A Study of Submandibular Gland Changes in Mice of a Murine Model of Sjögren’s Syndrome Administered Dental Pulp Stem Cell-Conditioned Medium

Recently researchers are attempting to develop a treatment for Sjögren’s syndrome using mesenchymal stem cell culture supernatant. In this study, we analyzed changes in the submandibular gland in Murphy Roths Large (MRL) mice of a Sjögren’s syndrome model administered human dental pulp stem cell-derived conditioned medium (DPSC-CM). MRL mice were injected with DPSC-CM twice per week for two weeks. Submandibular glands were analyzed after four days of final injection in after 4 days group and 29 days after final injection in after 29 days group, which were compared to each non-treated group. We measured salivary flow and conducted general histological, immunohistochemical, and quantitative real-time polymerase chain reaction (PCR) investigations. Both the after 4 and 29 days groups of mice treated with DPSC-CM showed significant increase in salivary flow compared to the non-treated group. Significant increases were observed in the stem cell marker (c-Kit), progenitor cell marker (CK5), and acinar cell marker (AQP5) in immunohistochemical analyses. Furthermore, a significant increase in the mRNA expression levels of anti-inflammatory cytokines TGF-β1 and IL-10 was observed. There was a significant decrease in the inflammatory cytokine IL-6. The results of this study show that the systemic administration of DPSC-CM to MRL mice restores the function of submandibular gland tissue and reduces inflammation. Furthermore, because the effects were observed even after 29 days of DPSC-CM administration, it was suggested that there would be long-term functional repair of submandibular gland tissue and control of inflammation. DPSC-CM showed a potential as long-term treatment for hyposalivation caused by Sjögren’s syndrome.