Medical researchers at WiCell, a private U.S. lab, have developed two new stem-cell lines in a process that has removed animal cells from its culture for the first time. The formerly preferred method for growing stem cells required the infusion of healthy animal cells to keep them alive, and scientists feared stem cells cultivated from this processed used therapeutically would leave their human recipients vulnerable to diseases afflicting the animal (mouse, etc.) from where the stem-cell culture derived.

This breakthrough is expected to add fuel to the fire of a legislative debate over whether federal funding should be extended to stem-cell lines created after August 2001, "Derivation and culture in serum-free, animal product-free, feeder-independent conditions mean that new human (embryonic stem) cell lines could be qualitatively different from the original lines, and makes current public policy in the United States increasingly unsound."

Read the article. (Biosingularity)
Stem Cell Q&A (Web MD)