Synthesis of Aligned Porous Polyethylene Glycol/silk Fibroin/hydroxyapatite Scaffolds for Osteoinduction in Bone Tissue Engineering

Abstract Background: The physical factors of the extracellular matrix have a profound influence on the differentiation behavior of mesenchymal stem cells. In this study, the effect of the biophysical microenvironment on rat bone marrow mesenchymal stem cell (BMSC) osteogenesis was studied both in vitroand in vivo. Methods: To prepare cell culture scaffolds of varying stiffness, increasing amounts of hydroxyapatite (HAp)were mixed into apolyethylene glycol/silk fibroin(PEG/SF) solution. The amount of HApranged from 25 to 100mg, which provided for different ratios between HApand the PEG/SF composite. In vitro, the effect of stiffness on the osteogenic differentiation of rat BMSCs was studied. The outcome measures, which were verified in vivo, included the protein expressionof runt-related transcription factor 2 and osteocalcin, alkaline phosphatase activity, and the mRNAexpression of osteogenesis-relatedmarkers.Results:Increasingamounts of HAp resulted in an increased elastic modulus of the cell culture scaffolds. The PEG/SF/HApfabricated with HAp (50mg) significantly increasedcell adhesion and viability(p<0.05) as well as the expression of all theosteogenesis-related markers (p<0.05). Conclusions:We developed a novel cell culture scaffold and demonstrated that substrate stiffness influenced the osteogenic differentiation of rat BMSCs.