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This Article Full Text Full Text (PDF) All Versions of this Article: 292/2/E594    most recent 00216.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Wang, Y.-H. Articles by Rowe, D. W. Search for Related Content PubMed PubMed Citation Articles by Wang, Y.-H. Articles by Rowe, D. W.

Effects of transient PTH on early proliferation, apoptosis, and subsequent differentiation of osteoblast in primary osteoblast cultures

¹Department of Craniofacial Sciences, School of Dental Medicine, University of Connecticut Health Center and ²Department of Genetics and Developmental Biology, School of Medicine, University of Connecticut Health Center, Farmington, Connecticut

Submitted 5 May 2006 ; accepted in final form 5 October 2006

In primary calvarial osteoblast cultures derived from transgenic mice expressing green fluorescent protein (GFP) under the control of 3.6-kb Col1a1 promoter, the emergence of GFP signal marks the transition of multipotential osteoprogenitors into preosteoblasts. Early transient treatment (days 1–7) of these cultures with parathyroid hormone (PTH) has an anabolic effect that is not associated with an increase in total DNA content or cell number in day 21 cultures. In the present study, the effect of early PTH treatment on cell proliferation and apoptosis was examined in greater detail in GFP(+) and GFP(–) cells using flow cytometry. In preconfluent cultures, PTH significantly reduced the proportion of cells in S phase but increased those in G₀/G₁ and G₂+M phases in both GFP(+) and GFP(–) subpopulations. PTH decreased apoptosis only in GFP(–) but not GFP(+) cells, indicating an increased survival of GFP(–) cells. In contrast, PTH did not change the amounts of cell proliferation and apoptosis seen in either compartment after these cultures reached confluence. To further assess the effect of early PTH treatment on osteogenic differentiation, secondary cultures of sorted GFP(+) or GFP(–) cells were obtained from day 7 primary cultures that had been treated for 1 wk with PTH. This treatment resulted in larger areas of GFP expression accompanied by increased xylenol orange/von Kossa staining in the secondary cultures of GFP fractions. Early transient PTH treatment appears to enhance the commitment of progenitor cells to an osteogenic fate and results in a higher proportion of cells that achieve full osteoblast differentiation.

parathyroid hormone; cell proliferation; apoptosis; osteoblast differentiation; flow cytometry

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