Engineering porous scaffolds using gas-based techniques

Scaffolds are used in tissue engineering as a matrix for the seeding and attachment of human cells. The creation of porosity in three-dimensional (3D) structures of scaffolds plays a critical role in cell proliferation, migration, and differentiation into the specific tissue while secreting extracellular matrix components. These pores are used to transfer nutrients and oxygen and remove wastes produced from the cells. The lack of oxygen and nutrient supply impedes the cell migration more than 500 mu m from the surface. The physical properties of scaffolds such as porosity and pore interconnectivity can improve mass transfer and have a great impact on the cell adhesion and penetration into the scaffolds to form a new tissue. Various techniques such as electrospinning, freeze-drying, and solvent casting/salt leaching have been used to create porosity in scaffolds. The major issues in these methods include lack of 3D structure, control on pore size, and pore interconnectivity. In this review, we provide a brief overview of gas-based techniques that have been developed for creating porosity in scaffolds.