Boston — WE first acquired the stem cells from the red receptacles of a local hospital’s labor and delivery ward, delivered to our lab at the University of Southern California. I would reach into the large medical waste containers and pull out the tree-like branches of the placenta, discarded after a baby had been born. Squeezing the umbilical cord that had so recently been attached to new life, the blood, laden with stem cells, would come dripping out.

But sometimes a different package would arrive at our lab. Despite my distaste for wringing placentas, I felt more squeamish about what lay inside the unassuming white box. Packed in the ice was a crescent-shaped sliver of dark red tissue: a human liver. Just like the placentas that were discarded after birth, this tissue was originally destined for medical waste following an abortion.

Although their fates were similar, their origins couldn’t be more different. One source was the byproduct of celebration, the other a procedure often marked with stigma and shame. While under the bright focus of the microscope the cells we isolated were indistinguishable, in our minds there was a significant difference.

Stem cell science is a big deal in California, thanks to the Institute for Regenerative Medicine, a state agency that has allocated almost $2 billion in research grants since 2004 (federal funding is still highly restricted). To meet the demand for cells, researchers turned to a procedure protected by federal law: abortions. The discarded tissue from terminated pregnancies, performed up to 26 weeks in California, is a rich source of stem cells.