Osteoporosis International

, Volume 7, Issue 6, pp 514–524

Demonstration of cellular aging and senescence in serially passaged long-term cultures of human trabecular osteoblasts

  • M. Kassem
  • L. Ankersen
  • E. F. Eriksen
  • B. F. C. Clark
  • S. I. S. Rattan
Original Article

DOI: 10.1007/BF02652556

Cite this article as:
Kassem, M., Ankersen, L., Eriksen, E.F. et al. Osteoporosis Int (1997) 7: 514. doi:10.1007/BF02652556

Abstract

The proliferative capacity and cellular and biochemical characteristics of human trabecular bone osteoblasts were analysed throughout their replicative lifespan in vitro. Like several other cell types, human osteoblasts demonstrated a typical Hayflick phenomenon of cellular aging comprising a period of rapid proliferation until cumulative population doubling level (CPDL) 22 to 24, followed by a phase of slow growth and the final cessation of cell division at CPDL 32 to 34. Comparing young cells (less than 20% lifespan completed) and old cells (more than 90% lifespan completed) revealed a progressive increase in population doubling (PD) time, a decrease in attachment frequency, a decrease in the number of S-phase positive cells, a decrease in the rates of DNA, RNA and protein synthesis, an increase in the protein content per cell and an increased proportion of senescence-specificβ-galactosidase positive cells. While osteoblastic production of collagen type I decreased progressively during aging, alkaline phosphatase activity dropped rapidly after the first few passages and then remained constant during the rest of the proliferative lifespan. Significant morphological changes from thin and spindle-shaped early passage young cells to large, flattened and irregularly shaped late passage old cells full of intracellular debris were observed. In comparison, osteoblasts established from an osteoporotic bone sample showed a maximum CPDL of less than 5, had a longer PD time and exhibited abnormal senescent morphology. Thus, we have demonstrated for the first time that human osteoblasts, like several other diploid cell types, have a limited proliferative capacity in vitro and undergo aging and senescence as measured by various cellular and biochemical markers. In addition, preliminary studies show that cells from osteoporotic bone have a severely reduced proliferative capacity. This model of bone cell aging facilitates study of the molecular mechanisms of osteoblast senescence as well as factors related to osteoblast dysfunction in patients with osteoporosis.

Keywords

Aging Lifespan Osteoblasts Osteoporosis Senescence 

Copyright information

© European Foundation for Osteoporosis and the National Osteoporosis Foundation 1997

Authors and Affiliations

  • M. Kassem
    • 1
  • L. Ankersen
    • 2
  • E. F. Eriksen
    • 1
  • B. F. C. Clark
    • 2
  • S. I. S. Rattan
    • 2
  1. 1.Danish Centre of Molecular Gerontology, University Department of Endocrinology and MetabolismAarhus University HospitalDenmark
  2. 2.Laboratory of Cellular Ageing, Department of Molecular and Structural BiologyAarhus UniversityAarhusDenmark
  3. 3.Pharma NordVejleDenmark

Personalised recommendations