Stem Cell Editing Programs the Immune System to Make Own Therapeutic Proteins

For pathogens like HIV, malaria, and rapidly evolving influenza strains, coaxing the immune system to produce the rare, highly potent antibodies needed for protection has long been a scientific bottleneck. Vaccines can train B cells to evolve such broadly neutralizing antibodies, but only under ideal conditions—and only in a small fraction of people. Even attempts to genetically edit mature B cells produced responses that faded as the cells died out.

A team at the Rockefeller University has now taken a more upstream approach: programming hematopoietic stem and progenitor cells (HSPCs)—the source of all B lymphocytes—to carry permanent genetic instructions for therapeutic antibodies or other proteins. Because the immune system naturally amplifies rare, useful cells after vaccination, even a tiny number of edited stem cells can seed a durable, boostable immune response.

“The immune system is inefficient in that it produces a vast quantity of cells to protect itself,” said Harald Hartweger, a research assistant professor in Michel Nussenzweig’s Laboratory of Molecular Immunology. “We wanted to take advantage of the immune system’s ability to amplify useful, rare cells.”

The study, published in Science and titled “B lymphocyte protein factories produced by hematopoietic stem cell gene editing,” demonstrates that CRISPR‑edited HSPCs can mature into B cells that express engineered antibodies upon vaccination. A standard vaccination then acts as the trigger: antigen exposure drives those edited B cells to expand, differentiate into plasma cells, and secrete high titers of the inserted antibody that last long-term.

According to the paper, as few as ~7,000 edited HSPCs were enough to generate “high titers of long‑lasting protective or therapeutic antibodies and/or cargo proteins.” In mice engineered to produce a broadly neutralizing influenza antibody, this response was strong enough to protect against an otherwise lethal viral infection.

The platform proved unexpectedly versatile. Edited B cells could also secrete non‑antibody proteins, pointing to potential applications in genetic diseases. And by mixing HSPCs engineered with different antibody instructions, the researchers created immune systems capable of producing multiple antibodies simultaneously, an approach that could limit viral escape in HIV or other rapidly mutating pathogens. Human HSPCs edited using the same strategy produced functional human B cells in an immunodeficient mouse model, offering an early sign of translational feasibility.

“Our goal is to permanently impact the genome with a single injection, so that the body can make proteins of interest,” Hartweger said. “That protein could be an antibody that’s universally protective against HIV or influenza, but it could also be any therapeutic protein.”

The team is now moving toward preclinical testing in non‑human primates to evaluate protection against HIV and exploring whether similar strategies could be applied to T cells. The broader vision is a generalizable, long‑term protein‑production platform, one that could support treatments for infectious disease, protein deficiencies, autoimmunity, metabolic disorders, and cancer, according to Hartweger.

As Nussenzweig puts it, “The present study proposes a workaround for the antibody problem—a way of getting around the possibility that we may never get to a universal HIV vaccine, while still providing a promising, long‑lasting solution.”

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