Similarity between in vitro and in vivo cellular aging

In vivo and in vitro cellular aging were compared by determining the division capacity of individual, cloned cells of (1) the primary stromal population of human bone marrow, obtained from donors of various ages, and (2) the population at various passage levels of an in vitro subcultivated culture of the same origin. We find a strong similarity between the two series of data. This observation provides a further argument that cellular aging in vitro represents a biologically relevant phenomenon.