High cell density is considered as a critical challenge for fabricating engineered tissue. Three-dimensional (3D) bioprinting permits artificial biomaterials loading with high cell density such as spheroids. In this work, a multi-functional microgel with a core-shell structure and delivering drug was fabricated by using the microfluidic platform via photo-crosslinking. The shell of microgel was composed of gelatin methacryloyl (GM) and proteoglycan mimics containing with methylprednisolone (MP) loaded liposome. Proteoglycan mimics had a GM backbone grafting with degraded glycosaminoglycans as side chains, which provided an extracellular matrix-like environment for cell growth. It combined with liposome endowed the adhesiveness of microgels, which were explored as a novel bioink for directly 3D printing. The core of microgel was composed of polyethylene glycol (PEG) dispersed cells, such as HELA and HepG2 cell lines. Compared with the GM control, microgels contained heparin (Hp) side chains promoted the cell growth, whereas the one contained chondroitin sulfate (CS) displayed inhibitory effect moderately. The embedded cells of microgels grew into spheroids after a long peroid which could form continuous cell tissue. Furthermore, these microgels displayed good biocompatibility to different neural cells, such as astrocytes, oligodendrocyte precursor cells (OPCs), and PC12. This work provided a novel bioink based on adhesive microgels for constructing artificial scaffold with high cell density. Acknowlegements: The grants of National Natural Science Foundation of China 22278180 (S. X.). European Research Council under the European Union’s Seventh Horizon 2020 research and innovation program through the ERC grant DiProPhys 101001615 (T.P.J.K).
Xu et al. (Sun,) studied this question.