Polyhydroxybutyrate/Hydroxyapatite Highly Porous Scaffold for Small Bone Defects Replacement in the Nonload-bearing Parts

In the present work, Polyhydroxybutyrate (PHB)/Hydroxyapatite (HA) porous composites (10%, 20%, 30 %, 40%, 50% weight HA) were obtained by sintering. PHB/20% HA optimally combines satisfactory mechanical properties with a high content of the bioactive component (HA). Porous PHB/20% HA scaffolds have shown high mechanical properties (compressive strength of 106 MPa and Young’s modulus of 901 MPa). A high volume fraction of interconnected pores (> 50 vol.%) was achieved with pore size of 50 μm - 500 μm. Biocompatibility of porous pure PHB and PHB/20%HA, as its osseointegration were assessed in vitro and after implantation in laboratory animals. PHB/20% HA (−5% ± 0.9%) and pure PHB (−3% ± 1.4%) samples after 24 hours of incubation with human leucocytes showed no significant level of cytotoxicity when p = 0.648 (p-value). In vitro massive adhesion of mouse Multipotent Mesenchymal Stromal Cells (MMSC) to the surface of both porous samples was shown. PHB/20% HA induced more intensive MMSC proliferation compared to pure PHB, which are 31% ± 6.1% and 20% ± 5.7 % respectively when p = 0.039. We observed the resorption (implant surface area was reduced by 49 %) and integration of the porous PHB/20% HA samples into surrounding tissues after 30 days of implantation. The signs of osteoclasts accumulation, neo-angigenesis and new bone formation were observed, which make PHB/20% HA promising for bone tissue engineering.