Fibrous polyisocyanide hydrogels for 3D cell culture applications

Three-dimensional (3D) cell culture models based on hydrogels are rapidly evolving into a prominent tool for tissue engineering, mechanobiology, disease modeling and drug screening. While a vast variety of synthetic gels have emerged in recent years, they fail to penetrate the market substantially for two major reasons: they poorly mimic the extracellular matrix or they are difficult to use in gel formation and cell extraction. Mimicking the complexity of nature is challenging: the extracellular matrix plays a crucial role in cell development and function, which goes well beyond simple mechanical support. Recently, we introduced polyisocyanide (PIC) hydrogels for 3D cell culture applications. The fibrous architecture and associated (non)linear mechanical behavior closely mimic the physical properties of biogels such as collagen and fibrin. As fully synthetic materials, PIC gels benefit from high tailorability and reproducibility. Moreover, the thermoresponsive properties of PIC gels make them easy to handle in the lab; the gels form instantly at 37 °C and cells are easily extracted after cooling to 5 °C. The potential of PIC gels has been demonstrated in a quickly expanding library of papers discussing different cell lines, primary cells and organoids, as well as in vivo experiments. This manuscript provides protocols on how to handle PIC gels in the chemistry and cell biology laboratories. Material preparation requires 72 h. Cell encapsulation takes 1 h and the time for downstream analysis depends on the (commercial) methods used. The protocols described are suitable for researchers with expertise in cell culture and molecular biology.