Development of an injectable gellan gum-based hydrogel with a well-defined architecture

Controlled cellular alignment plays a crucial role in the microarchitecture of many human tissues dictating their biological and mechanical function (e.g. muscle tissue, tendon, cartilage tissue, spinal cord) [1]. Among the biomaterials, injectable hydrogels able to respond to an external magnetic field producing hierarchical structure similar to the target human tissues play an important role in regenerative medicine. In the present work, we develop a novel tunable and injectable system starting from gellan gum (GG), a biocompatible bacteria-derived polysaccharide [2] and hyaluronic acid (HA), to resemble the extracellular matrix. GG/HA-based hydrogels gelation is triggered by positive ions. GG/HA were dropped through a 30G needle into cations containing solutions (e.g. PBS, cell culture media). To achieve an oriented architecture upon a static magnetic field (SMF), magnetic collagen fibers (MagC) were embedded into the GG matrix. The mechanical properties were evaluated by dynamic mechanical analysis and rheology, swelling degree, and stability were investigated for up to 21 days. The system was stable for up to 21 days in solution and the Young Moduli (12-19kPa) is comparable to the muscle tissue [3]. The biocompatibility was preliminarily screened by embedding murine fibroblasts and macrophages, and no loss in cell viability was observed up to 7 days.