Laboratory Services

SPECIALIZED INVESTIGATIONS

Percutaneous Penetration

• The rates of absorption and passage of test chemicals into and through human skin can be modeled in the in vitro percutaneous penetration assay. By utilizing various skin models and test protocols, a variety of dermal absorption and percutaneous penetration endpoints may be determined, such as the absorption and passage through the lipophilic stratum corneum, absorption and passage through the epidermis and dermis, and the potential for metabolism within the viable epidermis. Skin penetration assays may be utilized to evaluate the rate of absorption or passage of individual chemicals or formulation components in personal and skin care products, pesticides and herbicides, and pharmaceuticals to enhance product development goals, or to address product safety issues. Skin penetration assays may also be used to determine the extent of absorption of potentially toxic materials, for example, to address EPA and worker safety issues.

The Cytosensor™ Microphysiometer Bioassay Using L929 Cells

• This assay evaluates the potential toxicity of a test article by measuring the test material dose required to reduce the metabolic rate in treated cultures of L929 cells, using a Cytosensor™ Microphysiometer (Molecular Devices Corporation). The microphysiometer is a very sensitive instrument which electronically measures the metabolic rate of cell populations through small changes in acidic metabolites in the medium. In a normal undamaged cell population, the rate is constant and reproducible. Cells that have received a toxic insult develop a dose dependent, altered metabolic rate, which is generally decreased from the baseline ratio. Because of its sensitivity and noninvasive nature, the Cytosensor bioassay is excellent for dilution-based assays of mild products. Thus ocular damage from short term exposure to surfactants, or skin irritation due to chronic exposure to mild materials can both be modeled. The major advantage to working with the microphysiometer is that it allows rapid, 'real time' continuous measurement of metabolic changes in cell populations. In addition to irritation responses, it is efficient in determining early kinetic activity, functional cellular responses, and multiple signaling events associated with ligand / receptor interactions.

3T3 Neutral Red Uptake Phototoxicity Assay

• IIVS has broad experience in measuring the phototoxic potential of chemical ingredients and formulations using the Balb/c 3T3 mouse fibroblast - neutral red uptake phototoxicity assay. The IIVS Staff can adapt this method to specific client requirements for pharmaceutical, cosmetic, or chemical products. A validation statement for the assay has been made by ECVAM, and an OECD Test Guideline is in the final stage of approval.

Phototoxicity Assay Using the Epiderm Skin Model

• Combining the EpiDerm three-dimensional skin model into the phototoxicity protocol allows one to test solid or non-water soluble materials. Direct application of the test material can be made to the surface of the tissue which can then be irradiated or not to determine the test material's phototoxic potential.

USP Cytotoxicity

• IIVS offers the United States Pharmacopoeia (USP) cytotoxicity assay using Modified Eagles Medium (MEM) elution or agar overlay for medical device applications. The characteristics of the particular medical device, polymer, container, etc. determine which assay would be recommended. The MEM elution assay is designed to show the presence of toxic material eluted from a test sample as it affects L929 cells cultured in the presence of the extract. The degree of irritancy is determined microscopically in the percentage of cells deformed and lysed after exposure to the test material. In the agar overlay assay, test sample is placed onto the agar surface overlaid onto a L929 cell monolayer. Preventing direct damage while allowing diffusion of leachable chemicals from the sample. After treatment, the cells are exposed to neutral red dye to differentiate between the viable and stressed or lysed cells.

Bioassay Development

• IIVS develops custom, cell-based assays measuring efficacy/potency of specialty chemicals, drugs, and biologics. Numerous bioassays have been and can be developed by IIVS to address specific requirements in chemical, pharmaceutical, personal care, and household products companies. As examples, in vitro models have been characterized and optimized for: collagen synthesis, biological activity, transepidermal penetration, test material efficacy, anti-inflammatory activity, and viral studies.

Prevalidation and Validation

• IIVS has experience in managing programs for optimization of assay systems of specific interest to your company or organization, and in managing prevalidation and validation projects for groups of companies interested in bringing a system forward for regulatory acceptance. IIVS can be an active participant acting as the lead laboratory, providing the technology transfer, training, and standardized documentation (SOP and Protocol generation) for multi-laboratory projects. IIVS can prepare or assist in the preparation of data packages for submission either to ICCVAM or directly to a regulatory agency.

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