RESUMO
The tissue cryopreservation maintains the cellular metabolism in a quiescence state and makes the conservation possible for an indefinite period of time. The choice of an appropriate cryopreservation protocol is essential for maintenance of cryopreserved tissue banks. This study evaluated 10 samples of umbilical cord, from which small fragments of tissue (Wharton's jelly and cord lining membrane) were subjected to two protocols of cryopreservation: slow cooling and vitrification. The samples were frozen for a period of time ranging from 5 to 78 days. The efficiency of cryopreservation was evaluated by testing cell viability, histological analysis, cell culture, cytogenetic analysis and comparison with the results of the fresh samples. The results showed that the slow cooling protocol was more efficient than the vitrification for cryopreservation of umbilical cord tissue, because it has caused fewer changes in the structure of tissue (edema and degeneration of the epithelium) and, despite the significant decrease cell viability compared to fresh samples, the ability of cell proliferation in vitro was preserved in most samples. In conclusion, this study showed that it is possible to cryopreserve small fragments of tissue from the umbilical cord and, to obtain viable cells capable of proliferation in vitro after thawing, contributing to the creation of a frozen tissue bank.