The immune system of elderly mice was rejuvenated thanks to a therapy based on antibodies directed against blood stem cells, which change during aging. The technique, described in the journal Nature, was developed by the research group coordinated by Irving Weissman of the American University of Stanford, but before determining whether this approach can also be used in humans, preclinical and clinical studies will be needed. One of the characteristics of the immune system associated with aging is a change in the behavior of so-called hematopoietic stem cells (Hsc), which give rise to all types of blood cells, including white blood cells.
While you are young, HSCs produce both the so-called lymphoid and myeloid cells, two distinct types of white blood cells, in a balanced way, but as age advances a change is observed: there is an imbalance towards the production of myeloids. Precisely this greater quantity of myeloids would be the basis of two elements visible with aging, such as greater inflammation and reduced adaptive immunity, i.e. the specific responses that are activated against new pathogens. To better understand the phenomenon, American researchers have developed antibodies which, in mice, are able to selectively target aged Hsc, thus leading to a new balance between lymphoid and myeloid cells and restoring the balance present in young people.
This therapy led to a better response to viral infections in elderly mice and reduced inflammation, so that they were effectively rejuvenated. But the changes in the balance between the two types of lymphocytes, the researchers themselves warn, could also be connected to other aspects, for example the increase in lymphoids with age could increase the development of tumors, in particular leukemia. Possible future therapies for rejuvenating the immune system, therefore, will require in-depth studies in both the preclinical and clinical phases.
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