Expansion of Human Dental Pulp Cells In Vitro Under Different Cryopreservation Conditions

Background/Aim: To optimize the expansion of human dental pulp cells in vitro by exploring several cryopreservation methodologies. Materials and Methods: The intra-dental pulp tissues from healthy subjects were extracted and divided into three separate tissue segments, which were randomly divided into the three following groups; the fresh group, the 5% DMSO group, and the 10% DMSO group. In the fresh group, dental pulp cells were directly cultivated as primary cultures, whereas in the DMSO groups, the dental pulp cells were cultivated from cryopreserved pulp tissue segments one month later. Results: The cell yield and the time it took for the cells to grow out of the pulp tissue and attach to the culture plate varied among the three groups; the 5% DMSO group was inferior to the fresh group but superior to the 10% DMSO group (p<0.05). Moreover, no differences were found at the 1st passage amongst the three groups regarding the following aspects (p>0.05); colony formation rate and cell survival rate. Furthermore, no differences were noted at the 3rd passage regarding the following aspects (p>0.05); proliferation ability, cell growth curve and surface marker expression of dental pulp cells. Conclusion: Five percent DMSO may be the most optimal condition for tissue storage to preserve stem cells in situ.