Virus-free Embryonic-like Stem Cells Made From Skin Of Parkinson's Disease Patients ScienceDaily (Mar. 5, 2009) - Whitehead Institute researchers have developed a novel method to remove potential cancer-causing genes during the reprogramming of skin cells from Parkinson's disease patients into an embryonic-stem-cell-like state. Scientists then used the resulting induced pluripotent stem (iPS) cells to derive dopamine-producing neurons, the cell type that degenerates in Parkinson's disease patients. This marks the first time researchers have generated human iPS cells that have maintained their embryonic stem-cell-like properties after the removal of reprogramming genes. The findings are published in the March 6 edition of the journal Cell. "Until this point, it was not completely clear that when you take out the reprogramming genes from human cells, the reprogrammed cells would actually maintain the iPS state and be self-perpetuating," says Frank Soldner, a postdoctoral researcher in Whitehead Member Rudolf Jaenisch's laboratory and co-author of the article. Since August 2006, researchers have been reprogramming adult cells into iPS cells by using viruses to transfer four genes (Oct4, Sox2, c-Myc and Klf4) into the cells' DNA. Although necessary for reprogramming cells, these genes, the known oncogene c-Myc in particular, also have the potential to cause cancer. In addition, the four genes interact with approximately 3000 other genes in the cell, which may change how the cell functions. Therefore, leaving the genes behind in successfully reprogrammed cells may cause unintended alterations that limit the cells' applicability for therapeutic use, for drug screens or to study disease in cell culture. In the current method, Whitehead researchers used viruses to transfer the four reprogramming genes and a gene coding for the enzyme Cre into skin cells from Parkinson's disease patients. The reprogramming genes were bracketed by short DNA sequences, called loxP, which are recognized by the enzyme Cre. After the skin cells were reprogrammed to iPS cells, the researchers introduced the Cre enzyme into the cells, which removed the DNA between the two loxP sites, thereby deleting the reprogramming genes from the cells. The result is a collection of iPS cells with genomes virtually identical to those of the Parkinson's disease patients from whom original skin cells came. Removing the reprogramming genes is also important because of those genes' effect on an iPS cell's gene expression (a measure of which genes the cell is using and how much it's using those genes). When the researchers compared the gene expressions of human embryonic stem cells to iPS cells with and without the reprogramming factors, iPS cells without the reprogramming genes had a gene expression closer to human embryonic stem cells than to the same iPS cells that still contained the reprogramming genes. "The reprogramming factors are known to bind to and affect the expression of 3,000 genes in the entire genome, so having artificial expression of those genes will change the cell's overall gene expression," Dirk Hockemeyer, who is also a co-author of the Cell article. "That's why the four reprogramming genes can mess up the system so much. From now on, it will be tough for researchers to leave the reprogramming genes in iPS cells." Jaenisch says that the process to remove the reprogramming genes is very successful, when compared with earlier experiments. "Other labs have reprogrammed mouse cells and removed the reprogramming genes, but it was incredibly inefficient, and they couldn't get it to work in human cells," he says. "We have done it much more efficiently, in human cells, and made reprogrammed, gene-free cells." After removing the reprogramming genes, the Jaenisch researchers differentiated the cells from the Parkinson's disease patients into dopamine-producing nerve cells. In Parkinson's disease patients, these cells in the brain die or become impaired, causing such classic Parkinson's symptoms as tremors, slowed movement, and balance problems. Because the cells reside in the patients' brains, researchers cannot easily access them to investigate how the disease progresses at the cellular level, what kills the cells, or what might prevent cellular damage. Therefore, the ability to create patient-specific iPS cells, derive the dopamine-producing cells, and study those patient-specific cells in the lab could be a great advantage for Parkinson's disease researchers. Although the initial results are extremely promising, Jaenisch acknowledges that the process is far from over. "The next step is to use these iPS-derived cells as disease models, and that's a high bar, a real challenge. I think a lot of work has to go into that." Journal reference: Frank Soldner et al. Parkinson's disease patient-derived induced pluripotent stem cells free of viral reprogramming factors. Cell, March 5, 2009 Adapted from materials provided by Whitehead Institute for Biomedical Research. Whitehead Institute researchers "reprogrammed" human skin cells from Parkinson's disease patients into an embryonic-stem-cell-like state. After removing the reprogramming genes, the scientists used these so-called induced pluripotent stem (iPS) cells to create dopamine-producing neurons, the cell type that degenerates in Parkinson's disease patients. To confirm that the iPS cells had become dopamine-producing neurons, the researchers stained the cells green for a neuron-specific protein (class III beta-tubulin) and red for a dopamine-producing neuron-specific enzyme (tyrosine hydroxylase). (Credit: Image courtesy of Whitehead Institute for Biomedical Research) Australian First For Melbourne Stem Cell Scientists (Feb. 1, 2009) - Melbourne scientists have created Australia's first induced pluripotent stem cell lines. Scientists have derived the cells from skin cells, and reprogrammed them to behave as embryonic stem cells; a ... > read more New Technique Produces Genetically Identical Stem Cells (July 6, 2008) - Cells from mice created using genetically reprogrammed cells can be triggered via drug administration to enter an embryonic-stem-cell-like state without the need for further direct genetic ... > read more Human Skin Cells Reprogrammed Into Embryonic Stem Cells (Feb. 12, 2008) - Stem cell scientists have reprogrammed human skin cells into cells with the same unlimited properties as embryonic stem cells without using embryos or eggs. The implications for disease treatment ... > read more Stem Cells From Skin Cells Can Make Beating Heart Muscle Cells (Feb. 13, 2009) - A little more than a year after scientists showed they could turn skin cells back into stem cells, they have pulsating proof that these "induced" stem cells can indeed form the specialized cells that ... > read more Stem Cell Research Compares Methods Of Creating Patient-specific Stem Cells (Sep. 3, 2008) - Scientists will compare two different methods of creating patient-specific stem cells: somatic cell nuclear transfer and induced pluripotent stem ... > read more Rayilyn Brown Director AZNPF Arizona Chapter National Parkinson Foundation [log in to unmask] ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn