Abstract

Scaffold-free 3D microtissues have evolved into the most widely used technology for highly predictive and most scalable cell-based assays in drug safety and discovery. While they provide a faithful in-vitro approximation of the in-vivo tissue microenvironment, they were not amenable for modeling microphysiological features up to now. Focusing on advantages and challenges in daily industry use, we’ll describe two case studies illustrating how a 3D microtissue can be used as a predictive surrogate for drug discovery. One study investigates a complex co-culture system recapitulating the hallmarks of nonalcoholic steatohepatitis (NASH) in a screening-compatible format. Consisting of primary human hepatocytes, NPCs and stellate cells, these 3D microtissues can be elastically driven into and out of specific disease states. As second application, we will describe the use of reconstituted, 3D primary human pancreatic islets for discovery of anti-diabetic drugs. Finally, we present a new multi-organ-on-a-chip system featuring microfluidic channels and chambers that were specifically engineered for culturing 3D microtissues and organoids under physiological flow conditions. The platform complies with the SBS plate standard and is made of polystyrene to prevent unwanted compound absorption. It allows for an automated and on-demand interconnection of up to 10 microtissues per channel in a highly  flexible fashion. Enabling an automated removal and re-insertion of 3D microtissues from and into the device, this platform finally ads deep endpoints such as next-gen sequencing, lipidomics, FACS to the analytical toolbox for organ-on-a-chip applications. Summarizing, we will focus on the major challenges encountered when implementing human, primary cell based 3D and organ-chip assays – and our suggestions on how to address them in an industry-wide effort.