If you asked us a couple of years ago if there was any hope for the cure or treatment of mitochondrial diseases, the answer would have been, unfortunately, no, “not yet.” However, since last summer everything has changed. Thanks to science, we can finally glimpse in the distance, a halo of hope for this group of diseases that today have no cure.
In July 2020, a scientific study was published in the journal Nature that provides important answers that invite us to continue researching and working on the approach, treatment and cure of mitochondrial diseases; diseases that in turn, are included within the so-called rare diseases that this Sunday, February 28, celebrate their world day
But before explaining what this genetic advance in mitochondrial diseases consists of, let us first tell what these diseases are that mainly affect children and cause significant damage to many organs of the body.
Mitochondrial diseases
Worldwide, some 7,000 rare diseases have been described, that is, diseases that affect only five out of every ten thousand inhabitants. However, they may not be as infrequent as we think: in Spain alone, 3 million people live with a rare disease, which is a great impact for those affected and their families.
In the specific case of mitochondrial diseases, these affect 1 in 5,000 births, according to the MencĂa Foundation, and “are produced by mutating the DNA of the mitochondria and are characterized by the deterioration and dysfunction of fundamental organs, which it leads to serious health problems and premature deaths. ” It is key, therefore, to explain that mitochondria “are constitutive parts of the body’s cells, whose function is to generate the energy necessary to maintain life and for the development and correct function of organs and systems”, as exposes the Spanish Federation of Rare Diseases (FEDER).
We can say, therefore, that mitochondrial diseases are the result of the failure of the mitochondria to function. In addition, and according to the Association of Mitochondrial Pathology Patients (AEPMI) in this article on its website, they are genetic, chronic and degenerative diseases and “seem to cause the greatest damage to cells of the brain, heart, liver, muscle, kidney and endocrine and respiratory systems, because they are the organs with the greatest energy needs, especially the nervous system, muscles and heart “.
Hopeful treatment
95% of all rare diseases still need effective treatment options and mitochondrial diseases are one of them. As stated by the AEPMI, “all those affected by these diseases depend on medical and pharmacological advances, which are completely linked to research”. At present, as we have said, these mitochondrial diseases do not have a cure but only treatments that are targeted, maintains the AEPMI, to alleviate symptoms and delay the progression of the disease. But today we can say that a giant step has been taken, or at least a really important step in the knowledge of this disease.
As explained to EL ESPAĂ‘OL Lluis Montoliu, a scientific researcher at the National Center for Biotechnology (CNB-CSIC), until today, it was not possible or it was very difficult to reach the genome of the mitochondria – towards the interior of it – to be able to make changes to your DNA, not even with CRISPR gene editing techniques, better known as genetic scissors and genetic cutters.
CRISPRs, explains Montoliu, who is one of the leading experts in this technique, “are very versatile and work and work for almost everything, except for the mitochondria. The least they work is in the mitochondria.” That is, these gene editing techniques “cut and modify” any sequence in the genome of any cell, but they are not capable of reaching the mitochondrial DNA (which is inherited from the mother only).
Now, it is possible to reach the DNA of the mitochondria, as a result of another gene editing technique older than CRISPR, the so-called TALENs. As Montoliu explains, the scientist David Liu, a researcher at the Broad Institute of MIT and Harvard (USA), it occurred to him to enter (the mitochondria) by another way than CRISPRS, through the aforementioned TALENs. The researchers combined this technique with a complex chemical action that resulted in a new editing tool or system they called “DdCBE.” (Here the study published in July 2020 in the journal Nature).
As stated by the FundaciĂ³n Mencia in this article in a more precise and technical way, “this editing system uses a modified bacterial toxin and specific DNA binding proteins”, and is capable of “accessing the interior of the mitochondria, which until now it was a technical barrier to other genome editing strategies. ” This finding finally provides a method and a line of work for the study of mitochondrial diseases.
This new tool or strategy – Montoliu comments – “gives hope that it will be possible to modify the mutations of the mitochondria, since until now it could not be done”. In addition, and more generally, “now we know that the response of mitochondrial diseases is not or will not be the CRISPR, but the TALEN; but this does not matter. The important thing is that there are tools that serve, but for this we would have to discover them and validate them. And this is what these American researchers have done at a preliminary level. “
However, there is still a long way to go to be able to apply this to any therapeutic field, there is still a long way of research to develop; But this certainly opens a door to optimism for the cure and treatment of mitochondrial diseases. “It is a very early stage of the research, but there is a certain and real hope, because without this study we could say that it is not possible to modify the mitochondria genome at will or it is very difficult, but with this study already published, we can say that yes, that at least, there is hope “, concludes Montoliu.
