Enhancement of osteoblast gene expression by mechanically compatible porous Si‐rich nanocomposite

Abstract

Synthesis of a porous bioactive ceramic implant for load bearing applications is a challenging task in maxillofacial and orthopedic surgeries. A novel bioactive resorbable silica-calcium phosphate nanocomposite (SCPC) has recently been introduced as a potential bone graft. In the present study, we employed SCPC to develop a resorbable porous scaffold and analyzed the effects of composition and porosity on the mechanical properties. The ranges of compressive strength and modulus of elasticity of SCPC containing 32-56% porosity were 1.5-50 MPa and 0.14-2.1 GPa, respectively, which matched the corresponding values for trabecular bone. The compressive strength of dense SCPC was dependent on the Si content and acquired values (93-285 MPa) comparable to that of cortical bone. The superior mechanical properties of SCPC are attributed to the intricate interactions at the boundaries of the nanograins and to the homogenous distribution of hierarchical pore-structure throughout the material volume. X-ray computed tomography and mercury porosimetry analyses revealed high interconnectivity of the pores in the size range 3 nm to 650 microm. Quantitative real-time PCR analyses showed that neonatal rat calvarial osteoblasts attached to Si-rich SCPC expressed 5- and 26-fold higher osteocalcin mRNA levels compared to cells attached to ProOsteon hydroxyapatite disks and tissue culture polystyrene plates respectively, after four days in culture. Results of the present study strongly suggest that porous, bioactive resorbable SCPCs can serve as tissue engineering scaffolds for cell delivery to treat load-bearing bone defects in orthopedic and maxillofacial surgeries.

Dissolution kinetics of a Si‐rich nanocomposite and its effect on osteoblast gene expression

“…25 Relative quantification analysis was performed with LightCycler software version 4.0 (Roche, Indianapolis, IN). The concentration ratios of the target genes were calculated by normalizing mRNA for a particular gene against the mRNA of the housekeeping gene b-actin.…”

PDMSstar–PEG hydrogels prepared via solvent-induced phase separation (SIPS) and their potential utility as tissue engineering scaffolds

“…[23] Previous studies have demonstrated that the incorporation of inorganic silicon-containing materials into organic scaffolds enhances their bioactivity. [20-21, 60] In addition, scaffold hydrophobicity has also been shown to influence osteogenic differentiation. [25-26, 61] In our prior report, hydrogels were formed by introduction of an inorganic, hydrophobic methacrylated star polydimethylsiloxane (PDMS star -MA) into PEG-DA hydrogels.…”

Continuous gradient scaffolds for rapid screening of cell–material interactions and interfacial tissue regeneration

“…We observed that non-gradient PDMS star -PEG hydrogels increased stimulation of osteogenic differentiation of encapsulated MSCs in proportion to PDMS star -MA content [36]. This behavior was attributed to the inorganic, hydrophobic nature of PDMS star -MA, features commonly associated with other bioactive materials [11, 16, 51]. Thus, gradient scaffolds with a gradual change in bioactivity would be exceptionally useful, not only to screen cell-material interactions, but also for the ultimate regeneration of native-like osteochondral tissues which possess a gradual transition from osseous to cartilage tissue.…”