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Thursday, 29 November 2007
ESI generate clinical-grade hESC lines
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How Many Genes in the Human Genome?
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A molecular map for aging
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Tuesday, 27 November 2007
Stem cell therapies for brain more complicated than thought
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Researchers find mature heart cell potential in hESCs
UC Davis research scientist Ronald Li and his colleagues write in their study, “Functional Sarcoplasmic Reticulum for Calcium-Handling of Human Embryonic Stem Cell-Derived Cardiomyocytes: Insights for Driven Maturation,” that they observed cells that had begun the maturation process toward becoming heart cells. The article, available online in Stem Cell Express, will be published in the December issue of the journal Stem Cells.
“Previous experiments were able to derive heart cells from human embryonic stem cells,” said Li, who is an associate professor of cell biology and human anatomy at UC Davis School of Medicine and senior author of the study.
“... but those cells always remained too immature to be of any therapeutic use and actually could cause lethal arrhythmias in animal models. Now, what we’ve been able to do is push the therapeutic potential of human embryonic stem cells further so that eventually they might be used safely, and with enhanced efficacy, in transplantation cases.”
The main function of the heart is to mechanically pump blood in a highly coordinated fashion throughout the body. To do this, heart cells must receive electrical signals and contract in response to those signals. This link, called the excitation-contraction coupling, is dependent on the cells’ ability to move calcium ions across an internal organelle known as sarcoplasmic reticulum, or the so-called “calcium store.” The ability to handle calcium is disrupted in the cells of patients who experience heart failure. For future stem-cell based therapies to work, scientists will need to have heart cells that exhibit mature excitation-contraction coupling.
Until now, researchers studying heart cells (also called cardiomyocytes) derived from human embryonic stem cells have been unable to find evidence of functional calcium stores. Li found protein functions that are involved in the early stages of this coupling process. He and his colleagues now plan to move on and engineer the calcium-handling properties in order to enhance contractile properties in cardiomyocytes for both improved safety and functional efficacy.
In the current study, Li and his colleagues took human embryonic stem cells and grew them in cultures, allowing them to differentiate, or develop, into heart cells. Once they had these tiny, pulsing masses, the investigators energized the cells with small amounts of electrical current and chemicals, including caffeine. They then measured how the amount of intracellular calcium changed and looked for the presence of proteins and cellular structures known to be involved in excitation-contraction coupling.
Li and his colleagues are the first to find evidence of the functional calcium stores for excitation-contraction coupling. They also found four of the seven key proteins that play key roles in handling calcium in the cell, as well as functional sarcoplasmic reticulum.
The UC Davis researchers used different cell lines than those utilized in previous studies, which they say may explain why they were able to achieve a breakthrough in their investigation where others had not.
The UC Davis group also looked at a smaller number of cells during various stages of development, enabling them to more accurately dissect the different population subsets. The authors said that differences in cell culture and experimental conditions could also account for the results not seen in previous efforts.
According to Li, the fact that different cell lines exhibit different potentials for differentiation and maturation underscores the need to develop new and additional stem cell lines in order to advance critical research into potential therapies for patients.
“This is a good example of the type of exciting, bench-to-bedside research now under way at UC Davis and the potential it has for new treatments,” said Jan Nolta, director of the UC Davis Stem Cell Program in Sacramento.
“As additional embryonic stem cell lines become available for research, we’ll be able to more fully explore the possibilities inherent in this powerful field of bioscience.”
Li’s study is a first step toward deriving cardiomyocytes with fully functional contractile properties from human embryonic stem cells. With heart transplants being the current treatment of last resort due to severe shortages of donor organs and the complexity of transplantation, the long term goal of researchers like Li is to come up with alternatives that are both safe and effective.
“Our latest study gives us great hope of eventually achieving a breakthrough where stem cell therapy could be used in the types of cases that today require a heart transplant,” concluded Li.
Along with Li, co-authors of the paper are Jing Liu, Jidong Fu and David Siu all from UC Davis School of Medicine. The research was funded by the National Institutes of Health, California Institute of Regenerative Medicine, the Croucher Foundation and UC Davis School of Medicine.
