Adipose-Derived Stem Cells Preincubated with Green Tea EGCG Enhance Pancreatic Tissue Regeneration in Rats with Type 1 Diabetes through ROS/Sirt1 Signaling Regulation

Abstract

Type 1 diabetes stem-cell-based therapy is one of the best therapeutic approaches for pancreatic damage treatment due to stem cell tissue regeneration. Epigallocatechin gallate (EGCG) is one of the active components found in green tea. Experimental results suggest that EGCG shows beneficial effects on cell protection. This study explores whether a better pancreatic regeneration therapeutic effect could be found in mesenchymal stem cells pretreated with EGCG compared to stem cells without EGCG pretreatment. A cell model confirmed that adipose-derived stem cells (ADSC) incubated with EGCG increase cell viability under high-glucose (HG) stress. This is due to survival marker p-Akt expression. In an animal model, type 1 diabetes induced the activation of several pathological signals, including islet size reduction, extracellular fibrotic collagen deposition, oxidative stress elevation, survival pathway suppression, apoptosis signaling induction, and Sirt1 antioxidant pathway downregulation. Ordinary ADSC transplantation slightly improved the above pathological signals. Further, EGCG-pretreated ADSC transplantation significantly improved the above pathological conditions. Taken together, EGCG-pretreated ADSCs show clinical potential in the treatment of patients with type 1 diabetes through the regeneration of damaged pancreatic tissues.

Keywords: green tea EGCG; mesenchymal stem cells; pancreatic regeneration; survival p-Akt.

Figure 1

Characterization of adipose-derived stem cells. (a) Surface markers, (b) adipogenesis differentiation and (c) self-renewal markers.

Figure 2

Investigation of survival for ADSC in the presence of high glucose (33 mM). (a) Cell viability and (b) expression of survival protein marker for ADSC. (*** p < 0.001, # p < 0.05).

Figure 3

Investigation of (a) serum glucose levels, (b) serum TBARS levels and (c) TBARS pancreatic tissue levels for experimental animals. (*** p < 0.001, # p < 0.05, ## p < 0.01, %% p < 0.01).

Figure 4

Pancreatic tissue survival protein expression for experimental animals. (a) Western blotting analysis and (b) quantification. (# p < 0.05, ## p < 0.01, ### p < 0.001, ** p < 0.01, *** p < 0.001, % p < 0.05, %% p < 0.01, && p < 0.01).

Figure 5

Sirt1 pathway expression for pancreatic tissues in experimental animals. (a) Western blotting analysis and (b) quantification. (### p < 0.001, *** p < 0.001, % p < 0.05).

Figure 6

Pro-apoptotic protein expression in pancreatic tissues for experimental animals. (a) Western blotting analysis and (b) quantification. (# p < 0.05, ### p < 0.001, * p < 0.05, *** p < 0.001, %% p < 0.01, %%% p < 0.001, & p < 0.05, && p < 0.01, &&& p < 0.001).

Figure 6

Pro-apoptotic protein expression in pancreatic tissues for experimental animals. (a) Western blotting analysis and (b) quantification. (# p < 0.05, ### p < 0.001, * p < 0.05, *** p < 0.001, %% p < 0.01, %%% p < 0.001, & p < 0.05, && p < 0.01, &&& p < 0.001).

Figure 7

Pancreatic size measurement for experimental animals. (a) HE stain analysis and (b) quantification. (## p < 0.01, *** p < 0.001, % p < 0.05, & p < 0.01).

Figure 8

Pancreatic fibrosis analysis for experimental animals. (a) Masson’s trichrome stain analysis and (b) Western blotting analysis for fibrotic protein markers.

Figure 9

Suggestive signal pathway of this study.

Figure 10

Graphic summary of this study. The upward arrows mean upregulation.