Mussel-inspired adhesive hydrogels for local immunomodulation

The important function of the immune system is to protect the body from foreign pathogens and tumor cells, and to participate in the process of tissue repair and anti-tumor activity to achieve homeostasis. Systemic administration of immune biological agents (cytokines, drugs, peptides, etc.) helps promote tissue repair, eliminate tumors, and treat autoimmune diseases. However, systemic administration has low specificity for target tissues, resulting in unexpected consequences, such as hypoactive or hyperactive immune activity of non-target tissues, leading to autoimmune complications. To overcome these problems, recently, local immunomodulatory strategies based on adhesive hydrogels have been developed. One such strategy is mussel-inspired adhesive hydrogels, which have robust bioadhesiveness and can adhere to the expected target sites to provide local, long-term controlled release of immune biological agents, thus potentially maximizing the therapeutic efficacy and limiting the impact on the overall immune balance. In addition, mussel-inspired adhesive hydrogels show regulatory effects on local immune cells through catechol groups. Therefore, a variety of mussel-inspired hydrogels have been developed to achieve the desired therapeutic effects through local immunoregulation strategies. In this review, the current state of knowledge regarding the immune response in tissue repair and tumor therapy is introduced. Subsequently, strategies for the design of adhesive hydrogels are summarized. Subsequently, the rational molecular structure design of mussel-inspired adhesive hydrogels for robust tissue adhesiveness, as well as their local immunomodulatory mechanism, is discussed. Furthermore, the local immunomodulatory effects of mussel-inspired adhesive hydrogels in different biomedical applications are summarized. Finally, the challenges and prospects for the future design of mussel-inspired adhesive hydrogels for local immunomodulation are highlighted.