Showing papers by "Jim McWhir published in 2002"
TL;DR: The results raise the intriguing possibility that ASCs shown to contribute to multiple tissues in blastocyst-injection studies may not contribute as a result of pluripotency, and instead contributions may arise from spontaneous fusion events in which phenotype is determined by either cytoplasmic dominance, nuclear reprogramming, or both.
Abstract: Primary mouse brain cells were cultured with HPRT (hypoxanthine phosphoribosyl transferase)-deficient ES (embryonic stem) cells to see if the ES cells could provide cues sufficient to reprogram a pluripotential state. After 5 days of coculture, HPRT-deficient ES cells were killed by selection in HAT (hypoxanthine, aminopterin, thymidine) medium. We observed islands of HAT-resistant ES-like cells surrounded by differentiated cells. Cell lines generated from three such "islands" proved to be spontaneous, pluripotential ES-neural hybrids, and gave rise to a chimera following blastocyst injection. Re-expression of the ES-specific gene Foxd3 from somatic-derived chromosomes suggested that the somatic nucleus had been reprogrammed. Our results raise the intriguing possibility that ASCs shown to contribute to multiple tissues in blastocyst-injection studies may not contribute as a result of pluripotency. Instead contributions may arise from spontaneous fusion events in which phenotype is determined by either cyt...
67 citations
TL;DR: The extent to which this situation is changing, with particular reference to applications in biopharming, xenotransplantation, and large animal models, is assessed.
Abstract: Additive transgenesis by pronuclear injection of the mouse zygote has been in use for more than 20 yr and gene targeting in mouse embryonic stem cells for almost as long. Together, these techniques have revolutionized animal biology by helping to unravel much of what we now know about gene function. Both additive transgenics and targeting can also be performed in livestock species but the impact has not yet been substantial. In part, this has been the result of the inefficiency of the techniques but—at least in agriculture—also to a lack of obvious practicality. This review assesses the extent to which this situation is changing, with particular reference to applications in biopharming, xenotransplantation, and large animal models.
8 citations