why do scientists want to use stem cell lines

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Some of the most exciting embryonic stem cell lines are those that could closely model human disease. A mechanic hoping to understand a jet engine would be unhappy given a helicopter to study, but scientists studying human diseases routinely resort to studying artificial, animal equivalents of disease. Experiments with appropriate human cells could reveal information that experiments with mice could not. In 2003, scientists in the UK created stem cell lines using embryos from fertility clinics that would otherwise have been discarded because they carried mutations for genetic diseases. These lines, along with cell lines created elsewhere in Europe,.

Scientists hope to grow these stem cells into tissues afflicted by the disease, the better to assess and perfect treatments. (As of April 2007, none of these lines are eligible for U. S. government funding. ) Most embryonic stem cell lines are, though at least one company, in Singapore, is working on lines for exactly this purpose. Several US companies believe they can make therapeutic-grade cells from older lines. In 2007, multiple researchers reported that both mouse and human cells could be. Researchers believe for studying disease and potentially even cell therapy. As of mid-2008, these so-called induced pluripotent cells still need to be more extensively compared to embryonic stem cells, and the technique to make the cells requires permanently inserting multiple gene copies into the cells, making them more variable and less predictable.

Over a dozen countries have derived stem cell lines. Depending on the application they are intended for,. Every embryonic stem cell line is genetically distinct. Like the embryos they were made from, the lines are either male or female. Embryonic stem cell lines have also been created and grown under a variety of conditions. For all these reasons, stem cell lines behave differently in the lab. Some grow faster than others. A few lines are readily coaxed into heart cells, whereas other lines readily differentiate into neural stem cells and still others are particularly easy to maintain in culture.

In the United States, only research on human embryonic stem cell lines created before 2001 can receive federal funding. Of these, a dozen or less are in wide use. Many of these older lines have accumulated genetic flaws and don't grow as well as newer lines. Most researchers worry that the lines could be contaminated by the animal cells that they have been grown with; many researchers feel the lines don't grow well as newer lines. Moreover, at this time, the lines created for infertile couples reflect little racial or genetic diversity.

Governments around the globe have passed legislation to regulate stem cell research. In the United States, laws prohibit the creation of embryos for research purposes. Scientists instead receive leftover embryos from fertility clinics with consent from donors. Most people agree that these guidelines are appropriate. Disagreements surface, however, when political parties debate about how to fund stem cell research. The federal government allocates billions of dollars each year to biomedical research. But should taxpayer dollars be used to fund embryo and stem cell research when some believe it to be unethical? Legislators have had the unique challenge of encouraging advances in science and medicine while preserving a respect for life.

U. S. President Bush, for example, limited federal funding to a study of 70 or so hES cell lines back in 2001. While this did slow the destruction of human embryos, many believe the restrictions set back the progress of stem cell research. President Obama overturned Bush s stem cell policy in 2009 to expand the number of stem cell lines available to researchers. Policy-makers are now grappling with a new question: Should the laws that govern other types of pluripotent stem cells differ from those for hES cells? If so, what new legislation is needed?

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