It makes perfect sense. For millennia, the human body’s immune system has fought off bacteria and any foreign bodies that threaten the life and health of that person. But modern medicine can insert a lot of items – stents, scaffolds, hip implants, and nanoparticles, for example — that are designed to prolong life, or ease suffering or an illness.
It’s not surprising then when the body’s immune system naturally senses that those objects are foreign and starts attacking them. But engineers at the University of Washington (UW) have developed a polymer hydrogel that helps resist those natural responses, reports News Medical.
The researchers believe that the polymer could coat medical devices, such as prostheses or breast implants, to prevent the body from rejecting them. “It has applications for so many different medical implants, because we literally put hundreds of devices into the body,” says Buddy Ratner, a UW professor of bioengineering and of chemical engineering, who helped with the development. “We couldn’t achieve this level of excellence in healing before we had this synthetic hydrogel.”
The devices are expensive to develop, so it is frustrating when the body attacks them. News Medical explains how the attack works and its effects:
After an implant, the body usually creates a protein wall around the medical device, cutting it off from the rest of the body. Scientists call this barrier a collagen capsule. Collagen is a protein that’s naturally found in our bodies, particularly in connective tissues such as tendons and ligaments. If a device such as an artificial valve or an electrode sensor is blocked off from the rest of the body, it usually fails to work.
The UW polymer holds both a positive and negative charge, which deflects all proteins from sticking to its surface. The engineers tested the hydrogel in mice and found that collagen was loosely distributed around the polymer, which suggested that the immune systems of the mice did not detect the polymer’s presence.
In humans, the first few weeks after an implant are the most crucial. If a collagen capsule has not built up within that time, it’s likely that the body will not go in attack mode. However, it is still an improvement if a polymer can reduce rejection to nearly zero.
“Scientists have tried many materials, and with no exception, this is the first non-porous, synthetic substance demonstrating that no collagen capsule forms, which could have positive implications for implantable materials, tissue scaffolds and medical devices,” says Shaoyi Jiang, a UW professor of chemical engineering, who helped on the project by implanting the polymer into the bodies of mice.
Source: “Polymer substance fully resists the body’s natural attack response to foreign objects,” News Medical, 5/15/13
Image by Brian Wowk.