Osteogenic differentiation of mesenchymal stem cell on poly sorbitol sebacate scaffold under shear stress in a bioreactor

Mechanical loading plays a pivotal role in regulating bone anabolic processes. Understanding the optimal mechanical loading parameters for cellular responses is critical for advancing strategies in orthopedic bioreactorbased bone tissue engineering. This study developed a poly (sorbitol sebacate) (PSS) filmscaffold with a sorbitol-to-sebacic acid molar ratio of 1:4. The scaffold underwent extensive characterization, including physical and mechanical property evaluations, biocompatibility assessments, and cell adhesion analysis. The Young's modulus of the PSS polymer was determined to be 6.81 f 0.44 MPa under dry conditions, 6.37 f 1.09 MPa in a wet state, and 6.38 f 0.71 MPa after ethanol washing (70 %). The average contact angle of the PSS film was measured at 88.806 f 1.644 degrees, indicating moderate hydrophilicity. To investigate the osteogenic potential, a fluid flow inducing a shear stress of 1 Pa at a frequency of 1 Hz was applied to mesenchymal stem cells (MSCs) cultured on the PSS scaffold. Cells were exposed to dynamic fluid flow for one hour daily on days 4, 5, 6, and 7 of culture, followed by a static culture period of 14 days. The expression of osteogenic differentiation markers, including osteopontin (OPN), osteocalcin (OCN), type I collagen, and calcium deposition, was significantly elevated under dynamic conditions compared to static culture. This study highlights the importance of mechanical stimulation in enhancing MSC osteogenesis and underscores the osteoconductive properties of the PSS scaffold. These findings provide valuable insights into scaffold design and mechanical loading strategies for laboratory-based bone tissue engineering applications.