In the case of these biolasers, human kidney cells have been genetically enhanced to produce the proteins that make jellyfish glow.
These glowing cells were stuck between two tiny mirrors barely bigger than the cell itself, and when the cell was energized with blue light through a microscope, it fired out a bright green directional laser beam that was visible to the naked eye, just like a little laser pointer. Under a microscope, it looks like this:
(see above)
Currently, the researchers are working on ways to stick the mirror array inside the cell itself, and there’s still the problem of the energizing light source, but that could be solved by routing optical fibers directly through the body. Yeah, we’re talking about implanted fiber optic cabling. To power your laser cells. Welcome to science.
via Scientists combine humans with jellyfish to create living lasers | DVICE
The Committee to Nuke Elysium 