Effects of Human Dental Pulp Stem Cell-Derived Conditioned Medium on Atrophied Submandibular Gland after the Release from Ligation of the Main Excretory Duct in Mice

The salivary gland duct ligation model for the treatment of obstruction caused by salivary stones causes hypofunction of the salivary gland. However, sufficient results have not been obtained regarding the regeneration of acinar cells and the restoration of function, and the development of treatment methods is still ongoing. Here, we administered dental pulp stem cell-derived conditioned medium (DPSC-CM) containing various growth factors to mice and examined its effects. The main excretory duct of the submandibular gland was ligated; after 3 weeks, the ligation was released, and Dulbecco’s modified Eagle’s medium (DMEM) or DPSC-CM was administered biweekly via the right jugular vein. The mice were euthanized at 2, 4, and 8 weeks after the release of the ligation, and the submandibular glands were collected. After the release, the acinar cells had a time-dependent recovery. The DPSC-CM group exhibited a significant increase in the expression of progenitor cell marker cytokeratin 5 (CK5) at 4 weeks after the release of the ligation and acinar cell marker aquaporin 5 (AQP5) at 8 weeks compared with the control and DMEM groups by real-time RT-PCR. The administration of DPSC-CM in mice after the release of the submandibular main duct ligation promotes acinar cell regeneration.