Dinâmica de degradação e reparação de fibras elásticas sob tensão

Abstract

Extracelular matrix, the biological structure that supports cells in animal tissue, is composed of elastic fibers such as collagen and elastin. It is known that enzymes activity plays an important role in maintenance of these elastic fibers. The imbalance between destruction and repair of the elastic fibers can lead to diseases such as fibrosis and emphysema. In this study, we present a simple model to simulate enzymatic digestion and repair of elastic fibers under tension. The fiber is represented by a chain of linearly elastic springs in series surrounded by two layers of sites along which particles representing enzymes and fragments can diffuse. These particles can biding-unbinding in the fiber simulating the reaction process by changing the local stiffness by a multiplicative factor. We study the distribution of the number of visits of particles to the springs as function of time and the consequent change of the fiber stiffness, under different initial conditions (model parameters). We show that, due to no linearity of the model, the degradation effect prevails even when the concentrations of the two type of agents are the same. There is no relation between the number of degradative and rigidifying particles that garantee that the fiber stiffness remains constant. When an anisotropy factor is included on the model and the system behaviour becomes dependent on the tension applied to the fiber, we show that the increase of tension in general contributes to the increase on enzymatic activity. We believe this study can help better understand progression of diseases such as emphysema and fibrosis.