According to researchers at the University of Texas, an enzyme has been found, that instigates the growth and maturation of stem cells lurking in bone marrow, causing the stem cells to step up production and replace lost blood and immune system cells.
It is possible the enzyme may also spur the growth of stem cells elsewhere in the body. This information may help researchers determine how to harness the potential of adult stem cells to treat a variety of ailments. Stem cells are immature cells that give rise to the specialized cells that make up the body, and scientists believe they can be used to repair the damaged tissue that marks diseases like Parkinson's, diabetes and heart disease. In a developing embryo, stem cells are able to mature into all types of tissue.
AdvertisementSuch cells have traditionally been thought to be limited in potential--with, for example, gut stem cells giving rise to gut cells and brain stem cells producing only brain cells--although recent research has been challenging that thinking. For instance, transplanted bone marrow stem cells have shown up in mature kidney, liver, skin and gastrointestinal tissue.
A long-standing problem with adult stem cells is that they are relatively rare and secluded in the body, which has severely hampered attempts to investigate their use in treating disease. Dr. Shahin Rafii of Cornell University Medical College in Texas, and his colleagues report that adult stem cells are stimulated to do their job by an enzyme, metalloproteinase-9 (MMP-9). Injury turns on MMP9, Rafii explained, which helps release growth-promoting substances which, in turn, wake up the stem cells. The stem cells then move to a portion of the bone marrow where they can multiply and be released.
Rafii and his team discovered the significance of MMP9 when they examined mice that had been engineered to grow and develop without the enzyme. When the researchers treated the mice with chemotherapy that severely damaged bone marrow, 72% died, while all of the mice that still produced MMP9 survived because they successfully regenerated blood and immune system cells. He said that without MMP9, none of the stem cells woke up,and stay sleeping, hibernating
Rafii added that it would be difficult to administer MMP9 directly to adults who wanted to produce more of their own stem cells, but researchers may soon be able to administer the growth factors that, in turn, activate the enzyme to do its job.
Adult stem cells may some advantages over those derived from embryos, Rafii pointed out. Patients' tissues are unlikely to reject cells that come from their own bodies. And it is not yet known how to coax embryonic stem cells into desired mature cell types. This type of cloning is not intended to produce an offspring, but instead to produce an embryo that has stem cells are made specifically for treating a specific patient's disease.
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