At the present time, for many human diseases, medical research predominantly relies on having appropriate model systems to study disease states and in order to develop therapies. Nonhuman animal models, particularly transgenics, have allowed us to recreate disease states in vivo. However,
there is still a need to have corresponding in vitro model systems to study pathogenesis at the cellular level as well as for fast-tracking discoveries of therapeutic compounds. Ideally, an in vitro disease model would be established from human diseased tissue that can demonstrate relevant
degenerative mechanisms. The tremendous advances within the field of stem cell biology over the last decade may now make in vitro models possible for certain diseases that were previously thought unlikely.