In Vivo, In Shmee-vo
A lot of science is done in little glass and plastic vials, mainly because there are some things that are just too hard or unethical to do in live organisms. We even have words for the distinction between science done in a test tube (”in vitro”) versus done in a living system (”in vivo”).The gold standard, of course, is “in vivo”. You want data in vivo, because, frankly, a test tube full of chemicals (even chemicals extracted from cells) isn’t a substitute for a real living system.But really, what is “in vivo” depends on your point of view. If you’re a chemist, throwing your favorite molecule on a bunch of cells in a Petri dish is probably “in vivo” for you; after all, there’s living stuff there. But if you’re a doctor, “in vivo” means “in an animal.” Cells in a plate is just “in vitro.”And in reality, whether “in vivo” is a gold standard isn’t that clear cut. Sure, eventually you wan to see whether something happens in an actual living system, but what if you want to test whether two molecules physically interact (we’re not talking regulation here)? Then the “gold standard” would be an “in vitro” assay (i.e. chemicals in a tube), since in a live cell, there’s all sorts of things that can really jiggle up the FRET, colocalization, yeast two-hybrid, ELISA, or whatever other test that biologists and chemists like to use in living systems. There’s too much other “junk” in a living cell to really tell for sure. So you have to do it in a test tube, where you can control all the conditions.Just a though, the next time someone sneers at an “in vitro” experiment. Just smile and tell them “in vitro” is the new gold standard!
