Scaffold Design for Bone Tissue Engineering: From Micrometric to Nanometric Level - Biologically Responsive Biomaterials for Tissue Engineering - page 2

scaffold features to the requirements of the specific application on micrometric and
nanometric scale [ 15 ] .
Moving towards the current standing of biomaterials science and technology,
the challenging way to satisfy the compelling multifunctional needs and extend
material property combinations relies on the development of composite materials
made of degradable and partially degradable materials by using several technolo-
gies for imprinting controlled pore morphology and functional properties [ 3 ] . Here,
conventional techniques to emboss a controlled pattern of porosity in biodegrad-
able polymers (i.e., phase inversion/salt leaching, rapid prototyping) were prelimi-
narily reviewed, highlighting process-structure-property relationship. Secondly,
different strategies to include bioactive surface and bulk signals were proposed in
order to improve the osteointegration. Finally, the electrospinning technique was
proposed as a powerful technique to develop hierarchically organized nano-struc-
tured platforms that closely mimic—biochemically and topologically—the mECM
of bone.

1.2 Scaffold Design: Basic Criteria

Scaffold design is becoming essential to the success of scaffold-based tissue engi-
neering strategies. It must combine several structural and functional properties
through an appropriate selection of constituent ingredients, namely Elimina virgola
cells, materials, and signals, in order to adapt the scaffold features to the require-
ments of the specific application both on the micrometric and nanometric scale. In
particular, an ideal scaffold should possess a repertoire of cues—chemical, bio-
chemical, and biophysical—which are able to control and promote specific events
at the cellular (microscale) and macromolecular (nanoscale) level (Fig. 1.1 ).
Over the last two decades, the concept of cell guidance in tissue regeneration
has been extensively discussed. In particular, cell guidance by the scaffold, from
cell-material construct to the new engineered tissue, requires a complex balance
between chemical, biochemical, and biophysical cues, able to mimic the spatial
and temporal microenvironments of the natural extracellular matrix. A relevant
part of this evolution concerns the development of novel scaffold materials,
compatible with the cell guidance concept and resulting from contemporary
advances in the fields of materials science and molecular biology [ 8 ] .
In particular, the accurate design of materials chemistry allows the attainment of
the optimum functional properties that a scaffold can achieve [ 24 ] . Materials chem-
istry contributes to promote cell migration through the scaffold, providing develop-
mental signals to the cells and directing the cell recruitment from the surrounding
tissue. However, mass transport requirements for cell nutrition and metabolic waste
removal, porous channels for cell migration, and surface characteristics for cell
attachment impose the development of tailored porous structures by finely con-
trolled processing techniques. A successful scaffold must also balance architectural
features with biological function, allowing a sequential transition in which the
regenerated tissue may assume a greater role as the scaffold degrades.