Accurate geometric characterization of macroporous scaffold of tissue engineering

It is now well accepted that the scaffold for tissue engineering should take the porous form. The porous structure of a scaffold has a decisive influence on its properties and the biological outcomes of a tissue engineered structures. Due to the complicated feature of porous structure, currently there is no standard or even well accepted method for an accurate geometric characterization and description. Porosity and mean pore size are two parameters that often used widely, but they are not a real representative of and cannot reflect the nature of a porous structure. In the present paper, one conventional physical parameter, permeability, was suggested as a geometric parameter in the description of complicated porous structure encountered in the process of tissue engineering. It is proved that permeability is affected by a set of parameters, such as porosity, pore size and distribution, fenestration size and distribution, interconnectivity of pores and the orientation of pores. Furthermore, the new technique was compared with other conventional methods, including 2D image analyses, mercury intrusion, micro- computed tomography (mu-CT). The comparative results indicated that permeability can be taken as a semi-quantitative parameter for macro-porous structure. Since bone-healing process is site and size-dependant, the specific surface area (SSA) is important for quantifying a scaffold, therefore, a new method of measuring SSA is described.