Bioresorbability of chelate-setting calcium-phosphate cement hybridized with gelatin particles using a porcine tibial defect model

Calcium-phosphate cements (CPCs) are widely used to reconstruct and augment bones. To enhance the clinical usefulness of these cements, researchers have put great effort into improving their material properties and bioresorbability. To create a novel bioresorbable CPC, we successfully incorporated gelatin particles into a chelate-setting CPC, whose powder component consisted of hydroxyapatite surface-modified with inositol hexaphosphate and ¡-tricalcium phosphate. We expected that interconnected macropores could be formed inside the cement specimen through the degradation of the gelatin particles, resulting in cellular infiltration, specimen bioresorption, and subsequent new bone formation. To verify this hypothesis, we evaluated the bioresorbability and bone-forming ability of a gelatin-hybridized CPC implanted for eight weeks into porcine tibial defects. We also assessed the effects on the bioresorbability of polysaccharides (chitosan and chondroitin 6-sulfate) included in the liquid component of the CPC. Micro-CT observations and histological evaluations revealed that the use of chondroitin 6-sulfate could lead to enhancement of the bioresorbability and bone-forming ability. Of special note, the resorption rate reached nearly 85%, and new bone was observed at the resorbed sites inside the specimen. We conclude that gelatin-hybridized chelate-setting CPC containing chondroitin 6-sulfate is a promising bone substitute for non-load-bearing applications.