It was nearly a decade in the making, but the first human trial
using embryonic stem cells was approved on Friday. The trial,
which will test a stem-cell-based treatment for spinal-cord
injury, will begin later this summer and will use cells
generated by Geron Corp. The approval marks the first time human
stem cells, extracted and grown from embryos, will be
transplanted into patients. Adult stem cells, which are present
in many types of tissue, have been used in treatments for years
the most common being bone-marrow transplants in cancer care but
an embryonic study is a whole new thing. There's a good reason
it's being greeted with so much excitement. (See the top 10
medical breakthroughs of 2008.) Scientists believe that
embryonic stem cells are more versatile than adult cells in
generating the more than 200 different tissue types in the body.
The need for healthy new cells is particularly acute in the case
of spinal-cord injury, because once central-nervous-system
tissue is destroyed, it does not regenerat