A research team in China has developed a stem cell–based method to produce natural killer (NK) cells and CAR-engineered NK cells (CAR-iNK) from cord blood CD34+ hematopoietic stem and progenitor cells, addressing inefficiencies in traditional CAR-NK approaches that rely on mature NK cells.

The approach starts at the CD34+ HSPC stage, enabling earlier genetic modification, expansion, and commitment to the NK lineage, which leads to higher yields and more uniform cells.

The researchers used a three-step process: rapid expansion of CD34+ HSPCs with irradiated AFT024 feeder cells to achieve 800–1,000-fold growth in two weeks, culture with OP9 feeder cells to form artificial hematopoietic organoid aggregates for NK lineage commitment, and maturation to obtain highly pure iNK or CAR-iNK cells expressing endogenous CD16.

In preclinical models, both iNK and CAR-iNK cells showed strong anti-tumor activity, with CD19 CAR-iNK cells reducing tumor growth and improving survival in CDX and patient-derived xenograft models of human B-cell acute lymphoblastic leukemia (B-ALL).

A single CD34+ HSPC can produce up to 14 million iNK cells or 7.6 million CAR-iNK cells, suggesting that roughly one-fifth of a standard cord blood unit could generate enough cells for thousands to tens of thousands of treatment doses.

The method significantly reduces the viral vector needed for CAR engineering—about 1/140,000 to 1/600,000 of what mature NK cell modification requires by Day 42–49 of culture—lowering costs and potentially simplifying production.

Published in Nature Biomedical Engineering, the study points to substantial improvements in efficiency and cost for producing CAR-NK therapies, which could accelerate access to CAR-NK treatments.

Funding for the work came from Chinese national science bodies, including the Ministry of Science and Technology and the National Natural Science Foundation of China, among others.