 Welcome to the video presentation of Modeling Mechanical Signals on the Service of MicroCity and Cout-based Rapid Prototyped Scaffolding Models to protect early tissue development to be published in Biotechnology and Bioengineering by Wim Hendrickson. For more than 100 years ago, the link between mechanical loading and tissue formation was suggested. Kuhlman and Meyer saw the remarkable resemblance between stress lines in the crane and the femur. In the 60s, Powell introduced the idea of certain stresses and strains responsible for specific tissue type formation. Some time later, Vinnert element was employed to definitely link mechanical loading with tissue formation. With the arrival and application of Vinnert element modeling, several mechanical regulation theories were postulated. Combinations of mechanical stimuli, fluid flow and shear stress or strain results in different tissues being formed and remodeled until an equilibrium occurred. Among them was the theory of Carter, who included good vascularity as a prerequisite for bone formation. In short, their hypothesis says that bone is formed when there is a good blood supply and minimal cyclic stresses. According to Carter, an increase in stress results in carlos, while a further stress increase results in fibrous tissue. Some years later, Klaas and Heichler postulated their theory. They did not agree with the lack of investigation of local deformations and the prediction of the type of tissue formation from the stimuli. They stated that new bone formation will form along fronts of existing bone or calcified tissue, and that intermembranness bone formation or endoconeral pacification depends on the local strain and stress magnitude. However, shortly after Klaas and Heichler, Prennikhaus postulated his theory. He considered tissue composed of a fluid and solid phase. Shears, strain and fluid flow could predict cell differentiation and the potential tissue formed. A study performed by Kajeri Edel compared the different theories and the theory of Prennikhaus was the best approximation with experimental data. Based on this, the theory is the most established for linking mechanical stimuli with tissue formation. Therefore, it is often used for modeling tissue formation inside tissue engineering scaffolds. Models and literature take the deformation of the bi-material as shown in B, represented by the elements on the surface of the model, in which we turned volumetric strains to predict cell differentiation and tissue formation. However, the strain of the surface shown in A is not taken into account, which would be a better representation of the deformation sensed by cells attached to the surface. In a simple experiment with the top node of the tetrahedral was displaced, shears strained for the entire element, as shown in D, and for the separate element phases, as shown in C, were calculated. As can be seen, in C and D, the magnitudes are significantly different. To understand the effect of surface strains and volumetric strains, scaffolds with controlled architecture were obtained through 3D-fused deposition modeling. Fundament element models were derived from microsity scans of the scaffold. Scaffolds were subjected to a compressive strain of 10% applied at the top of the scaffold. Here you can appreciate the difference in magnitude between the surface strain shown in B, octahedral shear strain shown in C, and the volumetric strain shown in T. The chemical strain acts as a crossing of the fibers and extends towards the center of the pore along the bottom and top part of the fiber. Fluid flow was simulated as it was applied from the top of the scaffold to the bottom. In its side view, C is the top view, while B and D are close-ups. Fluid shear stress acts at the side of the wall, which is in contrast with the mechanical strain. For illustrative purposes, the theory of Prenagas was used to show the effective strain calculation on cell differentiation in the Unisor states of tissue formation. The top row shows cell differentiation based on mechanical strain only. The bottom row is in mechanical strain and fluid shear stress. Each column depicts the influence of the strain calculation. Octahedral shear strain has a higher strain, which results in more fibrous tissue and even cell death at some locations. For surface shear strain, majority scottlids with small parts of bone being present. For more information, please see our article at biotechnology and bioengineering contact us through email. Thank you very much.