Over 10,000 Americans are on a waiting list for liver transplants, and many more are ineligible for surgery due to poor health. To address this critical shortage, MIT engineers have developed injectable "mini-livers" that can take over the functions of a failing liver. These mini-livers, consisting of liver cells and supportive fibroblast cells encapsulated in hydrogel microspheres, were shown in mouse studies to remain viable for at least two months, producing essential enzymes and proteins. The mixture can be injected into fatty tissue, where blood vessels grow to support the new tissue. This technology is envisioned as both a long-term treatment and a bridge to full transplantation, potentially requiring immunosuppressants but offering an easier, less invasive alternative to repeated surgeries.
Separately, biotech company LyGenesis is conducting a clinical trial in humans, attempting to grow new miniature livers inside patients by injecting donor liver cells into lymph nodes. The first volunteer received an injection of 50 million hepatocytes into a lymph node in March 2025. This trial aims to treat 12 adults with end-stage liver disease, with the goal of stimulating enough healthy liver tissue growth to negate the need for a full transplant. One donated liver could potentially provide enough cells to treat up to 75 people, significantly addressing the organ shortage. Initial animal studies in mice and pigs demonstrated that injected liver cells flourish in lymph nodes, forming functional secondary livers that integrate with the host's circulatory system and can grow up to 70% of the native liver's size, adapting their growth based on the severity of the original liver damage.
The LyGenesis approach uses the lymph node as a "living bioreactor." The treatment involves injecting liver cells into abdominal lymph nodes via a flexible tube and ultrasound guidance. Patients will likely require immunosuppressant drugs, similar to traditional transplant recipients, to prevent rejection of the donor cells. While it may take two to three months for the new organ to grow sufficiently to take over functions like ammonia removal, experts believe even a small increase in liver mass (10-30%) could significantly benefit patients with end-stage liver disease. The trial plans to test increasing doses, with some participants potentially receiving injections into up to five lymph nodes, resulting in multiple "mini-livers" growing inside them. This dual progress in regenerative medicine offers hope for new solutions to liver failure, whether through directly injected "satellite livers" or lymph node-based regeneration.
