The team has only just started testing these custom stem cells in mouse models of diseases like rheumatoid arthritis. However, the dream is that they'll eventually be used to replace arthritic cartilage and, for all intents and purposes, serve as a vaccine against arthritis. That, in turn, could prevent the secondary damage that makes arthritis that much worse. On top of this, the scientists believe their basic approach could apply to any condition where there's a "feedback loop." Imagine if you could treat diabetes with cells that trigger insulin production in response to glucose, for instance. This kind of automatic cell-based medicine may be years away, but it is on the horizon.