Slowing Down of the Cell Cycle During Fibroblast Proliferation

During serial proliferation, the cell division cycle of normal human fibroblasts slows down due to several modifications in the cycle. It is now accepted that these modifications are associated with the cell ageing that occurs in vivo, which can also be reproduced in vitro. The slow down is due to different cycling characteristics, of each of the four fibroblast types that become progressively apparent during cell replication. Attempts were made to identify an event that could explain it all. However, among the plethora of functional changes that can be observed at the cellular, sub-cellular and molecular levels, none are likely triggers for the slow down of proliferation. There is, however, a basic phenomenon that is associated with the changes of the cell cycle, and can be identified to a great extent with the decreased probability of initiating and transiting the division cycle. It is the evolution of cell volume that is different for each of the four fibroblast types, and concerns the biology of conformation – a subject that has been neglected in the field of cell ageing, and is explained herein.