Structural Biochemistry/Embryonic Stem Cells
There is only one type of cell that is completely generic—its gene expression is tuned so broadly that it has unlimited career potential to become any kind of cell in the body. These undifferentiated cells exist a few days after conception and form the blastula, consisting of three layers, the ectoderm, endoderm, and mesoderm and about 100 cells. Embyonic stem cells have an almost unlimited capacity to divide due to high levels of telomerase that prevents telomare degradation in aging cells. Shortly after, a wave of growth hormones such as Testosterone and Sonic Hedgehog, induce the blastocyst to change from a spherical structure and begin to take on the rough morphology that the animal has.
Due to their almost unlimited capacity to divide and their potential to divide into any kind of cell in the body, embryonic stem cells are being looked at as therapies for many different types of neurodegenerative therapies such Parkinson's, Alzheimer's, and Huntingtons in which the neurons in an aging brain or body die and are not replaced. by attempting to induce stem cells to differentiate into these types of neurons and repopulate the affected regions; the progress of the disease can be halted or even reversed.
Embronic stem cells are also being considered for organ transplantations. If Embryonic stem cells are saved at birth from the placenta and umbilical cord. These cells can theoretically then be used to grow organs with the same blood type and identifying proteins in them, eliminating the need to wait for an organ donor which reduced the organ shortfall already present, and ensuring that the organ is a perfect match with the recipient's body, eliminating the chance of rejection and the need for anti rejection drugs.
Because embryonic stem cells are so few, numbering only a hundred or so per embryo, they are very expensive and difficult to harvest and maintain. This process inevitably destroys the developing embryo leading to charged political debate versus the cost of sacrificing a potential life versus the enormous benefits these types of cells could bring.
Although researchers have been studying stem cells from mouse embryos for more than 20 years, only recently have they been able to isolate stem cells from human embryos and grow them in a laboratory. In 1998, James A. Thomson of the University of Wisconsin, Madison, became the first scientist to do this. He is now at the forefront of stem cell research, searching for answers to the most basic questions about what makes these remarkable cells so versatile. Although scientists envision many possible future uses of stem cells for treating Parkinson’s disease, heart disease, and many other disorders affected by damaged or dying cells, Thomson predicts that the earliest fruits of stem cell research will be the development of powerful model systems for finding and testing new medicines, as well as for unlocking the deepest secrets of what keeps us healthy and makes us sick.
- U.S. Department of Health and Human Services. Inside the Cell. September 2005.<http://www.nigms.nih.gov>.