The effect of particle size on the in vivo degradation of poly(D,L-lactide- co-glycolide)/a-tricalcium phosphate micro- and nanocomposites

• Published in: Acta biomaterialia 2016-11, Vol.45, p.340
• Main Authors: Bennett, Sarah M, Arumugam, Meera, Wilberforce, Samuel, Enea, Davide, Rushton, Neil, Zhang, Xiang C, Best, Serena M, Cameron, Ruth E, Brooks, Roger A
• Format: Article
• Language: English
• Subjects: Biological properties; Bone growth; Bone healing; Bone implants; Calcium phosphates; Degradation; Femur; Image processing; Image segmentation; Mechanical properties; Nanocomposites; Osteogenesis; Particle size; Particulate composites; Polylactide-co-glycolide; Surgical implants; Tricalcium phosphate; Visual observation
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2016.08.046

This paper reports the effect of particle size within a resorbable composite on the in vivo degradation rate and host response. Resorbable composites based on poly(D,L-lactide-coglycolide) (PLGA) reinforced with tricalcium phosphate (TCP) have shown suitable degradation, biological and mechanical properties for bone repair. Composites with nano-sized TCP particles degrade more homogenously in vitro than equivalent composites with micro-sized particles. In this study, PLGA and PLGA/TCP composites containing micro- or nano-sized α-TCP particles were implanted into an ovine distal femoral condyle defect and harvested at 6, 12, 18 and 24 weeks. An intimate interface was observed between the new bone tissue and degrading implants. Visual scoring of histological images and semi-automated segmentation of X-ray images were used to quantify implant degradation and the growth of new bone tissue in the implant site. Bone growth into the implant site occurred at a similar rate for both composites and the PLGA control. However, the in vivo degradation rate of the nanocomposite was slower than that of the microcomposite and consequently more closely matched the rate of bone growth. For the first 6 weeks, the rate of in vivo degradation matched that of in vitro degradation, but lagged significantly at longer time points. These results point to the potential use of ceramic particle size in controlling composite degradation whilst maintaining good bone formation.