Model for calcium-mediated reduction of structural fluctuations in epidermis

Abstract

We propose a reaction-advection-diffusion model of epidermis consisting of two variables, the degree of differentiation and the calcium ion concentration, where calcium ions enhance differentiation. By analytically and numerically investigating this system, we show that a calcium localization layer formed beneath the stratum corneum helps reduce spatiotemporal fluctuations of the structure of the stratum corneum. In particular, spatially or temporally small-scale fluctuations in the lower structure are suppressed and do not affect the upper structure, due to acceleration of differentiation by calcium ions. Analytical expressions for the reduction rate of fluctuation amplitudes are shown.

Interplay between epidermal stem cell dynamics and dermal deformation

“…This phenomenon is in accordance with our model, which predicts that when elasticity of the basement membrane is lost or the dermis is hardened by photoaging, undulations are suppressed and as a result the thickness of the whole epidermis is reduced because of the diminishing surface area of the basement membrane accommodating fewer TA cells. Numerical experiments of the whole epidermis with varying membrane stiffness would be possible by incorporating the present model into our previous epidermal model [26,27].…”

“…Skin is an important organ that provides us with barriers such as protecting from damages and preventing dehydration [20,21], and its internal structure affects barrier functions: for example, diseases such as psoriasis are accompanied by altered structure of the epidermaldermal interface, where the germinative cell population increases and their activity is enhanced [22,23]. Al- though mathematical models have been proposed to understand skin barrier functions [24][25][26][27][28][29][30][31][32], the morphology of the epidermal-dermal interface and its relationship to stem cell patterning has been largely ignored, except for a speculation on the interplay between stem cell activities and the dermal structure [33].…”

A Computational Model of the Epidermis With the Deformable Dermis and Its Application to Skin Diseases

“…This is achieved in the previous and the present models by the assumption that calcium ions released at the time of cornification accelerate cell differentiation, which causes stabilization of the boundary of the cell layer. How this mechanism works has been analytically confirmed by using a reaction-diffusion-advection model 40 . Since the previous model did not distinguish the granular and the spinous cells, however, an additional mechanism is needed to create another boundary between the granular and the spinous layers.…”