Microarchitectural and mechanical characterization of oriented porous polymer scaffolds

Biodegradable porous polymer scaffolds are widely used in tissue engineering to provide a structural template for cell seeding and extracellular matrix formation. Scaffolds must often possess sufficient structural integrity to temporarily withstand functional loading in vivo or cell traction forces in vitro. Both the mechanical and biological properties of porous scaffolds are determined in part by the local microarchitecture. Quantification of scaffold structure-function relationships is therefore critical for optimizing mechanical and biological performance. In this study, porous poly(L-lactide-co-DL-lactide) scaffolds with axially oriented macroporosity and random microporosity were produced using a solution coating and porogen decomposition method. Microarchitectural parameters were quantified as a function of porogen concentration using microcomputed tomography (micro-CT) analysis and related to compressive mechanical properties. With increasing porogen concentration, volume fraction decreased consistently due to microarchitectural changes in average strut thickness, spacing, and density. The three-dimensional interconnectivity of the scaffold porosity was greater than 99% for all porogen concentration levels tested. Over a porosity range of 58-80%, the average compressive modulus and ultimate strength of the scaffolds ranged from 43.5-168.3 MPa and 2.7-11.0 MPa, respectively. Thus, biodegradable porous polymer scaffolds have been produced with oriented microarchitectural features designed to facilitate vascular invasion and cellular attachment and with initial mechanical properties comparable to those of trabecular bone.