Scientists in China have built a streamlined pipeline that turns a single cord‑blood stem cell into tens of millions of natural killer (NK) cells – a key weapon in the fight against cancer.
NK cells are part of the body’s first line of defense, hunting down virus‑infected and malignant cells without needing prior exposure. By attaching a laboratory‑engineered chimeric antigen receptor (CAR) to NK cells, researchers can steer them toward specific cancer markers, creating the so‑called CAR‑NK therapy.
Traditional CAR‑NK production relies on mature NK cells harvested from blood or cord blood. That approach is hampered by donor variability, modest gene‑editing efficiency, high manufacturing costs, and long lead times.
Starting From Cord‑Blood Stem Cells
Prof. Wang Jinyong’s team at the Chinese Academy of Sciences took a different route. They isolated CD34‑positive hematopoietic stem and progenitor cells (HSPCs) from cord blood and coaxed them directly into induced NK cells (iNK) or CAR‑engineered iNK cells (CAR‑iNK). Their work appears in Nature Biomedical Engineering.
Earlier attempts to generate NK cells from cord‑blood CD34⁺ cells suffered from low yields and immature functionality. The new strategy moves the genetic modification step forward, transducing the HSPCs before they commit to the NK lineage. This early‑stage engineering pairs CAR insertion with vigorous expansion and guided differentiation.
Three‑Stage Expansion and Differentiation
- Stage 1 – Stem‑Cell Amplification: CD34⁺ HSPCs (or CD19‑CAR‑transduced HSPCs) are cultured on irradiated AFT024 feeder cells, achieving an 800‑ to 1,000‑fold increase in just two weeks.
- Stage 2 – Organoid Commitment: The expanded cells are transferred onto OP9 feeder layers, forming artificial hematopoietic organoids that steer them toward the NK pathway.
- Stage 3 – NK Maturation: Committed cells are allowed to mature and proliferate, yielding highly pure iNK or CAR‑iNK populations that naturally express CD16.
Massive Output From One Stem Cell
Remarkably, a single CD34⁺ HSPC can produce up to 14 million iNK cells or about 7.6 million CAR‑iNK cells. The researchers estimate that just 20 % of a typical cord‑blood unit could supply enough cells for thousands of treatment doses.
Drastic Reduction in Viral Vector Use
The platform also slashes the amount of viral vector required for CAR insertion. Compared with conventional methods that modify mature NK cells, this approach consumes roughly 1/140,000 to 1/600,000 of the usual vector quantity by days 42‑49 of culture.
Powerful Tumor Killing in Leukemia Models
Both iNK and CAR‑iNK cells displayed strong cytotoxicity in laboratory tests. In mouse models of human B‑cell acute lymphoblastic leukemia—both cell‑line‑derived (CDX) and patient‑derived (PDX) xenografts—CD19‑CAR‑iNK cells slowed tumor growth and extended animal survival.
Funding was provided by China’s Ministry of Science and Technology, the National Natural Science Foundation, and additional national programs.