Efficient CAR-NK Cell Production From Stem Cells Boosts Cancer Immunotherapy

A team of researchers in China has developed a potentially more effective and affordable method for generating natural killer (NK) cells for cancer immunotherapy. This new approach addresses significant challenges associated with traditional methods of producing these crucial immune cells, offering a promising avenue for advancing cancer treatment.

Harnessing the Power of Natural Killer Cells

NK cells are a vital component of the body’s natural defenses against both viruses, and cancer. Their ability to identify and destroy abnormal cells makes them a compelling target for cancer therapies. A technique called chimeric antigen receptor (CAR)-NK therapy enhances this ability by equipping NK cells with lab-designed receptors – CARs – that allow them to precisely target cancer cells.

Overcoming Limitations of Current Methods

Traditional CAR-NK therapies rely on mature NK cells sourced from peripheral blood or cord blood. However, these methods are hampered by inconsistencies between cells, difficulties in genetic modification, high production costs, and lengthy preparation times. The research team, led by Prof. WANG Jinyong at the Institute of Zoology of the Chinese Academy of Sciences, sought to overcome these hurdles by starting with a different type of cell.

Did You Know? A single CD34⁺ hematopoietic stem and progenitor cell (HSPC) could generate as many as 14 million iNK cells or 7.6 million CAR-iNK cells using this new method.

A Novel Approach: Stem Cell-Derived NK Cells

Instead of modifying mature NK cells, the researchers began with CD34⁺ hematopoietic stem and progenitor cells (HSPCs) from cord blood. They then generated induced NK (iNK) cells, and CAR-engineered iNK (CAR-iNK) cells. Previous attempts to create NK cells from these cord blood-derived HSPCs faced challenges with efficiency and cell maturity. The team addressed this by performing the genetic engineering earlier in the cell’s development, directly at the CD34⁺ HSPC stage.

The Three-Step Production Process

The team’s process involves three key stages. First, CD34⁺ HSPCs (or CD19 CAR-transduced HSPCs) are expanded using irradiated AFT024 feeder cells, resulting in an 800- to 1,000-fold increase in cell numbers within 14 days. Next, these expanded cells are cultured with OP9 feeder cells to form artificial hematopoietic organoid aggregates, which promote efficient NK cell development. Finally, the cells are allowed to mature and multiply, yielding highly pure iNK or CAR-iNK cells that express endogenous CD16.

Expert Insight: This research represents a significant step toward potentially making CAR-NK therapy more accessible. By starting with stem cells and streamlining the production process, the team has addressed key limitations of existing methods, including cost and scalability.

The findings were published in Nature Biomedical Engineering.

Promising Results in Leukemia Models

Laboratory tests demonstrated the potent tumor-killing capabilities of both iNK and CAR-iNK cells. In mouse models of human B-cell acute lymphoblastic leukemia (B-ALL), CD19 CAR-iNK cells effectively reduced tumor growth and prolonged survival. The new method significantly reduced the amount of viral vector needed for CAR engineering – using approximately 1/140,000 to 1/600,000 of the amount typically required for mature NK cells.

What Could Happen Next

If these results continue to hold true, this approach could lead to more widespread clinical trials of CAR-NK therapy. Further research may focus on optimizing the process for different cancer types and exploring the long-term effects of these iNK and CAR-iNK cells. It is also possible that this method could be adapted for use with other types of stem cells or combined with other immunotherapies.

Frequently Asked Questions

What are NK cells and why are they important in cancer treatment?

NK cells are a type of immune cell that plays a critical role in the body’s early defence against viruses and cancer. They have the natural ability to detect and destroy abnormal cells, making them an attractive tool for cancer treatment.

What is CAR-NK therapy?

CAR-NK therapy involves equipping NK cells with a lab-designed receptor (a CAR) so they can recognize a specific marker on cancer cells and attack them more precisely.

How does this new approach differ from traditional CAR-NK therapy?

Traditional methods use mature NK cells, while this new approach starts with CD34⁺ hematopoietic stem and progenitor cells (HSPCs) from cord blood, generating induced NK (iNK) cells and CAR-engineered iNK (CAR-iNK) cells. This method also moves the genetic engineering step earlier in development.

Could this new method make cancer immunotherapy more accessible to patients?