Poly-å-caprolactone/hydroxyapatite composites for bone regeneration: in vitro characterization and human osteoblast responsePoly-å-caprolactone/hydroxyapatite composites for bone regeneration: in vitro characterization and human osteoblast response

Polycaprolactone (PCL), a semi-crystalline linear resorbable aliphatic polyester, is a good candidate as a scaffold for bone tissue engineering, due to its biocompatibility and biodegradability. However, the poor mechanical properties of PCL impair its use as scaffold for hard tissue regeneration, unless mechanical reinforcement is provided. To enhance mechanical properties and promote osteoconductivity, hydroxyapatite (HA) particles were added to the PCL matrix: three PCL-based composites with different volume ratio of HA (13%,20% and 32%) were studied. Mechanical properties and structure were analyzed along with biocompatibility and osteoconductivity. The addition of HA particles (in particular in the range of 20% and 32%) led to a significant improvement in mechanical performance (e.g. elastic modulus) of scaffold. Saos-2 cells and osteoblasts from human trabecular bone (hOB) retrieved during total hip replacement surgery were seeded onto 3D PCL-samples for 1-4 weeks. Following the assessment of cell viability, proliferation, morphology and ALP release, HA-loaded PCL were found to improve osteoconduction compared to the PCL alone. Our results indicated that PCL represents a potential candidate as an efficient substrate for bone substitution through an accurate balance between structural/mechanical properties of polymer and biological activities.