Telomeres and Haemopoetic Stem Cells

Stem Cells exhibit an extraordinary capacity for differentiation into other types of cells. They can practically any cell in the body with the proper treatment. However, the ability of stem cells to renew does decline as a person ages. A telomere is a specific region of DNA that repeats. It is located at the end of the chromosomes. Telomeres protect the end of the chromosomes from being destructed after a cell undergoes cell division. As time goes on and cells go through more division cycles, the telomeres begin to shorten. This limits a cells dividing capacity and this may be a cause of cell aging. Cells can no longer be replenished and the older ones die off, not to be replaced. Holmes et al. have recently investigated telemore dynamics in haemopoietic stem cells. Here is the abstract from the paper.

Telomere length dynamics differ in foetal and early post-natal leukocytes in a longitudinal study

Haemopoietic stem cells (HSC) undergo a process of self renewal to constantly maintain blood cell turnover. However, it has become apparent that adult HSC lose their self-renewal ability with age. Telomere shortening in peripheral blood leukocytes has been seen to occur with age and it has been associated with loss of HSC proliferative capacity and cellular ageing. In contrast foetal HSC are known to have greater proliferative capacity than post-natal stem cells. However it is unknown whether they undergo a similar process of telomere shortening. In this study we show a more accentuated rate of telomere loss in leukocytes from pre term infants compared to human foetuses of comparable age followed longitudinally for 8-12weeks in a longitudinal study. Our results point to a difference inHSC behaviour between foetal and early postnatal life which isindependent of age but may be influenced by events at birth itself.