U.S. Scientists Find a Way to Create Embryonic Stem Cells With Adult Skin Cells
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This is SCIENCE IN THE NEWS in V.O.A. Special English. I'm Bob Doughty. And I'm Barbara Klein. This week, we tell how blood from crocodiles could help people. We also will describe an experimental treatment for burn victims.
But first, we tell how American scientists turned human skin cells into what appear to be embryonic stem cells.
Last week, scientists at Harvard University in Massachusetts reported progress in embryonic stem cell research. The scientists said they joined an embryonic stem cell with a normal skin cell to create a new embryonic stem cell. They said their method could provide a way to make embryonic stem cells without having to destroy fertilized human eggs called embryos.
The destruction of human embryos is hotly debated in a number of countries, including the United States. Many people object to experiments using human embryos for religious or moral reasons. American law restricts the use of federal money for research involving embryos.
Stem cells are able to develop into any other kind of cell or tissue. Those taken from embryos are considered the most useful. Researchers believe they could use embryonic stem cells to treat some diseases and even injuries.
The Harvard University said they joined, or fused, a skin cell with an embryonic stem cell. They said the fusing process caused the stem cell to reset the genes in the skin cell. In simple terms, the skin cell was changed into an embryonic stem cell.
Chad Cowan took part in the Harvard study. He says it should be possible to develop replacement cells or even grow organs from the newly created stem cells. But, he and other members of the Harvard team say such possible uses are many years away.
The scientists said they grew embryos from human eggs they received from a private organization. They also said they got similar results in experiments when they used embryonic stem cells federally approved for research. Mr. Cowan said he believes most people will find this way of producing embryonic stem cells morally acceptable.
The scientists still face a major problem. The cell contains two groups, or sets, of genetic information. One set is from the skin cell. The other is from the starter embryonic stem cell. For any medical purpose, doctors would only want the genetic material of the patient to remain.
Scientists in Switzerland say they have used skin cells grown from a fetus to treat burns in children. The scientists say their method can produce a quicker and more complete recovery than current treatments.
The British medical publication, The Lancet, reported the findings.
The burn patients were eight children between the ages of fourteen months and nine years. All eight had either burns of the highest severity or what experts call deep partial-thickness burns. The fetal cells came from a woman whose pregnancy was ended at fourteen weeks. The woman gave the scientists permission to use four centimeters of skin from her fetus.
The scientists let the fetal cells divide in a laboratory. Then they mixed the cells with the protein collagen. Collagen is a substance that enables skin to stretch. The scientists say this process can provide many small pieces of skin tissue.
The scientists placed some of the pieces on top of the wounds of the children. As the tissue cells weakened, they were replaced with other pieces of tissue every three to four days. The scientists say the process was not difficult. They simply covered the wound with a piece of cloth.
Usually, doctors use skin from other parts of a patient's body to repair damage from burns. However, those skin cells reproduce slowly and sometimes painfully. And, the new skin often looks strange. That process is called grafting.
Patrick Hohlfeld of the University Hospital of Lausanne led the study. He said his team expected the fetal tissue to work much the same way. But, he said they were surprised by how much better it treated the wounds.
The report says the wounds on the young burn patients healed in about fifteen days. Most graft treatments take six times longer. And, the scientists say the repairs were complete. Most patients recovered full use of their damaged body parts. Their progress was observed for up to two years after being treated.
Other researchers say the results of the Swiss experiment still need to be compared to current medical treatments for burns. They noted that no one knows if the burns on the children would have healed on their own without the fetal cell treatment.
Scientists in northern Australia hope to use blood from crocodiles to develop new medicines for people. The scientists have been collecting blood from live crocodiles after capturing them and tying their mouths closed. They put a small instrument in the back of the animal's neck to get the blood.
The scientists hope to separate antibodies from the blood and develop drugs for human use. Antibodies are proteins that attack diseases inside the body. The scientists say they hope their work leads to development of antibiotic pills and liquids that you could put on wounds.
Earlier studies found that several proteins in crocodile blood killed bacteria that resist the drug penicillin. Recent tests have shown that the proteins also can kill the virus that causes AIDS.
The scientists say a crocodile's defense system against disease is much more powerful than that of the human body's defense system. They say the defense system of the crocodile attacks bacteria immediately when the body is infected. The defense system reportedly joins with the bacteria and tears it apart.
Scientist Adam Britton has been collecting blood from both salt-water and freshwater crocodiles. He says scientists might need years to create any medicine for people because the animal's defense system is so powerful.
However, other scientists say the human defense system will recognize the crocodile antibodies as foreign and attack them. They say this could cause serious health problems.
Scientists say they have developed a new cancer drug. They have tested it in only in laboratory animals. The drug is designed to invade and kill cancer cells but not healthy cells. First, the drug enters the cancer and destroys the supply of blood. Then it releases poison to destroy the cancer cells.
Researchers at the Massachusetts Institute of Technology in Cambridge carried out the study. The results appeared in Nature magazine.
Ram Sasisekharan is a professor at M.I.T. He says his team had to solve three problems. They had to find a way to destroy the blood passages, then to prevent the growth of new ones. But they also needed the blood passages to supply chemicals to destroy the cancer.
So, the researchers designed a two-part "nanocell." The cell is measured in nanometers, or one thousand-millionth of a meter. The particle used was two hundred nanometers -- much, much smaller than a human hair.
The researchers say it was small enough to pass through the blood vessels of the cancer. But it was too big to enter normal blood vessels. The surface of the nanocells also helped them to avoid natural defenses.
The scientists designed the cell as a balloon inside a balloon. They loaded the outer part with a drug that caused the blood vessels to fall in on themselves. That cut off the blood supply and trapped the nanocell inside the cancer. Then, the nanocell slowly released chemotherapy drugs to kill the cancer cells.
The team says the treatment reduced the size of the cancer and avoided healthy cells better than other treatments. The scientists say mice with the best current treatments lived thirty days. But they say eighty percent of the mice treated with the nanocells lived more than sixty-five days.
The study involved two different forms of cancer. The team says the treatment worked better against melanoma, a deadly skin cancer, than against lung cancer. However, more studies are needed before the new drug can be tested in humans.
This SCIENCE IN THE NEWS program was written by Cynthia Kirk, Nancy Steinbach, and Caty Weaver. Cynthia Kirk was our producer. I'm Barbara Klein. And I'm Bob Doughty. Join us again next week at this time for more news about science on the Voice of America.