ISSN:
1432-0827
Keywords:
Prostaglandin E2
;
Rat calvarial cell
;
Differentiation
;
Mineralization
;
Osteopontin
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
,
Physics
Notes:
Abstract The effects of PGE2 on mineralized bone nodule formation were studied in fetal rat calvarial (RC) cells in vitro. Continuous exposure of RC cells to 3x10-8M PGE2 induced a twofold increase in mineralized bone nodule formation and a 1.5-fold increase in alkaline phosphatase (ALPase) activity without affecting RC cell growth. These stimulatory effects were evoked by concentrations of 3x 10-9-3x10-6 M PGE2 and the maximal effect was observed with 3x10-8 M PGE2. The in vitro effects of PGE2 were evident when RC cells were exposed to it on days 8–14 and 8–21, which correspond to the post-confluent culture stage, but no effects were observed when the cells were exposed on days 1–7, the growth stage. The ALPase activity was also higher (1.2–1.4-fold) when 3x10-8 M PGE2 was added during the post-confluent stage. In order to determine the effect of PGE2 during the mineralization phase of bone nodules in the presence of a large population of osteoprogenitor cells, RC cells were exposed to dexamethasone for 7 days before PGE2 was added during the post-confluent stage. A significantly higher percentage of nodules mineralized were observed with 3x10-8-3x10-9 M PGE2 (1.6-and 1.4-fold, respectively), than in control cultures. Analysis of the mineral-related proteins by EDTA extraction of bone nodules followed by electrophoresis and Stains-All staining revealed an increased total amount of osteopontin extracted from the mineralized matrix after PGE2 treatment. The osteopontin content was highest after 3x10-8 M PGE2, with a 73% increase of the densitometric intensity of the bands, although this increase, reflected the increased number of mineralized bone nodules due to PGE2. These findings suggest that PGE2 may increase the proportion of functional osteoblasts able to produce mineralized bone nodules in the population by stimulating differentiation during the postconfluent stage of RC cell culture.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00298559
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