For decades, immunotherapy has held promise as one of the most elegant approaches to cancer treatment: empower the body’s own immune system to recognize and destroy tumors. In practice, however, that promise has been uneven, particularly against solid tumors, where immune cells often falter before the fight is won.
Researchers at the University of California, Los Angeles are advancing a new approach that reframes the problem not as one of targeting, but of endurance. Their solution is an implantable, bioengineered “charging station” designed to sustain and amplify immune cell activity directly within the tumor environment.
“It’s a hard battle for the body,” said study co-lead Lili Yang, a professor of microbiology, immunology & molecular genetics. “When cancer occurs, it means the immune system has already been fighting for a long time. It doesn’t mean the cells are not functional—they just need a boost.”
That need for a boost reflects a central limitation in modern immunotherapy. While techniques such as CAR-T cell therapy have shown striking success in certain blood cancers, their effectiveness drops sharply in solid tumors. The issue is not necessarily that immune cells fail to reach the tumor, but that they lose strength once they arrive.
Study co-lead Song Li, Chancellor’s Professor of Bioengineering at the UCLA Samueli School of Engineering, compares the problem to a vehicle attempting to climb a hill without sufficient fuel. “If you run out of gas or electricity, you cannot go up,” he said.
How it works
The device introduces a localized, persistent support system that provides immune cells with the biochemical “fuel” needed to proliferate, remain active, and continue attacking tumors over time. At its core is a microscale delivery platform built from alginate, a biocompatible polymer derived from seaweed. Alginate is already widely used in medical applications and is low cost and safe.
The material is fabricated into microparticles that can be injected near tumors, where they disperse through the surrounding tissue. Each particle acts as a localized depot or “charging station” that delivers a carefully engineered combination of biochemical signals. These include α-galactosylceramide, a glycolipid that selectively activates invariant natural killer T (iNKT) cells, and interleukin-15, a cytokine that promotes immune cell proliferation and survival.
“These are two critical signals,” Li said. “One activates the cells, the other stimulates proliferation and expansion.”
To achieve sustained delivery, the researchers employ a hierarchical design. Nanoparticles made of PLGA—a biodegradable polymer commonly used in dissolvable sutures—are embedded within the larger alginate microparticles.
Although alginate itself is not inherently bioactive, its properties allow for controlled persistence within the body. Depending on formulation, the microparticles can remain functional for a long period of time.
“In vivo, these cells would last one to two months, providing immune surveillance,” Li said, adding that degradation can be tuned through material composition and ionic interactions.
Sustained response
From an engineering standpoint, the system operates through a combination of diffusion-driven transport and direct cell-material interaction. The microparticles establish chemical gradients that recruit immune cells from surrounding tissue. Once cells approach the particles, contact with the surface delivers stronger activation signals, effectively “recharging” them.
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