Formulation of survival acceptor medium able to maintain the viability of skin explants over in vitro dermal...

In vitro assessments of skin absorption of xenobiotics are essential for toxicological evaluations and bioavailability studies of cosmetic and pharmaceutical ingredients. Since skin metabolism can greatly contribute to xenobiotic absorption, experiments need to be performed with skin explants kept viable in suitable survival media. Existing protocols for non-viable skin are modified to consider those conditions. The objective was to design a survival medium used as an acceptor fluid in Franz cells for testing cutaneous penetration of hydrophilic or lipophilic molecules. Their metabolism inside skin may be investigated under the same conditions. The determining factors involved in survival mechanisms in vitro are discussed. The consequences of short-term skin preservation at 4°C were also evaluated.

The metabolic activity of fresh skin samples mounted in Franz cells was studied by measurement of lactate release over 24 h in order to assess the impacts of pH, buffering, osmolality, ionic strength, initial glucose supply and the addition of ethanol or non-ionic surfactant in the acceptor part of Franz cells.

Survival media must maintain physiological pH (>5.5) be isotonic with skin cells (300 mOsm kg^-1 ) and contain at least 0.5 g L^-1 glucose. Several compositions able to preserve skin metabolism are reported. Storage of skin explants overnight at 4°C impairs skin metabolic activity. The present work provides guidelines for designing survival media according to constraints related to the scientific requirements of the experiments.