Enhanced Osteogenic Differentiation of Human Bone-Derived Mesenchymal Stem Cells in Three-Dimensional Printed Porous Titanium Scaffolds by Static Magnetic Field Through Up-Regulating Smads

Abstract

Background: The reconstruction of large bone defects remains a significant challenge for orthopedists. 3D printed porous titanium scaffold (3DP scaffold) is considered a promising material for repairing defects. However, its application is limited owing to its poor bioactivity. Static magnetic field (SMF) treatment is effective and non-invasive with the potential for clinical translation, and has been shown to improve bone regeneration. However, the osteogenic effect of SMF on human bone-derived mesenchymal stem cells (hBMSCs) in 3DP scaffolds, as well as its potential mechanism, are unclear. Methods: The osteogenic effect of SMF on hBMSCs in a 3DP scaffold was investigated in vitro and in vivo. In addition, the potential mechanism for promoting osteogenesis was investigated by proteomic analysis and verified in vitro. Findings: The data showed that the cell viability and proliferation of hBMSCs were not significantly affected by SMF. SMF promoted the cellular morphology, adhesion, and interaction of hBMSCs, and enhanced osteogenic differentiation. A total of 185 differential peptides were identified under SMF conditions by proteomic analysis. The transport of pSmad1/5/8 and pSmad2/3 to the nucleus by up-regulating Smad4 under SMF conditions was demonstrated. The in vivo experiment showed that bone regeneration was enhanced by SMF. Interpretation: Moderate SMF was a safe and effective method for enhancing osteogenesis in 3DP scaffolds in vitro and in vivo. This effect might be associated with up-regulating Smads and increased intranuclear translocation of pR-Smads. The details of the potential mechanism should be validated by further work. Funding Statement: This work was supported by the Fundamental Research Funds for Central Public Welfare Research Institutes, Chinese Academy of Medical Sciences (no. 2016ZX310177-7), and the National High-Tech R&D Program of China (863 Program, 2015AA020316, 2015AA033601). Declaration of Interests: The authors state: None. Ethics Approval Statement: The regulations of the Administration of Affairs Concerning Experimental Animals (China, 2014), the National Institutes of Health Guide for the Care and Use of Laboratory Animals (GB14925-2010), and the Laboratory Animal Center of Peking Union Medical College Hospital (PUMCH) were strictly adhered to. Animal experiments were approved by the Institutional Animal Care and Use Committee of PUMCH.