3D interconnected porous biomimetic scaffolds:In vitrocell response

Bone cell response to 3D bioinspired scaffolds was tested on osteoblast culture supernatants and by means of quantitative polymerase chain reaction (qPCR). Foaming and freeze-drying method was optimized in order to obtain three dimensional interconnected porous scaffolds of gelatin at different content of nanocrystalline hydroxyapatite (HA). Addition of a non toxic crosslinking agent during foaming stabilized the scaffolds, as confirmed by the slow and relatively low gelatin release in phosphate buffer up to 28 days. Micro-computed tomography (-CT) reconstructed images showed porous interconnected structures, with interconnected pores displaying average diameter ranging from about 158 to about 71 m as the inorganic phase content increase from 0 to 50 wt%. The high values of connectivity (>99%), porosity (> 60%) and percentage of pores with a size in the range 100-300 m (>50%) were maintained up to 30 wt% HA, whereas higher content provoked a reduction of these parameters, as well as of the average pore size, and a significant increase of the compressive modulus and collapse strength up to 8 ± 1 and 0.9 ± 0.2 MPa respectively. Osteoblast cultured on the scaffolds showed good adhesion, proliferation and differentiation. The presence of HA promoted ALP activity, TGF-β1 and osteocalcin production, in agreement with the observed upregulation of ALP, OC, Runx2, and TGF-β1 gene in qPCR analysis, indicating that the composite scaffolds enhanced osteoblast activation and extra-cellular matrix mineralization processes.