A natural substance that helps trees stay strong may one day help repair broken bones. Researchers have discovered that lignin, a major structural material found in plants, can be converted into a bone-friendly biomaterial that supports bone healing and new bone formation. Although it is known for its antioxidant and antibacterial properties, its potential for bone repair has remained largely unexplored. At suitable concentrations, the lignin material was biocompatible and even stimulated the growth of pre-osteoblasts, the cells responsible for building new bone. Plant-Based Matrix for Bone Apatite Biomineralization: In Vitro Bioactivity, Biocompatibility, and Degradability of Lignin and Lignin-Silica Composites.