3T3 Neutral Red Phototoxicity
(3T3 NRU PT)Testing Services

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The 3T3 Neutral Red Uptake Phototoxicity Assay (3T3 NRU PT) was developed and validated in a joint EU/COLIPA project from 1992-1997. In 1996, the 3T3 NRU PT was recommended by OECD as an in vitro approach for the assessment of chemicals phototoxicity potential. In April 2004, the 3T3 NRU PT protocol was finalized and adopted as the OECD 432 protocol, In Vitro 3T3 NRU phototoxicity test.

The 3T3 NRU PT can be utilized to identify the phototoxic effect of a test substance induced by the combination of test substance and light and is based on the comparison of the cytotoxic effect of a test substance when tested after the exposure and in the absence of exposure to a non-cytotoxic dose of UVA/vis light. Cytotoxicity is expressed as a concentration-dependent reduction of the uptake of the vital dye - Neutral Red.

Substances that are phototoxic in vivo after systemic application and distribution to the skin, as well as compounds that could act as phototoxicants after topical application to the skin can be identified by the test. The reliability and relevance of the 3T3 NRU PT have been evaluated and has been shown to be predictive when compared with acute phototoxicity effects in vivo in animals and humans.

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Test Materials Not Soluble in Media?

EPARS - Enhanced Phototoxicity screening Assay in Reconstituted Skin

One of the key issues with the 3T3 NRU PT is that your test material must be soluble in cell culture media. The alternative is to utilize an animal model or to use the Enhanced Phototoxicity screening Assay in Reconstitued Skin(EPARS). EPARS is a novel assay using 3D Human Tissue Constructs/Equivalents developed at MB Research. EPARS allows for topical application of a test material (lotion, cream, etc.)

For more information about EPARS and our other Phototoxicity/Photobiology capabilities, please contact Client Services.

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