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Tissue engineering is a highly interdisciplinary field that requires the integrated expertise of clinicians, cell biologists, engineers and material scientists, to make progress in the development and deployment of biological substitutes that restore, maintain, or improve tissue function. The purpose is to provide the opportunities for tissue regeneration and organ replacement. Key advances in biological materials especially in the area of stem cells; growth and differentiation factors generate realistic opportunities to create tissues in the laboratory using an engineered extracellular matrix or scaffold and biologically active molecules. The scaffold acts as an artificial extracellular matrix and it needs to mimic the chemical composition and physical architecture of natural extracellular matrix to facilitate cell adhesion, proliferation, differentiation and new tissue formation. In this contribution we review the role of the scaffold system in promoting cell adhesion, proliferation and differentiation with respect to the anisotropic nature of the scaffold system. We address both the anisotropy which may exist at a microscopic or mesoscopic scale, for example the shape of pores as well as the molecular level interactions which may arise in a scaffold containing a molecular organization with a preferred orientation which may have been induced during the processing procedures used to prepare the scaffold. Of course some approaches to the preparation of scaffolds systems are inherently anisotropic, for example the wide-spread utilization of meshes prepared by electrospinning. In other words although the overall scaffold is isotropic, the basic elements in terms of an electrospun fibre is highly anisotropic in terms of its external form and possibly in terms of its internal structure. By reviewing the possible advantages of the inclusion of anisotropic elements in the scaffold we add to the knowledge base which allows scaffolds design to be optimised for specific tissue growth. |
