Development of the Biopen a handheld device for surgical printing of adipose stem cells at a chondral wound site
Bioprinting is a process based on additivemanufacturing frommaterials containing living cells. These materials, often referred to as bioink, are based on cytocompatible hydrogel precursor formulations, which gel in amanner compatible with different bioprinting approaches. The bioink properties before, during and after gelation are essential for its printability, comprising such features as achievable structural resolution, shape fidelity and cell survival. However, it is thefinal properties of thematured bioprinted tissue construct that are crucial for the end application. During tissue formation these properties are influenced by the amount of cells present in the construct, their proliferation,migration and interactionwith thematerial. A calibrated computational framework is able to predict the tissue development andmaturation and to optimize the bioprinting input parameters such as the startingmaterial, the initial cell loading and the construct geometry. In this contribution relevant bioink properties are reviewed and discussed on the example ofmost popular bioprinting approaches. The effect of cells on hydrogel processing and vice versa is highlighted. Furthermore, numerical approaches were reviewed and implemented for depicting the cellular mechanics within the hydrogel as well as for prediction ofmechanical properties to achieve the desired hydrogel construct considering cell density, distribution andmaterial cell interaction.