July 25, 1997
Media Contact: Michael Purdy
Researchers at Johns Hopkins have developed the first human embryonic stem cell lines, cells that theoretically can form all the different cells and tissues of the body.
"We already have embryonic stem cell cultures from mice, hamsters, monkeys and chickens that can grow into all the specialized cell types that make up the animal," says John D. Gearhart, M.D., Ph.D., professor of gynecology and obstetrics and director of the research. If the human cell lines prove to have the same capabilities, researchers may use them to create lab-grown replacements for tissue lost to disease or injury.
Gearhart announced the development of the cell lines at a recent meeting of the International Congress of Developmental Biology, where he spoke at a session on the ethical considerations of human cloning and stem cells.
Gearhart and Michael Shamblott, a postdoctoral fellow at Hopkins, developed the cell lines from tissues obtained as a result of pregnancy termination.
The new human cell lines possess many of the same features found in the animal embryonic stem cell lines, including a series of biochemical and molecular markers on their surfaces and inside the cells, and a stable, normal number of chromosomes, the units in the cells that contain the genetic code.
Hopkins scientists are working to develop the cell lines so they can be manipulated to grow whichever tissue one wants, such as heart muscle, blood cells, or nerve cells.
"Based on results with animal studies, it seems likely that we will be able to alter the cells so that a patient's immune system will not recognize them as transplants and reject them," says Gearhart. "If so, we would have a universal cell donor--cells that could be transplanted to any recipient with little chance of rejection by the immune system."
Researchers have used embryonic mice stem cells to create germline mutations--changes in the mice's genetic code that are passed from one generation to the next.
"We will not perform any experiments aimed at genetically engineering the human germline in my lab or anywhere at Hopkins--it is not ethically acceptable," says Gearhart. "That's one of the reasons why we chose to present our studies in an ethics forum. We wanted to begin the process of establishing a set of guidelines for the ethical use of cells of this type."