In Vitro Cellular & Developmental Biology - Animal

, Volume 42, Issue 7, pp 216–224

Human diploid fibroblast cells in senescence; Cycling through polyploidy to mitotic cells

Articles Cell Growth/Differentiation/Apoptosis

DOI: 10.1290/0603019.1

Cite this article as:
Walen, K.H. In Vitro Cell.Dev.Biol.-Animal (2006) 42: 216. doi:10.1290/0603019.1

Summary

Previously, it was found that senescent cells can undergo a modified cell cycle with mitotic cells as the end results. The major cycling events started with polyploidization, followed by depolyploidization to multinucleated cells (MNCs). These latter cells produced mononuclear offspring cells that could express mitotic cell divisions. In this report the emphasis is on late senescent fibroblasts that exhibited the senescence-associated change in cell morphology to large flat cells. Prior to live cell photography, flat cell cultures were maintained for months in the same culture flasks and therefore judged to be in a late senescent phase. All of the cellular events outlined above were present in these old cell cultures. Time lapse pictures showed movements of mitotic daughter cells away from each other and alignment of the chromosomes on the metaphase plate was visible in other mitotic cells. These data challenge the common view that cell senescence is irreversible and, therefore, an antitumor mechanism. A new finding was that the spike in polyploid cells in the near senescent phase consisted of cells with pairs of sister chromosomes from endoreduplication of DNA (two rounds of DNA synthesis and no mitosis). The lack of cells with 92 single chromosomes (e.g., G2 tetraploid cells) suggested that these polyploid cells also went through a changed cell cycle. The question now is whether these atypical polyploid cells are a subpopulation in senescence that can undergo the cycling from polyploidy to genome-reduced mitotic cells.

Key words

depolyploidizationmultinucleated cells (MNCs)nuclear budding from MNCssubcell replication

Copyright information

© Society for In Vitro Biology 2006

Authors and Affiliations

  1. 1.Viral and Richettsial Disease LaboratoryCalifornia Department of Health ServicesRichmond
  2. 2.CROMOSRichmond