Non-destructive quantitative 3D analysis for the optimisation of tissue scaffolds

In tissue engineering, porous scaffolds are often used as three-dimensional (3D) supports for tissue growth. In scaffold design, it is imperative to be able to quantify the pore sizes and more importantly the interconnects between the pores. X-ray micro-computed tomography (μCT) has become a popular tool for obtaining 3D images of scaffold biomaterials, however images are only qualitative. In this work, methods were developed for obtaining pore size distributions for both the macropores and their interconnects. Scaffolds have been developed, by foaming sol–gel derived bioactive glasses, which have the potential to fulfil the criteria for an ideal scaffold for bone tissue engineering. μCT images were obtained from scaffolds with different pore structures. The images were thresholded and three algorithms were applied in 3D to identify pores and interconnects and to obtain pore size distributions. The results were validated against mercury intrusion porosimetry and manual 3D image analysis. The μCT data were then meshed such that predictions of permeability as a function of changes in the pore network could be made. Such predictions will be useful for optimising bioreactor conditions for tissue engineering applications. These techniques would be suitable for many other types of scaffolds.