Today in Science scientists reported a potentially big advance in creating embryos that can be used for stem cell transplants. Briefly put, they figured out how to take skin cells from patients, inject them into donated eggs emptied of their own DNA, and nurture them along until they had divided into a few cells. The cells were able to develop into a wide range of cell types, their chromosomes were normal, and they were so similar to the cells of the individual patients that they would not be rejected as foreign tissue. The research stopped there, but the dream behind this work is to heal your failing liver or heart or dopamine-producing neurons by clipping off a little skin and farm new cells that could regenerate those organs.
This research was designed in part to overcome a problem with stem cells that is part of the evolutionary baggage we carry–a problem I blogged about in January. Traditionally embyros have been nurtured by “feeder cells” from mice and calf serum. This turned out to cause make these embryos–and any stem cells derived from them–useless due to contamination. Roughly two million years ago, our ancestors lost a gene that produced a sugar on the surface our cells. Other mammals still produce it. The earliest hominids probably produced it too. But new species of hominids that emerged after two million years ago, such as our own and Neanderthals, didn’t have it.
It turns out that if you feed an embryo with cells or serum from other mammals, they will absorb the sugar and stick it on their surface. To the human immune system, they look foreign. In other words, human evolution can shed light on current stem cell research. The scientists who did the new research figured out how to avoid rejection by coming up with a way to nurture the embryos with human feeder cells, so that they could avoid sticking sugars on the stem cells that our ancestors lost long ago.
Reading about this advance, I felt a grim sense of irony. As I wrote in my original post, President Bush stopped federal funding for research on stem cells using new lines derived from embryos, despite the fact that most of the already existing lines were contaminated by this lost sugar. American scientists have been making some progress with stem cells with private money and state initiatives, but guess where scientists finally figured out how to solve this evolutionary problem with cell sugars? South Korea.
Reading about this research, I was also reminded of an article I read last week during the Kansas “trial” over evolution and creationism.
Leonard Krishtalka, the director of the Kansas University Natural History Museum, was quoted pointing out how Kansas is raising $500 million to foster a bioscience and biotech industry in the state. It was ironic, he said, that the state’s board of education was simulataneously “trying to remove and water down the basic fundamental concept of evolution that underlies all of biology.”
Case in point: try to imagine a stem cell therapy company deciding where to set up shop. I doubt they’d be excited about a state that doesn’t make sure their high school students understood mutations, natural selection, the origin of species, the fossil record, and all the other elements of evolutionary biology–that thinks it’s fine just to claim that the broken sugar gene in our genome was just stuck there for reasons unknown by some mysterious designer.
Originally published May 19, 2005. Copyright 2005 Carl Zimmer.