Title: Routine checking for cells viability in deposition 3D printing
Edwin-Joffrey Courtial has completed his PhD from IMP (Ingénierie des Matériaux Polymères) lab, Université Claude Bernard Lyon 1. He is a researcher specialized in materials science and rheological behaviors. These main activities are focus on correlation beetween (bio)materials formulations and rheological behaviors to define 3D (bio)printable conditions.
3D Bioprinting, i.e. biomaterials 3D printing including living cells, is one of the most advance technology in tissue engineering and regenerative medicine . The technique presents the capacity to produce efficiently and in a cost-effective way, tissues with cell density and shape recapitulating human tissue behaviours . Nevertheless, the use of extrusion based technology presents limitations such as low resolution and cells mortality, due to a high shear stress value inside the nozzle [2,3]. We are herein proposing the development and validation of a new routine enabling the monitoring of cells viability during 3D bioprinting. The method is based on the relation between bioink rheological properties, shear stress induced by the bioprinting process and cells viability. Rotational rheometer was used to define the bioink rheological behaviour. To access the shear stress map inside the bioprinting nozzle, a specific algorithm was developed based on Poiseuille tube flow of a pseudoplastic power law fluid . Fibroblast primary cells, already applied inhouse for skin tissue bioprinting, were chosen as a model cell line for our study. Living and labelled necrotic cells were counted before and post-printing process to evaluated cell viability and total cell recovery in various conditions. In view of preliminary results, the shear stress gradient can be controlled through bioink rheological behaviour and nozzle geometry. Moreover, memory effect of the flow, controlled by the nozzle shape, seems to have an impact on cell viability. In any case, it was shown that using adequate bioink rheological properties, cells viability can be optimal whatever the nozzle geometry and the applied flow value; protecting cells during the 3D bioprinting process.