| Tuesday, March 20, 2007 |
| STEM CELLS |
1). WHERE THE STEM CELLS COME FROM
Until recently, there were two main sources of cells. Now amniotic fluid may priovde another option. How the different methods stack up:
Amniotic Cells
Source:
Amniotic-fluid stem cells are collected by amniocentesis, in which some of the fluid surrounding the fetus is drawn out through a hollow needle inserted into the uterus. The cells can also be taken from the placenta or from tissues shed after birth.
PROS AND CONS:
Amniotic cells are hardy and pluripotent (they can grow into a variety of cel types), and reproduce quickly in the lab. Additionally, the way they're collected may allow scientists to sidwstep ethics debates. But amniocentosis carries a slight risk for the mother and child.
Embryonic Cells
Source:
Typically gathered from the inner cell mass of a 4 to 5 day old embryo (still a microscopic ball of cells at that stage), the embryonic cells are taken only from embryos that were fertilized in a lab and donated for research.
PROS AND CONS:
Their major drawback involves ethics: removing embryonic stem cells destroys the embryo. Otherwise, the cells are pluripotent and multiply rapidly.
Adult Cells
Source: In an adult's body, stem cells work to maintain and repair the tissues in which they're found, such as the brain,liver, bone marrow, skeletal muscle and blood vessels. But the cells are relatively rare, and collecting the large numbers needed for research can be difficult.
PROS AND CONS:
Adult stem cells are often able to grow only into their tissue of origin, making them less versatile.
2). HOW STEM CELLS WORK
By directing the way stem cells become specialized (called differentiation), scientists can choose which type of cells they create.
HARVESTING THE CELLS:
The stem cells are first gathered by one of the methods above. The number of cells collected depends on the method used.
PROLIFERATION:
A small number of stem cells can yield millions after several months. Large numbers of cells are needed for any practical use.
DIFFERENTIATION:
Scientists use chemicals or modify the cell's genes to induce the stem cells to become the desired type of specialized cells.
HOPES FOR THE FUTURE
Scientists are currently exploring the ways in whcih stem cells can be used to replace damaged cells with healthy ones. But among the most promising areas of research is how stem cells maybe used to rejuvenate tissues in patients with degenrative diseases such as Parkinson's. Though a remedy remains far off, stem-cell research offers some hope and insight into how a cure might work.
(Source: Abstracted from NEWSWEEKMAG/National Institute of Health News Reports) |
| posted by infraternam meam @ 9:10 PM |
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