Entropy meets Physiology: should we translate Ageing as Disorder?

Ageing is characterized by an alteration of several physiological processes and biological pathways that leads to an incremented susceptibility to age-related diseases and death. Normally, multipotential stem/progenitor cells may contribute to tissues homeostasis, and to minimize the age-depending DNA damages. Scientific research has demonstrated that ageing induces several complex changes affecting even the Mesenchymal Stromal/Stem Cells (MSCs) ability to self-renew, differentiate, and immunomodulate the human tissues, causing further alterations also in the local microenvironment. Cellular senescence can thus be considered as an overall response to several damages. Accordingly, ageing seems to create the proper conditions to decrease the tissues metabolic performance, and the cell-to-cell communication, resulting in a progressive tissue destruction; on the other hand, the MSCs functions appear to be severely reduced. This concise review summarizes the main alterations affecting the MSCs during ageing, and it also explains the role of inflammation as a key-player in the age-related syndromes. The hypothesis is to suggest a parallelism among the thermodynamic concept of "entropy" and biological ageing, speculating that both can increase within irreversible systems and both lead towards an irreversible disorder; so, the question is: should we translate Ageing as Disorder?