This is Sarah Long.
And this is Bob Doughty with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today we tell about research using special cells called stem cells.
Two months ago, President Bush approved limited federal government support of research on special human cells. The research involves stem cells taken from fertilized human eggs called embryos. Stem cells have qualities that may make them highly useful in the treatment of many diseases. The stem cells from embryos are the most useful. They are able to develop into all the kinds of tissues of the body. Scientists believe stem cells may be used to cure many diseases.
President Bush placed restrictions on government support for stem cell research. The Bush administration approved research on sixty-four groups of embryonic stem cells. These stem cell groups are in laboratories in the United States and several other countries. American government researchers are permitted to study only these embryonic stem cell groups. Private laboratories that do not use federal money are not affected by the limits on stem cell research.
Many groups disagreed with the president’s decision. Many scientists and some lawmakers believe there should be no limits placed on stem cell research. Also, some religious groups are concerned about government support for stem cell research. They believe all research on stem cells from embryos should be banned. Some groups oppose the research because they believe it takes human life.
There are many questions about the embryonic stem cell groups approved for research. Some scientists are concerned that not enough cell groups have been approved for research. Last month, Secretary of Health and Human Services Tommy Thompson said that only about twenty-four groups of embryonic stem cells were ready for research.Now, many scientists are also concerned that the approved groups of cells may not be pure or may not survive.
There are three kinds of stem cells. They are adult stem cells, embryonic stem cells and embryonic germ cells. Adult stem cells are taken from human tissue. Medical researchers have known for about forty years that these stem cells can create blood-making tissue.
However, scientists from the National Institutes of Health say that adult stem cells may not be as useful as other kinds of stem cells. They say adult stem cells are difficult to identify. The scientists do not believe that adult stem cells can reproduce themselves in large numbers.
Also, some health officials say there is no evidence that adult stem cells have the ability to become cells of any kind of organ or tissue. Most research appears to show that adult stem cells are limited in their abilities to treat disease.N-I-H researchers say that the most useful kinds of stem cells are taken from fertilized human eggs, or embryos.
Embryonic stem cells are taken from embryos created in laboratories to help women become pregnant. Scientists take embryonic stem cells from embryos that are four to five days old. During these first days, the cells in the embryo divide quickly. For a short period, each of the embryo’s cells is able to become any one of more than two-hundred different kinds of cells in the body.
The great value of embryonic stem cells appears to be their ability to reproduce in large numbers in the laboratory before they become specialized cells. Scientists call a group of stem cells taken from one embryo a line. Some stem cell lines have reproduced for up to two years and have increased their numbers several hundred times.
Scientists in many countries are currently doing research on lines of stem cells that continuously reproduce as unspecialized cells. Researchers hope to grow large numbers of these unspecialized cells in the laboratory. These cells can then be treated and purified so that they can be used to cure diseased tissue.
Researchers believe that embryonic stem cells may be used to help diseased organs develop healthy cells again. They hope that these stem cells can be used to treat diseases of the brain, heart, liver, pancreas and kidneys. These include diabetes, Parkinson’s disease and Alzheimer’s disease.
The third kind of stem cell is called an embryonic germ cell. These cells are taken from the unformed reproductive organs of five-to-ten-week-old fetuses. Embryonic germ cells do not reproduce as many times as embryonic stem cells. However, both embryonic stem cells and embryonic germ cells show an ability to change into many different kinds of cells. Yet stem cell research presents special problems. Some of the problems are scientific. Some are not.
A report by a group of top scientists warns that there are many difficulties in using stem cells for medical treatment. The National Academy of Sciences report notes that embryonic stem cells must be treated to become human tissue. However, the patient’s body may reject such tissue because the genetic material is different.
Scientists must develop other technologies to keep the body from rejecting new biological material from stem cells. The medical use of stem cells may still be far in the future. Yet currently approved embryonic stem cell lines may become too old in the years to come. Genetic change over time presents a major problem to stem cell researchers.
Last month, scientists at the University of Wisconsin announced that they had made human embryonic stem cells into blood cells. The human stem cells were grown with blood-making cells from mice. The human stem cells then developed into red and white blood cells and other cells found in human blood.
This successful experiment shows the difficulties involved in current stem cell research. Many experiments using human stem cells also involve biological products from animals.
Scientists from the National Academy of Sciences note that most embryonic stem cell lines are grown along with special cells from mice. Many published studies show that stem cell experiments at this time involve the use of biological material from mice, cows and monkeys.
For this reason, the National Academy of Sciences report calls for new embryonic stem cell lines to be developed. The report says that current stem cell lines may carry health risks because they have been developed using animal cells.
Other problems involving stem cell research are not scientific. In Nineteen-Ninety-Eight, a scientist at the University of Wisconsin first grew human embryonic stem cells in a laboratory. A biotechnology company called Geron (JERR-on) Corporation of Menlo Park, California provided much of the money for the early research.
Since then, Geron Corporation has sought legal rights to all products that come from research done by the University of Wisconsin. The university does not believe that its agreement with the company includes all of its discoveries.
Recently, the University of Wisconsin asked a court to limit Geron’s claim on its research. The legal dispute between these two groups could reduce the number of stem cell lines that researchers can use.
Another important part of the debate over stem cells involves religious beliefs. Many religious groups oppose all embryonic stem cell research. They consider it the same as taking human life.
In July, Pope John Paul the Second told President Bush that the Catholic Church opposes all forms of stem cell research. In the United States, the Southern Baptist Church and the United Methodist Church also strongly oppose the research.
Other religious groups accept the research with several restrictions because it may lead to cures for some diseases. A large organization of Jewish clergy generally supports stem cell research. The American Presbyterian Church also supports the research.
The debate over embryonic stem cell research is complex and will continue for some time. Scientists hope that stem cells will some day be used to treat disease. Yet new technologies must still be developed before such treatments can be used. However, experts say no solution can be reached easily because this research involves morality as well as medicine.
This SCIENCE IN THE NEWS program was written by Mario Ritter. It was produced by George Grow. This is Bob Doughty.
And this is Sarah Long. Join us again next week for more news about science in Special English on the Voice of America.