The human liver is the only organ that can fully regenerate from as little as 25% of its original mass.

The liver's regenerative capacity is driven primarily by hepatocytes, the functional cells of the liver. Unlike most mature cells in the body, hepatocytes retain a high capacity for proliferation. When the liver is damaged or partially removed, these cells exit their resting state and enter the cell cycle to replicate. This process is remarkably efficient, allowing the liver to regain its original weight within approximately 30 days in many cases.Research published in journals such as Nature Reviews Gastroenterology & Hepatology reveals that this regeneration is triggered by a complex network of growth factors and cytokines, including Hepatocyte Growth Factor (HGF) and Interleukin-6. These molecules signal the remaining tissue to initiate the regrowth process. This evolutionary adaptation likely developed because the liver serves as the body's primary detoxification center and is frequently exposed to harmful substances.Clinical evidence from living-donor liver transplants provides the most compelling demonstration of this phenomenon. In these procedures, a healthy donor typically contributes 50% to 60% of their liver to a recipient. Within two months, the donor's liver usually returns to nearly 100% of its original volume. The recipient's partial graft similarly expands to meet their body's metabolic demands during the same period.While the liver can regrow its mass, it does not always restore its original shape. Instead, the remaining lobes expand to compensate for the missing tissue. This regenerative capacity is not unlimited, however, as chronic scarring from conditions like cirrhosis can eventually inhibit the cells' ability to divide. Understanding these regenerative pathways remains a major focus of regenerative medicine and stem cell research today.