title: Long-term dynamic loading improves the mechanical properties of chondrogenic mesenchymal stem cell-laden hydrogel.
abstract: Mesenchymal stem cells (MSCs) are an attractive cell source for cartilage tissue engineering given their ability to undergo chondrogenesis in 3D culture systems. Mechanical forces play an important role in regulating both cartilage development and MSC chondrogenic gene expression, however, mechanical stimulation has yet to enhance the mechanical properties of engineered constructs. In this study, we applied long-term dynamic compression to MSC-seeded constructs and assessed whether varying pre-culture duration, loading regimens and inclusion of TGF-beta3 during loading would influence functional outcomes and these phenotypic transitions. Loading initiated before chondrogenesis decreased functional maturation, although chondrogenic gene expression increased. In contrast, loading initiated after chondrogenesis and matrix elaboration further improved the mechanical properties of MSC-based constructs, but only when TGF-beta3 levels were maintained and under specific loading parameters. Although matrix quantity was not affected by dynamic compression, matrix distribution, assessed histologically and by FT-IRIS analysis, was significantly improved on the micro- (pericellular) and macro- (construct expanse) scales. Further, whole genome expression profiling revealed marked shifts in the molecular topography with dynamic loading. These results demonstrate, for the first time, that dynamic compressive loading initiated after a sufficient period of chondro-induction and with sustained TGF-beta exposure enhances matrix distribution and the mechanical properties of MSC-seeded constructs.
authors.affiliation: McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of Pennsylvania, 36th Street and Hamilton Walk, Philadelphia, PA 19104, USA.
authors.forename: Alice H
authors.initials: AH
authors.lastname: Huang
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Farrell
authors.forename: Minwook
authors.initials: M
authors.lastname: Kim
authors.forename: Robert L
authors.initials: RL
authors.lastname: Mauck
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002356:Cartilage / Q000166:cytology / Q000502:physiology* / Q000601:surgery*; D002417:Cattle; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000502:physiology / Q000637:transplantation*; D005109:Extracellular Matrix / Q000737:chemistry / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D048091:Guided Tissue Regeneration / Q000379:methods; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry* / Q000627:therapeutic use; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000502:physiology; D013997:Time Factors; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000639:trends*; D053782:Transforming Growth Factor beta3 / Q000494:pharmacology; D016474:Weight-Bearing / Q000502:physiology
chemical_list: D016326:Extracellular Matrix Proteins; D053782:Transforming Growth Factor beta3; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate