The scientific breakthrough enabling transplanted cells to evade the immune system originated from studying pregnancy. Researchers questioned why a mother's body doesn't reject a fetus, which is genetically half-foreign (from the father). Understanding this natural tolerance at the maternal-fetal border provided the blueprint for Sana's cloaking technology.
To avoid complex pancreatic surgery, Sana Biotechnology implants insulin-producing cells into a patient's forearm. This seemingly novel approach was inspired by a long-standing surgical practice where parathyroid glands, removed during thyroid surgery, are transplanted into the forearm to preserve their function, proving the location's viability.
Sana Biotechnology employs a two-part strategy to make transplanted cells invisible to the immune system. First, they engineer the cells to remove their unique identifying "fingerprint." Second, they overexpress a protein called CD47, which acts as a "don't eat me" signal to another part of the immune system that hunts for cells lacking a fingerprint.
A major step toward a diabetes cure happened 25 years ago when doctors successfully transplanted pancreatic islets from cadavers. This proved that cell replacement therapy worked, allowing patients to get off insulin. However, the approach was limited by a severe shortage of donors and the necessity for patients to take toxic, life-long immunosuppressant drugs.