3D bioprinting a PCL/13-93B3 glass composite and its potential use as a bio-ink

A major limitation of using synthetic scaffolds in tissue engineering is little growth of incorporated cells in the interior of the scaffold, resulting in insufficient angiogenesis in the scaffold interior. Recently, cells have been 3D bioprinted concurrently with biomaterials to produce a cellularized, bioactive, angiogenic 3D environment. This thesis describes a novel solvent-extrusion method for printing polycaprolactone (PCL)/bioactive borate glass composite as a biomaterial for a cell-laden scaffold. Bioactive borate glass was added to a mixture of PCL and organic solvent to make an extrudable paste, creating scaffolds measuring 10×10×1 mm3 in overall dimensions with pore sizes ranging from 100-300 μm. We compared depositing hydrogel droplets to depositing hydrogel filaments in between the PCL/borate glass composite filaments. Degradation of the composite scaffold with and without the presence of hydrogel was investigated by soaking the scaffold in cell culture medium. The weight loss of the scaffold together with formation of a hydroxyapatite-like layer on the surface shows the excellent bioactivity of the scaffold. This work demonstrates that incorporating borate glass to increase the angiogenic capacity of the fabricated scaffolds is feasible. We also compared cell survival and viability between the composite bio-ink to two commonly used hydrogels, Matrigel and Pluronic F127. The viability and proliferation of cells in the different biomaterials were analyzed with different methods demonstrating that cell viability was similar between the different bio-inks. This 3D bioprinting method shows a high potential to create a bioactive, highly angiogenic 3D environment required for complex and dynamic interactions that govern the cell’s behavior in vivo --Abstract, page iii