StrataTest® Human Skin Research Model:

The full-thickness StrataTest® human skin model is the superior, reliable, cost-effective solution for in vitro consumer product testing, drug discovery and toxicity screening. Composed of both an epidermis and a dermis, StrataTest® tissue displays the same physical, chemical and histological characteristics of human skin. It is supplied in a readily-available, easy-to-use 24-well test format.

Many of today's animal and cell-based toxicity testing models are burdened by significant accuracy, reproducibility, cost and ethical concerns. The 27-country European Union, for example, has banned the sale of animal-tested cosmetic and consumer products. The unique characteristics of StrataTest® skin tissue provide not only an enhanced, high-quality in vitro testing model, they enable better prediction of in vivo biological responses than standard, two-dimensional, monolayer cultures. Unlike models that possess only an epidermal layer, the presence of both epidermal and dermal compartments permits paracrine signaling.

The StrataTest® human skin model was developed under the same standards as the company's flagship StrataGraft® human skin substitute, which recently was evaluated in a human clinical safety trial. Both products are manufactured using Stratatech's proprietary NIKS® human keratinocytes. NIKS® cells, which have been demonstrated to be pathogen-free and non-tumorigenic, provide a fully-stratified, multi-layered human skin substitute in every well of the StrataTest® test plate. The tissue grows precisely as new human skin does, fully replicating its structure and function. Unlike cultured human keratinocytes from other sources, the uniquely uniform NIKS® cells can be grown indefinitely in the laboratory, resulting in less batch-to-batch variability.

The StrataTest® human skin model offers consistent cell sourcing and quality, coupled with the faithful three-dimensional reproduction of native human skin. These characteristics provide customers with a highly-reproducible, accurate and cost-effective measurement of the in vitro response to a broad range of chemicals, compounds and other potential toxins.

Uses of the StrataTest® Human Skin Model

• drug screening

• acute toxicity

• wound healing assays

• phototoxicity

• corrosivity

• chronic toxicity

• irritancy

• genotoxicity

Advantages and Model Performance

Utilizes the NIKS® human progenitor keratinocyte cell line, a long-lived, pathogen-free and non-tumorigenic cell line that has been clinically tested

In organotypic culture, NIKS® human progenitor cells undergo keratinocyte terminal differentiation. Histological analysis (hematoxylin and eosin staining) confirms the formation of appropriate tissue architecture with the distinct basal, spinous, granular, and cornified layers characteristic of stratified squamous epithelia. Transmission electron microscopy has demonstrated the formation of a basement membrane between the epidermal and dermal compartments.

Epidermal barrier function comparable to native skin as measured by skin surface electrical impedance

Barrier function properties of StrataTest® skin tissues as measured by skin surface electrical impedance (DermaPhase Meter units; DPM). The values obtained for native skin, and skin where the barrier had been disrupted by tape-stripping, are also presented. Data represents the mean +/- the standard error of the mean.

Batch-to batch consistency that has been demonstrated with a high degree of reproducibility

StrataTest® skin tissues from four independent batches were exposed to 0.1% or 0.3% SDS for 24 hrs and assayed for cytotoxic effects. Cell viability was determined by using MTT reduction (A) and the extent of IL-1a secretion was detected by ELISA (B). For each batch, cell viability measurements were normalized to the negative control response. The effects were analyzed by one-way ANOVAs and comparisons between treatment groups were assessed using a Bonferroni post-hoc test. Both cell viability and IL-1 a secretion revealed a dose-dependent response. For cell viability, no significant difference was detected for exposure to 0.1% SDS (p>0.05), however a significantly lower viability was seen in 0.3% SDS treated samples (p<0.001). Similarly, 0.3% SDS exposure resulted in significantly higher IL-1 a release compared to the negative control, whereas 0.1% SDS exposure did not (p>0.05). Data represents the mean +/- the standard error of the mean.

Model performs equally well upon storage up to 7 days at 2-8°C, exhibiting consistency throughout the shelf-life of the product

StrataTest® skin tissues from multiple independent batches, stored for 2 or 7 days, were exposed to 1% Triton X-100 for up to 6 hrs and assayed for cytotoxic effects. Cell viability was determined by MTT reduction. For each experiment, cell viability measurements were normalized to the untreated control. Analysis of cell viability demonstrated a clear exposure time-dependent response. Results were analyzed by two-way ANOVA. Storage was not a significant contributor to variability (p=.605), unlike Triton X-100 exposure time (p<0.0001). The interaction of these variables was also not significant (p=.670). Data represents the mean +/- the standard error of the mean.

Ongoing Development

Pre-validation studies for irritancy and corrosivity testing using the full-thickness StrataTest® human skin model have been initiated. Stratatech will work with regulatory agencies (ICCVAM, ECVAM, JACVAM, etc…) as appropriate to enable development of optimized test protocols.

A full-thickness skin model in a 96-well format is currently under development. This new product will assist customers seeking a model system that offers the capacity for epidermal / dermal signaling in a format more amenable to increased throughput.

For product or ordering information:
stratatest@stratatechcorp.com
(608) 441-2749

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