Gizmodo has a fascinating story on an implant, the Biocapsule, developed by NASA to treat astronauts while they are on a space mission. The device, a small rod to be implanted under the skin before take-off, is made out of carbon nanotubes and is filled with cells that release a substance once a certain trigger activates them.
The cells are trapped withing the capsule, while substances are released by diffusion across the capsule wall, which is also the way nutritients can get in. The capsules could be capable of delivering multiple doses over a long period of time. The nanostructures are inert, making them well-tolerated by the body, and the Biocapsules themselves are inexpensive and easy to make.
One example application given is that of exposure to high levels of radiation in outer space: the device could be filled with cells that sense the increased levels of radiation and automatically disperse medicine to help the body compensate. Granulocyte colony-stimulating factor (G-CSF) might be a candidate drug for this, as it is already used to treat cancer patients undergoing radiation treatment. Other potential triggers could be heat exposure, exhaustion and sleep-deprivation.
Of course, the benefits of such an implant are not limited to outer space. In terrestrial diabetes patients, the capsule could contain pancreatic islet cells, functioning as an artificial pancreas. In cancer patients it could be implanted at the site of a tumor delivering high doses of chemotherapy.
The device is still in an early phase of development, with the first animal trials starting later this year. Visit Gizmodo (linked below) for the full story and a video of their visit to the Space Biosciences Division at NASA where the capsule is being developed.