title: Growth plate explants respond differently to in vitro static and dynamic loadings.
abstract: This study aimed at investigating the effects of static and dynamic compression applied on growth plate explants using matched compressive strains. Growth plate explants from 4-week-old swine ulnae were submitted to in vitro static (10% strain) or dynamic (oscillating between 7% and 13% at 0.1 Hz) unconfined compression for 48 h. The total growth plate height, the combined proliferative and hypertrophic thickness and the resulting ratio between these two thicknesses were evaluated. Standard immunohistochemistry was used to analyze the protein expression of key components of the extracellular matrix: aggrecan, type II collagen, type X collagen, and MMP13. In the statically loaded samples, the columnar organization of the cells was preserved but with slight columns deviation from the growth axis. Decreases in all histomorphological parameters were important and a notable loss of aggrecan, type II and type X collagens expressions was denoted. In the dynamically loaded samples, a severe loss of columnar arrangement was observed in the proliferative and hypertrophic zones. However, dynamic compressive loads preserved the proliferative and hypertrophic zones ratio and contributed to the synthesis of aggrecan and type II collagen in the extracellular matrix. The exact response of the growth plate to mechanical stresses along with optimal loading parameters could help improve the current treatment approaches or develop new treatment approaches for the underlying progressive musculoskeletal deformities.
authors.affiliation: Department of Mechanical Engineering, École Polytechnique de Montréal, Station Centre-Ville, Montréal, Québec, Canada.
authors.forename: Kim
authors.initials: K
authors.lastname: Sergerie
authors.forename: Stefan
authors.initials: S
authors.lastname: Parent
authors.forename: Pierre-Francois
authors.initials: PF
authors.lastname: Beauchemin
authors.forename: Irene
authors.initials: I
authors.lastname: Londoño
authors.forename: Florina
authors.initials: F
authors.lastname: Moldovan
authors.forename: Isabelle
authors.initials: I
authors.lastname: Villemure
mesh_terms: D053674:Aggrecans / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism; D024043:Collagen Type II / Q000378:metabolism; D024121:Collagen Type X / Q000378:metabolism; D019245:Compressive Strength / Q000502:physiology; D006132:Growth Plate / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism; D007150:Immunohistochemistry; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology*; D013314:Stress, Mechanical; D013552:Swine; D014457:Ulna / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism; D016474:Weight-Bearing / Q000502:physiology
chemical_list: D053674:Aggrecans; D015415:Biomarkers; D024043:Collagen Type II; D024121:Collagen Type X; D053509:Matrix Metalloproteinase 13