Implants embedded with antibiotics used to regenerate damaged bone

Each year, around four million people worldwide develop a bone infection following an open fracture or surgery. The gold standard treatment comprises a lengthy antibiotic therapy, usually delivered orally or intravenously, and the removal of infected bone tissue. This often leaves behind a hole too large for the body to fill via normal bone regeneration. 

To tackle this, a group of researchers from the Netherlands, Italy and Spain outlined a novel treatment approach they have developed – antibiotic-releasing and biodegradable 3D-printed scaffolds, capable of supporting bone regeneration and delivering antibiotics at the same time.

“Every person has their own individual body anatomy, which certainly requires a specific intervention in the event of bone injury,” explained Lorenzo Moroni, professor in bio-fabrication for regenerative medicine at Maastricht University’s MERLN institute in the Netherlands.

“3D-printed polymeric scaffolds possess several unique properties for bone regeneration: experts can tailor their shape to fit the specific patient’s anatomy, they are porous to allow cell infiltration, but at the same time mechanically strong, and they can degrade over time to make space for the newly formed bone.”

However, Moroni stressed that incorporating antibiotics in these scaffolds is not a straightforward process. This is because the 3D-printing process involves melting the material at high temperatures and antibiotics are heat sensitive.

The study’s multidisciplinary team of scientists found that covering the antibiotics with lamellar inorganic protectors, prior to mixing them with the polymer and placing them in the 3D scaffolds, not only protected the antibacterial agents, it also enabled a more controlled release.

This controlled release extended the period the antimicrobial remained active and helped to keep local antibiotic concentrations under potentially toxic levels., the researcher said. Meanwhile, the cells in contact with these scaffolds maintained their viability and could perform normal cell functions, including bone formation – the ultimate goal of the implant.

Maria Camara-Torres, the investigator who led the study, said this is a “great breakthrough” in the field of bone regeneration. “Until now, there have been limitations to the direct incorporation of antibiotics and other bioactive molecules within 3D-printed scaffolds because of the few polymers that can be processed at low temperatures,” she said.

She added that the team’s novel approach shows that experts can expand the library of polymers to include many more. “We hope our results encourage scientists to continue investigating the use of lamellar inorganic fillers in combination with biomolecules to increase the functionality of 3D-printed scaffolds in clinical applications.”

The study, ‘3D additive manufactured composite scaffolds with antibiotic-loaded lamellar fillers for bone infection prevention and tissue regeneration’, was published in the KeAi journal Bioactive Materials.