The local matrix distribution and the functional development of tissue engineered cartilage, a finite element study

Assessment of the functionality of tissue engineered cartilage constructs is hampered by the lack ofcorrelation between global measurements of extra cellular matrix constituents and the global mechanicalproperties. Based on patterns of matrix deposition around individual cells, it has been hypothesizedpreviously, that mechanical functionality arises when contact occurs between zones of matrix associatedwith individual cells. The objective of this study is to determine whether the local distribution of newlysynthesized extracellular matrix components contributes to the evolution of the mechanical properties oftissue engineered cartilage constructs. A computational homogenization approach was adopted, based onthe concept of a periodic representative volume element. Local transport and immobilization of newlysynthesized matrix components were described. Mechanical properties were taken dependent on thelocal matrix concentration and subsequently the global aggregate modulus and hydraulic permeabilitywere derived. The transport parameters were varied to assess the effect of the evolving matrix distributionduring culture. The results indicate that the overall stiffness and permeability are to a large extentinsensitive to differences in local matrix distribution. This emphasizes the need for caution in the visualinterpretation of tissue functionality from histology and underlines the importance of complementarymeasurements of the matrix's intrinsic molecular organization.