Enhanced bone healing by improved fibrin-clot formation via fibrinogen adsorption on biphasic calcium phosphate granules.

Abstract

Fibrin clots play an important role in bone tissue regeneration. This study aimed at improving the fibrin-clotting rate by coating the surface of biphasic calcium phosphate (BCP) granules with fibrinogen (FNG). FNG was coated on the BCP surface using an adsorption and freeze-drying method. The surface morphology of FNG-adsorbed BCP (FNG-BCP) was characterized using scanning electron microscopy (SEM), and the stability of the adsorbed FNG evaluated by gel electrophoresis and circular dichroism (CD) analysis. The biocompatibility of FNG-BCP was evaluated in vitro using human mesenchymal stem cells, and in vivo bone-healing efficiency determined using a rabbit calvarial bone defect model. SEM studies showed numerous irregularly distributed FNG fractions adsorbed onto the surface of BCP granules. Gel electrophoresis, CD analysis, and in vitro coagulation results showed that the adsorbed FGN maintained its native protein structure and clotting properties. Biocompatibility experiments showed that cell proliferation and adhesion were improved in cells cultivated on the FNG-BCP granules. After surgical implantation into the bone defects, the FNG-BCP granules coagulated at the defect site by reacting with the blood discharged from the surgical site tissue. In addition, at 8weeks, the volume of FNG40-BCP (P=0.012) was significantly higher than that of BCP alone in the newly formed bone. These results indicate that self-coagulating FNG-CBP granules may have the potential to be used as a bone substitute for enabling effective bone repair through rapid fibrin-clot formation.