Oral Epithelial Cells Expressing Low or Undetectable Levels of Human Angiotensin-Converting Enzyme 2 Are Susceptible to SARS-CoV-2 Virus Infection In Vitro

Human buccal epithelial cells as a model system for molecular analysis of DNA, RNA and protein

We report use of human buccal epithelial cells as an easy model system for isolation and molecular analysis of genomic DNA, RNA, and protein to study any gene of interest by Polymerase Chain Reaction (PCR), RNA expression by Reverse Transcription-PCR (RT-PCR), protein-profiling, and expression by western blot as well as DNA-methylation by Msp I/Hpa II-restriction digestion. We used simple methods to isolate genomic DNA, RNA and protein from human buccal cells collected by oral swab and cultured them in-vitro. The microscopic observation of haematoxylin and eosin (EA-50) stained cells, genomic PCR of house-keeping genes (GAPDH and β-actin), RT-PCR of GAPDH and β-actin mRNAs and whole cell protein-profiling by Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) were carried out. Expression of β-actin protein in supernatant and pellet fractions of the cells was determined by western blot analysis. MTT-assay was carried out to assess the cell viability and cell growth. Green Fluorescence Protein (GFP)-DNA was expressed in these cells by transient transfection. DNA-methylation in the genome was analyzed by Msp I/ Hpa II restriction digestion and agarose gel electrophoresis. Thus these methods can be used for molecular analysis of DNA, RNA and protein from the human buccal epithelial cells for studying and monitoring health, disease, population genetics/genomics and epidemiology under different conditions.