PHILADELPHIA The body's immune system exists to identify and destroy foreign objects, whether they are bacteria, viruses, flecks of dirt or splinters. Unfortunately, nanoparticles designed to deliver drugs, and implanted devices like pacemakers or artificial joints, are just as foreign and subject to the same response.
Now, researchers at the University of Pennsylvania School of Engineering and Applied Science and Penn's Institute for Translational Medicine and Therapeutics have figured out a way to provide a "passport" for such therapeutic devices, enabling them to get past the body's security system.
The research was conducted by professor Dennis Discher, graduate students Pia Rodriguez, Takamasa Harada, David Christian and Richard K. Tsai and postdoctoral fellow Diego Pantano of the Molecular and Cell Biophysics Lab in Chemical and Biomolecular Engineering at Penn.
It was published in the journal Science.
"From your body's perspective," Rodriguez said, "an arrowhead a thousand years ago and a pacemaker today are treated the same as a foreign invader.
"We'd really like things like pacemakers, sutures and drug-delivery vehicles to not cause an inflammatory response from the innate immune system."
The innate immune system attacks foreign bodies in a general way. Unlike the learned response of the adaptive immune system, which includes the targeted antibodies that are formed after a vaccination, the innate immune system tries to destroy everything it doesn't recognize as being part of the body.
This response has many cellular components, including macrophages literally "big eaters" that find, engulf and destroy invaders. Proteins in blood serum work in tandem with macrophages; they adhere to objects in the blood stream and draw macrophages' attention. If the macrophage determines these proteins are stuck to a foreign invader, they will eat it or signal other macrophages to form a barrie
University of Pennsylvania