TOKYO -- Japan's Astellas Pharma has partnered with an American startup to develop ultrasmall implantable devices that could be used to discover and treat conditions that are difficult to address with conventional pharmaceuticals.

The research will be based on the work of Iota Biosciences, which has created devices just a few millimeters long that can be implanted almost anywhere in the body, powered by ultrasound and free of bulky batteries.

Iota and Astellas envision implants based on this platform that can pick up electrical signals transmitted through nerves to monitor organs and tissues, as well as stimulate nerves or muscles to treat disease-affected areas directly, according to Friday's statement announcing the tie-up. Animal testing is slated to start in a few years.

Iota was established in 2017 to build on work by researchers at the University of California, Berkeley. Tokyo-based Astellas, which looks to turn medical devices into a new profit generator, made a small investment in the company in May 2018 through an American venture capital arm.