Injectability of temperature-responsive hydrogel derived from elastin-like polypeptide for cell delivery

Injectable hydrogels are promising biomaterials for tissue engineering applications due to their ability to deliver bioactive compounds or cells with minimal invasiveness. Temperature-responsive in situ gelling hydrogels, which undergo transition from liquid to gel in response to temperature stimuli, are desirable candidates for injectable hydrogels. Elastin-like polypeptides (ELPs) are well-known temperature-responsive biomaterials for cell scaffolds, drug delivery, and tissue engineering, due to their biocompatibility, biodegradability, and tunable mechanical properties. However, due to high hydrophobicity and heterogeneous aggregation, the development of injectable hydrogel-derived ELPs remains limited. In our previous study, we designed coiled-coil unit-bound ELPs (CUBEs) hydrogel systems, which integrate ELPs, a polyaspartic acid (polyD) chain, a functional peptide, and a coiled-coil peptide. In this study, we evaluated the injectability and cell delivery potential of a basic CUBE hydrogel system, called O-CUBE (AVGVP)₄₂-D₈₈-CL. The O-CUBE protein solution was mixed with human cervical cancer (HeLa) cells, serving as a cell model, and subsequently injected into culture medium pre-warmed to 37 °C to initiate in situ gelation. O-CUBE protein was successfully gelled at an approximately 90 % gelation rate after injection at 37 °C within pH ranges of 6-8. Encapsulated HeLa cells exhibited spheroid morphology, indicating that the hydrogel facilitated cell-cell interactions in three-dimensional culture. Further evaluation using a DNA assay revealed that HeLa cells can survive and proliferate within the hydrogel. These results demonstrate that the CUBE hydrogel system is a promising candidate to deliver cells with minimal invasiveness.