Israeli scientists say an overlooked plant byproduct produced in large quantities by farms and paper mills could one day help patients repair damaged bone, according to TPS-IL. A Hebrew University of Jerusalem study found that lignin, a natural structural polymer in plants, can be engineered into a material that not only promotes bone mineral formation but may help support the body’s natural bone-repair process.
The study, led by postdoctoral researcher Dr. Srinath Palakurthy together with Prof. Rivka Elbaum, found that lignin — known mainly for giving trees and crops their structural strength — can be engineered into a bioactive material that encourages the formation of hydroxyapatite, the calcium-based mineral that gives human bones and teeth much of their strength.
The researchers said the findings mark a step toward more sustainable, plant-based alternatives to bone graft materials currently in use, many of which are derived from animals or synthetic sources. Demand for such alternatives has grown as scientists search for safer and more environmentally friendly ways to repair damaged bone.
Lignin is one of the most abundant natural polymers on Earth and has long been recognized for its antioxidant and antibacterial properties. However, its potential in regenerative medicine — the field focused on helping the body repair or replace damaged tissues — had remained largely unexplored, the researchers said, because lignin’s complex and highly variable structure makes it difficult to predict how it will behave inside the body.
To study lignin’s potential, the team extracted two structurally distinct forms of lignin from sorghum plants and tested them alone and combined with silica, another natural material that plants incorporate into their tissues.
One form of lignin, rich in phenolic hydroxyl groups, proved to be an effective template for hydroxyapatite formation. Calcium began accumulating on the material’s surface within two weeks, followed by phosphorus deposition and the gradual growth of bone-like mineral crystals over four weeks. The material also degraded gradually under conditions designed to mimic the human body, a property the researchers said is important for scaffolds meant to be replaced by new bone during healing.
The team further tested how living bone-forming cells responded to the material. At the right concentrations, lignin proved not only compatible with the cells but actually enhanced the growth of pre-osteoblasts, the cells responsible for building new bone. Lignin-silica composites, the study found, maintained strong compatibility with the 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,” Palakurthy said. “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.”
Elbaum said the study points to broader lessons for regenerative medicine. “Our work shows that plants have already solved many of the engineering challenges we face in designing regenerative materials,” she said. “By learning from the natural partnership between lignin and silica in plant tissues, we developed a sustainable material that supports bone mineral formation while remaining compatible with living cells. It demonstrates how inspiration from nature can lead to new solutions for regenerative medicine.”
If the material advances to clinical use, its most direct application would likely be as an alternative to conventional bone grafts, many of which are currently derived from animal bone or synthetic compounds. Animal-derived grafts carry risks of disease transmission and immune rejection, while synthetic materials can be costly or integrate poorly with surrounding bone.
Because the lignin-based material both promotes mineral formation and degrades gradually, it could serve as a temporary scaffold that supports new bone growth before being naturally replaced by the body’s own tissue. Potential future uses could include filling bone defects after trauma, tumor removal or major surgery, supporting healing around dental implants or jaw reconstruction, and assisting procedures such as spinal fusion, which often rely on bone graft materials.
However, the researchers cautioned that further studies, including animal testing, will be needed before the material can be used in clinical settings.
The study was published in the peer-reviewed ACS Biomaterials Science & Engineering.
