About Nanoscaffolds in Regenerative Medicine

Langer and Vacanti in 1993 proposed the combined use of stem cells, scaffolds, and inductive factors as the basis for tissue engineering, researchers have been able to fabricate increasingly complex tissue/organ constructs and some are used clinically today as standard treatment for a variety of conditions. Scaffolds are processed in order to produce 3D structures, with proper shape, size, architecture, and physical properties, tailored to fulfil specific functions. Therefore, tissue engineering products are designed to mimic tissue architecture and responses.

So, key scaffold requirements are biocompatibility, controlled porosity and permeability, suitable mechanical and degradation kinetic properties comparable to the targeted tissue and, additionally, support for cell attachment and proliferation by the addition of nanotopographies to the biomaterial surface. Natural or synthetic materials are used to make scaffolds and depending on the final purpose, barriers (membrane or tubes), gels or 3D matrices are developed to mimic the extracellular environment of a target tissue or organ. Natural materials are derived from human or animal (xenogeneic) sources and are composed of extracellular components. They include collagen, silk protein, Matrigel, small intestinal submucosa, agarose, alginate and chitosan.

Although these materials have shown promising results in tissue repair, they have some drawbacks regarding mechanical properties, degradation, immunogenicity and cross-contamination. Synthetic scaffolds have been constructed using synthetic materials or a combination between natural and synthetic materials. Polyhydroxic acids, polytetrafluoroethylene, steel titanium, or ceramics are examples of synthetic polymers with improved biocompatibility. Natural materials, such as collagen, gelatine, chitosan, alginates and silk or synthetic poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA), poly-epsiloncaprolactone (PCL), or polyvinyl alcohol (PVA) polymers, are the most common materials employed for the fabrication of nanofibre scaffolds.

These matrices can be created with high structural precision, using complex polymers and assembly techniques, to control material properties such as stiffness, degradation and porosity. The advent of nanotechnology has allowed further developments in the field of biomaterials. Suitable nano-modified surfaces create a nanotopography which facilitates cell adhesion and can induce a better cellular response and specific cell differentiation than untreated surfaces.