A new study led by Dr. Srinath Palakurthy and Professor Rivka Elbaum of the Hebrew University of Jerusalem reveals that lignin, a natural plant polymer, can be transformed into a bioactive material that promotes the formation of bone-like minerals while supporting the growth of bone-forming cells, according to a Jul. 27 announcement.
The research demonstrates that lignin—a major structural component found in plants—can be engineered to encourage the formation of hydroxyapatite, which is the mineral responsible for giving human bones and teeth their strength. The study was published in ACS Biomaterials Science & Engineering and explores sustainable, plant-based alternatives to current bone graft materials, many of which are derived from animals or synthetic sources.
The team focused on two structurally distinct forms of lignin extracted from sorghum plants and compared their performance both alone and combined with silica. Their experiments showed that one form of lignin rich in phenolic hydroxyl groups served as an effective template for hydroxyapatite formation. Within two weeks, calcium began accumulating on the material's surface; phosphorus deposition followed; and over four weeks, bone-like mineral crystals gradually grew. The material also degraded gradually under physiological conditions—an important property for scaffolds intended to be replaced by newly formed bone during healing.
Tests with living bone-forming cells indicated that at appropriate concentrations, lignin not only proved biocompatible but also enhanced pre-osteoblast cell growth—the type responsible for building new bone. Lignin-silica composites maintained strong compatibility with these cells while offering improved degradability.
"Plants have evolved sophisticated strategies for building strong, functional structures, and we wanted to see whether we could borrow those structures, and adapt them for regenerative medicine," said Dr. Srinath Palakurthy. "Our findings show that naturally derived lignin can provide a sustainable platform that not only supports bone mineral formation but also creates an environment where bone-forming cells can thrive." The work highlights an innovative use for lignin—a renewable byproduct generated in large quantities by agriculture and paper industries—which could help reduce dependence on mined or animal-derived materials if developed further.
Although additional studies, including animal testing, will be required before clinical applications become possible, researchers say these findings establish proof-of-concept: plant-derived biomaterials may actively guide the body's own healing process rather than simply serving as passive scaffolds.
