IADR Abstract Archives
Delivery of Hemichannel Blocker for Topical Treatment of Pulpitis
Objectives: Connexins are trans-membrane proteins which are upregulated during pulpitis. 6 connexin proteins form a pore in the cell membrane, also known as a connexon or hemichannel, which enables the exchange of small metabolites and signalling molecules. These membranous pores increase pathologically during inflammation and can lead to increased host collateral damage. The objective of this study is to investigate use of a cis-benzopyran compound Tonabersat (SB-220453), a connexin hemichannel blocker, in the treatment of pulpitis
Methods: For the in-vitro stage, cultured DPSCs (P3-6, Lonza Poietics) were used to assess the degree of connexin-43 and hemichannel reduction upon incubation with 10µM-300µM Tonabersat (reconstituted in DMSO). Scratch wound assay was also carried out to determine the rate of wound closure. Subsequently, we used 12-week-old male Sprague-Dawley rats to create mechanical pulp exposures, which were left untreated for 2 days. Thereafter, teeth were subjected to partial pulpotomy on the day of treatment. Tonabersat, delivered either via pluronic gel, coated-polycaprolactone or polycaprolactone/polylactic-co-glycolic acid manufactured via dip-freeze technique, were applied on rodent pulp before capping with Biodentine® (n=8 per group),. Animals were sacrificed at days 1 and 5, subjected to histology and immunofluorescent staining to examine degree of hemichannel and connexin downregulation, as well as inflammation markers- MPO and NLRP3. Kruskal-Wallis analysis was performed.
Results: Tonabersat effectively reduced hemichannel expression at 300µM resulting in a notable increased rate of wound closure in-vitro. It was observed that the DMSO vehicle control in all 3 scaffolds had a negative effect, increasing inflammatory markers as well as demonstrating poorer H&E scores. Tonabersat delivered in all three scaffolds however, showed promising histological outcomes, and corresponding favourable reduction of hemichannel expression, further confirmed by reduced levels of MPO and NLRP3.
Conclusions: Future work employing Tonabersat for treatment of pulpitis would entail the exploration of other vehicle carriers and evaluating oral delivery methods.
Methods: For the in-vitro stage, cultured DPSCs (P3-6, Lonza Poietics) were used to assess the degree of connexin-43 and hemichannel reduction upon incubation with 10µM-300µM Tonabersat (reconstituted in DMSO). Scratch wound assay was also carried out to determine the rate of wound closure. Subsequently, we used 12-week-old male Sprague-Dawley rats to create mechanical pulp exposures, which were left untreated for 2 days. Thereafter, teeth were subjected to partial pulpotomy on the day of treatment. Tonabersat, delivered either via pluronic gel, coated-polycaprolactone or polycaprolactone/polylactic-co-glycolic acid manufactured via dip-freeze technique, were applied on rodent pulp before capping with Biodentine® (n=8 per group),. Animals were sacrificed at days 1 and 5, subjected to histology and immunofluorescent staining to examine degree of hemichannel and connexin downregulation, as well as inflammation markers- MPO and NLRP3. Kruskal-Wallis analysis was performed.
Results: Tonabersat effectively reduced hemichannel expression at 300µM resulting in a notable increased rate of wound closure in-vitro. It was observed that the DMSO vehicle control in all 3 scaffolds had a negative effect, increasing inflammatory markers as well as demonstrating poorer H&E scores. Tonabersat delivered in all three scaffolds however, showed promising histological outcomes, and corresponding favourable reduction of hemichannel expression, further confirmed by reduced levels of MPO and NLRP3.
Conclusions: Future work employing Tonabersat for treatment of pulpitis would entail the exploration of other vehicle carriers and evaluating oral delivery methods.