Effects of Prolyl Hydroxylase Inhibitor L-mimosine on Dental Pulp in the Presence of Advanced Glycation End Products

• We evaluated the response of monolayer cultures of dental pulp–derived cells and tooth slice organ cultures to the prolyl hydroxylase inhibitor L-mimosine in the presence of advanced glycation end products.
• In the presence of advanced glycation end products, L-mimosine increases vascular endothelial growth factor and interleukin-8 but not interleukin-6 in monolayer cultures of dental pulp–derived cells.
• In the presence of interleukin-1β and advanced glycation end products, L-mimosine increases vascular endothelial growth factor but not interleukin-6 and interleukin-8 in monolayer cultures of dental pulp–derived cells.
• L-mimosine decreases alkaline phosphatase and matrix mineralization under the influence of advanced glycation end products in monolayer cultures of dental pulp–derived cells.
• In the presence of advanced glycation end products, L-mimosine increases vascular endothelial growth factor but not interleukin-6and interleukin-8 in tooth slice organ cultures.
• Our data suggest that prolyl hydroxylase inhibitors can increase the production of angiogenic growth factors in the dental pulp in the presence of advanced glycation end products.

IntroductionProangiogenic prolyl hydroxylase (PHD) inhibitors represent a novel approach to stimulate tissue regeneration. Diabetes mellitus involves the accumulation of advanced glycation end products (AGEs). Here we evaluated the impact of AGEs on the response of human pulp tissue to the PHD inhibitor L-mimosine (L-MIM) in monolayer cultures of dental pulp–derived cells (DPCs) and tooth slice organ cultures.MethodsIn monolayer cultures, DPCs were incubated with L-MIM and AGEs. Viability was assessed based on formazan formation, live-dead staining, annexin V/propidium iodide, and trypan blue exclusion assay. Vascular endothelial growth factor (VEGF), interleukin (IL)-6, and IL-8 production was evaluated by quantitative polymerase chain reaction and immunoassays. Furthermore, expression levels of odontoblast markers were assessed, and alizarin red staining was performed. Tooth slice organ cultures were performed, and VEGF, IL-6, and IL8 levels in their supernatants were measured by immunoassays. Pulp tissue vitality and morphology were assessed by MTT assay and histology.ResultsIn monolayer cultures of DPCs, L-MIM at nontoxic concentrations increased the production of VEGF and IL-8 in the presence of AGEs. Stimulation with L-MIM decreased alkaline phosphatase levels and matrix mineralization also in the presence of AGEs, whereas no significant changes in dentin matrix protein 1 and dentin sialophosphoprotein expression were observed. In tooth slice organ cultures, L-MIM increased VEGF but not IL-6 and IL-8 production in the presence of AGEs. The pulp tissue was vital, and no signs of apoptosis or necrosis were observed.ConclusionsOverall, in the presence of AGEs, L-MIM increases the proangiogenic capacity, but decreases alkaline phosphatase expression and matrix mineralization.