Effect of freezing on the permeability of human buccal and vaginal mucosa
We have previously demonstrated that fresh human vaginal mucosa can be used as a model of human oral mucosa for in vitro permeability studies. Since it is not always practical to perform permeability experiments within hours of receiving tissue, it would be convenient to bank mucosa, while retaining barrier integrity. Since freezing and storage at -85°C has been used before for human and porcine buccal mucosa, it was considered appropriate to investigate the barrier properties to water, 17β-estradiol and dextrans of fresh and frozen human buccal and vaginal mucosa. Clinically healthy human vaginal and buccal mucosa specimens were obtained during vaginal hysterectomies and different oral surgical procedures. Pieces of tissue were taken and used directly or frozen for periods up to 10 months. Specimens of both fresh and frozen mucosa were kept for histological examination. Fresh and thawed specimens were used for permeability studies using water, 17β-estradiol and 4.4 and 12 kDa dextran. No significant differences were observed for the permeation of these compounds across fresh and frozen mucosa. These results support the use of frozen, banked buccal and vaginal mucosa, whenever it is not practical to use these two tissues within hours of removal from patients.