Influence of Apatite Crystallinity in Porous PLGA/Apatite Composite Scaffold on Cortical Bone Response

Abstract

Apatites with different level of crystallinity, Ca-deficient hydroxyapatite (CDHA) powder with low crystallinity and the mixture of carbonated hydroxyapatite (CHA) and CDHA powder with higher crystallinity, were prepared through from Ca-EDTA complex. Porous composite scaffolds of poly(lactide-co-glycolide) (PLGA) and apatites were manufactured by solution casting/particles leaching method. The biological properties of two composites, composite scaffold A (PLGA and CDHA with low crystallinity) and composite scaffold B (PLGA and CHA/CDHA mixture with higher crystallinity) were examined. The MC3T3E-1 osteoblast-like cells were cultures towards the composite scaffolds A and B. Morphological observation by scanning electron microscope revealed that cells firmly attached inside the micropores of the composite scaffold A, but that a few cells were present inside the composite scaffold B, although there were no significant difference in the cell viability between composite scaffold A and B. Two porous composite scaffolds A and B were implanted into the cortical bone of tibiae of rabbits. After 4 weeks’ implantation, bone response towards porous composite was histologically evaluated. High-resolution microfocus X-ray computed tomopraphy observation and histological appearances revealed that composite scaffold A provided greater degree of new bone formation than composite scaffold B. The original drill hole was partly filled with new bone in composite scaffold A. In conclusion, PLGA/apatite porous composite scaffold with low level of crystallinity apatite is one of promising materials for bone substitutes or scaffold materials for bone tissue engineering.