Biotech firms specializing in stem cell research rallied after Missouri voters passed a landmark measure that would protect federal funding for embryonic stem cell research.

In addition, Missouri voters supported Sen. Claire McCaskill, a Democrat who supported the measure and whose campaign featured ads with actor Michael J. Fox, who suffers from Parkinson's disease.

"That bill in Missouri was important because it provided affirmation that people in the heartland are interested in this research," said Stephen Brozak, analyst for WBB Securities. Brozak said President Bush could veto a stem cell bill, even if it passes a Democrat-controlled House. But Democrats can demand hearings with stem cell experts, which "can make for exceptional TV" and strengthen support, Brozak noted.

Research using stem cells from human embryos is contentious: Supporters say stem cell research can help cure debilitating diseases like Parkinson's and Alzheimer's, and might also repair brain damage and severed spines. But potential treatments are years away. President Bush earlier this year vetoed a bill that would provide federal funding for embryonic stem cell research.

Stemcells Inc. (STEM) surged 6.5 percent and Geron Corp. (GERN) climbed 2 percent in trading Wednesday. Both of these companies conduct research using stem cells from human embryos. Biotechs researching less controversial adult stem cells also got a lift, with Thermogenesis Corp. (KOOL) and Cytori Therapeutics (CYTX) rising about 1 percent.