Porous and biodegradable polycaprolactone-borophosphosilicate hybrid scaffolds for osteoblast infiltration and stem cell differentiation

Abstract The composition and microstructure of bone tissue engineering scaffolds play a significant role in regulating cell infiltration, proliferation, differentiation, and extracellular matrix production. While boron is an essential trace element for bone formation, growth, and health, boron-containing biomaterials are poorly studied. Specifically, the effect of boron in hybrid scaffolds on stem cell differentiation is unknown. We have previously reported the synthesis and characterization of class II hybrid biomaterials from polycaprolactone and borophosphosilicate glass (PCL/BPSG). In this study, PCL/BPSG hybrid porous scaffolds were fabricated by a solvent-free casting and particulate leaching method having consistent pore-size distribution, controlled porosity, and pore interconnectivity. The mechanical properties with respect to porogen loading and degradation time demonstrated that these scaffolds were competent for bone tissue engineering applications. In cell culture experiments, significant number of cells infiltrated and adhered into the scaffolds interior. Induced pluripotent stem cells (iPSCs) differentiation to osteogenic lineage was dependent on the amount of boron incorporated into the hybrid scaffolds. Consistent with this, scaffolds containing 2-mol% boron (calculated as % of the inorganic component) had an optimum effect on lineage expressions for alkaline phosphatase (ALP), osteopontin (OPN) and osteocalcin (OCN). These results suggest that PCL/BPSG hybrid scaffolds with optimum-level boron may enhance bone formation.