Expression of mimecan in the periodontal ligament tissue as a novel factor related with hypothermic tooth preservation

Abstract

Recent research suggests that there could be factors other than just viability of periodontal ligament (PDL) cells, which are related to delayed replantation of teeth. Hence, assessing changes in the components of the PDL tissue of extracted and preserved teeth under various storage conditions may be an important step in discovering the factors associated with delayed replantation. The aim of this study was to uncover factors responsible for PDL regeneration, by two-dimensional differential gel electrophoresis (2-D DIGE), a state-of-the-art quantification technology for two-dimensional gel proteomics. Four extracted teeth were immersed in the conservative solution that consisted of 1.0 L of Hartmann’s solution and 1.0 g of flumoxef sodium, immediately after extraction, and were categorized into the following groups: tissue sampling (fresh), tissue sampling after storage for a week (1-week storage), and tissue sampling after storage for 2 weeks (2-week storage). PDL tissues were collected from the mid-third area of the tooth root, using periodontal curette, and stored according to the period of the assigned group. Next, 2-D DIGE was performed. The spots with a higher density for the 1- and 2-week storage groups, compared with those in the fresh group, were selected and identified by liquid chromatography mass spectrometry (LC-MS). The mascot algorithm was used to identify peptide sequences present in the protein sequence database. Twenty-five spots were selected for mass spectrometry analysis, excluding three overlapping spots and five spots that were not detected in prep gel. Two spots were identified as mimecan, which is related to tooth regeneration. Another two spots were identified as alpha-1 collagen VI, which is related to extracellular matrix. The remaining two spots were identified as annexin A5 and complement 9, related to the apoptotic pathway of cell death. The results indicate that mimecan and type VI collagen play a positive role in PDL tissue repair. However, further research is necessary to confirm this.