Stem Cell Basics explains they have the potential to become one of many different types of cells in the human body. When the stem cell divides, it could become a retina cell, muscle cell, etc., or even another stem cell. A stem cell is unspecialized and is capable of renewing itself. Gut and bone marrow stem cells regularly replace older tissue. But it happens very infrequently and under special circumstances in other organs such as the pancreas and heart.
Much of the stem cell debate concerns the inner cells of the blastocyst, (4-5 day old embryo) the embryonic cells that basically duplicate a human being. These cells obviously have the ability to create any type of human tissue or organ, because that's what they do. The ethical debate results from the destruction of a growing embryo that could become a complete human.
But stem cells have the promise of miracle cures. Stem Cells Approved to Treat 'Orphan' Disease explains the FDA has approved stem cell treatment for a rare blindness syndrome. The ScienceFair article explains that less than 30,000 globally are afflicted with Stargardt's Macular Dystrophy, and the return on investment is insufficient to attract big Pharma to develop products.
In the last two or three years, induced pluripotent stem cells (iPSCs) have been created from adult cells, essentially switching them back to a juvenile state. While side-stepping the ethics of destroying a blastocyst, they also avoid the problems of tissue rejection. Although the inner cells of the blastocyst are unspecialized, they sometimes have markers that are recognized as foreign bodies by the recipient's autoimmune system. Anti-rejection drugs are then required throughout the patient's lifetime.
Still No Truce in the Stem Cell Wars explains that IPSCs are created by inserting four genes into the adult cell through a retrovirus. Although easily produced, their advocates have been dismayed because they age prematurely. For unknown reasons, the iPSCs stop dividing after only a few generations and they die prematurely.
Breakthrough Reveals Blood Vessel Cells Are Key to Growing Unlimited Amounts of Adult Stem Cells tells that endothelial cells of the vascular system proliferate stem cells. Researchers inserted a gene from andenoviruses into the endothelial cells have been able to maintain stem cell cultures for a year instead of the 4-5 days with iPSCs. Currently the technique is applicable to marrow and other blood-forming stem cells, but the Science Daily article indicates the concept can be applied to adult stem cells of other organs. In the short term, it should bring immediate help for bone marrow transplantation.
Comments