7 - Combining tissue engineering and drug delivery

Abstract

Publisher Summary The tasks that tissue engineering aims at accomplishing (tissue replacement and regeneration) are characterized by the challenging need to control a hierarchically complex system, which spans from the level of individual cells, through that of their collective behavior, to that of complex tissue architectures. Furthermore, this system evolves, and the real hurdle is, therefore, to control it in a dynamic fashion during its development, that is, during the morphogenesis of the tissue. Many, probably most, tissue engineering solutions make use of biological signals, which are naturally involved in modulating this morphogenetic process. Implantable tissue engineering constructs could thus be seen not only as physical, possibly remodel able supports for cell adhesion and migration, but also as sophisticated delivery systems for the molecules that bear the signals. The kind of signal, its intensity and the possibility to modulate it, would all depend on physical state, identity and physical properties of the molecule, and on its concentration and spatial localization. The signaling molecules can be in solution, aggregated/complexed, and immobilized in/on a solid-like phase. In the overwhelming majority of cases, the signaling compounds used in tissue engineering fall in the categories of cytokines, chemokines, growth factors, or immunomodulators; the nomenclature of these classes of compounds has often generated confusion. This chapter reviews the effects of signaling molecules in tissue engineering. It focuses on how, when externally provided, they are made available to target biological systems.