The efficacy of CAR-T cells in ablating solid tumours is significantly impeded by the densely packed tumour extracellular matrix (ECM).

This physical barrier severely restricts CAR-T cell infiltration within the tumour, thereby inhibiting their immunogenicity and antitumor response.

While combining CAR-T with hyaluronidase (HAase) to reduce ECM is apparent, the efficacy is limited because of low accumulation and penetration efficiency of HAase inside the tumour tissue.

A team of material scientists led by Xuesi Chen from Key Laboratory of Polymer Ecomaterials at Changchun Institute of Applied Chemistry recently present a HAase-loaded nanogel (H-NGs)-armed CAR-T cell inspired by metabolic oligosaccharide engineering (MOE) and the intelligently-designed nanogel developed in our previous work.

HAase was encapsulated within H-NGs during the cross-linking of supramolecular polymer chains based on the host-guest interaction 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 would cleave in a high ROS expressing TME.

H-NGs were conjugated on the surface of metabolic oligosaccharide engineered CAR-T cells via click chemistry to hitchhike into TME, followed by release of HAase at high ROS concentration.

Precisely released hyaluronidase degraded tumour stroma, improved CAR-T cell infiltration and enhanced solid tumour suppression.

The team published their work in Nano Research on April 15, 2025.

“In this study, we report a stimuli-responsive HAase-loaded nanogels (H-NGs) which are conjugated on the surface of CAR-T cells for synergistically improving HAase accumulation, ECM degradation and CAR-T cell efficacy. The conjugation of H-NGs on the T cell surface was achieved through metabolic oligosaccharide engineering (MOE) in a semi-quantitatively controlled manner. Intravenous injection of H-NGs armed CAR-T cells resulted in more ECM degradation than co-injection of CAR-T cells and free H-NGs, leading to an 83.2% tumour inhibition rate and relieves tumour suppressive microenvironment in the Raji solid tumour model.” said Xuesi Chen, professor in Changchun Institute of Applied Chemistry.

Dr. Chen is also the Chinese Academy of Sciences.

Many studies have shown that hyaluronidase (HAase) is an excellent tool for breaking down the physical barrier of tumours to improve the efficacy of solid cancer treatment.

To endow HAase with specific delivery and avoidance of clearance in blood, they are often combined with nanotechnology for therapeutics.

Unfortunately, the main distribution of nanoparticles around tumour vasculature usually limits the interaction of these stimuli-responsive nanoparticles with complex physiological environments (such as pH and reactive oxygen species (ROS)) in tumours, thus affecting their delivery efficiency within tumours.

“Given that CAR-T cells inherently possess the capability for tumour trafficking, it is conceivable to conjugate HAase-loaded nanoparticles onto the surface of these ‘living vehicles’. CAR-T cells would persistently transport the nanoparticles into regions distant from tumour vasculature, where in turn the specifically released HAase would degrade ECM which further augment the tumour infiltration of CAR-T cells. The two processes synergistically facilitate the complete eradication of solid tumours.” Xuesi Chen said.

To conjugate nanogels on the cell surface, per-O-acetylated N-azidoacetylmannosamine (Ac₄ManNAz) was selected as the agent for MOE.

As an azido-mannose derivative, Ac₄ManNAz exhibits inertness towards biological functions but demonstrates reactivity with specific reagents such as phosphines and alkynes, which are not found in most biological systems.

Therefore, it is suitable for cell surface engineering.

Besides, the thioketal linker (TK-linker) was introduced into H-NGs.

In the TME characterised by high ROS expression, the TK-linker would undergo cleavage as the research team previously reported, leading to the disassembly of H-NGs and the subsequent release of the encapsulated drugs.

Concurrently, the PBA group degrades under elevated ROS conditions, further facilitating the release of the loaded proteins.

These two designs ensured precise and efficient pseudo-autocrine delivery of HAase on the surface of CAR-T cells.

The research team expects that the study will successfully construct an intelligent delivery system based on supramolecular interactions, which will provide important technical support and theoretical basis for enhancing the therapeutic effect of CAR-T cell solid tumours.

“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 tumours. The proteomic analysis provided a comprehensive understanding of the mechanism by which CAR-T cells modified with H-NGs achieved superior efficacy against solid tumours. This strategy provides a highly effective combination therapy for CAR-T cells against solid tumours and opens up a new dimension of drug delivery pattern for degrading ECM.” said Xuesi Chen.

Other contributors include Wantong Song, Hanqin Zhao, Yuxi Gao, Sheng Ma, Xinghui Si, Yibo Qi, Zichao Huang, Yu Zhang from the Key Laboratory of Polymer Ecomaterials at Changchun Institute of Applied Chemistry; Lingyu Li from the Key Laboratory of Organ Regeneration and Transplantation of Ministry of Education at Jilin University; Jiaxuan Li and Tianmeng Sun from the Key Laboratory of Organ Regeneration and Transplantation of Ministry of Education at Jilin University.

Source: Tsinghua University Press