Selective HIFU Foaming to Fabricate Porous Polymer for Tissue Engineering Scaffolds

A novel technique is presented in this paper for the fabrication of tissue engineering scaffolds using the High Intensity Focused Ultrasound (HIFU). This acoustic method is a solvent-free, highly efficient and low cost process that has the potential in scaffold-based tissue engineering. HIFU fabrication technique is capable of creating hierarchically-structured porous polymeric materials, which have various topographical features at different length scales. This will in turn affect the cellular response and behavior of certain type of cells, such as the integration and growth of smooth muscle cells (SMCs). In this study, the effect of HIFU porous polymer fabrication was investigated. Scanning-mode HIFU insonation was performed in the HIFU polymer foaming experiments. The acoustic power and the scanning speed were chosen as the parameters and varied in different groups of experiments. The created microstructures were characterized using the scanning electron microscopy (SEM). The fabricated samples were used for cell culture studies with human aortic SMCs (Passage 4). It was found that the selective HIFU foaming process could be used to create hierarchical structures by choosing appropriate ultrasound parameters. The SMCs were viable on the HIFU-created porous PMMA specimens, and the topographical nature of a HIFU-created porous structure affected the cellular response of SMCs.