Polycaprolactone scaffolds for bone tissue engineering - Effects of a calcium phosphate coating layer on osteogenic cells

Biodegradable polycaprolactone (PCL) scaffolds made by fused deposition modelling (FDM) were coated with a layer of calcium phosphate using a biomimetic method and seeded with human bone marrow osteogenic cells. These bioconstructs were cultured in vitro over a period of time and both in vitro and in vivo analyses were carried out in order to investigate the efficacy of the calcium phosphate coating for improving cell attachment, proliferation and differentiation. In vitro analysis using AlamarBlue(TM) showed that the cells within the coated scaffolds had a higher proliferation rate compared to those in uncoated scaffolds. Alkaline phosphatase (ALP) activity was also found to be higher for the coated scaffolds. LIVE/DEAD(R) staining showed that more viable cells were present in the coated scaffolds. This was further confirmed using scanning electron microscopy (SEM). An in vivo biocompatibility study showed no adverse tissue inflammatory response as a result of the coating layer generated. X-ray diffraction analysis (XRD) and wavelength dispersive analysis (WDX) showed that the coating layer was structurally similar to hydroxyapatite. However, more analyses are required to confirm the exact nature of the material phase. This study shows the feasibility of improving the 3D scaffold based approach to bone tissue engineering by introducing an osteoinductive coating layer.