Bioentrepreneurial Idea

In Irvine researchers have discovered a dramatically improved method for genetically manipulating human embryonic stem cells, making it easier for easier for scientists to study and potentially treat thousands of disorders ranging from Huntington’s disease to muscular dystrophy and diabetes.
The technique for the first time blends two existing cell-handling methods to improve cell survival rates and increase the efficiency of inserting DNA into cells. The new approach is up to 100 times more efficient than current methods at producing human embryonic stem cells with desired genetic alterations.

“The ability to generate large quantities of cells with altered genes opens the door to new research into many devastating disorders,” said Peter Donovan, professor of biological chemistry and developmental and cell biology at UCI, and co-director of the UCI Sue and Bill Gross Stem Cell Research Center. “Not only will it allow us to study diseases more in-depth, it also could be a key step in the successful development of future stem cell therapies.”

This study appears online this week in the journal Stem Cells.

Donovan and Leslie Lock, assistant adjunct professor of biological chemistry and developmental and cell biology at UCI, previously identified proteins called growth factors that help keep cells alive. Growth factors are like switches that tell cells how to behave, for example to stay alive, divide or remain a stem cell. Without a signal to stay alive, the cells die.

The UCI scientists – Donovan, Lock and Kristi Hohenstein, a stem cell scientist in Donovan’s lab – used those growth factors in the current study to keep cells alive, then they used a technique called nucleofection to insert DNA into the cells. Nucleofection uses electrical pulses to punch tiny holes in the outer layer of a cell through which DNA can enter the cell.

With this technique, scientists can introduce into cells DNA that makes proteins that glow green under a special light. The green color allows them to track cell movement once the cells are transplanted into an animal model, making it easier for researchers to identify the cells during safety studies of potential stem cell therapies.

Scientists today primarily use chemicals to get DNA into cells, but that method inadvertently can kill the cells and is inefficient at transferring genetic information. For every one genetically altered cell generated using the chemical method, the new growth factor/nucleofection method produces between 10 and 100 successfully modified cells, UCI scientists estimate.

With the publication of this study, the new method now may be used by stem cell scientists worldwide to improve the efficiency of genetically modifying human embryonic stem cells.

“Before our technique, genetic modification of human embryonic stem cells largely was inefficient,” Hohenstein said. “This is a stepping stone for bigger things to come.”

Scientists can use the technique to develop populations of cells with abnormalities that lead to disease. They can then study those cells to learn more about the disorder and how it is caused. Scientists also possibly could use the technique to correct the disorder in stem cells, then use the healthy cells in a treatment.

The method potentially could help treat monogenic diseases, which result from modifications in a single gene occurring in all cells of the body. Though relatively rare, these diseases affect millions of people worldwide. Scientists currently estimate that more 10,000 human diseases are monogenic, according to the World Health Organization. Examples include Huntington’s disease, sickle cell anemia, cystic fibrosis and hemophilia.

UCI is at the forefront of stem cell research. The Sue and Bill Gross Stem Cell Research Center promotes basic and clinical research training in the field of stem cell biology. More than 60 UCI scientists use stem cells in their studies. These scientists study spinal cord injuries, brain injuries and central nervous system diseases such as multiple sclerosis, Alzheimer’s and Huntington’s. They also study muscular dystrophy, diabetes, cancer and other disorders.

UCI is raising money for a new building that would house its stem cell researchers, the core laboratory, training facilities and collaborative research space. It would accommodate evolving and expanding areas of stem cell study, serving as a university and regional hub for human embryonic stem cell research. UCI has applied to the California Institute for Regenerative Medicine for a facilities grant to build the structure.

April Pyle of UCLA and Jing Yi Chern of Johns Hopkins University also worked on the genetic modification study, which was funded by the National Institutes of Health.

http://stemcells.nih.gov/info/basics/basics1.asp/
http://stemcells.alphamedpress.org/
http://www.cnn.com/SPECIALS/2001/stemcell/
http://www.cellstemcell.com/
http://jwit.webinstituteforteachers.org/~hweiner/webquest/images/stem-cell-4.jpg/
Source : University of California - Irvine

biological breakthrough

CORVALLIS, Ore. – Researchers have made a fundamental advance in the understanding of cell biology that helps to explain how cells in higher organisms, including humans, send out signals that control cell division, cell death and other key functions.

