the present invention is a preparation containing a statin - encapsulated nanoparticle obtained by encapsulating statin in a nanoparticle containing a bioabsorbable polymer . the nanoparticle has a number average particle diameter of less than 1000 nm . the preparation is used to enhance the function of a stem cell . the present invention is a stem cell with an enhanced function . the stem cell takes up and contains the statin - encapsulated nanoparticle .