Dados do Trabalho

Título/Title/Titulo

MODELING AND SIMULATION IN THE HISTOARCHITECTURE OF THE ARTICULAR CARTILAGE FOR BIOFABRICATION

Introdução/Introduction/Introdución

The biofabrication of engineered tissues is an essential area to reconstruct and
regenerate tissues, and in the future, organs. The cartilage tissue is a complex biological system that
needs to be more studied. To understand complex biological systems such as cells, tissues, and
organs, it is not sufficient to identify and characterize the individual molecules in the system. It also is
necessary to obtain a thorough understanding of the interaction between biological components and its
relation with biomechanical properties. Until now, to the best of our knowledge, it has not been
possible to mimic the biological and biochemical properties of cartilage. New approaches to
developing a new tissue become an attractive target for bioprinting, which is emerging as an essential
tissue engineering strategy to recreate the histoarchitecture and the relationship between cells, matrix,
and microenvironment of cartilage. With a layer-by-layer assembly, 3D tissues with complex
structures can be bioprinted using images and simulations to study the biomechanical profile.

Objetivos - Metodologia - Resultados - Discussão dos Resultados/Objectives - Methodology - Results - Discussion of Results/Objetivos - Metodología - Resultados - Discusión de los resultados

The goal is to analyze the impact of stress on the hierarchical layers of the cartilage using finite
element method. Methodology: We developed an anisotropic and microstructural finite element
model of some components of articular cartilage to applied pressure. The variation of the physical
behavior of the model, an anisotropic characteristic, will be verified from the geometric configuration
of the collagen fibers among the chondrocytes, in order to mimic the real microstructure of interstitial
materials with isotropic properties. The microstructures of the articular cartilage layers modeled in the
Rhinoceros® 5.0 (McNeel North America, Seattle, WA, USA) software, and the file in format .stp
(step) was imported into Ansys 17.2 (ANSYS Inc, Houston, TX, USA) for the finite element analysis
(FEA). The model (BioCAD) consisted of the extracellular matrix – type II collagen - and
chondrocytes located in the deep zone. This zone was chosen because corresponds to a 45% of the
ECM volume. Chondrocytes were surrounded by a collagen matrix, a hydrogel and were assumed
spherical before load application. Material properties of the chondrocyte and the ECM were obtained
from the literature. The materials were considered isotropic, the BioCAD of cartilage components and
the boundary conditions have been selected in literature. Contact regions between the cartilage
components – cells, collagen, and interstitial fluid (~ water) – they were considered correctly bonded.
The collagen fiber contribution can be observed by analyzing the deformation and minimum principal stress. The results suggest that elongation of the collagen fiber - the major cartilage´s component - may involve a change in the ECM structure, probably because the collagen fibers interact with several molecules. The deformation analysis, allows us to visualize which regions are moving in response to the applied pressure. It was verified that there was a gradient of displacement along the whole structure. The minimum main tension is to emphasize the areas that undergo significant compression efforts, allowing to evaluate how the chondrocytes and the collagen distribute the efforts in the system.

Considerações Finais/Final considerations/Consideraciones finales

The use of computer simulations in a microscale study is a crucial factor to understand specifics properties of biological tissue for biofabrication of tissues.

Palavras-chave/Key words/Palabras clave

Modeling, Articular cartilage, Biofabrication, Computer simulations, Biomechanics.