Biomaterials and supercritical fluid technologies: Which perspectives to fabricate artificial extracellular matrix?

The foundation of tissue engineering for either therapeutic or diagnostic applications is the ability to exploit living cells. Tissue engineering utilizes living cells as engineering materials implanted, seeded or bioplotted into an artificial structure capable of supporting three-dimensional tissue formation. These structures, typically called scaffolds, are critical, both ex vivo and in vivo, to influence their own microenvironments. Scaffolds can serve the following purposes: allow cell attachment and migration, deliver and retain cells and biochemical factors, enable diffusion of vital cell nutrients or expressed products, exert certain mechanical and biological influences to modify the behaviour of the cell phase. Traditional tissue engineering strategies typically employ a “top-down” approach, in which cells are seeded on a biodegradable three dimensional monolithic polymeric scaffold. More recently they have been updated by a “bottom-up” approach, also known as modular tissue engineering; it is aimed to address the challenge of recreating bio-mimetic structures by designing structural micro-features to build modular tissues, used as building blocks to re-create larger ones. These two different approaches will require scaffolds with given characteristics obtainable by choosing different fabrication technologies. Conventional and innovative supercritical technologies for monolithic scaffold production or biopolymer micro/nano devices will be discussed in this chapter. Some examples of bone and cartilage tissue engineering produced by using modular scaffold will be also discussed, as well as the fabrication of artificial extracellular matrix for spatio-temporally delivery of biological and mechanical signal to address cell fate.