Even with the invention of the synthetic-lipid nanoparticles that enabled the delivery of the gene-editing synthetic mRNA molecules into cells, the mRNA technology was so unpredictable that successful in vitro studies (outside the body of a living organism), rarely if ever translate to successful in vivo studies (inside the animal).
When discussing the clinical applications of mRNA nanoparticles, Kathryn Whitehead, a nanoparticle scientist and Associate Professor from Carnegie Melon, stated; “We don’t even screen in vitro anymore. I find it more informative to test directly in an animal.”