that the deposits found in adult humans contained brown fat, but the new research has identified them as beige fat by their genetic makeup.
"Going forward, it means that what you want to study for potential therapies are the beige fat cells in these 'hotspots' we're all walking around with," said Spiegelman.
Even in small amounts, brown and beige fat can burn large amounts of calories.
"The therapeutic potential of both kinds of brown fat cells is clear," the authors write in the Cell article, "as genetic manipulations in mice that create more brown or beige fat have strong anti-obesity and anti-diabetic actions." Researchers are already seeking ways to exploit human brown fat for human benefits.