Mouse somatic cells were reprogrammed in 2006, 25 years after mouse embryonic stem cells were created.
Human somatic cells were reprogrammed in 2007, 9 years after human embryonic stem cells.
Rat somatic cells were actually reprogrammed a few weeks before rat embryonic stem cells were created.
Science declared reprogramming to be the breakthrough of the year and, while I’m certainly biased, it does make sense.
A subscribers-only review article by Doug Melton (whose in vivo reprogramming paper made a big splash this year) and John Gurdon (whose cloning of frogs in the 1960s anticipated current breakthroughs) chronicles the reprogramming field. They invoke the notion of “fleeting access” to explain why reprogramming rates are so low, particularly in specialized cells. The complexes of gene-inactivating proteins that cling to DNA sporadically dissociate from DNA allowing very short intervals during which reprogramming proteins can get to work. The concept explains why some cells are easier to reprogrma than others; most genes in embryonic cells and a subset of active genes in specialized cells will be more accessible. The actual reprogramming molecules differ depending on the technique (nuclear transfer into an oocyte, lineage switching, inducing pluripotency), but they conclude, however, the concept of fleeting access should appy in all cases.
In a news article describing reprogramming as the breakthrough of the year, Gretchen Vogel does a nice job surveying the year for non-specialists, but the format doesn’t let her list citations. (You can read Vogel’s article for free if you register)
Here are some relevant (free) articles from Nature Reports Stem Cells. The first stems from the Melton paper which reprogrammed pancreatic cells in vivo.
A new quest for short cuts between specialized states could lay bare the machinery governing cell fate
Scientists’ enthusiasm grows for induced pluripotent cells
In the quest to switch one cell type to another, how far can tweaking transcription factors go?
Selected research highlights and meeting notes
Scientists consider minimum standards for induced pluripotent stem cells
Reprogrammed cells may offer insight into neurodegenerative disease.
Human testis cells become pluripotent in culture
Embryonic-like stem cells from a single human hairCompared to fibroblasts, keratinocytes generate a hundred times more iPS cells in half the time
Mature B cells from reprogramming-ready mice become pluripotent
Mouse, human and monkey cells can be induced to pluripotency
Also, click here for more reprogramming articles from NPG.