The California Institute for Regenerative Medicine (CIRM) announced Feb. 16 that
a City of Hope investigator will receive one of the first grants awarded to fund human embryonic stem cell research resulting from passage of Prop. 71, also known as the California Stem Cell Research and Cures Initiative.
(Photo by Markie Ramirez)
Timothy O’Connor, Ph.D., professor in the Division of Biology, shares the honor with 71 investigators statewide. These SEED (for Scientific Excellence through Exploration and Development) grants are awarded to experts working outside the embryonic stem cell field in the hope they bring novel insight to stem cell biology.
For 20 years, first at the Institut Gustave Roussy in Villejuif, France, and in the last 10 at City of Hope, O’Connor has identified proteins that repair nicks and breaks in chromosomal DNA. “We are interested in how cells protect themselves from DNA damage, and how those strategies can be exploited for possible therapy,” he said.
Breaks in double-helical DNA strands occur following exposure to mutagens or radiation and much less frequently during normal cell division. Healthy cells express legions of proteins whose job is to repair battered DNA. Without them, cells can die or become cancer cells.
Although the amount is not yet finalized, the CIRM governing board will award O’Connor about $350,000 over two years to determine how efficiently DNA repair proteins operate in human embryonic stem, or ES, cells. Funds will support specialists who know how to keep finicky stem cells “happy” in a Petri dish. “ES cells take a lot of care and feeding,” explained O’Connor.
Steven Bates, a senior research associate at City of Hope since 1992, will handle the cells’ care. Bates devised a unique method to prepare “feeder” or support cells used to maintain ES cells in culture.
O’Connor notes that determining human ES cells’ vulnerability to DNA damage is impossible using a mouse or other animal model. But scientists must answer that question before human stem cells are infused into people as replacement therapies, because unlike drug therapy, stem cells are forever. Said O’Connor: “If you put a human ES cell in a person and it goes wrong, you are going to have a hard time getting it out.”
Some studies suggest that over long periods, ES cells accumulate mutations, or errors in their DNA sequence, more readily than other cells. “Our goal is to try to understand if repair processes differ at these very early stages of development from those in cells farther along the path of differentiation,” O’Connor said.
One technique O’Connor will use to accomplish that is to mutate a gene encoding a protein called luciferase, which emits light. The scientist then forces that nonfunctional luciferase gene into an ES cell and waits for it to glow. “After different time points, say eight to 48 hours, we can start to see a signal — that’s an indication that repair has occurred,” O’Connor said. Researchers then will compare the repair rate to that in non-ES cells.
Asked if he voted for Prop. 71, O’Connor said yes but with reservations. While having to take the matter to the voters was unfortunate, he said, “it is a good thing California has not waited for the federal government to finally do something — that’s a problem.”
“The CIRM is geared to do therapeutic things — to ask what happens if we put these cells into people,” he continued. “The answer is that if you are smart, you aren’t going to do that right away. You first have to understand their basic processes.”