Posts Tagged ‘iPS cells’
Human ES Cell Differentiation
Posted by admin in stem cells on June 21st, 2009
The widespread availability of huES cells to most laboratories shortly after their isolation – together with the progressive realization that progress with mouse ES cells might not be immediately translatable to their human counterparts – led to a sudden shift of starting material for pancreatic differentiation experiments. The report that arguably initiated this general move toward huES cells was conducted by Assady and collaborators in 2001. Both in adherent and suspension conditions, spontaneous huES cell differentiation resulted in the generation of insulin-producing cells as early as 2 weeks after the initiation of the protocol (peaking at day 19). Their number was relatively small, as only 60% of the EBs had positive staining and only 1–3% of the cells within these showed cytoplasmic insulin signal. In addition, glucose responsiveness was absent, probably due to the difficulty of detection in such a small representation of cells. Read the rest of this entry »
Embryonic Stem Cells and Pancreatic Differentiation
Posted by admin in stem cells on June 21st, 2009
Embryonic stem (ES) cells are derived from the early preimplantation blastocyst. These cells are immortal under defined conditions in vitro, and can be indefinitely expanded without loss of pluripotency. Proof-of-concept experiments demonstrate that they have the ability to spontaneously differentiate into insulin-producing cells, even if at a very low frequency. Here we review the most recent progress at defining conditions (chemical, genetic, or otherwise) for the directed differentiation of both mouse and human ES cells into insulinproducing beta cells. Read the rest of this entry »
Genetic Manipulation
Posted by admin in stem cells on June 21st, 2009
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 »