When a July 5 20 years ago was born Dolly, the cloned sheep, many hailed the takeover of the human being on DNA in anticipation of future developments, for example in the field of organ transplantation.
Other instead trembled before the advent of a world of identical beings raised as spare parts. Actually, none of that happened.
Human cloning, a complex, risky and ethically questionable process was eventually replaced by other technologies as a source of regenerative medicine.
“No produced what was expected, “said Rosario Isasi, of the Institute for Bioethics and Health Policy at the University of Miami
.” there was a moment of euphoria: it was thought that finally would be able to better understand the mechanisms of disease, use as a treatment for infertility, “he told AFP. “It was not like that.”
Dolly, the world’s most famous sheep, was the first mammal cloned by nuclear technique called Transfer Somatic Cell (SCNT).
involves removing the nucleus of the cell with the corresponding DNA of a cell other than an egg or sperm cell –a skin, for example- and implanting an unfertilized ovum, which previously removed the core.
in the case of Dolly, the cell was taken from a mammary gland.
After the transfer, the egg reprograms an embryo from DNA that begins to develop as a child of one progenitor.
It is not known at the date of such cloning humans.
Risk climbing
there is a global opposition to human reproductive cloning.
Aside from ethical objections and human to the creation of human beings as photocopies rights, there is also a security issue .
Only a handful of cloned animals survived the birth, and many had health problems later.
experts believe that moral opposition to cloning as a reproductive technique has dimmed in review the potential benefits of this technique in the field of regenerative medicine.
usually, people fear that scientists are unable to resist temptation.
“once defining the limits of safeguards, there is no way diverted to the reproductive applications, “says however Isasi.
Still, many people” feared to have a slip, that one thing leads to another, until something bad happens. That is the main concern that has prevented the use of technology “.
Investments in cloning research have declined and few countries-among them Belgium, China, Israel, Japan, South Korea, Britain and Singapur– authorize the creation of embryos for experimental purposes. in the United States, is not explicitly illegal.
in therapeutic cloning, scientists harvest stem cells from an embryo in its early stages or blastocyst, an aggregate of between 100 and 200 cells.
Targeting these cells into specialized development of liver or blood cells, for example, can help cure certain diseases or repair damaged organs.
As are raised from the own patient’s DNA, dramatically reduces the risk of transplant rejection.
However, producing stem cells in this way involves destroying embryos, another moral dilemma.
And while some scientists were able to create stem cells from SCNT, none managed to develop as a functional human organ.
Regardless of embryos
cloning may not have found direct application in medicine, but nevertheless prompted the development of other technologies, such as induced pluripotent stem cells. It is to develop specialized cells making date back to levels of previous development, which eliminates the need for recourse to embryos.
This technique, rewarded with a Nobel, has focused the attention of regenerative medicine, although not of all it established that the resulting cells function as stem cells obtained from embryos
Another ramification is the transfer of genes through mitochondria, which allows implanting DNA in a healthy egg to create an embryo that is free of abnormal mutations that could lead to the mother.
Aaron Levine, a specialist in Bioethics at Georgia Tech, said the biggest impact of cloning on human health likely comes from animals specially bred to produce organs, tissues or biological drugs that are not rejected by the human immune system.
“I think that human cloning will disappear,” he said. “There simply is not enough demand, there is not much one can do with cloning that can not be done otherwise.”
AFP
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