Growth and remodelling for profound circular wounds in skin

Abstract

Wound healing studies both in vitro and in vivo have received a lot of attention recently. In vivo wound healing is a multi-step process involving physiological factors such as fibrinogen forming the clot, the infiltrated inflammatory cells, the recruited fibroblasts and the differentiated myofibroblasts as well as deposited collagens. All these actors play their roles at different times, aided by a cascade of morphogenetic agents and the result for the repair is approximatively successful but the imperfection is remained for large scars with fibrosis. Here, we want to study wound healing from the viewpoint of skin biomechanics, integrating the particular layered geometry of the skin, and the role of the neighbouring wound epidermis. After 2 days post-injury, it migrates towards the wound centre to cover the hole, the migration being coupled to proliferation at the wound border. Such a process is dominated by the skin properties which varies with ages, locations, pathologies, radiations, etc. It is also controlled by passive (actin, collagen) and active (myo-fibroblasts) fibres. We explore a growth model in finite elasticity of a bilayer surrounding a circular wound, only the interior one being proliferative and contractile. We discuss the occurrence of an irregular wound geometry generated by stresses and show quantitatively that it results from the combined effects of the stiffness, the size of the wound, eventually weakened by actin cables. Comparison of our findings is made with known observations or experiments in vivo.

Growth induced buckling instability of anisotropic tube and its application in wound edge instability

“…Our findings are consistent with result obtained from isotropic model [35] model in terms of effects of wound size and stiffness ratio. However, we further reveal radial fiber orientation has stabilizing effects for various modes of growth.…”

“…If the determinant D(P), then there exist values a 1 and a 1 for which f (r) given by (35) solves the BVP. The root of D(P)=0 is found by bisection method.…”

“…Radial growth rate of wound tissue has been revealed to be greater near wound edge, as well as circumferential absorption. Ben Amar et al investigate instability during wound closure by applying buckling theory, where onset of buckling indicates one of the mechanisms of scarring [35]. Both models treat the granulation/scarring tissue as isotropic neohookean material.…”

Towards a unified approach in the modeling of fibrosis: A review with research perspectives

“…Most existing models with internal structures for fibrosis focus on the repair of the epithelial layer [146] and the remodeling of the fibrotic tissue [147]. Repair of the epithelial layer is a combination of two processes: migration of epithelial cells and cell proliferation.…”

“…In [236] the cell sheet is represented as a compressible inviscid fluid, and therefore individual cells are not distinguishable. Differently from the above mentioned models, cell proliferation has been assumed for the wound closure in [147,237]; cell proliferation limits the irregularity of the wound frontier. The interested reader to further macroscopic continuous models for both the physiological and pathological fibrosis is referred to the review paper [15].…”