Cryopreservation of an artificial human oral mucosa stroma. A viability and rheological study

The aim of this study was to evaluate the viability and biomechanical properties of artificial human oral mucosa stroma (HOMS) subjected to cryopreservation with different cryoprotectant solutions. Artificial HOMS based on a fibrin-agarose matrix with human gingival fibroblasts cultured 7 days in vitro were cryopreserved with three cryoprotectant solutions: (A) TC-199 Medium, DMSO 15%, albumin; (B) DMEM, FCS, DMSO 10%; (C) QC Medium, glycerol. As controls, artificial HOMS not subjected to cryopreservation (CF) and HOMS cryopreserved without cryoprotectant solution (CS) were used. Histological analysis by light microscopy showed that solutions A and B preserved a pattern of porosity similar to values in CF. Based on the number of intact cells in the fibrin-agarose matrix, substitutes preserved with solution B showed the best results. Cell proliferation detected with PCNA immunochemical methods showed that the cell proliferation index was highest in substitutes cryopreserved with solution B. The reculture method and cell viability analyses with Live & Dead(®) revealed increased number of viable in cells preserved with solution B. Artificial stroma substitutes in CS control samples showed the greatest alterations in microstructure and cell proliferation. Analysis of the biomechanical properties showed that substitutes cryopreserved with different solutions had adequate rheological parameters (yield stress, elastic modulus and viscous modulus) and were therefore suitable for use in regenerative medicine. These results establish effective methods of cryopreservation for all experimental situations and suggest that solution B (DMEM, FCS, DMSO 10%) was the best cryoprotectant for the cryopreservation of an artificial oral human mucosa substitute based on a fibrin-agarose matrix.