Effect of scaffold stiffness on cell functions for bone tissue engineering

• Κύριος συγγραφέας: Τσελεπίδη, Αθανασία
• Άλλοι συγγραφείς: Tselepidi, Athanasia
• Γλώσσα: English
• Έκδοση: 2022
• Θέματα: Bone tissue engineering; Scaffold stiffness; PLA scaffolds; Cell functions; Ιστοτεχνολογία οστών; Ακαμψία ικριωμάτων; Ικριώματα PLA; Κυτταρικές λειτουργίες

Bone Tissue Engineering specializes in the development and fabrication of artificial constructs (i.e scaffolds) compatible with the native host tissue, manufactured by a plethora of methods with one of the most prominent being 3D printing. The fabrication of these constructs aims to repair damaged bone tissue and is mainly focused on the regeneration of trabecular or cancellous bone. The general premise of BTE applications lie on the principle of the tissue engineering triad which states that the developed scaffolds should be biomimetic to the native host bone tissue, exhibit suitable mechanical and physiological properties for cell proliferation and act as porous templates for the incorporation of growth factors that enhance osteogenesis and cells (Mesenchymal stem cells, Osteoblasts, etc.) which will attach and proliferate, ultimately forming new tissue. The main focus of the present thesis is to fabricate scaffold structures with different stiffness and investigate how these two structures respond to conditions that simulate the human body, examine the influence of simulated body fluid (SBF) on their mechanical properties and surface topography as well as their cellular response in vitro. For this reason, two different cubic porous structures were 3D printed, the first with the shape of a grid with orthogonal pores of 500μm and porosity of 70% and the second with gyroid shape, pore size of 500μm and porosity of 83%. The stiffness of the two structures was estimated and they were immersed for 7, 14 and 21 days in total in simulated body fluid. SEM images were then acquired in order to observe the rate of degradation of the scaffolds and compressive mechanical tests were conducted so that we could study the scaffolds’ mechanical properties (modulus of elasticity and compressive strength) and the way they were influenced from the interaction with the sbf. The final step of the experimental part was HAP scaffold surface coating and performance of mice’s osteoblast culture in order to determine which of the two scaffolds would be a more suitable substrate for cell viability and proliferation, regarding bone tissue engineering applications. The results demonstrated that the cubic structure with pore size 500μm and porosity 70% performed better on all conducted experiments relatively to the gyroid. It did not exhibit any significant weight variations regarding its immersion in SBF for a total of 21 days and consequently the findings from its mechanical tests indicated that it had a higher stiffness (213.7MPa) and little deterioration of its modulus of elasticity and compressive strength. On the contrary, the gyroid structure with 500μm pore size and 83% porosity performed poorly on every test. Findings state that this structure had a low stiffness compared to the cubic one (56.1MPa) and exhibited an increasing weight loss during its immersion in SBF, resulting in extensive degradation and deterioration of its mechanical properties. Regarding the performance of cell culture on the scaffolds, the MTT assay test indicated that the cubic scaffold was a more suitable substrate for cell viability and proliferation.