A group of Korean Scientists reported on February 12 that they had successfully isolated an embryonic stem cell line from cloned blastocysts. Many newspapers reported it as the "successful cloning of a human embryo." In many people's minds, this "human embryo" is probably pictured as a human fetus that you would see on a sonogram. Scary, isn't it?
What has really been done by these Koreans? Basically, they took out the nucleus from a human oocyte, and replaced it with the nucleus they had isolated from a somatic cell. The oocyte then became a zygote without going through the fertilization process. The cytoplasm of the host oocyte would suppress the expression of the somatic cell genes and activate the embryonic ones. If cultured in optimal condition, in theory, the embryonic cell would develop into a human being, as a natural embryo does.
Of course, these scientists did not go that far, because of their country's legal restrictions. But they did culture the zygote in vitro, and developed it into an embryonic blastocyst. Then they isolated stem cells from the inner cell mass of the blastocyst and cultured the established stem cell line in different cultural conditions to help it differentiate into different human cells. They were successful.
What is the therapeutic benefit of this research? Let's take organ transplantation as an example. Because of the so called immune rejection, one's immune system would usually attack foreign organs or cells transplanted into one's body, which would lead to futile organ transplantation. However, using this new technique, the scientists can isolate the nucleus from a patient's somatic cell and inject it into a host oocyte whose nucleus has been taken out. This engineered oocyte then can be developed into an embryonic blastocyst. Stems cells can be isolated from the inner cell mass of this blastocyst and cultured under appropriate condition for developing into the organ the patient needs. Since this cloned organ has the same genetic material as the patient, little to no immune rejection should occur upon transplantation.
These scientists did flirt with the idea of human cloning. They cultured the isolated stem cells in suspension to form embryoid bodies, and they found that the stem cells differentiated into a variety of cell types. They also injected the stem cells into the testis of mice and identified tetranomas later in those testises containing human tissue representative of all three germ layers.
Nevertheless, being able to isolate stem cells from a cloned embryonic blastocyst is not equivalent to cloning a human. The real question is how far we are. But who would know the answer? The real alert from this scientific report is not that we are getting closer to cloning human, but that somewhere in the world, scientists may be doing things we have no way of knowing. We may be much closer than we think to human cloning.
But the research will go on. The scientists say they are doing this for "therapeutic purpose." They warn the world not to use this technique for the purpose of cloning of human. But once the technology is available, who is in the position to restrict its use?