Title: Effects of cyclic longitudinal mechanical strain
and dexamethasone on osteogenic differentiation of human bone
marrow stromal cells
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Author: M. Jagodzinski, M. Drescher, J. Zeichen,
S. Hankemeier, C. Krettek, U. Bosch and M. van Griensven
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Address: Department of Trauma Surgery, Hanover Medical
School (MHH), Hanover, Germany
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E-mail: Jagodzinski.Michael at mh-hannover.de
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Key Words: Bone marrow stretching stimulation stress
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Publication date: April 16th 2004
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Abstract: The aim of the study was to investigate
the effect of cyclic mechanical strain on differentiation
markers in the presence or absence of dexamethasone.
Human bone marrow stromal cells (BMSC) from seven donors (32.5±6.2
years) were cultivated with (D+) or without (D-) dexamethasone.
A cyclic mechanical strain with an elongation of 2% (D+2;
D-2) or 8% (D+8; D-8) was applied for three days with a stimulation
time of three times two hours each day. Levels of alkaline
phosphatase (ALP) and osteocalcin (OC) were compared after
time intervals of four and seven days. mRNA expression of
Collagen I, III and Cbfa1 was investigated after one, four,
and seven days.
ALP levels were significantly increased in the D+8 group after
four and seven days (147.1±6.3%; p<0.05 and 168.6±6,5%;
p<0.03) and in the D-8 group after 7 days (197.4±10.4;
p<0.04). Cyclic strain had a significant influence on ALP-secretion
(F=7.5; p<0.01).
In the D-8 group there was a significant increase in OC secretion
after 4 days (140.9±12.5%; p<0.05).; p<0.01).
The effect of stretching was significantly stronger than that
of dexamethasone (F=17.2 vs. 1.8). Collagen I (Col I) expression
was upregulated in D+8 cultures after 4 days (215.0±53.3
p<0.04) and after seven days (166.7±55.7; p<0.04).
Collagen III (Col III) expression was upregulated in D+2 and
D+8 cultures after 4 days (200.7±16.3 and 185.9±12.7;
p<0.04) and after seven days (154.4±10.1 and 118.8±16.4;
p<0.04). There was a significant increase of Cbfa1 expression
in D+8 cultures at all investigated time intervals (day 1:
105.5±3.7%; day 4: 104.7±3.0%; day 7: 104.4±2.1%;
p<0.03). Stretching (F=20.0; p<0.01) was a stronger
contributor to Cbfa-1 expression than dexamethasone (F=12.1;
p<0.01)
Cyclical mechanical stimulation with 8% elongation increases
ALP and OC levels and upregulates Col I and III synthesis
and Cbfa1 expression. In the short term, cyclical stretching
is a stronger differentiation factor than dexamethasone. Cyclical
stretching and dexamethasone both enhance the osteogenic commitment
of hBMSC.
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Article download: Pages
35-41. (PDF file)
DOI: 10.22203/eCM.v007a04 |