The brain works thanks to a network of 90 billion neurons, which unfortunately can only regress after having reached the maximum development. Although some areas have a faster decline than the others, on average we lose about 10% of grey matter and white matter every 10 years. Our reasoning skills therefore reach the maximum after twenty years and then decline inexorably. There are many neurodegenerative pathologies, and one of these is Alzheimer. Fortunately, today, thanks to the stem cells growth and differentiation factors taken at specific stages of embryonic life, it is possible to stop cellular senescence and thus prevent neurodegeneration.
Studies on the epigenetic code functioning have made it possible to understand that what was being studied was in fact the regulation code of genes expression, which is present in its entirety and with all its various functions whenever a life is formed. In fact, this code, though segmented and divided into different stages of differentiation, could still be studied and understood in its full operation. Indeed, whenever all the substances present at all different differentiation stages were obtained, we would have had the entire epigenetic code available, that is the code that can regulate all the genes of all the cells that make up an entire organism. In other words, we would have had the whole code, which regulates life: the “Code of Life”. The possibility of studying the entire epigenetic code exists only in the embryo and only in the period when differentiation of all organs and apparatus occurs. In that moment starting from a single totipotent stem cell (the fertilized egg) a differentiation of all types of stem cells through different stages occurs: pluripotent, multipotent, oligopotent stem cells, cells in progress of definitive differentiation and finally fully differentiated cells. After the completion of organogenesis it is no longer possible to study the entire epigenetic code at its whole extent and in its different functions. When indeed the organogenesis is complete, the epigenetic code is subdivided into various organs and tissues and each organ contains that part of the code that serves to control and regulate the gene expression of the cells of this specific organ. Therefore the opportunity to study all the different and amazing functions of the “Code of Life” no longer exists. Thus only at the time when it was decided to study the epigenetic regulation code, i.e. the period of differentiation of various organs and apparatus, it became possible to study all the different and incredible regulatory abilities of that code. And that is what has been done, starting from choosing a specific embryo as a model for cell differentiation study: in this case it was chosen an embryo of Zebrafish.