Proteome Expression in Human Periodontal Ligament after Delayed Hypothermic Preservation

Previous occasional successes after delayed replantation suggest that the presence of viable cells may not be the only factor for successful periodontal regeneration in delayed replantation. Various other factors such as proteins or the extracellular matrix (ECM) may play a role in this process. The purpose of this study was to characterize changes in the proteome components of periodontal ligament (PDL) tissue after hypothermic preservation of the tooth.

Extracted teeth were divided into 4 groups: immediate sampling, sampling after 1 week of preservation at 4°C, sampling after 2 weeks of preservation at 4°C, and sampling after 1 week of dry storage at room temperature as a negative control. PDL tissues were collected from the root and stored immediately in liquid nitrogen. The tissues were subjected to 2-dimensional gel electrophoresis, and spot selection was executed. Selected spots that maintained the protein volume were then processed with matrix-assisted laser desorption and ionization time-of-flight mass spectrometry to identify the nature of the proteins.

Thirty-five selected spots were analyzed. Sixteen spots were identified as vimentin, and 3 spots were type VI collagen. The size of the 16 vimentin spots decreased gradually with increasing storage time, from 0 to 2 weeks, and decreased rapidly after dry storage. However, only the dry storage group differed significantly from the immediately sampled group.

Vimentin was the most prominent protein followed by type VI collagen in volumetrically maintained protein spots. Although these proteins are known to be closely related with ECM integrity, the role of these proteins in delayed replantation is beyond the scope of this study. Further studies are needed to elucidate the possible role of these proteins for periodontal healing of delayed replantation.