Research Perspective Volume 2, Issue 4 pp 224—230

Figure 1. Continuous gene-expression changes in MSC upon long-term culture. MSC from human bone marrow were expanded for 11 passages and analyzed by Affymetrix GeneChip technology. Differential gene expression was always determined versus P2. Hierarchical cluster analysis of all expressed genes (19,448 ESTs) revealed continuous changes with higher passages. Hence, molecular changes in replicative senescence do not suddenly occur in late passages, but are acquired in the course of long?term culture.