Retrospective birth dating of cells in humans

These two areas have been named “neurogenic” because they are now widely believed to support adult neurogenesis.

However, similar evidence has been reported for “non-neurogenic” brain regions, including the neocortex, striatum, amygdala, hypothalamus, and substantia nigra (6,7,9,12,30,32).

Analysis of growth rings from pine trees in Sweden shows that the proliferation of atomic tests in the 1950s and 1960s led to an explosion in levels of atmospheric carbon 14.

The high turnover of adipocytes establishes a new therapeutic target for pharmacological intervention in obesity.The excitement stemmed only as far as the academic climate, however.There was no way to find out if these animal studies reflected what happens in humans since approaches such as Brd U labeling used for cell birth-dating in animals are toxic.To establish the dynamics within the stable population of adipocytes in adults, we have measured adipocyte turnover by analysing the integration of .Approximately 10% of fat cells are renewed annually at all adult ages and levels of body mass index. ; DRUID Henrik ; FRISEN Jonas ; The generation of cells in the human body has been difficult to study, and our understanding of cell turnover is limited.Retrospective birth dating is a generally applicable strategy that can be used to measure cell turnover in man under physiological and pathological conditions. Because this test can be used retrospectively, unlike many of the current methods used to detect cell proliferation, and because it does not require the ingestion of a radioactive or chemical tracer, the method can be readily applied to both in vivo and postmortem samples of human tissues.In today’s Cell, Frisen and colleagues report how they used the dating method to dismiss the possibility that neurogenesis takes place in the adult human cortex.About 40 years ago, Joseph Altman and his colleagues used the 3H-thymidine autoradiographic method to birthdate cells in the brains of adult rats and cats, and reported evidence for neurogenesis in the olfactory bulb, hippocampus, and neocortex (1-5).These findings were corroborated and extended by Michael Kaplan and his colleagues by combining 3H-thymidine autoradiography with electron microscopy (16-19).