Posted on 05/25/2008 8:58:10 PM PDT by neverdem
Research from the University of Southern California (USC) has discovered a new mechanism to allow embryonic stem cells to divide indefinitely and remain undifferentiated. The study, which will be published in the May 22 issue of the journal Nature, also reveals how embryonic stem cell multiplication is regulated, which may be important in understanding how to control tumor cell growth.
“Our study suggests that what we believe about how embryonic stem cell self-renewal is controlled is wrong,” says Qi-Long Ying, Ph.D., assistant professor of Cell and Neurobiology at the Keck School of Medicine of USC, researcher at the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at USC, and lead author of the paper. “Our findings will likely change the research direction of many stem cell laboratories.”
Contrary to the current understanding of stem cell self-renewal and differentiation, the findings suggest that embryonic stem cells will remain undifferentiated if they are shielded from differentiation signals. By applying small molecules that block the chemicals from activating the differentiation process, the natural default of the cell is to self-renew, or multiply, as generic stem cells.
“This study presents a completely new paradigm for understanding how to grow embryonic stem cells in the laboratory,” says Martin Pera, Ph.D., director of the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at USC. “The discovery has major implications for large scale production of specialized cells, such as brain, heart muscle and insulin producing cells, for future therapeutic use.”
Embryonic stem cells have only been derived from a very small number of species.
“We believe the process we discovered in mice may facilitate the derivation of embryonic stem cells from species like pigs, cows or other large animals, which have not been done before,” continues Ying. “If deriving embryonic stem cells from cows, for instance, is possible, then perhaps in the future cows might be able to produce milk containing medicines.”
With better understanding of the multiplication process of embryonic stem cells, researchers have additional insight on tumor cell growth as these cells share similar qualities. “Our study reveals part of the little known process of how embryonic stem cells multiplication is regulated. This is important for us in understanding how to control tumor cell growth moving forward in cancer research,” says Ying.
In the three decades since pluripotent mouse embryonic stem (ES) cells were first described1, 2 they have been derived and maintained by using various empirical combinations of feeder cells, conditioned media, cytokines, growth factors, hormones, fetal calf serum, and serum extracts1, 2, 3, 4, 5, 6, 7. Consequently ES-cell self-renewal is generally considered to be dependent on multifactorial stimulation of dedicated transcriptional circuitries, pre-eminent among which is the activation of STAT3 by cytokines (ref. 8). Here we show, however, that extrinsic stimuli are dispensable for the derivation, propagation and pluripotency of ES cells. Self-renewal is enabled by the elimination of differentiation-inducing signalling from mitogen-activated protein kinase. Additional inhibition of glycogen synthase kinase 3 consolidates biosynthetic capacity and suppresses residual differentiation. Complete bypass of cytokine signalling is confirmed by isolating ES cells genetically devoid of STAT3. These findings reveal that ES cells have an innate programme for self-replication that does not require extrinsic instruction. This property may account for their latent tumorigenicity. The delineation of minimal requirements for self-renewal now provides a defined platform for the precise description and dissection of the pluripotent state.
Illegal Imigration and Disease
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somehow, this statemet reminds me of the blind men that stumbled into the elephant.
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