Iloprost Induces Dental Pulp Angiogenesis in a Growth Factor-free 3-Dimensional Organ Culture System.

INTRODUCTION: Angiogenesis is a key determinant in dental pulp regeneration. Iloprost is a synthetic prostacyclin that promotes angiogenesis. A three-dimensional culture that mimics the in vivo condition has been used in tissue engineering. This study investigated the effect of iloprost on promoting dental pulp angiogenesis by using the tooth slice organ culture system.

METHODS: Tooth slices with intact pulp tissue were cut from molars extracted from 12 patients. Dental pulp tissue viability was determined by live/dead staining. The tooth slices were cultured with iloprost for 1 or 3 days. The microvessel density and expression of vascular endothelial growth factor were determined by immunohistochemical staining. Collagen density was determined by using Masson trichrome and immunofluorescent staining.

RESULTS: The pulp tissue in the tooth slices remained viable when cultured in serum-free medium. Iloprost increased the microvessel density as shown by a higher number of von Willebrand factor-positive cells. A significant increase in vascular endothelial growth factor expression was observed in the tooth slices cultured with iloprost. Iloprost stimulated collagen deposition, and this effect was abolished after inhibition of protein kinase A activity.

CONCLUSIONS: Human tooth slices provide a valuable and easy-to-obtain model to investigate the effect of bioactive molecules used in dental pulp regeneration. This study showed for the first time that tooth slices could be kept viable under serum-free conditions for up to 3 days. Iloprost promoted angiogenesis, increased new vessel formation, and induced collagen deposition. This study proposes the clinical value of iloprost as a drug for inducing angiogenesis that can increase the success of pulp regeneration.