D. Imbert et C. Cullander, Buccal mucosa in vitro experiments I. Confocal imaging of vital staining and MTT assays for the determination of tissue viability, J CONTR REL, 58(1), 1999, pp. 39-50
Delivery of drugs through the skin and the buccal mucosa has been considere
d as an alternative to per oral dosing for those substances that are degrad
ed in the gastro-intestinal tract, or are subject to first-pass metabolism
in the liver. In the buccal mucosa, contrary to skin, the diffusion barrier
s are located within living cell layers, hence the physiological state of t
he tissue is likely to significantly affect in vitro diffusion profiles. In
this study, we were interested in assessing the viability of excised bucca
l mucosa and determining the limits of tissue usage under common in vitro e
xperimental conditions. Using confocal laser scanning microscopy (CLSM), we
have shown that optical sectioning of samples exposed to calcein AM and et
hidium homodimer-1 (used as 'live' and 'dead' cell probes respectively) can
be employed to accurately and reliably determine the viability of buccal m
ucosa biopsies. The results of the CLSM assay were remarkably consistent wi
th that of an MTT assay. In both studies, viability in PBS at 34 degrees C
was lost after about 8 h post-mortem, whereas it could be sustained for up
to 24 h in KBR. (C) 1999 Elsevier Science B.V. All rights reserved.