On Jun. 19, 2026, University of Southern California (USC) scientists report in a paper published in Cell, a new way of generating a renewable and expandable supply of the progenitor cells that give rise to macrophages. These immune cells help drive the body’s response against pathogens, and they hold strong promise as the basis for immunotherapies against cancer and other diseases.

The paper demonstrates that progenitor cells known as granulocyte-monocyte progenitors (GMPs), which give rise to macrophages and other immune cells, can be extensively expanded in the laboratory and engineered both to target specific cancer markers and help stimulate broader immune responses.

“The study establishes a scalable and engineerable GMP platform for cellular immunotherapy and introduces concepts that we believe could have broad implications for both cancer immunotherapy and stem cell biology,” said the paper’s corresponding author Qi-Long Ying, MD, PhD, professor of stem cell biology and regenerative medicine at the Keck School of Medicine of USC.

One of these broader implications is that self-renewal, a defining property of stem cells but not of progenitor cells, can be maintained in a GMP, which is already committed to generating macrophages and other closely related immune cells.

“The prevailing view has been that long-term self-renewal in the blood system is primarily a property of the hematopoietic stem cells that can generate any type of blood or immune cell,” said Ying. “We found that, under the right conditions, GMPs can also self-renew, dividing extensively while keeping their identity and ability to produce functional immune cells. That gives us a scalable starting point for engineering cell therapies for cancer, infectious disease and potentially many other conditions.”