Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.
Atomic bomb fallout settles brain dispute. Can the neural stem cells in adult brains create new neurons, or not? That question has created a long-running dispute in the neuroscience community with decades of dogma saying “no.” That began to drop away when researchers in Sweden in 1998 seemed to show that new neurons do indeed form in the adult brain. With some follow-up data many in the neuroscience community began to come around to “yes.” But skeptics remained. A breakthrough paper in the journal Cell this week brought around a CIRM colleague who is a neuroscientist and now admits to being a reformed skeptic. The work by another Swedish team took advantage of the fact that the nuclear bomb tests during the cold war doubled the amount of the radioisotope carbon 14 that is normally in the air. Since our cells retain the carbon they use when they grow, the team could look at brain samples from cadavers who had lived before and after those tests in the 50s and 60s and determine if the brain tissue had the extra carbon 14. It did, and more than any one expected. That means significant new neuron growth in our aging brains. The Journal Science did a nice job of explaining the work here.
Federal regulation of our own stem cells. The Food and Drug Administration regulates the introduction of all new medicines and medical devices, but there has always been some leeway for physicians to do new procedures under the “practice of medicine” exemption. Harvesting and reusing our own stem cells has always straddled the border of these two routes to clinical use. The FDA says that if those cells are manipulated to change them then they should be regulated. Many patients disagree. Now, a Harvard Law professor has written a very cogent discussion of the issue and come down somewhat on the side of the patients who want more liberal access. When I was at Harvard Med (which is in Boston), it wasn’t unusual for our faculty to disagree with their colleagues across the river in Cambridge at Harvard Law when they weighed in on medical regulatory and ethical issues. I have to say I agree with part of this blog post but not all of it. The regulation of autologous stem cells probably does need to be retooled, but many of the firms working to create new stem cell therapies have shown that they can conduct high quality clinical studies within the current regulated framework. I should also note that the blog used data for the numbers of clinical trials using embryonic and iPS stem cells that were not interpreted correctly and are much larger than reality.
Lessons from earthworms. Many creatures lower in the evolutionary chain than mammals have an amazing ability to regenerate. A colleague blogged about that ability in an amphibian, the axolotl, here. The earthworm, that friend of every ten-year-old with a fishing pole, has the ability to regrow in spades, even when cut by a spade wielded by a ten-year-old. The Washington Post did a nice explainer on the worm’s skill here.
Stem cells preferences for adulthood. Embryonic and reprogrammed stem cells can become any tissue in the body, but individual cell lines clearly have preferences to become brain or heart, for example. If research teams could determine the proclivities of each cell line in advance they could greatly speed up and improve the efficiency of their efforts to create specific types of adult tissues. Here is a story about a team at Children’s Hospital, Boston that has found a marker that indicates whether a cell line really prefers to become tissue from the endoderm, the layer of the embryo that makes the digestive track, liver and kidneys. They think their method may find markers for the other tissues as well.