title: In vitro microdistraction of preosteoblasts: distraction promotes proliferation and oscillation promotes differentiation.
abstract: Osteoblast biology is influenced in vivo by a 3-dimensional (3D) extracellular matrix that mediates their adhesion and interaction and by a constant state of compressive and tensile forces. To study the role of mechanical stress on osteoblasts in vitro, these parameters must be addressed. Therefore, this study describes the use of a novel, in vitro system that subjects cells to distractive and compressive forces in a 3D environment. This system, termed a microdistractor system, was used to apply linear forces to 3D collagen type I gels containing preosteoblasts. Gels were induced for up to 16 days in osteogenic medium and subjected to either constant linear distraction (distraction gels) or to repeating cycles of distraction and compression (oscillation gels). The effect of these stresses was evaluated over time by measuring proliferation rates, protein synthesis (i.e., cellular activity), and osteogenic differentiation levels. While linear forces in general appeared to increase protein synthesis, force-specific effects on proliferation and differentiation were observed. Specifically, distraction forces appeared to enhance MC3T3 proliferation while distraction/compressive forces appeared to accelerate their osteogenic differentiation program. Therefore, these results suggest that the microdistraction system may be an appropriate in vitro system for the study of mechanobiology in osteoblast phenotype.
authors.affiliation: Regenerative Bioengineering and Repair Lab, Division of Plastic and Reconstructive Surgery, David Geffen School of Medicine at University of California, Los Angeles, Calif., USA.
authors.forename: Joubin S
authors.initials: JS
authors.lastname: Gabbay
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Zuk
authors.forename: Amir
authors.initials: A
authors.lastname: Tahernia
authors.forename: Morad
authors.initials: M
authors.lastname: Askari
authors.forename: Catherine M
authors.initials: CM
authors.lastname: O'Hara
authors.forename: Tharun
authors.initials: T
authors.lastname: Karthikeyan
authors.forename: Kodi
authors.initials: K
authors.lastname: Azari
authors.forename: Jeffery O
authors.initials: JO
authors.lastname: Hollinger
authors.forename: James P
authors.initials: JP
authors.lastname: Bradley
mesh_terms: D016475:3T3 Cells; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology*; D024042:Collagen Type I / Q000737:chemistry; D003470:Culture Media / Q000737:chemistry; D004867:Equipment Design; D005347:Fibroblasts / Q000378:metabolism / Q000502:physiology*; D005782:Gels / Q000737:chemistry; D051379:Mice; D042282:Microdissection / Q000379:methods*; D009924:Organ Culture Techniques; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology; D014176:Protein Biosynthesis; D013314:Stress, Mechanical; D013997:Time Factors
chemical_list: D024042:Collagen Type I; D003470:Culture Media; D005782:Gels; D000469:Alkaline Phosphatase