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 high peak of C-14 in the atmosphere that caused ny the above-ground test detonations of nuclear weapons during 1955-1963, lending the method a high resolution. 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, albeit at a low level, in the adult left ventricular wall of the heart. Whereas the search for evidence of neurogenesis is still on-going, studies on the neocortex have shown that the nerve cells there are as old as the individual. The focus is now on hippocampus and olfactory bulb, regions known from animal data to show adult neurogenesis. In parallel, immunohistrochemistry with various markers of neurogenesis is carried out to explore the pattern compared to th radiocarbon dating. These studies take advantage of the access to well-characterized human postmortem brain samples procured by KI Donatum.