A biodegradable porous composite scaffold of PGA/β-TCP for bone tissue engineering

Polyglycolic acid (PGA) and beta-tricalcium phosphate (β-TCP) each have many applications as tissue repair materials. In this study, three-dimensional (3D) porous composite scaffolds of PGA/β-TCP (in 1:1 and 1:3 weight ratios) were fabricated using the solvent casting and particulate leaching method. PGA/β-TCP scaffolds with high porosity, interconnected 3D pores and rough surfaces were obtained and were observed using scanning electron microscopy (SEM) and micro-computed tomography (micro-CT). The PGA/β-TCP scaffolds were investigated during the repair of critical bone defects (3 mm diameter, 2 mm depth) in rat femoral medial-epicondyles, compared with hydroxylapatite (HAP) and no implant as controls. Quantitative imageology analysis (volume and density of new bone) and qualitative histological evaluations (hematoxylin and eosin staining; tartrate-resistant acid phosphatase-hematoxylin counterstaining) were characterized using in vivo micro-CT images and histological sections at 0, 14, 30 and 90 days after surgery. Significant differences of all variables were tested by multivariate analysis (p < 0.05). The results showed that the bone reformation by using the PGA/β-TCP scaffolds began within 14 days of surgery, and were healing well at 30 days after surgery. By 90 days after surgery, the bone replacement was almost completed and presented a healthy bone appearance. The new bone mineral densities (mg/cm3) with HAP, PGA/β-TCP (1:1) and PGA/β-TCP (1:3) at 90 days after surgery were: 390.4 ± 18.1, 563.8 ± 26.9 and 606.3 ± 26.9, respectively. The new bone mineral density with the PGA/β-TCP scaffold was higher than with HAP (p < 0.001), and with the PGA/β-TCP (1:3) scaffold was higher than with the PGA/β-TCP (1:1) scaffold at each time examined (p < 0.05). The biodegradation percents (%) of HAP, PGA/β-TCP (1:1) and PGA/β-TCP (1:3) at 90 days after surgery were: 35.1 ± 5.5, 99.0 ± 1.0 and 96.2 ± 3.3, respectively. The biodegradation percents of the PGA/β-TCP scaffolds were higher than HAP at each time examined (p < 0.01), and matched the osteogenesis rates. The PGA/β-TCP scaffolds were almost replaced by new growing bone within 90 days after surgery. Thus the PGA/β-TCP composite scaffold, especially weight ratio 1:3, exhibited a strong ability for osteogenesis, mineralization and biodegradation for bone replacement.