Technique Can Be Used for Bone Grafts and Regenerating Cartilage, Teeth, Tendons

Crushed eggshells
Eggshells are exceptionally well-suited for bone tissue engineering applications due to their unique chemical composition, which is primarily calcium carbonate.

08/13/2024
By Edwin L. Aguirre

Eggshells, which are primarily composed of a form of calcium called calcium carbonate, are used in a wide range of applications – from a supplement in chicken feed to natural pest control for the garden, and from a nontoxic abrasive cleaner to an art material for creating ornaments and mosaics.

Now, researchers are also using eggshells to grow tissues that can be implanted in patients to repair, replace or regenerate damaged or diseased tissues and organs such as bones and cartilage.

Among them is Assoc. Prof. Gulden Camci-Unal of the Department of Chemical Engineering. Since 2016, she has been conducting tissue engineering research in her lab using finely crushed eggshells to create microscopic 3D structures, or scaffolds, where bone cells can grow and proliferate.

Prof. Gulden Camci-Unal and her grad student in the lab Image by Edwin L. Aguirre
Chemical Engineering Assoc. Prof. Gulden Camci-Unal, left, and biomedical engineering and biotechnology Ph.D. student Mert Gezek examine an eggshell-reinforced implantable tissue scaffold they have fabricated in the lab at the Saab Emerging Technologies & Innovation Center on North Campus.

Most recently, she has advanced these efforts by using a biocompatible and biodegradeable synthetic polymer to strengthen the eggshell-based scaffolds, as well as employing 3D printing technique to create more precisely shaped structures for implanting.

Repurposing Eggshells for Personalized Medicine

“Each year, millions of tons of eggshells are routinely discarded worldwide. Since they are considered as waste, their potential as unconventional biomaterial is largely overlooked in the medical field,” says Camci-Unal, who is the Robert and Gail Ward Endowed Professor in Biomedical Materials Development.

“Our goal is to repurpose this eggshell waste for personalized medicine. Eggshells possess minerals that are also found in human bones, making them a promising candidate for biomedical applications,” she says. 

3D printer Image by Edwin L. Aguirre
The researchers mix the eggshell microparticles with a thermoplastic polymer called polycaprolactone to create composite pellets. The pellets are then melted and used as “ink” in a 3D printer to build the scaffold’s mesh structure layer by layer.
According to Camci-Unal, bone defects stemming from congenital anomalies, trauma, fractures and surgical removal of tumors have long posed significant challenges to a person’s quality of life and self-esteem. 

“Lab-grown bone grafts reinforced with eggshell microparticles not only support bone growth and healing, but they can also lessen the risk of complications, thereby reducing hospital stay and hastening recovery,” she says.

Aside from bone tissue engineering, other potential applications for eggshell-reinforced scaffold composites include dental restorations as well as skull, face and jaw repairs, bone to cartilage reconnections, cartilage regeneration and musculoskeletal applications.

Harnessing the Power of 3D Printing Technology

Initially, Camci-Unal used gelatin-based hydrogels reinforced with eggshell microparticles to create the bone scaffolds for implanting. 

This time, she is mixing the powdered eggshells with a hard thermoplastic polymer called polycaprolactone, and then feeding the eggshell-polymer “ink” into a 3D printer to build the scaffolds. The resulting structures have much higher mechanical strength and load-bearing capacity than those made with hydrogels.

3D scaffold Image by Edwin L. Aguirre
A close-up view of the 3D-printed scaffold model used by the researchers in their material characterization and in vitro experiments. The disk measures 4 millimeters in diameter.
“3D printing can mimic the architectural and biological features of natural tissues more effectively than traditional methods,” she says. “It allows us to design patient-specific implants and precisely fabricate scaffolds in the clinically needed shapes and sizes.”

Camci-Unal says this innovative approach provides an affordable, cost-effective and sustainable solution to bone repair challenges. 

“The precision of 3D printing technology will enable us to design customized and intricate structures tailored to the individual patient’s needs,” she notes. “For instance, a patient’s bone defect can be scanned with a laser, and then an eggshell-based implant can be 3D-printed to exactly fit in that defect.” 

Assisting Camci-Unal in the lab research are biomedical engineering and biotechnology Ph.D. student Mert Gezek and chemical engineering postdoctoral researcher Mine Altunbek and undergraduate student Maria Eduarda Torres Gouveia.

The team’s preliminary findings on 3D-printed scaffolds were published in June in the peer-reviewed journal ACS Applied Materials & Interfaces. Camci-Unal’s research is currently supported by UML internal funds. She is now in the process of applying for external funding and recruiting project collaborators.

“By transforming a waste material into a medically valuable product, we aim to provide sustainable solutions to critical clinical challenges in bone repair and regeneration,” Camci-Unal says.

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