2013-09-29 19:03:31
One of the most fascinating properties of some animals is to completely regenerate severed parts of their bodies. If we think about it, however, we should not be too surprised by this ability. After all, most animals come from a single initial cell: the fertilized egg. This cell constitutes the starting point of a program, that is, a series of stages, of events, that happen in a spatial and temporal order, and that end up generating a complete organism, with its organs, limbs, systems… In this In this sense, the regeneration of, for example, an amputated limb, as can happen in the case of some amphibians, consists only of reactivating the part of the program that generated it in the first place. The mystery of regeneration is no greater than that of generation.
The animals with the most spectacular regenerative capabilities, however, are not amphibians, but planarian worms, of the genus Platyhelminths. Planaria worms of some species can be cut into slices – as if it were a small sausage – from head to tail. Well, each of these slices is capable of regenerating a complete worm (which, very unfortunately, does not happen with a chorizo, not even those with a designation of origin).
What worms regenerate…
Due to the interest in being able to stimulate even a primitive capacity for regeneration in some of our organs or limbs, which would undoubtedly be a great achievement in medicine, some researchers are dedicating a lot of effort to understanding the regenerative capabilities of planarian worms. The reason for this is found in the similarity of the molecular mechanisms that humans share with them and that, due to their importance for life, have been conserved for hundreds of millions of years throughout evolution. It is possible that we are still able to activate regenerative processes that we have dormant or silenced today, but that we have not completely lost during our evolution, just as birds, which descended from dinosaurs, can be genetically manipulated to generate teeth. It is, therefore, important to study what genes and mechanisms the extraordinary regenerative capacity of planarian worms is based on.
A good strategy to approach this study is to compare different species of planarian worms with different regenerative capacities, since not all of them can regenerate from slices cut from their bodies. For example, worms of two species of planarian, Dugesia japonica and Schmidtea mediterranea, can regenerate any sectioned part of their bodies several times, regardless of whether they are sectioned from top to bottom or from left to right; However, three other species of planarian do not possess such extraordinary regenerative abilities and are, among other things, unable to regenerate the head from a tail fragment, if the worm has been cut beyond two-thirds of its length. Measurement is from the head. What genes and proteins are responsible for these differences, which may also be responsible for explaining the little or no regenerative capacity of humans and other animals?
… let the citizens enjoy it
Three groups of researchers study this topic in each of the three species of planarian with the lowest regenerative capacity and publish their results in separate articles in the journal Nature. The three research groups agree on important findings. The first of them is that the healing process of the cuts made to the regenerating worms leads to the formation of a structure called blastema. The blastema is also formed in amphibians or other animals with regenerative capabilities. Apparently, this structure somehow replicates the embryonic formation process; restarts the formation program of organs and tissues, including that of nervous tissue.
But, without a doubt, the most transcendental finding in which the three research groups converge is that of the identification of the most important gene for the regenerative process to occur correctly. This is the Wnt gene, an old acquaintance of cancer researchers, since it is homologous to one of the first oncogenes – or tumor-causing genes – that was identified in breast cancer. It may seem surprising, but it is not so surprising when we think that cancer is a process of cellular growth, although disorderly, that could perhaps become a regeneration process if it happened in an organized and orderly manner, as happens in planarian worms and others. animals.
Who knows, perhaps understanding the cancerous process will also help to understand the regenerative process and modify it, and vice versa. In this sense, two of the three groups mentioned find that by modifying the levels of functioning of the Wnt gene in species of planarian worms with low regeneration capacity, they increase it very significantly and are now capable of completely regenerating, head included, from a small fragment of tail.
Although carried out with worms, these experiments shed new light on the mechanisms of regeneration and largely reveal its genetic and molecular actors. It is one more step towards achieving the dream of regenerating sick or amputated limbs or organs, and thus also regenerating the happiness and quality of life of many people.
WORKS BY JORGE LABORDA.
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