Biological Response of Next-Generation of 3D Ti-6Al-4V Biomedical Devices Using Additive Manufacturing of Cellular and Functional Mesh Structures

Motivated by the successful fabrication of patient-specific biomedical implants that can potentially replace hard tissue (bone), particularly knee and hip stems and large femoral intramedullary rods, using additive manufacturing by electron beam melting (Murr et al. Phil. Trans. R. Soc. A 2010; 22:1999-2032), we describe here the combined efforts of engineering and biological sciences as a systemic approach to study osteoblast functions of 3D mesh arrays with particular focus on pore size and the potential to use 3D fabricated porous biomedical devices for bone healing. First, the interconnecting porous architecture of monolithic mesh arrays was conducive to cellular functions including attachment, proliferation, differentiation, and mineralization. The underlying reason is that the fabricated structure provided a channel for initiation of cell migration and impregnation of the mesh structure by cells and tissue leading to generation of mineralized extracellular matrix by differentiating pre-osteoblasts. Second, a parametric study on the interconnecting pore diameter of mesh arrays indicated that the average pore diameters studied (similar to 400-800 mu m) had no apparent effect on the differentiation and mineralization, and influenced only the proliferation phase. Third, from the biomechanical point of view, the cell-invaded and cell-integrated 3D mesh structure and resulted in the superior formation of tissue.