USC scientists engineer renewable immune progenitor cells that slow tumor growth in mice

Cell-based cancer immunotherapy has changed treatment for some patients, but it faces two stubborn problems: making enough cells and keeping them working long enough to matter. Many current products are made individually from a patient's own mature immune cells, which is slow, costly and often yields cells that tire out. A renewable, off-the-shelf source would be a significant step forward.

Researchers at the Keck School of Medicine of USC, led by Qi-Long Ying, MD, PhD, took a different approach and published it in Cell. They focused on granulocyte-monocyte progenitors (GMPs), immature cells that normally give rise to macrophages and other immune cells. Under carefully controlled laboratory conditions, the GMPs kept multiplying while preserving their identity and their capacity to become functional immune cells.

The team then genetically modified the GMPs to recognize specific cancer markers and to strengthen broader immune responses. In mice, the engineered cells established themselves in bone marrow, continued to generate new immune cells, and slowed the progression of both blood cancers and solid tumors. That suggests a system that can keep producing tumor-fighting cells inside the body.

The finding also has implications for basic biology. Long-term self-renewal has traditionally been attributed mainly to hematopoietic stem cells, while progenitors were thought to have limited capacity. Showing that GMPs can self-renew in culture challenges that assumption and may inform stem cell research more broadly.

For now, the practical implication is promise rather than a treatment. The work offers a scalable, engineerable platform that could eventually support longer-lasting, ready-made immunotherapies.

Important caveats apply. All reported efficacy comes from mouse experiments, which often fail to predict human outcomes. Safety questions, such as unwanted immune activation or uncontrolled cell growth, must be answered before clinical trials. Readers should consult the full paper for dosing, tumor models, durability of response and comparison against existing therapies.