Caffeinated Stem Cells

Forty-one years after Sir John Gurdon was the first scientist to transfer an adult cell’s genetic material (DNA) into a DNA-less egg (work done in frogs for which Gurdon won the 2012 Nobel Prize in Physiology or Medicine), scientists have successfully removed the DNA from human eggs and replaced it with DNA from mature human cells. The resulting human embryo, for the first time ever, progressed far enough in development to enable the derivation of human embryonic stem cells. The work, done by collaborators from Oregon, Boston, and Thailand and published yesterday in Cell, presents possibilities for the development of stem cells with the exact same genetic makeup as patients to enable researchers to specifically study and treat disease.

One quirky piece of the research is that the scientists found that treating the eggs with a bit of caffeine made the transfer of adult DNA into the eggs more efficient, yielding embryos that developed more typically and from which better quality stem cells were derived.

UPDATED 23 May 2013:  This paper has received criticism for the use of several of the same images in various contexts to illustrate different characteristics of stem cells, whether certain experiments where validated by repetition in an acceptable way,  and for the quick time from submission to acceptance at Cell. The submission to acceptance time is generally on the order of months. For more about these issues read the piece at Nature and the forum on the open reviewing site PubPeer.

Neuronal Support Cells Get the Message

During motor neuron development in zebrafish, a class of glial (support) cells, called perineurial glia, migrates out of the spinal cord based on signals that have been unknown until now.  Sarah Kucenas and colleagues at the University of Virginia showed in new work, published this week in the Journal of Neuroscience, that the Notch signaling pathway plays a role in correct migration of perineurial glia and in the differentiation of Schwann cells, the cells that ensheath nerve axons. Using the zebrafish embryo, which is optically clear, the researchers visualized Notch signaling and cell migration in real time, generating convincing and beautiful evidence that perineurial glia rely on Notch signaling to move the long distances necessary for their function.

Wallabies teach us about mammalian development

Developmental biologists have historically used mice to study the development of mammalian embryos. In work published online January 29 in Development, Stephen Frankenberg and his colleagues from the University of Melbourne, showed that embryos of the tammar wallaby, a marsupial, develop somewhat differently from mouse embryos. Some early embryonic genes seem to play similar roles in tammar and mouse, Frankenberg and colleagues showed. The protein products of other genes, however, appear in different cellular locations in tammar embryos than in mouse embryos, which suggests that these proteins may function differently in the two species and in other mammals. This work challenges established ideas and demonstrates the possibility of wider evolutionary variability in mammalian development than previously expected.