Environment-responsive dendrobium polysaccharide hydrogel embedding manganese microsphere as a post-operative adjuvant to boost cascaded immune cycle against melanoma
Abstract
Rationale: Surgical resection is a primary treatment for solid tumors, but high rates of tumor recurrence and metastasis post-surgery present significant challenges.Manganese (Mn 2+ ), known to enhance dendritic cell-mediated cancer immunotherapy by activating the cGAS-STING pathway, has potential in post-operative cancer management.However, achieving prolonged and localized delivery of Mn 2+ to stimulate immune responses without systemic toxicity remains a challenge.Methods: We developed a post-operative microenvironment-responsive dendrobium polysaccharide hydrogel embedded with Mn 2+ -pectin microspheres (MnP@DOP-Gel).This hydrogel system releases Mn 2+ -pectin microspheres (MnP) in response to ROS, and MnP shows a dual effect in vitro: promoting immunogenic cell death and activating immune cells (dendritic cells and macrophages).The efficacy of MnP@DOP-Gel as a post-surgical treatment and its potential for immune activation were assessed in both subcutaneous and metastatic melanoma models in mice, exploring its synergistic effect with anti-PD1 antibody.Result: MnP@DOP-Gel exhibited ROS-responsive release of MnP, which could exert dual effects by inducing immunogenic cell death of tumor cells and activating dendritic cells and macrophages to initiate a cascade of anti-tumor immune responses.In vivo experiments showed that the implanted MnP@DOP-Gel significantly inhibited residual tumor growth and metastasis.Moreover, the combination of MnP@DOP-Gel and anti-PD1 antibody displayed superior therapeutic potency in preventing either metastasis or abscopal brain tumor growth.Conclusions: MnP@DOP-Gel represents a promising drug-free strategy for cancer post-operative management.Utilizing this Mn 2+ -embedding and ROS-responsive delivery system, it regulates surgery-induced immune responses and promotes sustained anti-tumor responses, potentially increasing the effectiveness of surgical cancer treatments.