title: Effects of cyclic longitudinal mechanical strain and dexamethasone on osteogenic differentiation of human bone marrow stromal cells.
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.
authors.affiliation: Department of Trauma Surgery, Hanover Medical School (MHH), Hanover, Germany. Jagodzinski.Michael@mh-hannover.de
authors.forename: M
authors.initials: M
authors.lastname: Jagodzinski
authors.forename: M
authors.initials: M
authors.lastname: Drescher
authors.forename: J
authors.initials: J
authors.lastname: Zeichen
authors.forename: S
authors.initials: S
authors.lastname: Hankemeier
authors.forename: C
authors.initials: C
authors.lastname: Krettek
authors.forename: U
authors.initials: U
authors.lastname: Bosch
authors.forename: M
authors.initials: M
authors.lastname: van Griensven
mesh_terms: D000328:Adult; D000469:Alkaline Phosphatase / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D048430:Cell Shape; D048429:Cell Size; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics; D024061:Collagen Type III / Q000235:genetics; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013314:Stress, Mechanical; D017154:Stromal Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors
chemical_list: D024042:Collagen Type I; D024061:Collagen Type III; D050659:Core Binding Factor Alpha 1 Subunit; D012333:RNA, Messenger; D015675:Osteocalcin; D003907:Dexamethasone; D000469:Alkaline Phosphatase