Buccal Epithelial Cell Cultures

However, the number of compounds tested in vitro on human EpiOral buccal culture is currently very limited [50], Therefore, further studies are needed to better evaluate usefulness of this novel model in testing drug buccal delivery potential. 

In addition, CYP substrates had permeation rates comparable to that of caffeine, a high-permeability, nonmetabolized, and completely absorbed 

Currently, most strategies for buccal delivery of peptide drugs have focused on the application of excipients that would shorten the time of absorption and adhere drugs to a local site on the mucosa, thus decreasing exposure to proteolytic degradation and possible release of drug back into the mouth cavity. This strategy has been utilized in the buccal delivery of insulin, enkephalin, and testosterone [37, 70]. 

Human Aminopeptidase3, b Carboxypeptidaseb Esteraseb Dehydrogenase0 CYP1A1, 1A2, 2C, 2D6, 2E1, 3A4/7, 3A5d Aminopeptidaseb 

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The use of buccal cell cultures for assessing the permeability of the buccal mucosa has attracted recent attention (see Chap. 7 for a more extensive summary). In order to culture buccal epithelial cells, the cells must be harvested from an appropriate source and cultured under specific conditions using an appropriate growth medium, temperature, and humidity [46], Cell cultures have been successfully grown from hamster cheek pouch. These cultured cells, however, did not differentiate to form a complete keratinized surface as seen in the normal hamster cheek pouch, and they consequently displayed a greater permeability to compounds when compared with keratinized hamster cheek pouch mucosa [134], Therefore, the cultured hamster cheek cells more closely mimicked the human buccal mucosa due to their lack of keratinization, and so this may be an appropriate model for predicting permeability through the human buccal mucosa. 

Of the different types of oral mucosal cell cultures that have been used [47,48], the most commonly used ones are explants of primary cultures. Small pieces of excised buccal or sublingual tissue are placed in a support system and fed with culture medium. The outgrowths obtained from these tissue explants are then transferred and grown in appropriate media. For example, outgrowths of fibroblasts [49] thus obtained have been described. Gibbs and Ponec [50] reconstructed the epithelium of mucosal tissue by placing a tissue biopsy (with the epithelial side upwards) onto a fibroblast-populated collagen gel. The explants obtained were cultured immediately at the air liquid interface until the epithelium had expanded over the gel (2-3 weeks). These explant cultures may retain many of the in vivo tissue characteristics. 

Sundqvist, K., et al. 1991. Growth regulation of serum-free cultures of epithelial cells from normal human buccal mucosa. In Vitro Cell Dev Biol 27A 562. 

Freshly excised buccal or sublingual tissues have also been used to generate dissociated cells. Hedberg et al. [49] used one such culture to measure the expression of alcohol dehydrogenase-3 in cultured cells from human oral mucosal tissue. Human buccal tissue was incubated with 0.17% trypsin in phosphate-buffered saline (PBS) at 4°C for 18 to 24 h to obtain dissociated primary keratinocytes, and subsequently these keratinocytes were seeded onto fibronectin and collagen-coated dishes in serum-free epithelial medium. 

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