Rett Syndrome and induced Pluripotent Stem cells goes “Green”
June 17, 2009
Stem cell researchers at The Hospital for Sick Children have now devised a method, reported in the scientific journal Nature Methods, that will facilitate the generation of induced Pluripotent Stem (iPS) cells. I have previously blogged about the promise of iPS cells (see related articles). iPS cells are cells which have been reprogrammed from a differentiated somatic cell (such as your skin cells) to a pluripotent stem cell (like an embryonic stem cell, only that you don’t need to use embryos!). The generation of iPS cells is inherently very rare which occurs at a frequency of about 0.01% meaning you can generate about one iPS cell line out of hundred thousand cells. Out of which, many lines fail to satisfy the different rigorous tests necessary to be given the prestigious name of “iPS cell”.
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Stem Cell Breakthrough: Toronto reprograms by jumping genes in and out
March 2, 2009
Toronto stem cell researchers have now, for the first time, devised a way to reprogram somatic cells from human back to a pluripotent-like state termed induced pluripotent stem (iPS) cells without the use of harmful viruses. I have blogged about the incredible feat of iPS cells recently as the scientific journal Science has named it “Breakthrough of the year”. These iPS cells are thought to hold the same regenerative potential as human embryonic stem cells but with additional advantages as it side steps the ethical issues related to the use of human embryos. Therefore, scientists now have a way of making patient-specific stem cells for uses such as disease modeling, drug screening, and hopefully one day, cell replacement therapy.
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Breakthrough of 2008 - Reprogramming
January 26, 2009
In December 2008, the scientific journal Science, named the incredible process of stem cell reprogramming breakthrough of the year 2008. Reprogramming is the reversal of the state of a somatic cell (i.e. a differentiated cell or a cell that has become a skin cell or kidney cell) back to a state reminiscent to that of a pluripotent state (i.e. an embryonic stem cell).
A New Era for Disease Modeling and Drug Screening
December 29, 2008
Induced Pluripotent Stem (iPS) cells are cells that have been reprogrammed from skin fibroblasts back to a state reminiscent of Embryonic Stem (ES) cells. Human iPS cells were first discovered back in November 2007 by pioneer Dr. Shinya Yamanaka at Kyoto University (reported in scientific journal Cell in November 2007). iPS cells are thought to hold the same potential as ES cells in regenerative medicine such as disease modeling, drug screening, and cell replacement therapy, but with additional advantages as it bypasses the ethical issues relating to the use of human embryos.
Induced pluripotent stem cells take small step away from viruses
October 6, 2008
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Induced pluripotent stem cells (iPS) are stem cells that are created by infecting adult skin cells with four different viruses that carry “pluripotency” factors. This means that the cells develop the characteristics of embryonic stem cells and have the ability to become any kind of cell.
iPS cells have significant advantages over embryonic stem cells as they bypass the ethical issues relating to the use of human embryos. However, one disadvantage of iPS is the use of retroviruses. These viruses do more than turn the adult skin cells into iPS cells. They also integrate themselves into the genome of these cells which makes them unsafe for therapy. Alterations in genes are the cause of many diseases, like cancer.
In a recent publication in Science Express, Scientists at the Harvard Stem Cell Institute, built on their previous discovery to creating iPS cells from skin cells, and significantly improved the method generating iPS cells using another class of virus known as Adenovirus.
Adenoviruses are better than retroviruses as they do not integrate into the genome but still deliver high levels of the proteins needed to create iPS cells. Using adenoviruses, the group led by Dr. Konrad Hochedlinger, found a way to create the desired stem cells, without the potential disease-causing risk.
However, adeno-iPS are not a perfect solution and cells did had one drawback; the efficiency of generating adeno-iPS cells were much lower (0.001~0.0001%) than using conventional retroviruses (0.01~0.1%). While this is a significant step towards generating iPS cells without side-effects, much work needs to be done to improve efficiency in creating them. Fortunately, other methods of generating integration-free iPS cells, such as chemicals, are promising.
This is part of what makes research as exciting as it is. There are always more solutions on the horizon.
First step towards banking disease-specific pluripotent stem cells
September 30, 2008
Scientists at the Harvard Stem Cell Institute have recently reported in the scientific journal Cell that they have been able to create stem cells from patients with a wide variety of genetic diseases.
The group, led by Dr. George Daley, achieved this task by taking fibroblasts from the skin or bone marrow of patients with genetic diseases and subsequently infecting these cells with a cocktail of viruses. This caused the cells to back to a state that is similar to pluripotent stem cells (i.e. embryonic stem cells).
These disease-specific cells are of great value as they give researcher more information about the nature of the genetic mutation (and hence the disease) that is carried in these stem cells. Not only will these disease-specific cells help scientists understand what role these cells play in the development of disease, but the information carried in these cells will aid in drug development.
Diseases included in this discovery are adenosine deaminase deficiency-related severe combined immunodeficiency , Shwachman-Bodian-Diamond syndrome, Gaucher diseaseI, Duchenne and Becker muscular dystrophy, Parkinson’s disease , Huntington’s disease, type 1diabetes, Down syndrome, and the carrier state of Lesch-Nyhan syndrome.
As controversy over the use of embryonic stem cells in research continues, this discovery helps bypass some of the ethical issues involve as these stem cells can generated by acquiring a fibroblast from patients rather than from an embryo.
Aaron Cheung is a graduate student in the lab of Dr. James Ellis at SickKids.
Rett Syndrome and induced Pluripotent Stem cells goes “Green”
June 17, 2009 by Aaron Cheung
Stem cell researchers at The Hospital for Sick Children have now devised a method, reported in the scientific journal Nature Methods, that will facilitate the generation of induced Pluripotent Stem (iPS) cells. I have previously blogged about the promise of iPS cells (see related articles). iPS cells are cells which have been reprogrammed from a differentiated somatic cell (such as your skin cells) to a pluripotent stem cell (like an embryonic stem cell, only that you don’t need to use embryos!). The generation of iPS cells is inherently very rare which occurs at a frequency of about 0.01% meaning you can generate about one iPS cell line out of hundred thousand cells. Out of which, many lines fail to satisfy the different rigorous tests necessary to be given the prestigious name of “iPS cell”.
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