Julho de 1997 Source: REUTERS
BALTIMORE (Reuter) - Scientists at Johns Hopkins University have developed the first laboratory cultures of human stem cells -- unspecialized cells that can grow to form all the different cells and tissues of the body.
The breakthrough may pave the way to the eventual laboratory production of human tissues, such as heart muscle or nerve cells, that have been lost to disease or injury, the researchers said in a release issued late Friday.
It could also allow scientists to introduce changes into the genetic code that are passed from one generation to the next, although any such research would be prohibited at Johns Hopkins.
Such ``germline'' mutations have already been produced in mice.
``We will not perform any experiments aimed at genetically engineering the human germline in my lab or anywhere at Hopkins -- it is not ethically acceptable,'' said Dr. John D. Gearhart, a professor of gynecology and obstetrics at Johns Hopkins and lead researcher on the project.
The developments were first disclosed during a session on the ethics of cloning and stem cell research at a recent International Congress of Developmental Biology.
Gearhart said he had chosen the forum so the process of establishing ethical guidelines for this type of research could begin immediately.
The human stem cell cultures were developed from tissues obtained as a result of pregnancy termination, Johns Hopkins said.
The researchers are working to develop the cell lines so they can be manipulated to grow desired tissues such as heart muscle, blood cells, or nerve cells, the university said.
``Based on results with animal studies, it seems likely that we will be able to alter the cells so that a patient's immune system will not recognize them as transplants and reject them,'' Gearhart said.
``If so, we would have a universal cell donor -- cells that could be transplanted to any recipient with little chance of rejection by the immune system,'' he said.
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