Instructive Natural-Based Hydrogels as Platforms for Stem Cell Cultures for Tissue Engineering Applications

The spatiotemporal organization of the stem cell niche providesvaluable cues for the development of biomimetic environmentsthat could have potential to stimulate the regenerative process.In vitro such highly hydrated ۳D environments can be partiallyrecreated using hydrogels. We propose the use of natural-basedbiomaterials to produce hydrogels able to encapsulate differentcell types. In fact, due to their hydrophilic nature and richnessin chemically active groups, such polymers can be usedto produce a variety of crosslinked structures fabricated usingaqueous-based or other environmental-favourable procedures.Examples are shown on such hydrogels obtained with distinctshapes, internal organization and sizes. Such biomaterials encapsulatingmesenchymal stem cells may be used as implantabledevices to regenerate tissues. Alternatively, in order toavoid diffusion limitation of nutrients to the cells location sites,hydrogel particles may be used to support cellular organizationover their surface, acting as cells supports for injectablescaffolds. By decorating the surface with antibodies these particlesare able to recruit specific cell populations, enhancing thetherapeutic potential of such system. Polysaccharides may bealso used to coat liquefied capsules that may entrap viable cells,using the layer-by-layer technology. The presence of solid microparticlesinside such capsules offers adequate surface areafor adherent cell attachment increasing the biological performanceof these hierarchical systems, while maintain both permeabilityand injectability. The liquid environment allows fora free-organization in the space of the cells towards the formationof new microtissues. The compartmentalization of distinctcell types (including mesenchymal stem cells and endothelialcells) may enhance the osteogenic capability of this system, thatcould be useful in bone tissue engineering applications.