Researchers at USC have found a way to grow many immune‑cell precursors in the lab. These cells could become powerful tools for fighting cancer and other diseases.
What Are GMPs?
GMP stands for granulocyte‑monocyte progenitor. These are early‑stage cells that normally make macrophages and other immune cells. Macrophages help protect the body from infections and are now being studied as cancer fighters.
Making GMPs Grow and Stay Young
The team discovered that, with a special mix of chemicals, GMPs can keep dividing for a long time without losing their identity. This is similar to how stem cells renew themselves, a property scientists did not expect from progenitor cells.
Because the cells stay youthful, they can be expanded in large numbers and later turned into functional immune cells.
Why Use Macrophage Precursors?
Macrophages naturally move into tumors, eat cancer cells, and call other immune cells to help. While T‑cell therapies work well for blood cancers, macrophage‑based treatments may work better for solid tumors.
Old methods of using mature macrophages have problems: they are hard to grow, tough to modify genetically, and often get damaged when frozen. They also tend to collect in the lungs or liver instead of spreading through the body.
Engineering GMPs to Attack Cancer
The scientists added a chimeric antigen receptor (CAR) to the GMPs. This CAR lets the cells recognize a marker on cancer cells. They also added a second signal that boosts nearby immune cells, helping T‑cells fight the tumor.
Both signals stay active even when donor and patient cells do not match, opening the possibility of ready‑made, off‑the‑shelf treatments.
Testing in Mice
After growing and engineering mouse and human GMPs, the researchers gave them to mice. The cells settled in the bone marrow and kept producing engineered macrophages and other immune cells.
In mice with blood cancers and solid tumors, the CAR‑GMPs slowed disease growth. Cells that carried both the CAR and the extra immune‑activating signal worked even better.
Beyond Cancer
The same approach helped mice with chronic granulomatous disease, a genetic disorder that weakens the immune system. Treated mice fought bacterial infections more effectively, showing the method could help other immune problems.
What This Means
Having a renewable source of engineered immune cells could make cell therapies cheaper and easier to produce. It also shows that the stage at which a cell is engineered matters a lot for its success.
The study was published in the journal Cell under the title "Expansion and CAR engineering of granulocyte‑monocyte progenitors for cellular immunotherapy."