ES Stem Cells Become Neurons: May Not Be Pluripotent

This PR press release contains two stories instead of one: First, researchers at UCLA apparently morphed embryonic stem cells into neural stem cells, and then, into working neurons. This is only the second time of which I am aware that ES cells were made primarily into the kind of cells that scientists were aiming for. From the press release:

UCLA’s Yi Sun, an associate professor of psychiatry and biobehavioral sciences, and Howard Hughes Medical Institute investigator Thomas Sudhof at the University of Texas Southwestern Medical Center were able to produce 70 to 80 percent of neurons in cell culture. Sun and Sudhof also were able to isolate the neurons and determine that they had a functional synaptic network, which the neurons use to communicate. Because they were functional, the neurons can be used to create a variety of human neurological disease models.

Note that these cell lines are not being considered for therapeutic purposes and the press release does not say whether they came from “Bush-approved” lines.

Here’s another interesting point that the media might miss: The scientists discovered that ES cells may not be pluripotent, that is, able to become any kind of cell. Rather, they might be predisposed to become cells from a certain lineage. Again, from the press release:

A second important discovery in Sun’s study showed that two embryonic stem cells lines derived in similar manners, and therefore expected to behave similarly when differentiating, did not. Using the same techniques to prod the two embryonic stem cells lines to differentiate, Sun found that one line had a bias to become neurons that are found in the forebrain. The other line differentiated into neurons found in rear portions of the brain and spinal cord. The finding was surprising, and significant, Sun said.

“The realization that not all human embryonic stem cell lines are born equal is critical,” Sun said. “If you’re studying a disease found in a certain part of the brain, you should use a human embryonic stem cell line that produces the neurons from that region of the brain to get the most accurate results from your study. Huntington’s disease, for example, is a forebrain disease, so the neurons should be differentiated from a cell line that is biased to produce neurons from the forebrain.”

Sun said there are ways to prod an embryonic stem cell line biased to become neurons found in the rear brain to become neurons found in the forebrain. However, there are limits to how much prodding can be done.

Pluripotency has been the gold standard supporting scientists’ claim that ES cells offer the “best hope,” for regenerative medical treatments. So far, that claim has been entirely theoretical. This research may indicate that the expected pluripotency of embryonic stem cells may not materialize.