Characterizing an injectable alginate hydrogel as a co‐encapsulating system for beta cells and curcumin in type 1 diabetes therapy

Encapsulating insulin‐secreting cells within biocompatible hydrogels is a tissue engineering approach for type 1 diabetes treatment. Macroencapsulation is preferred over other encapsulation methods due to its easy implantation and retrieval. However, this treatment has challenges, including the need for invasive surgery for macrocapsule implantation and host response, resulting in fibrotic overgrowth around the implant and subsequent failure of the graft. Herein, an injectable alginate hydrogel, fabricated by different concentrations of Na2HPO4 as a retarding agent, was applied to avoid surgery. According to characterization tests, hydrogel made by 0.3 M Na2HPO4 showed a higher swelling ratio and diffusion coefficient, appropriate for the diffusion of nutrients, oxygen, and insulin. It was also stiffer with a lower swelling rate, demonstrating more robust elastic and solid‐like behaviour, suitable for cell attachment. Its small pore size (133.04 ± 53.28 μm), additionally, was essential for inhibiting immunoglobulins penetration. Thus, this hydrogel was used for RIN‐5F cells encapsulation and demonstrated good biocompatibility (>88% viability), and maintained the insulin‐releasing function of cells. Afterward, we co‐encapsulated beta cells with curcumin as an anti‐inflammatory drug and investigated the effect of this agent on cell behaviour in vitro. It was indicated that curcumin did not adversely affect viability and insulin secretion. Overview of hydrogel synthesis, characterization, and encapsulation of cell and curcumin within the hydrogel matrix.