Proof-of-Concept Organ-on-Chip Study: Topical Cinnamaldehyde Exposure of Reconstructed Human Skin with Integrated Neopapillae Cultured under Dynamic Flow.

Pharmaceutical and personal care industries require human representative models for testing to ensure the safety of their products. A major route of penetration into our body after substance exposure is via the skin. Our aim was to generate robust culture conditions for a next generation human skin-on-chip model containing neopapillae and to establish proof-of-concept testing with the sensitizer, cinnamaldehyde.

The microfollicle: a model of the human hair follicle for in vitro studies.

Access to complex in vitro models that recapitulate the unique markers and cell-cell interactions of the hair follicle is rather limited. Creation of scalable, affordable, and relevant in vitro systems which can provide predictive screens of cosmetic ingredients and therapeutic actives for hair health would be highly valued. In this study, we explore the features of the microfollicle, a human hair follicle organoid model based on the spatio-temporally defined co-culture of primary cells.

Reconstructed human skin shows epidermal invagination towards integrated neopapillae indicating early hair follicle formation in vitro.

Application of reconstructed human Skin (RhS) is a promising approach for the treatment of extensive wounds and for drug efficacy and safety testing. However, incorporating appendages, such as hair follicles, into RhS still remains a challenge. The hair follicle plays a critical role in thermal regulation, dispersion of sweat and sebum, sensory and tactile functions, skin regeneration, and repigmentation.

Bioengineering of a Full-Thickness Skin Equivalent in a 96-Well Insert Format for Substance Permeation Studies and Organ-On-A-Chip Applications.

The human skin is involved in protecting the inner body from constant exposure to outer environmental stimuli. There is an evident need to screen for toxicity and the efficacy of drugs and cosmetics applied to the skin. To date, animal studies are still the standard method for substance testing, although they are currently controversially discussed Therefore, the multi-organ chip is an attractive alternative to replace animal testing.

A Method for Determination and Simulation of Permeability and Diffusion in a 3D Tissue Model in a Membrane Insert System for Multi-well Plates.

In vitro cultivated skin models have become increasingly relevant for pharmaceutical and cosmetic applications, and are also used in drug development as well as substance testing. These models are mostly cultivated in membrane-insert systems, their permeability toward different substances being an essential factor. Typically, applied methods for determination of these parameters usually require large sample sizes (e.

Asymmetry of the Receding Hairline in Men With Early Androgenetic Alopecia.

Background: The Norwood classification system is commonly used to ascertain the progress of androgenetic alopecia (AGA) with a robust and quick assessment, but it lacks precision in the frontal region, notably during the onset of male pattern hair loss.

Objective: Due to the ongoing technical improvement in restorative hair transplantation practices, we aim to develop simple quantitative methods for measuring the progression of AGA.

Methods: Here, we used a quantitative system to evaluate the progress of AGA of the frontal receding hairline in a case study with 41 patients.

Alterations in Hair Follicle Morphology and Hair Shaft Production After Follicular Unit Transplantation.

Follicular unit transplantation is the most commonly performed technique in modern restorative hair transplantation surgery. It relies on the acquisition of intact follicular units from microdissected scalp skin strips and their subsequent transplantation into the recipient regions affected by alopecia. Ideally, the translocation of follicular units from the balding-resistant areas of the scalp (usually the occipital region) to the recipient site should not result in any morphological change in the grafts.

Hair Follicle Plasticity with Complemented Immune-modulation Following Follicular Unit Extraction.

Background: During hair transplantation as an effective therapy for androgenetic alopecia, hair follicles were typically trans-located from the nonaffected occipital to the balding frontal or vertex region of the scalp. Although this is an autologous intervention, the donor and recipient hair follicle tissue differ in composition and local environment.

Settings And Design: In two case studies, we investigated the changes in hair follicle morphology and the immune status of scalp and body hair follicles from different origins transplanted to the eyebrows and the frontal scalp using follicular unit extraction.

Integrating biological vasculature into a multi-organ-chip microsystem.

