Navigation Links
Biologists develop efficient genetic modification of human embryonic stem cells
Date:1/7/2010

Biologists have developed an efficient way to genetically modify human embryonic stem cells. Their approach, which uses bacterial artificial chromosomes to swap in defective copies of genes, will make possible the rapid development of stem cell lines that can both serve as models for human genetic diseases and as testbeds on which to screen potential treatments, they say.

"This will help to open up the whole human embryonic stem cell field. Otherwise, there's really few efficient ways you can study genetics with them," said Yang Xu, professor of biology at the University of California, San Diego who directed the research. Xu and co-authors Hoseok Song and Sun-Ku Chung, both postdoctoral fellows in Xu's research group, describe their technique in the January 8 issue of the journal Cell Stem Cell.

Most attempts to alter the genetic makeup of the cells have proved too inefficient, Xu said. His group used bacterial artificial chromosomes, or BACs, to improve the yield.

BACs are synthesized circles of human DNA, which bacteria will replicate just like their own native chromosomes. Commercially available BACs can be modified within bacterial cells to insert altered copies of specific genes. Once the modified BACs are introduced into human cells, they will sometimes pair up with a matching segment of a human chromosome and swap segments of DNA, a process called homologous recombination.

The advantage of using BACS to alter the genetic code in human cells comes from the long flanking sequences on either side of the modified gene, which increases the chance that the BAC with line up with native DNA in position for a swap. Other genetic approaches have been limited by shorter segments of DNA.

Using BACs, the team was able to substitute modified genes in 20 percent of treated cells. Standard methods of genetic modification typically achieve modification in fewer than one percent of cells, Xu said.

His group successfully transferred a defective copy of the gene p53, which suppresses cancer, into a human embryonic stem cell line. By repeating the process in a second round, they developed a line of cells in which both copies of the genes were disrupted.

They also report success with a different gene, ATM, which when mutated in humans causes Ataxia-telangiectasia, a disease characterized by a host of systemic defects including increased cancer risk, degeneration of specific types of brain cells and degraded telomeres, the protective caps at the end of each chromosome.

Genetically engineered mice with two bad copies of the ATM gene share some of these traits with human patients, but not all. Neurons don't degenerate in ATM mice, for example, and the telomeres are long. "If you want to study accelerated shortening of telomeres, you can't do it in the mouse. You can only do it in human cells," Xu said.

Those differences propelled Xu's group to develop human cell lines instead, with the hope that some of the processes that go wrong in human patients could be studied in the lab. Already, they have demonstrated that their ATM-deficient embryonic stem cell line has damaged telomeres. Other characteristics, such as the degeneration of specific types of neurons, will be the subject of future experiments, Xu said.

The authors say their approach can easily be adapted to modify other human genes within other stem cells lines. For their initial work, Xu's group used a cell line that easily forms new colonies from single cells, but they also repeated the procedure in a cell line called H9, which has proved difficult to manipulate.

Because H9 was among the few cells lines approved for use by researchers funded by the federal government before new lines began to be approved in mid-December 2009, many researchers already have considerable experience with coaxing the cells into differentiating into specific types of tissues, for example, which would make the ability to genetically modify them particularly valuable.


'/>"/>

Contact: Yang Xu
scinews@ucsd.edu
University of California - San Diego
Source:Eurekalert

Related medicine news :

1. Biologists Question Animal Brain Size Theory
2. Where tumor cells boldly go: Weill Cornell cancer biologists shed light on the metastatic niche
3. Cell biologists identify new tumor suppressor for lung cancer
4. Microbiologists receive top Canadian recognition
5. Boston College biologists build a better mouse model for cancer research
6. Biologists Discover How Dengue Virus Matures
7. FDA clears TransOral robotic surgery developed at Penn
8. Michael J. Fox Foundation Awards $1 Million for Critical Step Toward Development of Dyskinesia Treatments
9. Nu-Tek Products Develops Cultured Soymilk Powder
10. Milton & DeKruif Launches New Client Development Campaign
11. Safety and Quality Software Developer Quantros, Inc. Launches Healthcare IT Consulting Division
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/25/2017)... ... June 25, 2017 , ... CareSet Labs released the Root NPI ... This is a new, greatly improved version of the Doctor Referral teaming dataset commonly ... Fred Trotter and subsequently called the the “Doctor Referral Dataset” as released by Medicare ...
(Date:6/24/2017)... ... June 24, 2017 , ... Genes Advice, a new company ... Florida and Texas doctors' offices and clinics. This breakthrough testing is part of ... recognizes the role genes play in determining an individual's tolerance of and reaction ...
(Date:6/24/2017)... ... , ... The weather is heating up and the days are getting longer, ... aware that the summer months provide more than warmer temperatures that are perfect for ... negatively affected from direct exposure to the sun. When it comes to the security ...
(Date:6/23/2017)... ... June 23, 2017 , ... "The Better Care Reconciliation Act ... harm to people with all chronic conditions, including mental illnesses, while increasing the ... the Affordable Care Act (ACA) requirement that insurers cover pre-existing conditions, it does ...
(Date:6/23/2017)... ... 24, 2017 , ... Studies show evidence that carotenoids and antioxidants derived either ... in these patients. , But how often do ophthalmologists and optometrists in Sweden recommend ... risk of or with early symptoms of AMD? A study published recently ...
Breaking Medicine News(10 mins):
(Date:6/9/2017)... Calif. , June 9, 2017 AirXpanders, ... company focused on the design, manufacture, sale and distribution ... market on the progress of its commercial roll-out in ... now available in more than one hundred (100) medical ... AeroForm offers a needle-free alternative for women ...
(Date:6/7/2017)... , June 7, 2017 Endo International plc ... 7, 2017, the Hon. Joseph R. Goodwin , ... West Virginia , entered a case ... Pelvic Repair System Products Liability Litigation (the "MDL") that ... cases to provide expert disclosures on specific causation within ...
(Date:6/3/2017)... 3, 2017  Eli Lilly and Company (NYSE: ... from the Phase 3 MONARCH 2 study showed ... inhibitor, in combination with fulvestrant, significantly improved progression-free ... in women with hormone-receptor-positive (HR+), human epidermal growth ... have relapsed or progressed after endocrine therapy (median ...
Breaking Medicine Technology: