Polylactic acid fibre-reinforced polycaprolactone scaffolds for bone tissue engineering

The employment of composite scaffolds with a well-organized architecture and multi-scale porosity certainly represents a valuable approach for achieving a tissue engineered construct to reproduce the middle and long-term behaviour of hierarchically complex tissues such as spongy bone. In this paper, fibre-reinforced composites scaffold for bone tissue engineering applications is described. These are composed of poly-l-lactide acid (PLLA) fibres embedded in a porous poly(ɛ-caprolactone) matrix, and were obtained by synergistic use of phase inversion/particulate leaching technique and filament winding technology. Porosity degree as high as 79.7% was achieved, the bimodal pore size distribution showing peaks at ca 10 and 200 μm diameter, respectively, accounting for 53.7% and 46.3% of the total porosity. In vitro degradation was carried out in PBS and SBF without significant degradation of the scaffold after 35 days, while in NaOH solution, a linear increase of weight lost was observed with preferential degradation of PLLA component. Subsequently, marrow stromal cells (MSC) and human osteoblasts (HOB) reached a plateau at 3 weeks, while at 5 weeks the number of cells was almost the same. Human marrow stromal cell and trabecular osteoblasts rapidly proliferate on the scaffold up to 3 weeks, promoting an oriented migration of bone cells along the fibre arrangement. Moreover, the role of seeded HOB and MSC on composite degradation mechanism was assessed by demonstrating a more relevant contribution to PLLA degradation of MSC when compared to HOB. The novel PCL/PLLA composite scaffolds thus showed promise whenever tuneable porosity, controlled degradability and guided cell–material interaction are simultaneously requested.