Three-dimensional biodegradable microscaffolding: Scaffold characterization and cell population at single cell resolution

Engineering artificial tissue scaffolds with a similar organization to that of the natural tissue is a key element to the successful recapitulation of function. However, three-dimensional (3-D) fabrication of tissue scaffolds containing complex microarchitectures still remains a challenge. In addition, little attention has been paid to the issue of how to incorporate cells within 3-D tissue scaffolds that contain precisely engineered architectures. Here we report a 3-D biodegradable microscaffolding (3D-BMS) technology and its process characterization as well as a microscale cellular loading technology as an efficient way to massively populate biodegradable polymers with cells at single cell resolution. In this study a particular emphasis was given to characterization of the material properties of the biodegradable polymers undergoing the 3D-BMS processes. Optimal process conditions were identified in order to avoid any unwanted change in material properties, such as crystallinity and scaffold strength, that have a direct impact on the degradation speed and physical integrity of the constructed scaffolds. For precise control of the cell distribution within the microstructured scaffolds a high precision microsieve structure was designed to localize rat hepatocytes and human articular chondrocytes in the biodegradable polymers. Cell suspensions were passed at a predetermined flow rate through biodegradable polymer layers that contained tapered microholes in a massively parallel process. This high resolution cell seeding method allows accurate manipulation of cell placement in thin layers of biodegradable polymers.