Age determination of tissues
In collaboration with Jonas Friséns group and Kirsty Spaldings group at CMB, Karolinska Institute, postmortem samples from autopsy cases have been collected, processed and subjected to a sensitive C-14 analysis in order to offer an age determination of different tissues. The strategy takes advantage of the changes of C-14 in the atmosphere caused by the above-ground test detonations of nuclear weapons during 1955-1963. Since C-14 is incorporated into living matter in relation to the content in the atmosphere, levels in nuclear DNA that are different from those at birth of the individual can be used to detect regeneration of cell populations. Using cell sorting, and isolation of carbon from chromosomal DNA, the specific age of cardiomyocytes in the heart ventricular wall, and of neuronal and non-neuronal cell populations in select brain regions, has been determined. These studies have provided evidence of a continuous turnover of cardiomyocytes, and of neurons in hippocampus. Also, these analyses have also shown that interneurons in striatum regenerate at a rate that indicates a functional significance, whereas no turnover was observed in the olfactory bulb or the neocortex in the adult human brain. The project also includes cell lineage studies to add to our understanding of the origin of different specialized cells. Studies are also carried out to evaluate the possible influence of various intrinsic and environmental factors on the renewal rates of discrete cell populations. These studies take advantage of the access to well-characterized human postmortem tissue samples procured and processed by KI Donatum.