Issue title: Selected papers of the 5th International Symposium on Mechanobiology of Cartilage and Chondrocyte, Athens, May 2007
Article type: Research Article
Authors: Raimondi, Manuela T.; ; ; | Candiani, Gabriele | Cabras, Mariasara; | Cioffi, Margherita | Laganà, Katia | Moretti, Matteo | Pietrabissa, Riccardo
Affiliations: Laboratory of Biological Structure Mechanics, Department of Structural Engineering, Politecnico di Milano, Milano, Italy | IRCCS Istituto Ortopedico Galeazzi, Milano, Italy | CNR, Istituto di Chimica del Riconoscimento Molecolare, Milano, Italy | Laboratory of Biocompatibility and Cell Cultures, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milano, Italy
Note: [] Equally contributing authors.
Note: [] Address for correspondence: Manuela Teresa Raimondi, PhD, Dipartimento di Ingegneria Strutturale, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133 Milano, Italy. Tel.: +39 02 23994365; Fax: +39 02 23994364; E-mail: manuela.raimondi@polimi.it.
Abstract: We have studied an in vitro engineered cartilage model, consisting of bovine articular chondrocytes seeded on micro-porous scaffolds and perfused with very low regimens of interstitial flow. Our previous findings suggested that synthesis of sulphated glycosaminoglycans (sGAG) was promoted in this model, if the level of shear generated on cells was maintained below 10 mPa (0.1 dyn/cm2). Constructs were stimulated with a median shear stress of 1.2 and 6.7 mPa using two independent culture chambers. Quantification of the applied stresses and of oxygen consumption rates was obtained from computational modelling. Experimentally, we set a time zero reference at 24 hours after cell seeding and total culture time at two weeks. The cell metabolic activity, measured by MTT, was significantly lower in all constructs at two weeks (−73% in static controls, −66% in the 1.2 mPa group and −60% in the 6.7 mPa group) vs. the time zero group, and significantly higher (+33%) in the 7 mPa group vs. static controls. The ratio between synthesis of collagen type II/type I, measured by Western Blot, was significantly higher in the 1.2 mPa constructs (+109% vs. the 6.7 mPa group, +120% vs. the time zero group and +286% vs. static controls). A trend of decreased α-actin expression was observed with increased ratio of type II to type I collagen, in all groups. These results reinforce the notion that, at early time points in culture, hydrodynamic shear below 10 mPa may promote formation of extra-cellular matrix specific to hyaline cartilage in chondrocyte-seeded constructs.
Keywords: Tissue engineering, cartilage, mechanobiology, shear, oxygen, perfusion, porous scaffold
DOI: 10.3233/BIR-2008-0490
Journal: Biorheology, vol. 45, no. 3-4, pp. 471-478, 2008
