Identification and In Vitro Expansion of Buccal Epithelial Cells

Increased Expression of p63 Protein and Sonic Hedgehog Signaling Molecule in Buccal Epithelial Holoclones

Construction of many tissues and organs de novo requires the use of external epithelial cell sources. In the present study, we optimized the isolation, expansion, and characterization of porcine oral epithelial cells from buccal tissue (Buccal Epithelial Cells, BECs). Additionally, we tested whether key markers [cytokeratin 14 (ck14), p63 protein, and sonic hedgehog molecule (shh)] expression profiles are correlated with three buccal epithelial clone types. Two digestion methods of BECs isolation [Method 1, M1 (collagenase IV/dispase and accutase) and Method 2, M2 (collagenase IV/dispase and trypsin/EDTA)] were compared. Cells obtained by more effective method were further cultured to the third passage and analyzed. Holoclone-, meroclone-, and paraclone-like colonies were identified based on BEC morphology. Immunofluorescent staining was performed to compare selected markers for the indicated buccal clone types. Comparative analysis demonstrated the advantage of isolation using M1 over M2. Cells from the third passage exhibited average 92.73% ± 2.27% presence of ck14. Real-time polymerase chain reaction confirmed expression of tested genes [cytokeratin 8 (ck8), ck14, integrin β1, and p63]. The highest level of ck14, shh and p63, was observed for holoclones. The comparable ck14 expression was observed in the mero- and paraclones. Meroclones expressed significantly lower levels of shh compared with paraclones. The weakest p63 expression was observed in the paraclone-like cells. It was demonstrated that holoclones are the richest in shh (+) and p63 (+) stem cells and these cells should appear to be a promising alternative for obtaining epithelial cells for tissue engineering purposes.

Subconjunctival Injection of Transdifferentiated Oral Mucosal Epithelial Cells for Limbal Stem Cell Deficiency in Rats

Rat limbal niche cells (LNCs) have been proven to induce transdifferentiation of oral mucosal epithelial cells (OMECs) into corneal epithelial-like cells termed transdifferentiated oral mucosal epithelial cells (T-OMECs). This investigation aimed to evaluate the effect of subconjunctival T-OMEC injections on alkali-induced limbal stem cell deficiency (LSCD) in rats. LNCs were cocultured with OMECs in the Transwell system to obtain T-OMECs, with NIH-3T3 cells serving as a control. Subconjunctival injection of single T-OMEC or OMEC suspension was performed immediately after corneal alkali injury. T-OMECs were prelabeled with the fluorescent dye CM-DiI in vitro and tracked in vivo. Corneal epithelial defect, opacity, and neovascularization were quantitatively analyzed. The degree of corneal epithelial defect (from day 1 onward), opacity (from day 5 onward), and neovascularization (from day 2 onward) was significantly less in the T-OMEC group than in the OMEC group. Cytokeratin 12 (CK12), pigment epithelium-derived factor, and soluble fms-like tyrosine kinase-1 were expressed at a higher rate following T-OMEC injection. Some CM-DiI-labeled cells were found to be coexpressed with CK12, Pax6, and ΔNp63α in the corneal epithelium after subconjunctival injection. Subconjunctival injection of T-OMECs prevents conjunctival invasion and maintains a normal corneal phenotype, which might be a novel strategy in the treatment of LSCD.