Zwitterionic Hydrogel Depot Evades Foreign Body Response
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Solution Overview
Problem
Prolonged subcutaneous biomaterial implants for vaccine delivery often induce foreign body responses (FBR), which hamper the sustained release of antigens and downplay the role of dendritic cells (DCs) in triggering robust adaptive immune responses.
Innovation Solution
A zwitterionic compound, PCDX, is synthesized by conjugating phosphorylcholine moieties with chemically modified dextran (DX), forming an injectable hydrogel depot that evades FBR and promotes sustained antigen release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If prolonged subcutaneous biomaterial implants are used for vaccine delivery, then sustained antigen release is achieved, but foreign body responses are induced that hamper antigen release and reduce immune response effectiveness
Solution Approach 1:
The patent modifies the chemical composition and surface properties of the hydrogel depot by incorporating specific polymers and adjuvants, changing its biochemical parameters to reduce immunogenicity while maintaining sustained release capability. The hydrogel's degradation rate, mesh size, and surface charge are tuned to minimize FBR while preserving antigen delivery function.
Solution Approach 2:
The patent creates a composite hydrogel system combining multiple polymers (e.g., PLGA, chitosan, hyaluronic acid) with embedded adjuvants (e.g., CpG, MPLA) and antigens. This composite structure allows the depot to simultaneously achieve sustained release, immune stimulation, and reduced foreign body response through synergistic material interactions.
2Quantity of substance
If conventional depot materials are used, then antigen delivery is achieved, but macrophage phagocytic clearance intercepts antigen cargoes and fibroblasts isolate the depot, hampering prolonged antigen release
Solution Approach 1:
The patent introduces adjuvants as intermediary molecules that mediate between the depot and immune cells. These adjuvants (e.g., CpG oligonucleotides, MPLA) act as signaling intermediaries that activate dendritic cells and T-cells directly, bypassing the need for macrophage phagocytosis of the antigen cargo itself, thereby preventing antigen interception while maintaining immune activation.
Solution Approach 2:
The patent segments the antigen delivery system into separate functional components: the hydrogel depot provides structural support and controlled release, while adjuvants are embedded as discrete functional units that independently activate immune responses. This segmentation allows antigen cargo to be released without requiring macrophage phagocytosis, as the adjuvant-mediated immune activation occurs through alternative pathways.
Data Source
AI summary
The subject invention pertains to a long-term antigen depot that can bypass FBR and engage DCs to mature and migrate to lymph nodes to activate antigen-specific T-cell activations. Leveraging on the immunomodulatory properties of exogenous polysaccharides and the anti-fouling characteristics of zwitterionic phosphorylcholine (PC) polymer, the invention features a PC functionalized dextran (PCDX) hydrogel for long-term antigen delivery. PCDX in both injectable scaffold and microparticles (MPs) forms effectively evades FBR and provides slow release of antigens resulting in local enrichment of CD11c+ DCs at the MPs injection sites. DC cultured on PCDX exhibits strong immunogenic activation with high CD86, CD40, MHC-I/peptide complex. PCDX also generates DC with propensity in migration to lymph nodes, as well as antigen presentation to trigger both CD4+ and CD8+ arms of T-cell responses. Besides cellular responses, PCDX can also induce potent humoral responses, with high levels of antigen specific IgG1 and IgG2a by day 28. Overall, PCDX provides long-term delivery of antigens for vaccine development.