American scientists have identified precursor cells that can develop into fat cells.
Researchers from the Howard Hughes Medical Institute and Rockefeller University, who made this discovery while observing the growth of fat in a skinny mouse after injecting it with different kinds of immature cells, say that these cells may help understand how changes in the numbers of fat cells might increase and lead to obesity.
Published in the online edition of the journal Cell, the finding can have significant implications for understanding how fat cells affect conditions such as diabetes and cardiovascular disease.
"The identification of white adipocyte progenitor cells provides a means for identifying factors that regulate the proliferation and differentiation of fat cells," says senior author Jeffrey Friedman, who is the Marilyn M. Simpson Professor at Rockefeller and a Howard Hughes Medical Institute investigator.
For their study, the researchers genetically engineered a mouse to lack white fat and mimic a condition in humans called lipodystrophy, both linked with diabetes.
The researchers later injected the "fatless" mouse with these cell populations, and found that only one of the isolated cell populations, which express the CD24 cell-surface marker protein, produced fat tissue in the fatless mouse.
"I injected the CD24+ cells - which represent a very small population of cells in normal adipose tissue - into a site where the fat would normally develop in the fatless mouse, and I found that a normal sized fat depot forms at the site of injection," says Rodeheffer.
The study also revealed that the injection of the fat-producing cells corrects the fatless mouse's diabetes, and the fat cells secrete adipocyte-specific signaling proteins called cytokines.
According to the researchers, the two findings confirmed that the cells produced in the fatless mouse were functional fat cells.
"This finding gives us a better understanding of the basic biology of adipose tissue and opens the door for us and for other researchers to be able to study these cells in living animals and determine the molecular factors that regulate formation of adipose tissue," says Rodeheffer.
"We then can potentially study how the growth and differentiation of these cells are regulated in obesity and determine whether or not the molecular events that are involved in the regulation of adipose tissue are contributing factors to other pathologies, such as diabetes and cardiovascular disease, that are associated with obesity and metabolic syndrome," adds the researcher.