Researchers at the Changchun Institute of Applied Chemistry have developed a novel approach to enhance CAR-T cell therapy effectiveness against solid tumors by engineering cells with hyaluronidase-loaded nanogels that can degrade the dense extracellular matrix (ECM) barrier surrounding tumor tissues. The study, published in Nano Research on April 15, 2025, demonstrates significant improvements in tumor suppression rates.
Overcoming the ECM Barrier Challenge
The efficacy of CAR-T cells in treating solid tumors faces a major obstacle: the densely packed tumor extracellular matrix that severely restricts CAR-T cell infiltration, thereby inhibiting their immunogenicity and antitumor response. While combining CAR-T therapy with hyaluronidase (HAase) to reduce ECM has shown promise, the efficacy has been limited due to low accumulation and penetration efficiency of HAase inside tumor tissue.
"Given that CAR-T cells inherently possess the capability for tumor trafficking, it is conceivable to conjugate HAase-loaded nanoparticles onto the surface of these 'living vehicles'," explained Professor Xuesi Chen from the Key Laboratory of Polymer Ecomaterials at Changchun Institute of Applied Chemistry and the Chinese Academy of Sciences.
Innovative Nanogel Design and Engineering
The research team developed HAase-loaded nanogels (H-NGs) using supramolecular polymer chains based on host-guest interactions between adamantane (Ad) and cyclodextrin (CD). The Ad groups were anchored on α,β-poly(N-hydroxyethyl)-L-aspartamide (PHEA) backbones using a thioketal (TK) linker, which cleaves in high reactive oxygen species (ROS) expressing tumor microenvironments.
To attach the nanogels to CAR-T cells, the team employed metabolic oligosaccharide engineering (MOE) using per-O-acetylated N-azidoacetylmannosamine (Ac4ManNAz). This azido-mannose derivative exhibits inertness towards biological functions but demonstrates reactivity with specific reagents such as phosphines and alkynes, making it suitable for cell surface engineering through click chemistry.
Dual-Response Mechanism for Targeted Release
The nanogels incorporate two complementary mechanisms for precise HAase release within the tumor microenvironment. The thioketal linker undergoes cleavage in high ROS conditions, leading to H-NG disassembly and subsequent release of encapsulated drugs. Simultaneously, phenylboronic acid (PBA) groups degrade under elevated ROS conditions, further facilitating protein release. These designs ensure precise and efficient pseudo-autocrine delivery of HAase on the CAR-T cell surface.
Significant Therapeutic Improvements
In preclinical studies using the Raji solid tumor model, the H-NG armed CAR-T cells demonstrated superior performance compared to conventional approaches. Intravenous injection of H-NG armed CAR-T cells resulted in more extensive ECM degradation than co-injection of CAR-T cells and free H-NGs, achieving an 83.2% tumor inhibition rate.
"The degradation of ECM mediated via HAase improved CAR-T cell infiltration and weakened immunosuppressive TME, thereby augmenting the therapeutic effect of CAR-T cells on solid tumors," said Professor Chen. The approach not only enhanced physical infiltration of CAR-T cells into the tumor core but also appeared to alter the immunosuppressive nature of the tumor microenvironment.
Mechanistic Insights and Future Implications
The study provides comprehensive mechanistic understanding through proteomic analysis of how CAR-T cells modified with H-NGs achieve superior efficacy against solid tumors. CAR-T cells persistently transport the nanoparticles into regions distant from tumor vasculature, where the specifically released HAase degrades ECM, which further augments tumor infiltration of CAR-T cells. The two processes synergistically facilitate more complete solid tumor eradication.
"This strategy provides a highly effective combination therapy for CAR-T cells against solid tumors and opens up a new dimension of drug delivery pattern for degrading ECM," Professor Chen noted. The research team expects this intelligent delivery system based on supramolecular interactions will provide important technical support and theoretical basis for enhancing CAR-T cell therapeutic effects in solid tumors.
