How do stem cells age?
Like the car you drive, your stem cells accumulate wear and tear over time. Storing your young stem cells can ensure they remain undamaged even as the years pass.
Each time a stem cell divides, DNA may be damaged as it is replicated and split between the two new cells. Older stem cells have not only gone through more divisions, but they produce less helicase proteins that protect DNA from damage during the replication process.Nature. 2014; 512(7513):198-202.
Mitochondria produce ATP, which is used by the cell for energy. However, the process of producing ATP involves reactive oxygen species, that damage the mitochondria over time. Damaged mitochondria produce less ATP, and provide less energy to older stem cells.Biochim Biophys Acta. 2015; 1847(11):1380-6.
Diminished actin turnover
Actin is a structural protein critical to stem cell division and function. Aged stem cells replace actin more slowly than younger ones. This decreased actin turnover leads to less efficient cell division, and an impaired ability of the stem cell to respond to its environment.Subcell Biochem. 2012; 57:331-52.
The ends of DNA are capped with repeating regions called telomeres that protect the coding region of DNA from damage during division. Over time, the telomeres of stem cells grow shorter, and as a result, the risk of DNA damage with each cell division grows.Curr Aging Sci. 2014; 7(3):161-7.
In response to accumulating damage to their DNA and organelles, stem cells produce tumor suppressor proteins that instruct the cell to cease dividing. This important safety mechanism, which prevents stem cells from becoming tumors, leads to the loss of stem cells with age.Cell Stem Cell. 2013; 12(2):152-65.