Immune cells patrol our bodies looking for threats, but sometimes medical therapies are wrongly identified as the enemy. These capsules made from jelly-like hydrogel are designed to carry drugs or transplanted cells deep into damaged organs. They’ve been attacked – mobbed by immune cells (dyed green here, with blue nuclei) and overgrown with fibrosis (red). As well as being painful for patients, fibrosis (or scar tissue) can prevent these devices from releasing their cargo effectively. To elude the immune defences, crafty researchers ignored the logic of spy films. Making the devices bigger, not smaller – increasing from half a millimetre up to two millimetres in diameter – prevented their detection. Investigating how and why the immune system reacts to differently-sized capsules could have huge implications – drug delivery that is more ‘biocompatible’ may be a simple matter of making these tiny devices just a little bit bigger.
Written by John Ankers
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.