Buccal mucosal cells

PENG Y s, PENG Y M, MCGEE D L and ALBERTS D s (1994) Carotenoids, tocopherols and retinoids in human buccal mucosal cells intra- and inter-individual variability and storage stability. J Clin Nutr 59(3) 636-43. 

In a recent study, we evaluated the uptake of topically applied RP in buccal mucosal cells (BMCs). This could be a way to circumvent the hepatic pathway and to increase the bioavailability of micronutrients in special target tissues (Sobeck et al., 2003). 

Erhardt, J. G., Mack, H., Sobeck, U., and Biesalski, H. K. (2002). p-Carotene and a-tocopherol concentration and antioxidant status in buccal mucosal cells and plasma after oral supplementation. Br. ]. Nutr. 87,471-475. 

Sobeck, U., Fischer, A., and Biesalski, H. K. (2003). Uptake of vitamin A in buccal mucosal cells after topical application of retinyl palmitate A randomised, placebo-controlled and double-blind trial. Br. J. Nutr. 90, 69-74. 

Often, low levels of carotenoids in biological samples provide significant challenges in quantification by HPLC-PDA alone. Electrochemical detection (ECD) has been successful in quantifying low concentrations of carotenoids (MacCrehan and Schonberger, 1987 Finckh et ah, 1995 Yamashita and Yamamoto, 1997). More information about ECD can be found in Chapter 2. ECD has also been successful in quantifying carotenoid isomers in foods, plasma, prostate tissue, cervical tissue, and buccal mucosal cells (Ferruzzi et ah, 1998,2001 Allen et ah, 2003 Unlu et ah, 2007). Electrochemical array detection for all-irans - 3-carotene has been reported to be 10 fmol on column, which is approximately 100-1000 times more sensitive than UVA is detectors (Ferruzzi et ah, 1998). 

NR Badcock, DA O Reilly, CB Pinnock. Liquid chromatographic determination of retinol and alpha-tocopherol in human buccal mucosal cells. J Chromatogr 382 290-296, 1986. 

YS Peng, YM Peng. Simultaneous liquid chromatographic determination of carotenoids, retinoids, and tocopherols in human buccal mucosal cells. Cancer Epidemiol Biomarkers Prev 1 375-382, 1992. 

As E vitamers are easily oxidizable, the use of an antioxidant during sample pretreatment would seem to be warranted. However, the effect of this practice on analyte recovery varies. There appears to be none for human plasma, unlike, e.g., for rat plasma and buccal mucosal cells. In contrast, the addition of an antioxidant is essential in connection with the analysis of erythrocytes to prevent dramatic losses of tocopherols due to their interaction with coextracted, iron-containing pigments. Likewise, the harsh conditions of saponification (alkaline pH, high temperature) do require this protective measure. As antioxidants, pyrogallol, ascorbic acid, and butylated hydroxytoluene are most commonly used. 

Reifen, R., Haftel, L., Faulks, R. et al (2003) Plasma and buccal mucosal cell response to short-term supplementation with all- frflns-carotene and lycopene in human volunteers. Int. J. Mol Med., 12, 989-993. 

A large number of clinical intervention studies have examined the effect of supplemental p-carotene on intermediate cancer endpoints, as shown in Table 1. The results of these trials indicate that supplemental p-carotene consistently results in regression of oral precancerous lesions (oral leukoplakia, oral dysplasia), and a decreased frequency of micronucleated buccal mucosal cells. While many of the trials of oral precancerous endpoints were not placebo-controlled, and thus somewhat difficult to interpret because spontaneous regression can occur, those that were placebo-controlled nonetheless demonstrated significant benefit to p-carotene relative to placebo. From Table 1 it appears that the chemopreventive efficacy of p-carotene varies by site, with evidence for efficacy in the oral cavity and possibly esophagus, mixed evidence in cervix and lung, and convincing evidence of a lack of efficacy in the prevention of recurrent colorectal polyps. 

Stich HF, Rosin MP, Vallejera MO (1984) Reduction with vitamin A and p-carotene administration of proportion of micronucleated buccal mucosal cells in asian betel nut and tobacco chewers. Lancet I 1204-1206... 

Interest in the role of vitamin E in disease prevention has encouraged the search for reliable indices of vitamin E status. Most studies in human subjects make use of static biomarkers of status, usually a-tocopherol concentrations in plasma, serum, erythrocytes, lymphocytes, platelets, lipoproteins, adipose tissues, buccal mucosal cells, and LDL, and the a-tocopherol 7-toco-pherol ratio in serum or plasma. Other markers of vitamin E status include susceptibility of erythrocyte or plasma LDL to oxidation, breath hydrocarbon exhalation, and the concentration of a-tocopherol quinone in cerebrospinal fluid. There is no consensus as to the threshold concentration of plasma or sermn a-tocopherol at which a person can be defined as having inadequate tocopherol status, but values of <11.6, 11.6-16.2, and >16.2 pmol are normally regarded as indicating a deficient, low, and acceptable vitamin E status, respectively. It is recommended that... 

