Advancing our understanding of the cellular and molecular basis of disease is vital to enabling us to develop newer, more effective, and more reliable preventative and diagnostic tools, as well as establish new therapeutic options and enhance patient outcomes.
Human tissue provides a vital source of DNA from which scientists can investigate the cellular and molecular underpinnings of disease. However, access to human tissue can be challenging as often invasive procedures are required to collect this tissue, which can put the patient at risk. Therefore, cells that are readily available via non-invasive procedures present a viable route to revealing the cellular and molecular basis of disease without posing additional risk to the patient.
Buccal cells have emerged as one such type of cell that can be obtained non-invasively. Here, we discuss the importance of investigating such cells, the current methods of buccal cell collection, and the recent advancement in cell collection.
Image Credit: Dusan Petkovic/Shutterstock.com
Why is buccal cell investigation important?
Cells of the human cheek offer valuable information that can help scientists perform early diagnoses of certain health conditions, including cancer. Epithelial buccal cells that are found in the oral cavity provide an easy-to-access source of DNA that can be analyzed using PCR or other genotyping tests, which can detect changes associated with various serious diseases. It is estimated that changes in the epithelial cells, which cover the lining of the body’s organs and cavities as well as the outside skin, account for most cases of cancer (estimated at around 85%).
Over the years, scientists have proven that analysis of buccal cells can provide a method of early detection of numerous types of cancer, including oral cancer and lung cancer. As buccal cells can be collected non-invasively, research efforts have focussed on developing effective and reliable collection methods of these cells to advance preventative strategies and early diagnoses for a range of diseases.
Currently, there are several established methods of buccal cell collection, we discuss this below before assessing the recent advancements in this field.
The current state of buccal cell collection
Currently, a range of non-invasive methods are commonly used to obtain samples of buccal cells from patients. Buccal swabs are one such example and are one of the most common oral sampling methods used in medicine. Other methods include the use of cytobrushes (cytology brushes that collect cells from the cheeks), the “swish and spit” method, the use of DNA treat “Guthrie” cards, and the technique of exfoliating buccal cells by rubbing the cheeks against the teeth.
While methods of buccal cell collection are already firmly established in research and clinical practice, scientists are still working on developing these methods given the importance of buccal cell investigation in furthering our knowledge of many diseases. Recent years have seen some key advancements in this field.
Recent advancements in buccal cell collection
A 2018 study demonstrated how buccal cells can be collected with mouthwash to obtain mRNA and protein as well as DNA. The study used immunofluorescent analysis to identify that most buccal cells collected were derived from nonkeratinized parabasal epithelia, with a small proportion originating from proliferative cells.
Reverse transcription PCR, Western blot analysis, and immunofluorescence were able to successfully detect gene expression in the harvested buccal cells. This was the first study to show that mRNA and protein could be isolated from buccal cells obtained via mouthwash. It presents a simple and non-invasive method of collecting buccal cells for medical research.
Other recent research has resulted in improving currently used methods of buccal cell collection. One research team recently demonstrated that the cytobrush method could be improved by using two brushes per buccal surface, and proved that this was more effective than brushing the area with more strokes. The data showed that increasing the number of strokes on the buccal surface did not result in an increased yield of RNA. Using two brushes, however, doubled this yield. The results demonstrate that the current cytobrush method could easily be improved by the addition of a second brush, therefore, enhancing the method cost-effectively.
Another significant development in the collection of buccal cells has been the integration of pharmacokinetics into the method. In a recent study, scientists compared the variation between the yield of buccal cells collected by dry-flocked swabs compared with sponge-tipped swabs. The results showed that DNA yield was highest for sponge-tipped swabs.
Additionally, data showed that sponge-tipped swabs yielded the highest genotyping call rates across all genotyping assays. Therefore, sample collection with sponge-tipped swabs offers a DNA source of sufficient quantity and quality required pharmacogenetic variant detection.
Future directions for buccal cell research
Given the importance of buccal cell research in the development of diagnostics, preventative methods, and therapeutics for a range of diseases, it is likely that we will see further advancements in methods of buccal cell collection in the coming years.
It can be predicted that advancements will focus on making buccal cell collection easier for use with different assays, depending on the purpose of the research, ie. which disease it relates to and what information is sought from the cell DNA.
- Geiger, J., Cedars, E., Zang, Y., Normolle, D., Li, H., Grandis, J., Centuori, S., Johnson, D. and Bauman, J., 2021. Clinical trials optimizing investigator and self‐collection of buccal cells for RNA yield. Laryngoscope Investigative Otolaryngology, 6(1), pp.116-121. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7883625/
- Hayney, M., Poland, G. and Lipsky, J., 1996. A Noninvasive ‘Swish and Spit‘ Method for Collecting Nucleated Cells for HLA Typing by PCR in Population Studies. Human Heredity, 46(2), pp.108-111. https://www.karger.com/Article/Abstract/154335
- Küchler, E., Tannure, P., Falagan-Lotsch, P., Lopes, T., Granjeiro, J. and Amorim, L., 2012. Buccal cells DNA extraction to obtain high quality human genomic DNA suitable for polymorphism genotyping by PCR-RFLP and Real-Time PCR. Journal of Applied Oral Science, 20(4), pp.467-471. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3881822/
- Michalczyk, A., Varigos, G., Smith, L. and Ackland, M., 2004. Fresh and cultured buccal cells as a source of mRNA and protein for molecular analysis. BioTechniques, 37(2), pp.262-269. https://www.future-science.com/doi/10.2144/04372RR03
- Richards, B., Skoletsky, J., Shuber, A., Balfour, R., Stern, R., Dorkin, H., Parad, R., Witt, D. and Klinger, K., 1993. Multiplex PCR amplification from the CFTR gene using DNA prepared from buccal brushes/swabs. Human Molecular Genetics, 2(2), pp.159-163. https://academic.oup.com/hmg/article-abstract/2/2/159/556506