Sebaceous gland: Milestones of 30‐year modelling research dedicated to the “brain of the skin”

Sebaceous glands (SGs) are acinar holocrine-secreting appendages of the epidermis and localize to most areas of the body surface. 1 Generally, SGs constitute a crucial component of the pilosebaceous unit and are intimately associated with the junctional zone (JZ), an area of the upper and permanent part of the hair follicle (HF). While the outer layer of the SG contains proliferative cells, the inner compartment is composed of sebocytes, specialized keratinocytes, that produce a mixture of an oily and waxy material, called sebum. [1][2][3] Upon differentiation and maturation of sebocytes, the lipidcontaining sebum is released by holocrine secretion through a specialized secretory duct of the gland into the follicular canal to reach the surface of the skin. 4 This complex mixture of lipids contributes significantly to the barrier function of mammalian skin by reducing water loss from the surface of the skin and facilitates water repulsion and thermoregulation. 1,5 Although all the details of the physiological complexity of SGs are not completely understood, sebum has antimicrobial activity, contains antioxidants and protects against UVB-induced apoptosis. 1,4,[6][7][8] Distinct regions of the skin and surface epithelium generate SGs independently from HF structures, e.g.

Section: S Ebaceous G L and S Tem Cell S In Vitro And Org Anoid Culmentioning

confidence: 99%

Stem and progenitor cells in sebaceous gland development, homeostasis and pathologies

Geueke

Niemann

2021

“…From gaining molecular insight into essential aspects of skin development and homeostasis to preclinical testing of new drug candidates for skin diseases to their use as "tissue farms" to grow new skin substitutes for burn and trauma patients, 3D cultures are becoming a mainstay approach both in basic and translational dermatological research (Figure 1). Current 3D culture technologies include the following: (i) free-floating cultures of spherical organoids initiated from pluripotent stem cells; (ii) layered constructs consecutively assembled by seeding primary skin cells into extracellular matrix scaffolds 38 to contain stratified epidermis, sebocyte spheroids 39 or hair pegs 40 ; (iii) freshly micro-dissected skin and hair follicle explant cultures [41][42][43][44] ; and (iv) organ-on-a-chip cultures that incorporate capillary structures and allow active perfusion using microfluidics. 45,46 However, so-called 3D skin "equivalent" cultures are not without limitations.…”

Section: What Org Anot Ypi C Culture S C An and C An ' T Domentioning

confidence: 99%

“…In an effort to translate similar tissue engineering approaches to the human system, Weber et al developed a 3D model for co-culturing human neonatal foreskin keratinocytes with human foetal scalp dermal cells that permits their self-organization into hair peg-like structures. 40 When grafted after in vitro self-assembly to nude mice, at least some peg-like structures matured towards functional human hair follicles.…”

Section: G Rowing Hair S In a Pe Tri D Is Hmentioning

confidence: 99%

Fostering a healthy culture: Biological relevance of in vitro and ex vivo skin models

Atwood

Plikus

2021

The field of experimental dermatology research has dramatically benefited from the insights yielded by in vivo studies on animal models. Indeed, much of our understanding of the mechanisms that regulate embryonic skin development, adult skin homeostasis and physiological skin responses to stress, such as wound healing, has been educated by studies conducted in animal models, including mutant mice. These works become commonly published on the pages of Experimental Dermatology and, in fact, represent one of the core interests of the journal. Highlighting in vivo mouse model studies are recent works on hair follicle development and growth 1-5 and wound healing. 6-8 Further, studies in animal models often help to elucidate aspects of disease pathogenesis, and mouse models are used to investigate mechanisms of human skin conditions such as atopic dermatitis, 9-13 contact dermatitis, 14-16 psoriasis, 17,18 rosacea 19 and squamous cell carcinoma 20 to name a few. On the other hand, not all human skin diseases or aspects of human skin physiology can be reliably modelled in rodents. This is not surprising, considering that humans and rodents are separated by an estimated 96 million years of evolution. 21 Addressing this fact, many studies are being conducted on patient-derived primary skin cells, including human keratinocytes, 22-25 melanocytes, 26-30 fibroblasts 31-34 and cell co-cultures. 35-37 However, typical in vitro culture conditions fail to replicate and, in fact, do not come close to imitating the biomechanical and biochemical complexity of the microenvironment in which cells exist and to which they respond to in native tissues. Further, ingredients in commonly used cell culture media and the two-dimensional constraints of growth on plastic result in cells being exposed to a lot of artificial cues, to which they adapt but also prominently alter their gene expression profile and functional activities in the process. Therefore, behaviours displayed by skin cells in twodimensional cultures need to be comprehensively validated under more native-like conditions in order to be deemed biologically and physiologically relevant. Helping to bridge the gap, threedimensional (3D) organotypic cultures and organ culture techniques have long been a highly instructive tool for investigating complex, tissue-level behaviours by skin cells.

“…The role of sebaceous glands and hair follicles in cutaneous physiology and pathobiology [ 12,13] is covered by two essays. Zouboulis et al [ 14] give an overview of the last decades of sebaceous gland research, with a major focus on currently developed in vitro assays that should help to understand the complex interactions of sebaceous glands and their microenvironment. The authors provide a look into the future addressing the major questions concerning sebaceous gland biology in the context of human disease.…”

mentioning

confidence: 99%

“…The authors provide a look into the future addressing the major questions concerning sebaceous gland biology in the context of human disease. [ 14,15] Instead, Vogt et al [ 16] present an persuasive synthesis on the role of hair follicles in cutaneous regeneration and skin immunity. Specifically, they explain different routes of immunization via the hair follicle and propose a central role of the hair follicle microbiome, [ 16,17] thus complementing the currently predominant focus on the skin and gut microbiome.…”

mentioning

confidence: 99%

Focus theme issue: Celebrating the ADF‐EXD partnership: A look back into the future of experimental dermatology

Gaffal

2020

The Society for Dermatological Research (Arbeitsgemeinschaft Dermatologische Forschung/ADF, www.adf-online.de) was founded in 1973 as an independent, non-profit daughter organization of the German Dermatological Society (Deutsche Dermatologische Gesellschaft [DDG]) with the specific aim to promote the close cooperation between all scientists working in the field of dermatological research including clinical departments, academic institutes and industry research laboratories. At that time, experimental skin research had become increasingly important, as it greatly expanded the very often clinical-descriptive view of skin diseases. The founders of the ADF, including Enno Christophers, Guenter Goerz, Egon Macher, Constantin Orfanos, Gerd Plewig and H. Schaefer, set out to help develop dermatology in the German-speaking countries into a modern scientifically based discipline, with the support of young scientists in the field as one declared main goal of the new research. Until today, the ADF remains strongly committed to promote and foster young colleagues in dermatological research.