Exosome and Mesenchymal Stem Cell Treatment for Salivary Gland Dysfunction in Primary Sjögren Syndrome

Participants will receive exosome injections into both submandibular glands. The exosome preparation is derived from umbilical cord-derived mesenchymal stem cells and contains 5 billion particles per 1 mL. Each submandibular gland will receive 0.5 mL at two injection sites per application. Two applications will be performed, with the second application 2 weeks after the first.

Exosomes derived from umbilical cord-derived mesenchymal stem cells. The preparation is a cell-free extracellular vesicle product containing 5 billion particles per 1 mL. Each participant will receive 0.5 mL in each submandibular gland at two injection sites. Two applications will be performed, with the second application 2 weeks after the first.

Participants will receive mesenchymal stem cell injections into both submandibular glands. The mesenchymal stem cells are derived from umbilical cord tissue and produced by Yeditepe University at a concentration of 10 million MSCs per 1 mL. Each submandibular gland will receive 0.5 mL at two injection sites per application. Two applications will be performed, with the second application 2 weeks after the first.

Umbilical cord-derived mesenchymal stem cells (MSCs), produced by Yeditepe University, at a concentration of 10 million MSCs per 1 mL. Each bilateral submandibular gland will receive 0.5 mL at two injection sites per application. Two applications will be performed, with the second application 2 weeks after the first.

Participants will receive serum physiologic (saline) injections into both submandibular glands. Each submandibular gland will receive 0.5 mL at two injection sites per application. Two applications will be performed, with the second application 2 weeks after the first.

Serum physiologic (saline). Each bilateral submandibular gland will receive 0.5 mL at two injection sites per application. Two applications will be performed, with the second application 2 weeks after the first.

Change in salivary flow rate, measured by salivary gland scintigraphy. Salivary flow rate will be expressed in mL/min. Baseline values obtained from the participants' existing sialoscintigraphy performed at Yeditepe University will be compared with the values obtained at Month 6.

Change in xerostomia severity assessed using the 11-item Xerostomia Inventory XI. Total scores range from 11 to 55, with higher scores indicating greater severity of xerostomia. The questionnaire will be administered at Month 1 and Month 3.