What's a gene gun?

One of my friends recently got a job at a lab where they are attempting to cure congenitally deaf mice using gene therapy/stem cells. Our conversation was abbreviated, but I think I understand the general theory - the scientists inject stem cells into the cochlea of baby mice. There the stem cells, guided by the cells around them, begin to differentiate, and grow into tiny hairs. These hairs sense sound vibrations and turn them into electrical signals to be delivered to your brain by nerves (in biospeak, they are the sensory transduction apparatus of hearing). The scientists also inject genes (with a gene gun!) to help tell the stem cells what to do.

The best part? The mice glow green! Actually, just the hairs glow green, but it makes their entire heads glow. It's an easy genetic modification, and lets you see if the therapy took - but wow! Everything is more neon in the modern age ... even mice.

The next steps are
1. testing to see if the mice can hear now ("It looks like the hair cells wire up to the primary auditory cortex, but they haven't done satisfactory behavioral testing yet" says my friend).
2. Applying it to people! Since adults are much less flexible than babies, this would probably be used on embryos first, if they can get it to work at all.

This didn't answer all my questions, of course. How does a gene gun work? What do they use to inject the stem cells (it's a new invention, as far as I know)? How would one inject them into a human embryo? in utero?

I also wonder what the societal implications of this idea might be. The Deaf community is very strong, and although it's had some challenges to deal with recently, I also know that its members really value belonging to a community and don't see deafness as a problem. Some deaf parents specifically choose to have children that are deaf.

Here's an interesting study that attempted to measure some attitudes towards genetic testing for deafness among hearing people and deaf people. It found that among the Deaf, genetic testing was not of interest. I imagine a genetic "solution" would be similarly unpopular.

There is already an ongoing debate over cochlear implants - implants which allow deaf children to become part of the hearing world. Will modern medical science mean the end of Deaf culture?

lily

ps - more topics for consideration:

ITER -and fusion! And other paths to fusion ...
What is vitamin A anyway? and is it toxic?
and more mathemagic