Plate Nº 29 · recorded October 16, 2026
Health & Medicine ResearchReported finding
USC Team Grows Renewable Cancer-Fighting Immune Cells in Breakthrough Study
USC scientists grew self-renewing immune progenitor cells, engineered them to attack tumors, and slowed blood cancers and solid tumors in mice — a preclinical but scalable path to off-the-shelf therapy.
By Priya Raman4 min read807 words
In brief
- The study was published in Cell on October 16, 2026, by a USC Stem Cell-led team (Cell 2026; 189(17): 5378).
- Granulocyte-monocyte progenitors were expanded in the lab, genetically engineered with CAR receptors, and shown to self-renew — a ability previously attributed mainly to hematopoietic stem cells.
- In mice, the engineered cells engrafted in bone marrow and slowed progression of both blood cancers and solid tumors.
- An added immune-activating signal worked even with donor-recipient immune mismatch, suggesting off-the-shelf potential.
- All cancer-treatment results are preclinical; human safety and efficacy remain unproven.
On October 16, 2026, scientists at the Keck School of Medicine of USC published a study in the journal Cell describing a potentially endless supply of engineered immune cells that can attack cancer from within the body. In mice, the cells settled into bone marrow and slowed the progression of both blood cancers and solid tumors.
The work centers on an immature immune cell called a granulocyte-monocyte progenitor, or GMP (a parent cell that normally develops into macrophages and related defenders). First author Shi Yue, MD, and corresponding author Qi-Long Ying, MD, PhD, professor of stem cell biology and regenerative medicine at USC, found that GMPs can multiply extensively in the laboratory while keeping their identity — and still be genetically programmed to fight cancer.
What makes the discovery surprising?
The finding overturns a long-standing assumption about how blood cells develop. Self-renewal — the capacity to divide repeatedly without losing original properties — has been attributed mainly to hematopoietic stem cells, the master cells that generate every major blood and immune cell type. Progenitors such as GMPs sit further along the developmental path and were thought to lack that staying power.
Ying said the results challenge that view. "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," he said. "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."
The team achieved this with a precisely defined chemical mixture that keeps GMPs alive and multiplying while preventing them from maturing too early. Collaborators in Ravi Majeti's laboratory at Stanford University independently reproduced the maintenance and genetic engineering of the cells, strengthening confidence in the method's reliability.
Why target macrophages?
Macrophages — the name is Greek for "big eaters" — engulf bacteria, damaged cells and debris, and some can penetrate tumors. That tumor-invading talent makes them attractive where existing engineered T-cell therapies have struggled: solid masses in organs and tissues.
Mature macrophages, however, are hard to work with. Three problems stand out:
- They are difficult to multiply in large quantities outside the body.
- They resist genetic modification and can be damaged during freezing and storage.
- After infusion, they tend to pool in the lungs and liver and disappear relatively quickly.
Starting one stage earlier, with GMPs, offers a workaround. "This method for the expansion and engineering of GMPs opens the door to numerous translational applications, much like T cell expansion and engineering," said Majeti, Director of the Institute for Stem Cell Biology and Regenerative Medicine at Stanford. "We have already demonstrated engineering of these cells to drive multiple potent functions, and there is a lot more to be explored."
How were the cells engineered to fight cancer?
The researchers gave the GMPs a chimeric antigen receptor, or CAR (a synthetic receptor that lets an immune cell recognize a specific marker on cancer cells). This is the same core technology used in CAR T-cell therapies that modify a patient's own T cells.
Some progenitors also received an added immune-activating signal designed to recruit and stimulate nearby T cells. That signal worked even when donor and recipient immune characteristics did not match — a result that opens the door to off-the-shelf treatments manufactured in advance in large batches, rather than personalized therapies prepared one patient at a time.
What did the mouse experiments show?
Administered to mice, the engineered progenitors established themselves in bone marrow and other blood-forming sites, where they generated continuing supplies of engineered macrophages and related cells. Cells carrying CAR receptors slowed disease progression in both blood cancers and solid tumors. The effect was stronger when the CAR receptor was combined with the immune-activating signal.
In a separate experiment, GMPs restored the ability of mice with chronic granulomatous disease — an inherited disorder that leaves immune cells unable to kill certain microbes — to fight bacterial infection, pointing toward uses beyond cancer.
The researchers caution that all cancer-treatment results remain preclinical. Further research will be needed to establish whether engineered GMPs are safe and effective in people, particularly if the cells are meant to persist and keep producing immune cells over long periods.
The broader lesson, Ying suggests, concerns timing as much as engineering. "Our study suggests that the future of immunotherapy may depend not only on designing better CAR receptors, but also on choosing the right developmental stage of the cell," he said.
The study, "Expansion and CAR engineering of granulocyte-monocyte progenitors for cellular immunotherapy" (Cell, 2026; 189(17): 5378), was funded in part by the Chen Yong Foundation of the Zhongmei Group, Myelogene Inc., the L.K. Whittier Foundation and the Eli and Edythe Broad Innovation Award.
via stemcell.keck.usc.edu (Original)
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Senior reporter covering people, launches and day-to-day practice in general science news at SciBeat.
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