The growth and maintenance of human embryonic stem cells in the absence of contaminated animal products has been demonstrated by University of California, San Diego (UCSD) School of Medicine researchers in the Whittier Institute*, La Jolla, California. Published in the April 2005 issue of the journal Stem Cells, the study shows that laboratory culture media enriched by a human protein called activin A are capable of maintaining human embryonic stem cells in a continuous undifferentiated state, ready for research. Undifferentiation means the stem cells have not begun the developmental path to become specific human tissue or organs.
