| Περίληψη: | 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.
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