Nanites

Nanites
A widespread, but very expensive technology, Nanites are marvels of microengineering. Robots, the size of cells, that can be programmed and equipped to perform all kinds of different functions, be it inside or outside a living creature. By far, their most common use is for medicinal purposes; those who can afford them can enjoy such things as instant tissue repair, significantly longer life, and over-all improved organ functionality. There are those, however, that have turned them into tools of torture, and imprisonment. Capable of inflicting great pain, or death, they are sometimes administered via syringe to unfortunate captives of crime-lords, or high-value terrorists in Alliance hands. Either way, they are extremely capable little buggers. Some are advanced enough to respond to verbal commands from their own host, or in the case of a captive and jailor, the jailor's.

Having medicinal nanites effectively removes any chance of death from natural causes. Even age struggles against them.

Removing them can be either extremely easy, or extremely difficult. They can be recalled to pass through urine or fecal matter, but often in the case of rescued captives infected with them, they must be removed forcibly - often with the use of another nanites, programmed to remove the hostile variant from the host.