Effects of Mesenchymal Stem Cell-Derived Secretome on Glycemic Control and Pancreatic Islet Morphology in Streptozotocin-Induced Diabetic Rats

Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia and progressive pancreatic islet dysfunction. The mesenchymal stem cell (MSC)-derived secretome has been investigated as a potential cell-free therapeutic approach because of its reported paracrine, anti-inflammatory, and tissue-reparative effects. This study evaluated the effects of MSC-derived secretome administration on day-28 random blood glucose levels and pancreatic islet morphology in streptozotocin (STZ)-induced diabetic rats. Twenty-one male Sprague–Dawley rats were randomly assigned to three groups: negative control, diabetic control, and secretome-treated diabetic groups (n = 7 per group). The treated group received 0.5 mL of umbilical cord MSC-derived secretome intraperitoneally once weekly for three consecutive weeks, beginning on day 8 after STZ induction. Day-28 random blood glucose levels were analyzed using the Kruskal–Wallis test followed by Bonferroni-adjusted Mann–Whitney U tests. Pancreatic islet area was analyzed using one-way analysis of variance followed by Bonferroni-adjusted post hoc comparisons. Day-28 random blood glucose was lower in the secretome-treated diabetic group than in the diabetic control group (263.71 ± 122.29 vs. 423.00 ± 36.89 mg/dL; adjusted p = 0.0378). Pancreatic islet area differed among the three groups (p = 0.0043), with a significant difference between the negative control and diabetic control groups (p = 0.004). The difference between the diabetic control and secretome-treated diabetic groups was not statistically significant (p = 0.061). Qualitative examination of hematoxylin and eosin (H&E)-stained sections suggested better-preserved islet morphology in the treated group. These findings indicate lower day-28 random blood glucose following secretome treatment, while evidence for an improvement in pancreatic islet area remains inconclusive. The study does not establish β-cell regeneration.