Have Blood, Will Travel The radiation astronauts encounter in
deep space could put vital blood-making cells in jeopardy.
August 19, 2004: In the time it takes you to read this sentence,
more than 10 million red blood cells in your body will die.
Don't be alarmed; it's natural, and stem cells in your bone
marrow are constantly making enough new cells to replace the
dying ones. But what if those blood-making cells stopped
working? Without a fresh supply of red and white blood cells,
you would quickly become anemic, your immune system would
collapse, and without medical attention, you would die. This
could be a concern for astronauts taking long trips beyond Earth
orbit. It's well known that space radiation can damage cells in
astronauts' bodies. Less well understood is the specific threat
to the key blood-making cells. Understanding that threat, and
developing remedies, is the job of Alan Gewirtz, a medical
doctor at the University of Pennsylvania (Division of Hematology
and Oncology). He's bombarding stem cell