Half-synthetic half-biological material replaces soft facial tissues, letting doctors shape implants to order

In reconstructive surgery, if a doctor needs a bone he or she can turn to a range of plastics, ceramics, or metals as suitable replacements. But when it comes to soft tissues--like the kind found in that most cosmetically important area, the face--replacements are scarce, and the ones that do exist aren’t very good, especially when it comes to fixing large-scale deformities.

But a new transplantable biomaterial, part biological and part synthetic, could help surgeons rebuild even the hardest to fix disfigurements. Just inject, shape, and blast with green light.

The material, developed by researchers at Johns Hopkins University, blends polyethylene glycol, a synthetic material, with hyaluronic acid, a biological material already in use in soft tissue replacement. It’s injectable, so it requires no surgery, and it’s pliable, so doctors can sculpt it into the proper shape after it has been injected. A specific wavelength of green LED light then solidifies the liquid polymer where it sits, turning the biomaterial's chaotic arrangement of polymer chains into a rigid structure.

The material is also tunable. In lab tests, the researchers mixed various cocktails with different ratios of hyaluronic acid and polyethylene glycol, resulting in implants with different characteristics of pliability and durability--characteristics that would allow doctors to customize the biomaterial for any particular implant. Durability is important, because the implants are not permanent. In those lab tests, the implant with the most longevity only lasted about 500 days before the rat that was hosting it completely absorbed it into its body. That means patients would need to replace their implants roughly every year or so.

The good news is, the absorption of the material has thus far shown no real adverse effects in the rats, or even in humans. The researchers have already tested their biomaterial in three human subjects in Canada. The implants lasted about three months, and none of the subjects experience any unexpected side effects, save a little inflammation around the site of the implant.


/Popular Science/