Three-dimensional plotted scaffolds with controlled pore size gradients : effect of scaffold geometry on mechanical performance and cell seeding efficiency

摘要

Scaffolds produced by rapid prototyping (RP) techniques have proved their value for tissue engineeringapplications, due to their ability to produce predetermined forms and structures featuring fully interconnectedpore architectures. Nevertheless, low cell seeding efficiency and non-uniform distribution of cellsremain major limitations when using such types of scaffold. This can be mainly attributed to the inadequatepore architecture of scaffolds produced by RP and the limited efficiency of cell seeding techniquesnormally adopted. In this study we aimed at producing scaffolds with pore size gradients to enhance cellseeding efficiency and control the spatial organization of cells within the scaffold. Scaffolds based onblends of starch with poly(e-caprolactone) featuring both homogeneously spaced pores (based on poresizes of 0.75 and 0.1 mm) and pore size gradients (based on pore sizes of 0.1–0.75–0.1 and 0.75–0.1–0.75 mm) were designed and produced by three-dimensional plotting. The mechanical performance ofthe scaffolds was characterized using dynamic mechanical analysis (DMA) and conventional compressiontesting under wet conditions and subsequently characterized using scanning electron microscopy andmicro-computed tomography. Osteoblast-like cells were seeded onto such scaffolds to investigate cellseeding efficiency and the ability to control the zonal distribution of cells upon seeding. Scaffolds featuringcontinuous pore size gradients were originally produced. These scaffolds were shown to have intermediatemechanical and morphological properties compared with homogenous pore size scaffolds. Thepore size gradient scaffolds improved seeding efficiency from !35% in homogeneous scaffolds to !70%under static culture conditions. Fluorescence images of cross-sections of the scaffolds revealed that scaffoldswith pore size gradients induce a more homogeneous distribution of cells within the scaffold.