Can humans regenerate organs like some animals can?

The answer

The human liver is the only internal organ capable of substantial regeneration, able to regrow to its original size within weeks after up to 75% has been surgically removed. This occurs through compensatory hyperplasia, where remaining hepatocytes re-enter the cell cycle and proliferate until the original liver mass is restored. Other human tissues show limited regeneration: the gut lining completely replaces itself every 3 to 5 days, skin continuously regenerates its outer layers, and bone can heal fractures. However, humans cannot regenerate limbs, heart muscle, or nervous tissue to any significant degree, unlike axolotls, zebrafish, and some lizards. Research into why humans lost regenerative abilities (which may relate to tumor suppression mechanisms) and how to reactivate regenerative pathways using stem cells, growth factors, and tissue engineering scaffolds represents one of the most active frontiers in biomedical science.