Retrospective Birth Dating of Cells in Humans
SummaryThe generation of cells and its regeneration (cell turn over) in human body has been a major area of research. Several studies have been conducted using molecular markers of proliferation to calculate the age of the cell and its regeneration.
C-dating in archeology is used for determining the age of the biological material. Similar to this method, it is possible to retrospectively determine the age of cells without the need for delivering any chemical to the individual. 14C in the atmosphere reacts with oxygen and forms CO2, which enters the biotope through photosynthesis and then human body through their consumption of plants and the animals that live off plants. Extensive testing of nuclear weapons between the mid 1950s and early 1960s resulted in the generation of large quantities of 14C, which rapidly distributed evenly in the atmosphere around the globe. Similarly, the level of 14C present in genomic DNA closely parallels atmospheric levels and can be used to establish the time point when the DNA was synthesized and cells were born. The dramatic increase in atmospheric 14C levels and the subsequent exponential decline have resulted in different amounts of 14C being integrated into the DNA of cells depending on the time point the DNA was synthesized which can be used to establish the age of cells. This strategy is used to determine the age of cells in the cortex of the adult human brain, particularly the occipital neurons that are as old as the individual. These cells are not exchanged as the nonneuronal cells in the brain. Retrospective birth dating is a generally applicable strategy to measure cell turn over in man under physiological and pathological conditions. Analysis of cell turnover in different pathologies may further the understanding of certain diseases.
Kirsty L. Spalding, Ratan D. Bhardwaj, Bruce A. Buchholz, Henrik Druid and Jonas Frisén, Retrospective Birth Dating of Cells in Humans. (2005) Cell, Vol. 122, 133–143, July 15, 2005,