> ATERA – Reconstructed Human Epidermis

The ATERA – Reconstructed Human Epidermis (RHE) consists of normal human-derived keratinocytes cultured for 19 days at the air-liquid interface, resulting in a multilayered epidermal equivalent in vitro that is histological similar to the human epidermis. The ATERA – RHE is characterized by a high barrier function and metabolic activity and can be employed for safety and efficacy testing of chemicals and final formulations. To ensure global availability, models are transported on an agarose-based solidified medium together with ATERA – growth and maintenance medium.

Culture

The ATERA – RHE is generated from normal human keratinocytes isolated from foreskin biopsies. Following an in vitro expansion step that allows the production of large quantities of epidermal models from one donor, cells are seeded on a synthetic carrier membrane and lifted at the air-liquid interface. Due to these particular cell culture conditions, combined with the use of a special serum free tissue culture medium, a natural differentiation process is triggered and a multilayered epidermis is formed. In the standard configuration, the models are cultured under these conditions for 19 days. However, depending on the testing application, the ATERA – RHE can also be provided at a younger age, i.e. at day 10 or day 14.

——

Histology

The ATERA – RHE reflects the histological architecture of human epidermis. Besides a basal, spinous and granular layer, a multilayered stratum corneum is formed that is responsible for a natural barrier function. Moreover, the basal cell layer exhibits a natural cubic formation.

ATERA-Skin-Models-RHE-2017

Histological image of the ATERA RHE

The ATERA – RHE can be employed to test the safety and efficacy of chemicals, cosmetics, and pharmaceutical compounds. Due to a dry surface, the ATERA – RHE allows realistic topical application scenarios for a broad range of liquid and solid substances. Moreover, a systemic application can be simulated by applying test substances directly into the culture medium.

——

Safety

Test method :

——

Efficacy

Test method :

  • Anti-oxidative capacity
  • Anti-inflammatory activity
  • Hydration
  • Anti-aging
  • Epidermal differentiation
  • Percutaneous absorption
  • Effects of UVA and UVB irradiation
  • Sub-clinical irritation
  • UVB protection
  • Genomic signatures
  • Wound healing
  • Epidermal barrier function
  • Epidermal permeability and metabolism

Scientific

Refinement of RHE-based testing strategies:

Impedance spectroscopy as new tools for hazard identification and efficacy testing.

Groeber F, Engelhardt L, Guillon F, Nikoyan-Ginosian A, Le Varlet B, De Wever B , Walles H.

ESTIV 17-20 October 2016, Juan-les-Pins, France

 

A new standard in 3D tissue reconstruction:

‘‘Open Source’’–Based Engineered Human Tissue Models: A New Gold Standard for

Nonanimal Testing Through Openness, Transparency, and Collaboration, Promoted by the ALEXANDRA Association.

Bart De Wever, Alan Goldberg, Chantra Eskes, Erwin Roggen, Philippe Vanparys,

Klaus Schröder, Béatrice Le Varlet, Howard Maibach, Sonja Beken, Benoit De Wilde,

Constantin Turchina, Ginette Bogaert, and Jean-Pierre Bogaert.

AIVT (2015) 1-1 DOI: 10.1089/aivt.2014.0011

——

Modelling the human epidermis in vitro: tools for basic and applied research.

Poumay Y, Coquette A.

Arch Dermatol Res. (2007)298(8):361-9. DOI: https://doi.org/10.1007/s00403-006-0709-6

——

A simple reconstructed human epidermis: preparation of the culture model and utilization in in vitro studies.

  1. Poumay, F. Dupont, S. Marcoux, M. Leclercq-Smekens, M. Hérin, A. Coquette

Arch. Dermatol. Res., 296 (2004), pp. 203–211 DOI: http://dx.doi.org/10.1007/s00403-004-0507-y

——

Regulatory

Skin irritation test method validation study:

– Catch-up validation study of an in vitro skin irritation test method based on an open source reconstructed epidermis (phase I).

Mewes KR, Fischer A, Zöller NN, Laubach V, Bernd A, Jacobs A, van Rompay A, Liebsch M, Pirow R, Petersohn D.

Toxicol In Vitro (2016) 36:238-53. doi: : http://dx.doi.org/10.1007/s00403-004-0507-y

——

Catch-up validation study of an in vitro skin irritation test method based on an open source reconstructed epidermis (phase II).

F. Groeber, L. Schober, F.F. Schmid, A. Traube, S. Kolbus-Hernandez, K. Daton, S. Hoffmann, D. Petersohn, M. Schäfer-Korting, H. Walles, K.R. Mewes.

