Key Regulatory Role of Dermal Fibroblasts in Pigmentation as Demonstrated Using a Reconstructed Skin Model: Impact of Photo-Aging

Abstract

To study cutaneous pigmentation in a physiological context, we have previously developed a functional pigmented reconstructed skin model composed of a melanocyte-containing epidermis grown on a dermal equivalent comprising living fibroblasts. The present studies, using the same model, aimed to demonstrate that dermal fibroblasts influence skin pigmentation up to the macroscopic level. The proof of principle was performed with pigmented skins differing only in the fibroblast component. First, the in vitro system was reconstructed with or without fibroblasts in order to test the global influence of the presence of this cell type. We then assessed the impact of the origin of the fibroblast strain on the degree of pigmentation using fetal versus adult fibroblasts. In both experiments, impressive variation in skin pigmentation at the macroscopic level was observed and confirmed by quantitative parameters related to skin color, melanin content and melanocyte numbers. These data confirmed the responsiveness of the model and demonstrated that dermal fibroblasts do indeed impact the degree of skin pigmentation. We then hypothesized that a physiological state associated with pigmentary alterations such as photo-aging could be linked to dermal fibroblasts modifications that accumulate over time. Pigmentation of skin reconstructed using young unexposed fibroblasts (n = 3) was compared to that of tissues containing natural photo-aged fibroblasts (n = 3) which express a senescent phenotype. A stimulation of pigmentation in the presence of the natural photo-aged fibroblasts was revealed by a significant increase in the skin color (decrease in Luminance) and an increase in both epidermal melanin content and melanogenic gene expression, thus confirming our hypothesis. Altogether, these data demonstrate that the level of pigmentation of the skin model is influenced by dermal fibroblasts and that natural photo-aged fibroblasts can contribute to the hyperpigmentation that is associated with photo-aging.

Bioprinting of biomimetic skin containing melanocytes

“…It is, however, interesting to note that the pigmentation appeared in rather freckle/lentigo‐like morphology instead of more uniform skin colouring. This shared a degree of similarity with the previous example of skin pigmentation based on the manual construction of full‐thickness skin model . Epidermal pigmentation is a complex process that begins from melanin production by the MC and subsequent transfer to surrounding KC via melanosome.…”

“…Further study is necessary to reveal the detailed KC‐MC interactions. In addition, while the exact physiological mechanism is difficult to ascertain from our study, FB‐MC interactions, which seems to play an important role in skin pigmentation and melanoma invasion, are considered important and require further investigation.…”

“…The complexity and inhomogeneity of skin, such as dermal glands and hair follicles, prohibit the creation of a complete skin structure; however, manufacturing protocols that create a simple full‐thickness skin model (ie, having both dermal and epidermal components) are available; for example, the fibroblasts (FBs) are mixed with collagen hydrogel precursor, and then crosslinked to form a composite of FB‐containing dermal layer on top of a transmembrane insert. The composite is cultured for a period of a few days to weeks (to allow for the growth of FB), and then, a sterilized containment structure, such as a metal ring, is positioned onto the dermal layer to allow for seeding of keratinocytes (KCs) . The constructed tissue is subsequently subjected to air‐liquid‐interface (ALI) culture, whereby the exposure of the KC to the air induces the differentiation of the KC monolayer into the epidermal layers, thus completing the two major macrostructures of the skin (ie, the dermis and epidermis consisting of basal, spinous, granular and cornified layers).…”

Design, optimization and characterization of coenzyme Q10- and D-panthenyl triacetate-loaded liposomes

“…11 Delivery of active ingredients to deeper layers of the skin, mainly to fibroblasts found inside the dermis, is necessary for obtaining desired effect. Fibroblasts, the main skin cells, are an important target in antioxidant, 12 photoaging 13 and wound-healing 14 applications. Nanoparticulate carrier systems, especially lipid-based carriers, are generally used to enhance penetration and overcome poor absorption problem of both hydrophilic and lipophilic compounds.…”

Senescent fibroblasts in melasma pathophysiology

“…A pivotal role of photoaged fibroblasts in determining the pigmentation phenotype of ageing skin was recently highlighted . Under ultraviolet (UV) irradiation, fibroblasts become senescent and produce more skin ageing‐associated secreted proteins (SAASP) compared with normal fibroblasts .…”