Articles

Therapeutic cloning to obtain stem cells


If instead of inserting in an uterus the egg whose nucleus has been replaced by one of a somatic cell, we allow it to divide in the laboratory, we have the ability to use these cells - which in the blastocyst phase are pluripotent - to manufacture different fabrics.

This will open fantastic prospects for future treatments because today only cells with the same characteristics of the tissue from which they were taken can be grown in the laboratory. It is important for people to understand that in cloning for therapeutic purposes only tissues will be generated in the laboratory without implantation in the womb.

It is not a matter of cloning a fetus within a few months into the womb and then removing its organs as some believe. There is also no reason to call this embryo egg after the core transfer because it will never have this destiny.

A survey published in the magazine Science by a group of Korean scientists (Hwang et al., 2004) confirms the possibility of obtaining pluripotent stem cells by the technique of therapeutic cloning or nucleus transfer. The work was done thanks to the participation of sixteen women volunteers who donated a total of 242 eggs and "cumulus" cells (cells that surround the eggs) to contribute research aimed at therapeutic cloning. the cells cumulus, which are already differentiated cells, were transferred to the eggs from which the nuclei themselves had been removed. Of these, 25% were able to divide and reach the blastocyst stage, thus capable of producing pluripotent stem cell lines.

Therapeutic cloning would have the advantage of avoiding rejection if the donor were the person himself. It would be the case, for example, to replenish the marrow in someone who became paraplegic after an accident or to replace heart tissue in a person who had a heart attack. However, this technique has its limitations. The donor could not be the person himself when it was someone affected by genetic disease, because the pathogenic mutation causing the disease would be present in all cells. If someone else's embryonic stem cell lines were used, there would also be the problem of donor-recipient compatibility. This would be the case, for example, for someone affected by progressive muscular dystrophy, as their muscle tissue would need to be replaced. He could not use his own stem cells, but a compatible donor that could possibly be a close relative.

Furthermore, we do not know whether, in the case of cells obtained from an elderly person affected by Alzheimer's disease, for example, whether the cloned cells would be the same age as the donor or if they were young cells. Another open question concerns the reprogramming of genes that could make the process unfeasible depending on the tissue or organ to be replaced.

In summary, as much as we are in favor of therapeutic cloning, it is a technology that needs a lot of research before being applied to clinical treatment. For this reason, the great hope in the short term for cell therapy, comes from the use of stem cells from other sources.

References: HWANG, S. W .; RYU, Y. J .; PARK, J. H .; PARK, E. S .; LEE, E. G .; KOO, J.M. et al. "Evidence of a Plurpotent Embryonic Stem Cell Line Derived from a Cloned Blastocyst". Scienceexpress, Feb 12 2004

Text adapted from Zatz, Mayana. "Cloning and stem cells". Cienc. Cult., jun. 2004, vol.56, no. 3, pp. 23-27, ISSN 0009-6725.