The discovery should open new avenues to research on cancer, the scientists said.

The new study, to be published Friday in the journal Science by biochemists from Oregon State University and Wake Forest University, may also help resolve a significant debate in the science community about the role of hydrogen peroxide in cellular signaling and control of life processes.
This chemical would be recognized by most people as a common disinfectant found in the family medicine cabinet, used to cleanse wounds or a kitchen countertop.

But the new study provides strong evidence for how hydrogen peroxide is able to signal cells to divide, differentiate, or even commit suicide. These biochemical functions are essential to human life, and if they are dysfunctional may lead to cancer – which, from a simple perspective, is uncontrolled cell division.

“Hydrogen peroxide, like some other oxidative molecules, is usually a toxin we’re trying to get rid of,” said Andrew Karplus, a professor of biochemistry at OSU. “In most cases it’s an unnecessary byproduct that results from our processing of oxygen, which we need to live. And there is a considerable community of scientists who believe that’s about all it is, a toxin that needs to be eliminated.”

But another group of researchers, Karplus said, point to a wide range of evidence that hydrogen peroxide plays a key role in cellular signaling and communication – a switch, in a way, that’s only flipped on rare occasion but is critical to such cellular processes as division and programmed cell death. It’s never been clear, however, exactly how the same chemical can be both an unwanted toxin and a chemical that’s literally essential to the survival of higher life forms.

The newest findings, Karplus said, appear to answer that question.

In this research, the scientists were studying the function of peroxiredoxin, an enzyme whose primary task in a wide range of plant, animal and even bacterial life forms appears to be the detoxification of hydrogen peroxide.

The new discovery started out as purely basic research, Karplus said – the OSU and Wake Forest researchers were trying to model the atomic structure of peroxiredoxin from salmonella bacteria, as part of their programs in protein crystallography and understanding the basic biochemical processes of life.

They found that the peroxiredoxin from bacteria does a great job of detoxifying hydrogen peroxide, keeping it from killing cells. But when the scientists then compared the peroxiredoxin from bacteria with that from humans, they found that the enzyme from humans was larger and, for some reason, appeared only to be able to detoxify low levels of hydrogen peroxide – larger amounts of hydrogen peroxide would overwhelm the peroxiredoxin and kill it. What they discovered was that the extra size of peroxiredoxin molecule in humans causes it to work a little more slowly, and that makes in vulnerable to being killed.

“This was really pretty strange,” Karplus said. “There’s not a lot of biological precedent for an enzyme that exists primarily to get rid of another molecule, but when too much of that molecule exists, the enzyme itself becomes the victim. In humans, depending on the levels of these two compounds, this is a little dance of death in which sometimes the hydrogen peroxide is the winner.”

But the fact that hydrogen peroxide can actually survive, and even overwhelm the compound that exists to detoxify it must have evolutionary value, the researchers believed. They hypothesized that this adaptation allows the peroxiredoxin to act much like a floodgate would, keeping resting levels of hydrogen peroxide low, while permitting higher levels to flow throughout the cell to perform their signaling function.

“What we now understand, in other words, is how hydrogen peroxide could function in mammals and other higher life forms both as a toxin and a signal,” Karplus said. “In our bodies, hydrogen peroxide appears to be part of the mechanism that induces cell death at appropriate times – for instance, in cancer cells when they are attacked by our immune system.”

Some anti-cancer drugs, such as cisplatin, actually function by causing more hydrogen peroxide to be made in cells, Karplus said. And some cancer cells that are resistant to cisplatin or other forms of cancer therapy such as radiation appear to be making larger amounts of peroxiredoxin. The findings that emerged from this basic research program could have immediate value to suggest new types of cancer research, Karplus said, and eventually therapies.

http://www.cancer-info.com/cancer.gif/
http://www.jongonews.com/articles/07/0330/10850/MTA4NTAMpPAxkaK.html
http://www.drrathresearch.org/lab_research/cancer.html