Nanotech skin patch turns white fat into brown fat

“Body sculpting” is a currently fashionable term that embraces a multitude of generally expensive vanity sins: diet plans, cosmetic surgery and personal trainers among them.

Soon, however, another technique to banning the body’s unwanted fatty deposits could be added to the arsenal: nanotech skin patches.

In research published in the journal ACS Nano, a team led by biomechanical engineer Yuqi Zhang from the University of North Carolina describes a medicated patch saturated with nanoparticles and topped with micro-needles that can turn areas of white fat into brown.

Brown fat comprises much smaller triglyceride droplets than white, and thus has a higher concentration of energy-burning mitochondria. Common in babies – where it functions as both energy storage and insulation – brown fat is rare in adults.

Induced to form, however, it burns through its energy reserves quickly, elevating the body’s rate of glucose and fatty acid clearance. Over time burning brown fat can improve insulin sensitivity and increase the overall metabolic rate.

For these reasons, converting white fat into brown has been touted as a likely treatment for both obesity and diabetes, although an August 2017 study in the journal Redox Biology reported that the strategy has so far not brought about “substantial reductions in body weight” in humans.

The latest approach has so far been trialled only in mice.

The strategy is in effect a more targeted way of administering any of a number of drugs developed to promote the conversion of white fat into brown. Currently, these medications are given as pills or injections, and thus spread through the whole body.

This is not merely inefficient, but, co-author Li Qiang notes, “can lead to side effects such as stomach upset, weight gain, and bone fractures”.

Qiang and colleagues designed a one centimetre-square patch to demonstrate proof of concept in a mouse model. The patch is suffused with nanoparticles, each just 250 nanometres wide, into which a browning drug is placed.

The surface of the patch is covered by dozens of microscopic needles so small and sharp that when applied to the skin they are painless.

In this way, the patch delivers the drugs only to precisely targeted areas, minimising side-effects and maximising delivery efficiency.

To test the system, the scientists loaded up patches with either rosiglitazone, a compound used in many browning treatments, or a beta-adrenergic receptor agonist dubbed CL 316243, which works in mice but not in humans.

The patches were then pressed onto one side of several of the rodents. Another cohort remained untreated, functioning as controls.

Each treated mouse showed a 20% fat reduction on its patched side and none on the other.  Treated mice also consumed 20% more oxygen – indicating an increased metabolic rate – than the controls.

Although there is still a long way to go before fat-converting nano-patches will be available for human use, the researchers are quick to point out that, scaled up and clinically tested, they may well introduce a new way of bespoke body sculpting.

“Many people will no doubt be excited to learn that we may be able to offer a noninvasive alternative to liposuction for reducing love handles,” says Qiang.

“What’s much more important is that our patch may provide a safe and effective means of treating obesity and related metabolic disorders such as diabetes.”