Atomic force microscopy for biomechanical and structural analysis of human dermis: A complementary tool for medical diagnosis and therapy monitoring

Abstract

Skin mechanical properties are usually measured considering the entire skin thickness and very little is known about the mechanical behaviour of individual skin layers. We propose atomic force microscopy (AFM) as a tool to quantify nanoscale changes in the biomechanical properties and ultrastructure of human papillary dermis exposed to different mechanical and physical stimuli. Samples from 3 human skin biopsies were studied: one stretched by obesity, one subjected to a high level of sun exposure and normal skin as control. Slices of the papillary dermis layer were harvested at controlled depths from each skin biopsy and 25 μm areas of each slice were imaged and D-periodicity of collagen fibres measured by AFM, together with their stiffness. Standard histological analysis was also carried out to correlate biochemical properties and their distribution with stiffness and topography. We obtained similar stiffness values between the sample affected by obesity and the control sample at any depth level into the dermis, while the sun-exposed sample presented a significantly lower stiffness. Additionally, all samples presented an increase in the stiffness at higher depths into the papillary dermis layer. Collagen fibres close to the epidermis of sample affected either by obesity and sun exposure-the former even more than the latter-are thicker and present a larger D-period than those in the control sample. Our results open the possibility to use structural and mechanical analysis based on AFM as a complementary tool for medical diagnosis and therapy monitoring.

Label-Free Infrared Spectral Histology of Skin Tissue Part I: Impact of Lumican on Extracellular Matrix Integrity

“…The difference of dermis size is explained by an increase in interfibrillar space and diameter of type I collagen fibers in the absence of lumican as previously described by Chakravarti and collaborators (Chakravarti et al, 1995(Chakravarti et al, , 1998. However, in the present report, spectral analysis of collagen by correlation remains qualitative and requires further investigation to evaluate its properties such as fiber size and orientation (Jeanne et al, 2017) as well as its quantitative contribution and mechanical characteristics (Aziz et al, 2018;Peñuela et al, 2018). It is important to note that IRSH can not only distinguish different structures of the skin but can also specifically target ECM macromolecules such as collagen.…”

Mechanobiology of Epithelia From the Perspective of Extracellular Matrix Heterogeneity

“…Its compliance is highly dependent on the relative amount of collagen, elastin, and the level of network crosslinking, which varies according to tissue and age (Birch, 2019). According to several independent measurements, IM Young's modulus can range between 1 and 100 kPa (Pailler-Mattei et al, 2008;Booth et al, 2012;Peñuela et al, 2018; Figure 1). Additionally, the differing content of polysaccharides such as hyaluronic acid ensures different water retention of the matrix layer, varying its resistance to compressive forces (Lodish et al, 2003).…”

Aplicabilidade da estereologia e microscopia de força atômica à pesquisa dermatológica veterinária (revisão de literatura)

“…Além disso, pode caracterizar as propriedades biomecânicas da epiderme e derme, como a rigidez, por exemplo, pelo módulo de Young (FERREIRA, 2006;PAYDAR, 2016). Nesse, as imagens atômicas são obtidas pela técnica de contato intermitente, no qual a sonda de AFM, com dimensões nanométricas, presa à extremidade do Cantilever, de 125µm, toca a superfície celular, determinando suas características biomecânicas (Figura 02) (PINTO, 2015;PEÑUELA et al, 2018;KWON, 2019).…”

“…Apesar desses benefícios, ainda é escassa sua utilização em dermatologia veterinária, limitando-se a estudos cicatriciais em murinos (RAGHUWANSHI et al, 2017). Em dermatologia humana, recentemente descreveu-se a composição nanoestrutural da pele (ECKERSLEY et al, 2018), corneócitos (DANZBERGER et al, 2018) e fibras colágenas (QUIGLEY et al, 2018) A rigidez da epiderme, a espessura, orientação e periodicidade das fibras de colágeno, presentes na derme papilar humana, bem como suas particularidades nanoestruturais, foram recentemente mensuradas (OLEJNIK, A.;NOWAK, I 2017;PEÑUELA et al, 2018;CHANG et al, 2017). Essas descrições são importantes para determinação de parâmetros de normalidade, haja visto que entidades nosológicas distintas podem alterar as propriedades mecânicas da pele e seus componentes, as quais podem ser identificadas por AFM (VIELMUTH, 2018).…”