People are accustomed to throwing out the shells when cooking eggs, but researchers at South Korea-based Chonnam National University developed a scaffold for bone regeneration using the shells’ inner lining that could make use of such waste while improving upon traditional medical devices.

Researchers described their scaffold in a study published in Biotechnology and Bioengineering on Feb. 2. They said that their take on these medical devices, which are used for tissue repair and reinforcement, could be used as a platform for bone regeneration because of the devices’ demonstrated flexibility and mechanical strength. 

Pointing to not just edible food but also inedible waste including eggshells, United Nations researchers recently revealed that about 17% of all food is wasted worldwide. Researchers involved in the new study have been doing their part, however, by hoarding shells to use in their work.

“Eggshell membrane is mostly thrown away after cooking,” Jangho Kim, study author and associate professor at the Department of Rural and Biosystems Engineering at Chonnam National University, told The Academic Times. “However, our research group focused on the components of eggshell membrane.”  

Reinforcing scaffolding materials using calcium-rich eggshells boosts bone healing and nerve tissue regeneration, the new research shows. People can get these membranes for almost free, Kim noted. 

“We believe that it has great potential to replace collagen-based medical devices, as well as to enhance the functions of existing tissue regenerative medical devices by utilizing discarded eggshell membranes,” Kim added. 

The researchers cited issues with other biomaterials that are currently used in scaffolds, including “rapid absorption period, low tensile strength and high costs.” The new scaffold is based on a biodegradable polyester known as polycaprolactone, which is used to develop biomedical devices. 

The material is often used for tissue regeneration, but with limitations regarding its compatibility with the biology of the tissue, as well as the performance of tissue regeneration. The “highly hydrophobic surface properties” of polycaprolactone pose an additional disadvantage, Kim said, while adding, “We showed that these disadvantages of polycaprolactone scaffolds can be overcome using eggshell membrane.”

Eggshell membrane is a very thin film lining the inside of eggshells that is difficult to use as a medical device, though its potential use as a platform for applications such as tissue regeneration has been documented in other research. It was made into a solution state so that it could be easily processed and developed into a medical device in the new study, leading to the development of the researchers’ new polycaprolactone‐based scaffold. 

The new study builds on previous work suggesting that a coating with the soluble form of eggshell membrane protein can successfully regulate cells both outside and inside a living organism — in vitro and in vivo — thanks to the alignment of its nanostructures. 

By simply coating this solution on existing medical devices designed to regenerate bone tissue, the team showed that their performance was improved. The researchers expect the scaffold they developed will make it possible to use such materials to develop platforms for various types of medical devices, gene and drug delivery sensors and cell therapies, too. 

Using a calvaria bone defect mouse model, the researchers found that coating scaffolds with eggshell membrane before applying them to the site where tissue was damaged promoted bone regeneration along the specific surface features that form at the nanoscopic scale. 

Changes were observed in the cells around the scaffold, spanning from how they were shaped and structured to how these cells proliferated, adhered to and were different from others. 

“We found that the unique physical and chemical properties of eggshell membrane, the surface and the mechanical properties can be further improved,” Kim says, taking issue with the existing conventional polycaprolactone-based approach of using nanotopography patches. 

Next, the team is interested in researching the practical use of bone regeneration platforms using the eggshell membrane-based medical devices. It also expects that these scaffolds can be used in the regeneration of tendon, skin and cartilage, according to Kim. 

The study, “Eggshell membrane as a bioactive agent in polymeric nano topographic scaffolds for enhanced bone regeneration,” published Feb. 2 in Biotechnology and Bioengineering, was authored by Daun Kim, Yonghyun Gwon, Sunho Park, Woochan Kim, Kwidug Yun and Jangho Kim, Chonnam National University.