23-02-2012 14:54 http://www.euronews.net Dutch scientist Mark Post hopes that he will be able to produce the world's first test-tube burger later this year. He says it will look, and taste identical to a regular quarter-pounder. In the laboratory, he has already grown small strips of beef from bovine stem cells, and is now looking at ways to increase production. It is white because there are no blood cells. But researchers hope that once cooked, these cells will look and taste the same as conventionally produced meat.

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The method, developed over several years in the lab of Prof. Ehud Shapiro of the Institute's Biological Chemistry, and Computer Science and Applied Mathematics Departments, uses mutations in specific genetic markers to determine which cells are most closely related and how far back they share a common parent cell, to create a sort of family tree for cells. Shapiro and members of his lab, including Drs. Shalev Itzkovitz and Rivka Adar, together with Prof. Nava Dekel and research student Yitzhak Reizel of the Biological Regulation Department, used their method to see if ova could be descended from bone-marrow stem cells. Their findings indicated that any relationship between the two types was too distant for one to be an ancestor of the other.

These scientists also found, surprisingly, that the ova of older mice had undergone more cell divisions than those of younger mice. This could be the result of replenishment during adulthood, but an alternate theory holds that all eggs are created before birth, and those that undergo fewer divisions are simply selected earlier on for ovulation. Further experimentation, says Shapiro, will resolve the issue.

Cell lineage trees are similar to modern evolutionary and taxonomic trees based on genome comparisons between organisms. Shapiro and his team used mutations in cells that are passed on to daughter cells over an organism's lifetime (though not on to the next generation). By comparing a number of genetic sequences called microsatellites – areas where mutations occur like clockwork – they can place cells on trees to reveal their developmental history.

A number of papers published by Shapiro, his team and collaborators in recent months have demonstrated the power and versatility of this method. One study, for instance, lent support to the notion that the adult stem cells residing in tiny crypts in the lining of the colon do not harbor, as thought, "immortal DNA strands." Immortal strands may be retained by dividing stem cells if they always relegate the newly-synthesized DNA to the differentiating daughter cell and keep the original stand in the one that remains a stem cell.

A second study addressed an open question about developing muscle cells. Here they found that two kinds of progenitor cell - myogenic cells, which eventually give rise to muscle fiber, and non-myogenic cells – found within the same muscle are more closely related than similar cells in different muscles.

One immediate advantage of the cell lineage analysis method developed by Shapiro's team is that it is non-invasive and retrospective, and as such can be applied to the study of human cell lineages. Most other studies of development rely on genetically engineered lab animals in which the stem cells are tagged with fluorescent markers. In addition to providing a powerful new research method that does not rely on such markers, Shapiro believes that it could one day be adapted as a diagnostic tool that might, for instance, reveal the history of an individual's cancer and help doctors determine the best course of treatment.

Provided by Weizmann Institute of Science (news : web)

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Lineage trees reveal cells' histories

MINNEAPOLIS - A first-of-its-kind study is just getting underway at University of Minnesota Physicians Heart at Fairview, in Minneapolis. The FDA-approved trial is designed to test the impact of stem cells on restoring the heart's muscle function in patients suffering from advanced heart failure. The results of the trial could impact the future of health care in the area of heart disease, and may one day save lives.

Lee Magnuson, 58, of Spring Brook, WI, became one of the first patients to enroll in the study.

"To me it was a no brainer, I had to contribute," said Magnuson.

Magnuson suffered a heart attack on October 5, 2010. He spent about a year being treated with medication and undergoing cardiac rehabilitation in an attempt to strengthen his heart muscle.

But, by August of 2011, he said, his doctor could tell things were not going well. That is when his doctor recommended implanting a left ventricular assist device (LVAD). The device helps pump blood from the lower left chamber of the heart to the rest of the body. His doctor also told him about the U of M study.

"This trial is designed for heart failure patients in the end stage of heart failure, with no options for treatment," explained Ganesh Raveendran, M.D., who is the principal investigator of the clinical trial. "The question this trial is designed to answer is whether or not patients on a left ventricular assist device with the stem cell component do better than patients with only the device, which right now is the standard care for patients experiencing advanced heart failure."

The trial is currently enrolling qualified patients. All patients involved in the study will undergo a marrow harvest in which stem cells will be taken from the marrow of their own hip bone. Then, during implantation of the LVAD, two thirds of the patients enrolled in the study will receive an injection of their own stem cells. A third of the patients will be randomly assigned to the control group, and will receive only an LVAD and an injection of saline.

The trial is double-blind, meaning U of M researchers will not know which patients have received stem cells and which did not until the trial concludes.

So far, three patients have enrolled. Researchers hope to eventually recruit 24 people from around the region. The study will last approximately two years.

In November, Magnuson became the first of the patients to have an LVAD implanted and receive an injection.

Throughout the trial, Magnuson and the other patients will undergo a series of tests in which doctors slowly decrease the effort of the LVAD and place more pressure back on the heart's own pumping function. The purpose of the tests is to assess the impact of the stem cells on restoring the functionality of heart muscle. Researchers want to know whether there is any improvement in the size of the heart and the pressure inside the heart chambers. The tests include echocardiograms, PET scans, walking assessments, blood pressure measurements and quality-of-life questioning.

Researchers will eventually compare the results of those tests to see if there was a difference between the two groups of patients.

"The hope is that this group of patients suffering from severe heart failure eventually should be able to get some cells and improve the heart function," said Dr. Raveendran.

That answer will come once the patients either undergo a transplant or they die. Only then will doctors be able to study the hearts to learn the true impact of the stem cells.

Last month, Magnuson was put on a waiting list for a heart transplant.

"So it's a matter of waiting now, it's a matter of time," explained Magnuson.

He remains optimistic about the future, but says his heart issues also have taught him to be a realist.

"My quality of life is, before it was work, work, work, and it's going to not be so much work anymore and we're going to enjoy things," reflected Magnuson. "You all of a sudden realize that you're not going to live forever."

To learn more about the study:
Call the U of M Physicians Heart at Fairview - 612-625-5949
Email - stemcells@umnheart.com
Webpage - http://www.med.umn.edu/lcru/

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U of M researchers aim to restore heart muscle using stem cells