THE ESSENTIAL
- The OSK genes helped reduce cell death in neurons that were already damaged.
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The aging of cells is due to various epigenetic modifications that damage the normal functioning of genes, which make up the genome. It is when the latter ages that the cell ages. Scientists then had the idea of reversing this degeneration, so that the genome and cells regain their youth. These researchers from Harvard University School of Medicine have just published their work in Nature magazine. –
To perform their experiments, the scientists used three genes: Oct4, Sox2, and Klf4 (a trio called OSK or reprogramming genes). They were selected because they are already used in the laboratory to perform cell dedifferentiation, that is to say the transformation of a differentiated adult cell into a stem cell in a state close to juvenile, called a pluripotent stem cell. But, as part of their work, the researchers used another technique: they modify the epigenetic markers of cells.
Mouse neurons have rejuvenated
In their number one experiment, they worked on the regeneration of neurons, via retinal ganglion cells, which are part of the optic nerve behind the eye. They carried out their experiments on mice, whose neurons have the particularity of regenerating when they are at the embryonic stage and after the birth of the animals. However, after some time of life, this ability disappears. But, here, they injected them with OSK genes, which made it possible to reduce the cell death of neurons that were already damaged and, above all, which allowed the creation of new neurons! With the OSK gene, they therefore succeeded in restoring the capacity of neurons in the embryonic and young form of the animal.
A real reversal of aging, which goes even further. Scientists also found that OSK genes could reverse the methylation process in retinal ganglion cells. This corresponds to the end of life of a cell. With the injection of the reprogramming genes, this process was reversed, essentially around the genes involved in light detection and synaptic transmission. In other words, these have rejuvenated.
Mice have regained the vision of their youth
As for vision, the subject of the second experiment, the researchers worked on glaucoma, an eye disease caused by aging. It is characterized by an increase in the pressure inside the eye, which damages the optic nerve. Gradually, patients lose their sight, to the point of blindness. Also thanks to the OSK genes, mice made sick for the experiment, regained 50% of what they had lost sight. Finally, in a final experiment, the scientists worked on one-year-old mice. They have 15% weaker vision than younger mice, five months old. The one-year-old animals therefore had injections of reprogramming genes for four weeks. At the end of this period, they could see as well as the younger mice.
These experiments prove that with injections of OSK genes, cells adjust their epigenetic changes, which in turn rejuvenates them. They become comparable to cells present in younger mice. But these results are not sufficient to be validated by the scientific community. In addition, cell modification involves many risks, including the appearance of certain cancers. Many experiments and clinical trials therefore still need to be validated before OSK genes are used as a treatment.
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