Stealth Nanoparticles...

By binding to an immune system cell's receptor (grey), a man-made component (yellow) of a protein could prevent the body from getting rid of a therapeutic nanoparticle. DIEGO PANTANO

Small man-made peptides can help to sneak drug-bearing nanobeads past the ever-vigilant immune system, a group of US researchers has found.

To work effectively, drugs and imaging agents need to get to the diseased cells or tumours where they’re needed most. Although scientists are developing nanoparticles that help to deliver drugs to the right place, all therapeutic molecules face a deadly foe — the immune system. Its macrophages are designed to spot any intruding molecules in the blood and destroy them in a process called phagocytosis.

Researchers at the University of Pennsylvania in Philadelphia have now found a way to stop macrophages from destroying drug-bearing nanoparticles. They have designed and made a small segment of a crucial membrane protein called CD47, which is recognized by macrophages as being safe. This means that molecules that contain CD47 can get past macrophages and into blood cells.

Nature: Stealth nanoparticles sneak past immune system’s defences