Accelerated degradation of HAP/PLLA bone scaffold by PGA blending facilitates bioactivity and osteoconductivity

The incorporation of hydroxyapatite (HAP) into poly-L-lactic acid (PLLA) matrix serving as bone scaffold is expected to exhibit bioactivity and osteoconductivity to those of the living bone. While too low degradation rate of HAP/PLLA scaffold hinders the activity because the embedded HAP in the PLLA matrix is difficult to contact and exchange ions with body fluid. In this study, biodegradable polymer poly (glycolic acid) (PGA) was blended into the HAP/PLLA scaffold fabricated by laser 3D printing to accelerate the degradation. The results indicated that the incorporation of PGA enhanced the degradation rate of scaffold as indicated by the weight loss increasing from 3.3% to 25.0% after immersion for 28 days, owing to the degradation of high hydrophilic PGA and the subsequent accelerated hydrolysis of PLLA chains. Moreover, a lot of pores produced by the degradation of the scaffold promoted the exposure of HAP from the matrix, which not only activated the deposition of bone like apatite on scaffold but also accelerated apatite growth. Cytocompatibility tests exhibited a good osteoblast adhesion, spreading and proliferation, suggesting the scaffold provided a suitable environment for cell cultivation. Furthermore, the scaffold displayed excellent bone defect repair capacity with the formation of abundant new bone tissue and blood vessel tissue, and both ends of defect region were bridged after 8 weeks of implantation.

Automated summary

The addition of PGA into HAP/PLLA scaffold accelerated the degradation process, leading to increased degradation rate and pore formation, which promoted the deposition and growth of bone-like apatite as well as provided a favorable environment for osteoblast adhesion and proliferation. This led to excellent bone defect repair capacity demonstrated by the formation of abundant new bone tissue and blood vessel tissue, ultimately bridging both ends of the defect region after 8 weeks of implantation.