Temperature-responsive injectable hydrogel derived from elastin-like polypeptide as a cell carrier

Injectable hydrogels are promising biomaterials for tissue engineering applications because they deliver bioactive compounds or cells with minimal invasiveness. Temperature-responsive hydrogels, which transition from a liquid to a gel in response to environmental temperature, are candidates for injectable hydrogels. Elastin-like polypeptides (ELPs) with temperature-responsive capabilities have been well studied for drug delivery and tissue repair, yet their development as injectable biomaterials remain limited. In our previous study, we designed hydrogels formed from coiled-coil unit bound ELPs (CUBEs), which incorporated ELPs, a poly-aspartic acid (poly D) chain, a coiled-coil peptide (CL), and a functional peptide. However, injectability of CUBEs has not been studied. Here, we evaluated the injectability and cell delivery potential of O-CUBE, (AVGVP)₄₂-D₈₈-CL, which is a basic CUBE hydrogel system. We injected O-CUBE mixed with human cervical cancer (HeLa) cells into pre-warmed culture medium to initiate in situ gelation. O-CUBE protein was successfully gelled at an approximately 90% gelation rate after injection at 37℃ in a solution with pH 6 to 8. The injected HeLa cells exhibited spheroid morphology, indicating that the hydrogel facilitated cell-cell interactions in three-dimensional culture. Further evaluation with a DNA assay showed that the HeLa cells can proliferate in the O-CUBE hydrogel. Results demonstrate that the CUBE hydrogel system is a promising candidate for an injectable hydrogel cell delivery system with minimal invasiveness.