The problems of chemical differentiation could be circumvented, at least in theory, by sequentially transfecting huES cells with the genes encoding for the key transcription factors whose activation is known to choreograph pancreatic development. With this idea in mind, many groups around the world have used a number of vectors to deliver active cassettes to stem cells of all origins, including Pdx1, Pax4, Foxa2, Ngn3, NeuroD  and many others. Among the vectors, adenoviruses have been highly favored due to the fact that they infect both dividing and nondiving cells, and usually do not integrate in a permanent manner into the genome. Retroviruses, in contrast, have a preference for Read the rest of this entry »