The use of genetically engineered mice in aging research

The primary model systems used for studying the role of regulated gene expression in senescence and the effects that genetic variations have on this process have been to date either mammalian cells in vitro or invertebrate systems such as yeast, C. elegans, and Drosophila. Both types of model systems have been very useful in elucidating potential genetic pathways involved in the aging process and are appealing owing to a variety of factors, not the least of which is the ease of genetic manipulation. As such, they constitute a good starting point for understanding the phenomenon of aging. However, such models have their limitations; no tissue culture system can yet approach the subtleties of complex cell-cell interactions existing in the whole, intact animal, and although significant evolutionary conservation has been found between many genes in invertebrates and humans, they are still farther removed from humans than available vertebrate model systems.