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ZenMaster For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html
Wednesday, 21 November 2007
Reprogramming of human fibroblasts to ESCs achieved
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Tuesday, 20 November 2007
UW-Madison scientists also guide human skin cells to embryonic like state
UW-Madison scientists guide human skin cells to embryonic state Tuesday, 20 November 2007 In a paper published in the online edition of the journal Science, a team of University of Wisconsin-Madison researchers reports the genetic reprogramming of human skin cells to create cells indistinguishable from embryonic stem cells. The finding is not only a critical scientific accomplishment, but potentially remakes the tumultuous political and ethical landscape of stem cell biology as human embryos may no longer be needed to obtain the blank slate stem cells capable of becoming any of the 220 types of cells in the human body. Perfected, the new technique would bring stem cells within easy reach of many more scientists as they could be easily made in labs of moderate sophistication, and without the ethical and legal constraints that now hamper their use by scientists. The new study was conducted in the laboratory of UW-Madison biologist James Thomson, the scientist who first coaxed stem cells from human embryos in 1998. It was led by Junying Yu of the Genome Center of Wisconsin and the Wisconsin National Primate Research Center. "The induced cells do all the things embryonic stem cells do," explains Thomson, a professor of anatomy in the University of Wisconsin School of Medicine and Public Health. "It's going to completely change the field." In addition to exorcising the ethical and political dimensions of the stem cell debate, the advantage of using reprogrammed skin cells is that any cells developed for therapeutic purposes can be customized to the patient. "They are probably more clinically relevant than embryonic stem cells," Thomson explains. "Immune rejection should not be a problem using these cells." An important caveat, Thomson notes, is that more study of the newly-made cells is required to ensure that the "cells do not differ from embryonic stem cells in a clinically significant or unexpected way, so it is hardly time to discontinue embryonic stem cell research." The successful isolation and culturing of human embryonic stem cells in 1998 sparked a huge amount of scientific and public interest, as stem cells are capable of becoming any of the cells or tissues that make up the human body. The potential for transplant medicine was immediately recognized, as was their promise as a window to the earliest stages of human development, and for novel drug discovery schemes. The capacity to generate cells that could be used to treat diseases such as Parkinson's, diabetes and spinal cord injuries, among others, garnered much interest by patients and patient advocacy groups. But embryonic stem cells also sparked significant controversy as embryos were destroyed in the process of obtaining them, and they became a potent national political issue beginning with the 2000 presidential campaign. Since 2001, a national policy has permitted only limited use of some embryonic stem cell lines by scientists receiving public funding. In the new study, to induce the skin cells to what scientists call a pluripotent state, a condition that is essentially the same as that of embryonic stem cells, Yu, Thomson and their colleagues introduced a set of four genes,Oct4, Sox2, NANOG, and LIN28, into human fibroblasts, skin cells that are easy to obtain and grow in culture. Finding a combination of genes capable of transforming differentiated skin cells to undifferentiated stem cells helps resolve a critical question posed by Dolly, the famous sheep cloned in 1996. Dolly was the result of the nucleus of an adult cell transferred to an oocyte, an unfertilized egg. An unknown combination of factors in the egg caused the adult cell nucleus to be reprogrammed and, when implanted in a surrogate mother, develop into a fully formed animal. The new study by Yu and Thomson reveal some of those genetic factors. The ability to reprogram human cells through well defined factors would permit the generation of patient-specific stem cell lines without use of the cloning techniques employed by the creators of Dolly. "These are embryonic stem cell-specific genes which we identified through a combinatorial screen," Thomson says. "Getting rid of the oocyte means that any lab with standard molecular biology can do reprogramming without difficulty to obtain oocytes." Although Thomson is encouraged that the new cells will speed new cell-based therapies to treat disease, more work is required, he says, to refine the techniques through which the cells were generated to prevent the incorporation of the introduced genes into the genome of the cells. In addition, to ensure their safety for therapy, methods to remove the vectors, the viruses used to ferry the genes into the skin cells, need to be developed. Using the new reprogramming techniques, the Wisconsin group has developed eight new stem cell lines. As of the writing of the new Science paper, which will appear in the Dec. 21, 2007 print edition of the journal Science, some of the new cell lines have been growing continuously in culture for as long as 22 weeks. Reference: Induced Pluripotent Stem Cell Lines Derived from Human Somatic Cells In addition to Yu and Thomson, authors of the new study include Maxim A. Vodyanik, Kim Smuga-Otto, Jessica Antosiewicz-Bourget, Jennifer L. Frane and Igor I. Slukvin, all of UW-Madison; and Shulan Tian, Jeff Nie, Gudrun A. Jonsdottir, Victor Ruotti and Ron Stewart, all of the WiCell Research Institute. See also: Yamanaka Turns Human Fibroblasts to ESC-like Cells Turning Adult Cells Embryonic How to Make Stem Cells Stay Growing ......... ZenMaster
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Yamanaka Turns Human Fibroblasts to ESC-like Cells
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Sunday, 18 November 2007
Genetic Testing: Customer DNA analyses
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Dolly Professor Abandons Human Cloning
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Thursday, 15 November 2007
‘Stem Cells to Cure Parkinson's in 5 Years’
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Stem cells extracted from cloned macaque embryos
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Wednesday, 14 November 2007
Human ESC's derived from PGD embryos with Fragile X
"Certainly, stem cell lines such as this will help science unravel the mechanisms associated with human genetic disorders, and hopefully lead to new therapeutic treatments and interventions in the future," said Robert Lanza of Advanced Cell Technology in Los Angeles, CA, who was not involved in the research. Such an approach has been overshadowed by the focus on developing stem cells as treatments for various disorders, he noted. ......... ZenMaster
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Retroviruses spurred evolution of gene regulatory networks
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Tuesday, 13 November 2007
Steps towards spinal cord reconstruction
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Sunday, 11 November 2007
UN Analysis on Human Cloning
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Thursday, 8 November 2007
Draft Guidelines for Stem Cell Research in India
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Tuesday, 6 November 2007
New Jersey Voters Defeat Stem Cell Measure
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NJ to vote on stem cell bond act The state decides on $450 million for research Tuesday, 06 November 2007 New Jersey residents will vote today (November 6) whether to devote $450 million to stem cell research over the next ten years. The referendum, introduced by state Governor Jon Corzine in July, would, if passed, put New Jersey among a group of states, including California, New York and Massachusetts, that have devoted extensive funds to stem cell research. According to the Governor's press release, this act "authorizes the sale of state general obligation funds in the amount of $450 million over 10 years" to be given to stem cell researchers. Last year, Corzine signed into law a bill that provided $270 million for new research facilities — $150 million of which will go to the New Jersey Stem Cell Institute. Recently, New Jersey has allocated smaller grants to support stem cell research, but on the whole the state has been somewhat behind other states. ......... ZenMaster
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