Reacción a "Potentially fertilisable human eggs generated from skin cells"

According to research published in Nature Communications, human skin cells can be used to produce viable eggs. This pilot study demonstrates that cell reprogramming could be a possible way to treat infertility in humans, although further research is needed to ensure its efficacy and safety before clinical application.

One of the most common causes of infertility is low ovarian reserve with no egg production or poor egg quality, mainly due to the woman's increasing age. In these cases, assisted reproduction techniques are ineffective. Therefore, some researchers have proposed somatic cell nuclear transfer as an alternative. This process involves transplanting the nucleus of a somatic cell from the patient (such as a skin cell) into a donated egg from which the nucleus has been removed. However, while gametes (eggs and sperm) have half the set of chromosomes (23), somatic cells have 46 chromosomes, which would mean that when the egg is fertilised with the somatic cell nucleus, it would have an extra set of chromosomes.

A method has been developed to remove this extra set of chromosomes, which has been tested in mouse models, but its effectiveness has not yet been demonstrated with human cells.

In addition, another added problem is the reprogramming of somatic cells, which are specialised to perform a specific function in the organ from which they were obtained, in order to return to their point of origin, from which they can be transformed into functional cells of any organ in the human body.

Shoukhrat Mitapilov and his team extracted the nucleus from skin cells and inserted it into donated eggs with the nucleus removed. To solve the problem of the extra set of chromosomes, they induced a process called ‘mitomeiosis,’ which mimics natural cell division and removes one set of chromosomes, resulting in a functional gamete. The process yielded 82 functional eggs, which were fertilised in the laboratory. A small proportion of these fertilised eggs (approximately 9%) developed to the blastocyst stage at 6 days, although all embryos were genetically abnormal.

This study is of enormous importance, as it demonstrates that this process is potentially viable in human cells, opening the door to future research on this technique.

The authors point out several limitations in their study, such as the fact that most embryos did not survive beyond the fertilisation stage and the presence of chromosomal abnormalities in the blastocysts. In addition, they report the impossibility of distinguishing between developmental arrest due to chromosomal abnormalities and incomplete epigenetic reprogramming of somatic chromosomes. Since all embryos analysed had chromosomal imbalances, it is difficult to separate the effects of aneuploidy from reprogramming defects. The modest blastocyst development rate (8.8%) likely reflects the influence of both factors.

The success of nuclear transfer cloning depends on the elimination of somatic epigenetic programmes and the establishment of totipotency in cloned embryos; therefore, more thorough research is required to clarify possible reprogramming errors before considering its clinical application.

In addition, the important ethical considerations of the study must be taken into account. In fact, several years ago, the Ethics Committee of the American Society for Reproductive Medicine published a document presenting several ethical arguments against the use of somatic cell nuclear transfer for the treatment of infertility due to concerns about its safety, possible unknown effects on children, families and society, and the existence of other ethically acceptable methods of assisted reproduction.