Toxicol In Vitro 36 (2016) 254–261: http://dx.doi.org/10.1016/j.tiv.2016.07.008

– – – –

To ensure reproducible results for our customers, high quality control standards are employed. All cell batches used for tissue reconstruction are tested before use for Hepatitis B, Hepatitis C, HIV, and Mycoplasma. The stratum corneum and its lipid composition is sufficient to resist the rapid penetration of the cytotoxic benchmark chemical, Triton X-100 1%, as estimated by ET50. Indeed, barrier function is tested on each cell batch and the acceptability range for the ET50 is established to be at least 3h. Furthermore, only model batches are provided that comply with our internal quality criteria listed below for the standards ATERA – RHE:

Quality criterion Used assay Lower acceptance limit Upper acceptance limit
Metabolic activity MTT reduction (O.D. Value) 0.6
Barrier function ET-50 test 3h
Morphology Histology Natural differentiated epidermis with:
• 1 distinct basal layer
• 2 to 4 spinous layer
• 1 to 3 granular layer
• A thick corneous layer

Contact information

To order the ATERA – RHE please contact us under :
Phone : +33 6 87 21 40 68 and: +33 6 81 64 24 75 or e-mail on our contact page

——

Available models

Besides the standard ATERA – RHE, additional model types can be ordered that vary in the culture period and surface area, depending on the specific needs.

Model Day of culture Surface area Reference number
ATERA RHE 19 0.59 cm2 ASME19059
ATERA RHE 19 1.12 cm2 ASME19112
ATERA RHE 14 14 0.59 cm2 ASME12059
ATERA RHE 14 14 1.12 cm2 ASME12112
ATERA RHE 10 10 0.59 cm2 ASME12059
ATERA RHE 10 10 1.12 cm2 ASME12112

——

Conditions of order

Tissue culture medium is provided free of charge for 5 days of tissue culture. In case a prolonged culture period is needed, additional tissue growth medium can be purchased. The minimum order size is 12 tissue models.

> ATERA – Full-Thickness Skin

The ATERA Reconstructed Human Full-Thickness (RHFT) skin model features morphological equivalence with human skin and allows convenient handling in research applications.

Comparable to human skin, the RHFT consists of a dermal and epidermal layer that are connected by a functional basement membrane. The dermal layer is generated by seeding human primary fibroblasts into a high-density collagen matrix. As such the cells behave in a microenvironment comparable to the human dermis. In addition, human epidermal keratinocytes are seeded on top of the dermal matrix. Due to a special serum free tissue culture medium and the cultivation at the air-liquid interface, the epidermal cells differentiate and form a well stratified epidermis featuring a natural barrier function. As the full thickness skin model shows a high correlation to the in vivo human skin with only minimum signs of contraction, it is applicable for a variety of testing applications including complex toxicological endpoints such as genotoxicity testing or efficacy testing of pharmacological and cosmetic formulations. Additionally, the non-contracting human full-thickness skin model can also be used for cutaneous wound healing assays.

Culture

The ATERA – Full-Thickness skin model is cultured at the air-liquid-interface for 11 days in standard tissue culture inserts. The model has constant surface area of 1 cm² allowing direct and easy substance application. Compared to other collagen-based skin models, ATERA RHFT shows much lower contraction and weight loss over time and therefore allows measuring trans-epithelial electrical resistance, indicative for skin barrier function.

——

Histology

The ATERA – Full-Thickness skin model resembles native human skin in its histological architecture as well as in displaying a wide spectrum of corresponding physiological parameters.

Atera Skin Models RHFT

Figure 1: The models are cultured in standard cell culture inserts and have a surface area of 1 cm² (A). In contrast to standard RHFTs the ATERA RHFT model shows an increased mechanical stability (B). Due to the culture at the air-liquid-interface (C) primary keratinocytes differentiate physiologically and form all epidermal layers as in native skin (D). SEM Images of the RHFT model compared to conventional collagen model (E) showed the intact collagen ultrastructure in both images, with a higher number of collagen fibers in the ATERA model. SC: Stratum corneum; SG: Stratum granulosum; SS: Stratum spinosum; SB: Stratum basale; DL: Dermal layers; RHFT models marked with arrowheads

The ATERA – Full-Thickness skin model can be used for a broad range of endpoints in safety and efficacy testing including e.g. genotoxicity, efficacy testing and wound healing. Besides the possibility to topically challenge the model with both hydrophilic and hydrophobic substances and formulations, hydrophilic substances can also be added to the basolateral compartment to mimic systemic application scenarios.

To ensure reproducible results for our customers, high quality control standards are employed. All cell batches used for tissue reconstruction are tested before use for Hepatitis B, Hepatitis C, HIV, and Mycoplasma.

Quality criterion Used assay Acceptance limit
Tissue morphology H&E staining
  • Well defined epidermal layer with 1 layer of basal cells, 2 to 4 layers of stratum spinosum and stratum granulosum and a corneous layer without cell nuclei.
  • Consistent dermal layer with homogenously distributed fibroblasts
Barrier function ImpSpec  Impedance above 500 Ohm*cm²

Contact information

To order the ATERA – Full-Thickness skin model please contact us under:
Phone : +33 6 87 21 40 68 and: +33 6 81 64 24 75 or e-mail on our contact page

——

Available models

Besides the standard ATERA – RHE, additional model types can be ordered that vary in the culture period and surface area, depending on the specific needs.

Model Day of culture Surface area Reference number
ATERA RHFT 12 days 1.1 cm2 ASMFT-11
ATERA RHFT 7 8 days 1.1 cm2 ASMFT-7
ATERA RHD 7 days 1.1 cm2 ASMD-7

——

Conditions of order

Tissue culture medium is provided free of charge for 5 days of tissue culture. In case a prolonged culture period is required, additional tissue growth medium can be purchased. Minimum number of models to be orders is 12 models. The minimum order size of culture medium is 60 ml.