On Jun. 24, 2002, researchers at the University of Minnesota Stem Cell Institute (SCI) announced they had found the first evidence that adult bone marrow-derived cells can differentiate in vitro and in vivo into cells of all three embryonic germ layers (endoderm, ectoderm and mesoderm) in similar manner as embryonic stem cells (ES cells).

SCI Director Catherine Verfaillie, M.D., reported that cells grown from adult mouse and rat bone marrow can be cultured without aging and with active telomerase, an enzyme found in embryonic stem cells that prevents aging.

In a separate published paper, Ron McKay and colleagues at the National Institute of Neurological Disorders and Stroke in Bethesda, Md., show that mouse ES cells can be used in cell-replacement therapy in an animal model of Parkinson’s disease. From cultured ES cells, the group generated a large supply of neurons that produce dopamine.When transplanted into the brains of rats with damaged dopamine neurons (modeling Parkinson’s disease), the neurons functioned normally. Furthermore, the rats treated with the new neurons showed signs of recovery in behavioral tests.