Combination of 20(R)-Rg3 and HUCMSCs Alleviates Type 2 Diabetes Mellitus in C57BL/6 Mice by Activating the PI3K/Akt Signaling Pathway

Type 2 diabetes mellitus (T2DM) is a global health challenge characterized by insulin resistance and pancreatic β-cell dysfunction. While human umbilical cord mesenchymal stem cells (HUCMSCs) show therapeutic potential, their efficacy can be limited by the unfriendly in vivo microenvironment. 20(R)-Rg3, a ginsenoside with anti-inflammatory and antioxidant properties, may enhance HUCMSC function, but the combined effect and mechanism of this "cell-molecule" strategy remain unclear. This study aimed to investigate the therapeutic effects and underlying mechanisms of a combination therapy using 20(R)-Rg3 and HUCMSCs in a high-fat diet (HFD) and streptozotocin (STZ)-induced T2DM mouse model. Diabetic mice were treated with PBS, HUCMSCs alone, or HUCMSCs pre-treated with 20(R)-Rg3. Fasting blood glucose and body weight were monitored. Insulin resistance was assessed via oral glucose tolerance tests (OGTTs) and intraperitoneal insulin tolerance tests (IPITTs). Serum biochemical parameters (lipids, liver and kidney function, insulin, C-peptide) were analyzed. Histopathological examination (H&E, PAS staining) of the liver, kidney, and pancreas was performed, alongside immunofluorescence for islet hormones. Transcriptomic analysis (RNA-seq) was conducted on HUCMSCs with or without 20(R)-Rg3 pretreatment to elucidate potential signaling pathways. Results demonstrated that the combination significantly reduced hyperglycemia and improved insulin sensitivity more effectively than HUCMSCs alone. It also ameliorated dyslipidemia, enhanced liver and kidney function, promoted glycogen synthesis, and facilitated pancreatic islet regeneration. Transcriptomic analysis indicated that the synergistic effect is primarily mediated through activation of the PI3K/Akt signaling pathway. These findings suggest that 20(R)-Rg3 potentiates the therapeutic efficacy of HUCMSCs, providing a promising combinatorial strategy for T2DM treatment.