title: Oscillatory fluid flow induces the osteogenic lineage commitment of mesenchymal stem cells: The effect of shear stress magnitude, frequency, and duration.
abstract: A potent regulator of bone anabolism is physical loading. However, it is currently unclear whether physical stimuli such as fluid shear within the marrow cavity is sufficient to directly drive the osteogenic lineage commitment of resident mesenchymal stem cells (MSC). Therefore, the objective of the study is to employ a systematic analysis of oscillatory fluid flow (OFF) parameters predicted to occur in vivo on early MSC osteogenic responses and late stage lineage commitment. MSCs were exposed to OFF of 1Pa, 2Pa and 5Pa magnitudes at frequencies of 0.5Hz, 1Hz and 2Hz for 1h, 2h and 4h of stimulation. Our findings demonstrate that OFF elicits a positive osteogenic response in MSCs in a shear stress magnitude, frequency, and duration dependent manner that is gene specific. Based on the mRNA expression of osteogenic markers Cox2, Runx2 and Opn after short-term fluid flow stimulation, we identified that a regime of 2Pa shear magnitude and 2Hz frequency induces the most robust and reliable upregulation in osteogenic gene expression. Furthermore, long-term mechanical stimulation utilising this regime, elicits a significant increase in collagen and mineral deposition when compared to static control demonstrating that mechanical stimuli predicted within the marrow is sufficient to directly drive osteogenesis.
authors.affiliation: Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland; Dept. of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Elena
authors.initials: E
authors.lastname: Stavenschi
authors.affiliation: Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland; Dept. of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Marie-Noelle
authors.initials: MN
authors.lastname: Labour
authors.affiliation: Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland; Dept. of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin 2, Ireland; Dept. of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Ireland; Advanced Materials and Bioengineering Research Centre, Trinity College Dublin & RCSI, Dublin 2, Ireland. Electronic address: dahoey@tcd.ie.
authors.forename: David A
authors.initials: DA
authors.lastname: Hoey
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001696:Biomechanical Phenomena; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D019070:Cell Lineage; D005786:Gene Expression Regulation; D057446:Hydrodynamics; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D051379:Mice; D010012:Osteogenesis; D033081:Shear Strength; D013314:Stress, Mechanical; D013997:Time Factors
chemical_list: D015415:Biomarkers
keywords: Bioreactor; Bone; Fluid flow; Mechanobiology; Mesenchymal stem cell