Human beings have two types of fat in various amounts. Of the two white fat is considered the bad kind as it stores excess energy in large triglyceride droplets. The favored brown fat, on the other hand, has smaller droplets and a large number of mitochondria that burn fat to produce heat. We are born with a relative richness of brown fat, which insulates us to cold temperatures, but as we grow older, most brown fat is lost. For years, researchers have been searching for therapies that can transform an adult’s white fat into brown fat (a process called browning) as a treatment for obesity and diabetes. Converting energy-storing white fat into energy-burning brown fat locally raises the body’s overall metabolism.
Researchers from Columbia University Medical Center in New York (CUMC) and the University of North Carolina have formulated a medicated skin patch that is intended to burn off extra fat and treat metabolic disorders, such as obesity and diabetes. In the new treatment approach tested on obese mice, drug compounds known to promote browning are first encased in nanoparticles too small to be seen by the naked eye. The nanoparticles are then placed into a centimeter-square skin patch filled with many microscopic needles. When the patch is applied the needles painlessly pierce the skin and slowly release the drug from nanoparticles into the underlying tissue.
There are several clinically available drugs that promote browning, but all must be given as pills or injections, which can lead to side effects such as stomach upset, weight gain, and bone fractures. The new skin patch appears to alleviate these complications by delivering most of the drug directly to the targeted fat tissue, instead of systemically throughout the body like taking pills or injections do. Mice treated with the skin patches loaded with drug compounds known to promote browning had a 20 percent reduction in fat on the treated side compared with the untreated side. The treated mice also had significantly lower fasting blood glucose levels than untreated mice, with genetic analyses confirming that the treated side contained more genes associated with brown fat than on the untreated side. The study researchers have submitted a patent for the nanoparticle-containing patch technology.