Since the derivation of human embryonic stem (ES) cells, there has been
enormous scientific and political interest in the stem cell arena, with
expectations that these cells may one day be used to treat individuals with
spinal cord injuries and degenerative conditions such as Parkinson's
disease. One limitation to growing these cells is that they require a layer
of mouse embryonic fibroblast (MEF) feeder cells, which apparently promote
maintenance of human ES cells in an undifferentiated state. Xu et al. show
that human ES cells can be grown under feeder-free conditions as long as
matrix proteins--Matrigel or laminin--are included in MEF-conditioned
medium. These cells express the same factors as ES cells grown on MEF
feeder cells. Furthermore, they have a normal karyotype, stable growth
rate, and high telomerase activity and are able to differentiate into cells
from all three germ layers. -- BAP

Nature Biotechnol. 19, 971 (2001).