A chip-based system mimicking the transport function of the human cardiovascular system has been established at minute but standardized microsystem scale. A peristaltic on-chip micropump generates pulsatile shear stress in a widely adjustable physiological range within a microchannel circuit entirely covered on all fluid contact surfaces with human dermal microvascular endothelial cells. This microvascular transport system can be reproducibly established within four days, independently of the individual endothelial cell donor background.

Skin and hair on-a-chip: in vitro skin models versus ex vivo tissue maintenance with dynamic perfusion.

Substantial progress has been achieved over the last few decades in the development of skin equivalents to model the skin as an organ. However, their static culture still limits the emulation of essential physiological properties crucial for toxicity testing and compound screening. Here, we describe a dynamically perfused chip-based bioreactor platform capable of applying variable mechanical shear stress and extending culture periods.

'Human-on-a-chip' developments: a translational cutting-edge alternative to systemic safety assessment and efficiency evaluation of substances in laboratory animals and man?

Various factors, including the phylogenetic distance between laboratory animals and humans, the discrepancy between current in vitro systems and the human body, and the restrictions of in silico modelling, have generated the need for new solutions to the ever-increasing worldwide dilemma of substance testing. This review provides a historical sketch on the accentuation of this dilemma, and highlights fundamental limitations to the countermeasures taken so far. It describes the potential of recently-introduced microsystems to emulate human organs in 'organ-on-a-chip' devices.

Cartilage oligomeric matrix protein (COMP) forms part of the connective tissue of normal human hair follicles.

Hair follicle cycling is driven by epithelial-mesenchymal interactions (EMI), which require extracellular matrix (ECM) modifications to control the crosstalk between key epithelial- and mesenchymal-derived growth factors and cytokines. The exact roles of these ECM modifications in hair cycle-associated EMI are still unknown. Here, we used differential microarray analysis of laser capture-microdissected human scalp hair follicles (HF) to identify new ECM components that distinguish fibroblasts from the connective tissue sheath (CTS) from those of the follicular dermal papilla (DP).

De novo formation and ultra-structural characterization of a fiber-producing human hair follicle equivalent in vitro.

Across many tissues and organs, the ability to create an organoid, the smallest functional unit of an organ, in vitro is the key both to tissue engineering and preclinical testing regimes. The hair follicle is an organoid that has been much studied based on its ability to grow quickly and to regenerate after trauma. But hair follicle formation in vitro has been elusive.

Design and prototyping of a chip-based multi-micro-organoid culture system for substance testing, predictive to human (substance) exposure.

Dynamic miniaturized human multi-micro-organ bioreactor systems are envisaged as a possible solution for the embarrassing gap of predictive substance testing prior to human exposure. A rational approach was applied to simulate and design dynamic long-term cultures of the smallest possible functional human organ units, human "micro-organoids", on a chip the shape of a microscope slide. Each chip contains six identical dynamic micro-bioreactors with three different micro-organoid culture segments each, a feed supply and waste reservoirs.

Pilot study of bipolar radiofrequency-induced anastomotic thermofusion-exploration of therapy parameters ex vivo.

Purpose: Vessel sealing has been well-established in surgical practice in recent years. Bipolar radiofrequency-induced thermofusion (BIRTH) of intestinal tissue might replace traditionally used staples or sutures in the near future. In this experimental study, the influence of compressive pressure, fusion temperature, and duration of heating on the quality of intestinal anastomosis was investigated to obtain the relevant major parameters for the in vivo use of this system.

Ink4a/arf deficiency promotes ultraviolet radiation-induced melanomagenesis.

Cutaneous malignant melanoma (CMM), already known for its highly aggressive behavior and resistance to conventional therapy, has evolved into a health crisis by virtue of a dramatic elevation in incidence. The underlying genetic basis for CMM, as well as the fundamental role for UV radiation in its etiology, is now widely accepted. However, the only bona fide genetic locus to emerge from extensive analysis of CMM suppressor candidates is INK4a/ARF at 9p21, which is lost frequently in familial and occasionally in somatic CMM.