Designing implantable devices that are ignored by the immune system can be a challenge, so scientists usually rely on materials that are naturally biocompatible.
At MIT, researchers have discovered that the size and shape of implantable microparticles is also important as to whether the immune system will attack them.
The team was developing implantable capsules as a potential for Type 1 diabetes that can hold pancreatic islet cells. It was important for the researchers to allow them to interface with the perfusing blood and release insulin as needed and to minimize the scarring around the implanted capsules.
What investigators discovered the spherical capsules 1.5 millimeter in diameter were functional months after implantation in diabetic mice, while those that are smaller, at .5 mm wide, were completely engulfed by scarring and prevented them from sensing blood sugar and to release insulin.
Similar results were achieved in non-human primates. Various other tests on different shaped devices made out of glass, polystyrene, stainless steel, and polycaprolactone, polyester, showed that the shape matters as well as the size.