Why did they use the mice with the progeria gene? Wouldn't the results be more impressive in wild-type mice? Were they just trying to get around the 2-3 year lifespan of a lab mouse faster?
The paper primarily reports results that pertain to mice with a genetic defect that causes progeria. Mice with this defect have a shorter-than-normal lifespan.
Doxycycline has also been shown to greatly increase life expectancy! Of patients currently suffering from bacterial infection.