Wednesday, July 17, 2013

Scientists inactivate extra chromosome in stem cells from people with Down's syndrome

People with Down's syndrome have an additional copy of chromosome 21. Image from U.S. Department of Energy Human Genome Program
Spoiler alert: The research reported here is not funded by CIRM and is far, far from being ready to test in people. But for those of us who clearly remember a day when reprogrammed stem cells were but a much discussed goal it's always exciting to see how powerful they've turned out to be in disease research.

One reason scientists were so eager to create reprogrammed stem cells (these are the stem cells generated from adult cells like skin or blood, also called iPS cells) is to use them to study disease. For example, if you take a skin cell from someone with Down's syndrome, the resulting iPS cells will also carry the genetic defect that causes the syndrome--in this case an extra copy of chromosome 21. Scientists can then study the cells and test drugs to see if any are able to eliminate the defects in a lab dish. Eventually, the goal is to take those successful drugs from the lab to people.

Scientists at the biotech company Sangamo have been helping scientists do just that--using their technology to try to deactivate the disease-causing genes in iPS cells in a lab dish. (Sangamo is part of our HIV/AIDS disease team led by City of Hope scientists John Zaia, where their technology is being put to use deactivating a gene the HIV virus uses to enter cells.)

Ron Leuty of the San Francisco Business Times wrote today about a scientists at University of Massachusetts who used Sangamo's technology to silence the extra chromosome in iPS cells generated from people with Down's syndrome. That work is published in the July 17 issue of Nature.

Could the finding lead to a therapy for Down's syndrome? Leuty quotes Sangamo’s chief scientific officer and vice president of research Philip Gregory, "It’s very tempting to speculate." But, he says, the first therapies will likely be in diseases like hemophilia, Huntington's disease or in the CIRM-funded HIV/AIDS project.

The authors of the paper pointed to decades of basic research that led up to their recent discovery:
Our hope is that for individuals and families living with Down’s syndrome, the proof-of-principle demonstrated here initiates multiple new avenues of translational relevance for the 50years of advances in basic X-chromosome biology.
Amy Adams

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