Humble eggshell may be the next bone graft material

We may soon be donating our unwanted eggshells to science, thanks to new research that has used the humble chicken eggshell to create a new bioactive material for performing safe and effective bone grafts.

Bone grafting is a common way to fill voids or interstices in bones caused by trauma or surgery such as tumor resection. Worldwide, approximately two million bone grafts are performed each year in orthopedic surgery, neurosurgery, plastic surgery and dental surgery.

Bone graft materials come from various sources. Autologous transplants use the bone of the person receiving the transplant. Allogeneic transplants use donor bone harvested in surgeries such as hip replacements and disinfected for use in others. Xenogenic bone is derived from non-living bones of another species, usually cows or pigs, and processed at high temperatures to prevent immune rejection and contamination.

Due to their ability to generate new bone, autologous and allogeneic transplants remain the gold standard. Although xenogenic grafts are a feasible alternative, they rely on the availability of materials of animal origin, which have a strong environmental cost and raise ethical concerns. To find a safe and effective xenograft material, researchers turned to the humble but abundant chicken egg.

Researchers have developed a new dissolution-precipitation method to create amorphous calcium phosphate (ACP) particles from chicken egg shells. ACP is essential for the formation of mineralized – i.e. hard and strong – bone and has previously been used as a bone substitute due to its components.

“Eggshell is an ideal raw material for synthesizing bone grafting materials because it contains a lot of calcium and phosphorus components,” said Qianli Ma, lead author of the study. “In addition, certain trace minerals associated with bone regeneration, such as magnesium and strontium, are also found in the eggshell.”

To create their “Eggshell ACP”, the researchers first heated eggshells to 900°C (1,652°F) for one hour to break down organic matter and turn calcium carbonate into oxide calcium. Calcium oxide was added to distilled water, creating a white suspension. Phosphoric acid was stirred into the suspension, and the ACP precipitate was filtered and washed with distilled water before being immersed in liquid nitrogen.

In another first, researchers embedded the ACP particles in a 3D spheroid to better analyze the bone-forming (osteogenic) activity of the particles through the interaction between host bone tissue and graft materials.

They found that in vitro eggshell PCR particles realistically interacted with osteoblasts, the cells that build bone. Moreover, they were non-toxic, immunocompatible and effective in promoting bone regeneration.

“This technique promises to create an unlimited supply of bioactive and long-lasting bone graft materials while reducing environmental pollution,” said Håvard Jostein Haugen, corresponding author of the study. “The osteoblastic spheroids constructed in the study provided a more practical model for biomaterials research, reflecting the three-dimensional interactions between cells and biomaterials.”

The researchers hope their findings will encourage more research into using ordinary food waste as a biomaterial.

The study was published in the journal Smart materials in medicine.

Source: KeAI Communications Co Ltd via Eurek alert!

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