A recent study, however, has shown that aminopeptidase activity is present on the surface of porcine buccal mucosa, and that various aminopeptidase inhibitors, including amastatin and sodium deoxycholate, reduce the mucosal surface degradation of the aminopeptidase substrate, leucine-enkephalin [149], Since the peptidases are present on the surface of the buccal mucosa, they may act as a significant barrier to the permeability of compounds which are substrates for the enzyme. In addition to proteolytic enzymes, there exist some esterases, oxidases, and reductases originating from buccal epithelial cells, as well as phosphatases and carbohydrases present in saliva [154], all of which may potentially be involved in the metabolism of topically applied compounds. 

Because of the possible effects of active and carrier-mediated processes and metabolic biotransformation, the issue of tissue viability is important for in vitro buccal mucosal experiments. The barrier nature of the buccal mucosa resides in the upper layers of the epithelium, where unlike in the stratum corneum, the cells contain a variety of functional organelles [119, 122, 125, 150], and so tissue viability may be an important component of the barrier function of the tissue. Various methods have been employed to assess the viability of excised buccal mucosa, including measurement of biochemical markers, microscopic methods, and linearity of transport data [42], While biochemical methods, including measurement of adenosine 5 -triphosphate (ATP) levels and utilization of glucose, provide information on the metabolic activity of the tissue, this does not necessarily relate to the barrier function of the tissue. In excised rabbit buccal mucosa, levels of ATP were measured and found to decline by 40% in 6 h, and this correlated well with transmission electron microscopic evaluation of the tissue (intact superficial cells) [32], In addition, the permeability of a model peptide was unaltered up to 6 h postmortem, but at 8 h, a significant change in permeability was observed [32], These investigators therefore claimed that excised rabbit buccal mucosa could be used for diffusion studies for 6 h. 

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. 

Extent of Damage to Mucosal Cells. Permeation enhancement implies possible alteration of the protective permeability barrier either by 1) an increase in the fludity of intercellular lipids (relatively non-toxic) and/ or 2) extraction of intercellular lipids or denaturation of cellular proteins (much more damaging/toxic). Therefore, it is imperative that the permeation enhancer 1) exert a reversible effect 2) not be systemically absorbed and 3) not cause cumulative toxicity or permanent changes in the barrier properties. Application of up to 1% sodium lauryl sulfate or cetylpyridinium chloride to the ventral surface of the tongue of dogs resulted in desquamation, widening and separation of keratin.f The buccal mucosa of rabbits treated with... 

Mecfianism of Action An antineoplasticadjunct that binds to the keratinocyte growth factor receptor, present on epithelial cells of the buccal mucosa and tongue, resulting in the proliferation, differentiation, and migration of epithelial cells. Therapeutic Effect Reduces incidence and duration of severe oral mucositis. 

In comparison to the skin, the buccal mucosa offers higher permeability and faster onset of drug delivery, whereas the key features which help it score over the other mucosal route, the nasal delivery system, include robustness, ease of use, and avoidance of drug metabolism and degradation. The buccal mucosa and the skin have similar structures with multiple cell layers at different degrees of maturation. The buccal mucosa, however, lacks the intercellular lamellar bilayer structure found in the stratum corneum, and hence is more permeable. An additional factor contributing to the enhanced permeability is the rich blood supply in the... 

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. 

Buccal tissue is a robust tissue owing to its continuous exposure to a multitude of substances and its high cellular turnover rate.92 93 The absence of Langerhans cells in the oral mucosal tissues reduces sensitivity to potential allergens.94,95 Hence irritation and hypersensitivity reactions due to drugs and their formulation excipients may be minimal in the short term as well as chronic treatment by this route. 

The above procedure was also employed to investigate buccal absorption from the HEMAC experimental delivery device. As in the case of the diffusion cell the drug-loaded disc was positioned on the inner central surface of the buccal mucosa. An impermeable film coated with mucosal adhesive (F-4000, Adhesives Research, Glen Rock, PA) on the periphery was then positioned over the HEMAC disc to prevent dehydration and to secure the device in place on the mucosal surface. The disc was allowed to remain in contact with the mucosa for 4 h before it was removed for quantitation of residual drug content. Blood samples were collected over the same interval as for the saturated solution and processed in the same manner. 

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