Human-Relevant Screening Techniques

Human-relevant screening techniques: reconstructed human epidermis, organ-on-chip model, skin irritancy test by reconstructed corneal epithelium, and skin corrosivity testing by direct peptide reactivity assay.

Modern drug development increasingly emphasises human-relevant screening techniques that can provide reliable information while reducing dependence on traditional animal testing. These approaches are particularly valuable in the early evaluation of drug candidates, cosmetics, chemicals, and other substances for skin irritation, skin corrosion, toxicity, and therapeutic safety. They use human cells, tissues, biochemical systems, or advanced microphysiological models to reproduce important aspects of human biology.

The reconstructed human epidermis (RhE) model is an in-vitro technique developed using human keratinocytes to form a multilayered epidermis-like tissue. It can be used to evaluate skin irritation and corrosion by assessing changes in tissue viability following exposure to a test substance. Because the model closely resembles important characteristics of human epidermis, it provides a useful alternative to conventional animal-based testing.

The organ-on-a-chip model represents another advanced human-relevant approach. It uses microfluidic systems containing human cells or tissues to reproduce selected structural, mechanical, and physiological characteristics of human organs. These models can simulate interactions between tissues and their responses to drugs or toxic substances, thereby supporting more predictive drug screening and safety assessment.

For ocular or irritancy assessment, reconstructed corneal epithelium models can be used to study the potential of substances to cause irritation or damage to corneal tissue. These models provide a controlled laboratory platform for evaluating tissue responses without directly exposing living animals.

The Direct Peptide Reactivity Assay (DPRA) is a non-animal biochemical method primarily used to assess the skin-sensitising potential of chemicals. It measures the ability of a test substance to react with synthetic peptides containing amino acids such as cysteine and lysine.

Together, these techniques represent important advances toward mechanism-based, ethical, reproducible, and human-relevant safety evaluation, making them increasingly important in modern pharmaceutical and toxicological research.

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