Researchers See Adult Stem Cell Progress: They Self-Renew, Repair Tissue

Bioethics   |   Steven Ertelt   |   Dec 15, 2008   |   9:00AM   |   WASHINGTON, DC

Researchers See Adult Stem Cell Progress: They Self-Renew, Repair Tissue

by Steven Ertelt Editor
December 15
, 2008

Stanford, CA ( — Two groups of researchers have made more progress with the use of adult stem cells — showing they are both more ethical and more effective than their embryonic counterparts. In this latest find, they demonstrated that adult stem cells can self renew and repair tissue damage.

Stanford University scientists issued a report at the 48th annual meeting of the American Society for Cell Biology (ASCB) on Sunday.

They transplanted the skeletal adult muscle stem cells into special immune-suppressed mice whose muscle satellite cells had been wiped out in a hind limb by irradiation. The stem cells restored lost function to mice with hind limb muscle tissue damage.

The team used luminescent imaging as well as quantitative and kinetic analyses to track each transplanted stem cell as it rapidly proliferated and engrafted its progeny into the irradiated muscle tissue.

The scientists then injured the regenerated tissue, setting off muscle cell growth and repair, and subsequently showed that the muscle stem cells and descendents rescued the second animal’s lost muscle healing function.

After isolating the luciferase-glowing muscle stem cells from the transplanted animal, the scientists cloned the cells in the lab. Like the original muscle cells, the cloned copies were intact and capable of self renewal.

After demonstrating that the transplanted stem cells proliferated and fully restored the animal’s lost function, the scientists recovered new stem cells from the transplant with full stem cell potency.

Dr. David Prentice, a former Indiana State University biology professor who is a leading pro-life bioethicist, told he is excited about the news.

"The work by the Stanford group is exciting, because it shows with very definitive experiments that even a single muscle adult stem cell can grow and repair muscle damage, while still maintaining a pool of muscle stem cells for future repair, or as in these experiments, for transplant," he explained.

"These detailed experiments lay the groundwork for the potential use of muscle adult stem cells to treat various muscle disorders in patients," Prentice added.

Meanwhile, researchers at the University of Pennsylvania School of Medicine have discovered stem cells in the esophagus of mice that were able to grow into tissue-like structures and when placed into immune-deficient mice were able to form parts of an esophagus lining.

They reported their findings online this month in the Journal of Clinical Investigation.

"The immediate implication is that we’ll have a better understanding of the role of these stem cells in normal biology, as well as in regenerative and cancer biology," senior author Anil K. Rustgi, MD said in a statement.

Dr. Rustgi said the findings could soon lead to treatments for patients using the adult stem cells.

"Down the road, we will develop a panel of markers that will define these stem cells and use them in replacement therapy for diseases like gastroesophogeal reflux disease [GERD] and also to understand Barrett’s esophagus, a precursor to esophageal adenocarcinoma and how to reverse that before it becomes cancer," Rustgi explained.

The researchers set out to identify and characterize potential stem cells–those with the ability to self renew–in the esophagus to understand normal biology and how injured cells may one day be repaired.

First, they grew mouse esophageal cells they suspected were adult stem cells. Those cells formed colonies that self renewed.

The investigators then tested their pieces of esophageal lining in whole animals. When the tissue-engineered patches were transplanted under the skin of immunodeficient mice, the cells formed epithelial structures.

Eventually the researchers will develop genetically engineered mouse models to be able to track molecular markers of esophageal stem cells found in a micorarray study. The group has already developed a library of human esophageal cell lines and is looking for human versions of markers already identified in mice.

"The ultimate goal is to identify esophageal stem cells in a patient, grow the patient’s own stem cells, and inject them locally to replace diseased tissue with normal lining," says Rustgi.

Dr. Prentice, with the Family Research Council, also commented on the Penn study.

"This report is interesting because they were able to isolate and grow the adult stem cells from mouse esophagus, and also get the cells to help with repair of damaged esophagus tissue in mice," he said. "The results are promising for use of these adult stem cells in repair of various types of esophagus damage, including reflux disease."

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