INTRODUCTION: Cryopreservation aims to stop reversibly the biological functions of living tissues at low temperatures, and is an important resource for the storage of human cells for later use. AIM: To assess the proliferation of mesenchymal cells from human periodontal ligament cryopreserved by two different protocols. METHOD: Periodontal ligament cells were obtained from third molars with an indication for surgical removal. After processing, cells were grown and maintained at 37 °C in 5% CO2 until they reached 70-90% confluency, with medium changing every three days. In the first passage cells were divided into two groups, according to the protocol used: Group -80 °C - cryopreserved in ultrafreezer for 45 days, Group -196 °C - cryopreserved in liquid nitrogen for 45 days. After this time, cells from both groups were thawed and plated for the experiment. The growth curve of the groups was drawn from counting cells in a Neubauer chamber and by the MTT assay method, in the intervals of 24, 48 and 72 hours. The data were analyzed using the Mann-Whitney test with a significance level of 5%. RESULT: There was an upward cell growth in both protocols used, but a higher proliferative rate was observed in group cryopreserved in liquid nitrogen (p < 0.05). CONCLUSION: Cryopreservation has proven to be an effective technique for the storage and of mesenchymal cells from the periodontal ligament, especially when stored at a temperature of -196 °C.
Periodontal ligament; cryopreservation; cell proliferation