Tetramethylpyrazine enhances angiogenesis in diabetic hindlimb ischemia by modulating the THBS1/PI3K/AKT signaling axis and reversing aberrant expression of MFN1/FIS1-related mitochondrial fusion-fission proteins

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BACKGROUND: Type 1 diabetes with hindlimb ischemia (T1DM-HLI) is a prevalent diabetic microvascular complication characterized by impaired angiogenesis. Tetramethylpyrazine (TMP) demonstrates therapeutic potential in vascular disorders, but its role in T1DM-HLI remains unclear. PURPOSE: This study investigates the protective effect of TMP on impaired angiogenesis in T1DM-HLI and underlying mechanisms. METHODS: We evaluated TMP's effects on angiogenesis, oxidative stress, and mitochondrial fusion/fission balance in streptozotocin-induced and femoral artery-ligated T1DM-HLI mice and high-glucose-treated human umbilical vein endothelial cells (HUVECs). RNA sequencing identified key molecular mechanisms. Molecular docking predicted an interaction between TMP and thrombospondin-1 (THBS1). We show that TMP rescues impaired angiogenesis and disordered mitochondrial dynamics, effects possibly mediated through suppression of THBS1 and activation of the PI3K/AKT axis. RESULTS: TMP restored hindlimb perfusion and promoted vascular endothelial growth factor A (VEGFA)-driven angiogenesis in T1DM-HLI mice, while enhancing HUVEC proliferation, migration, and tube formation. It attenuated oxidative stress and reversed aberrant expression of proteins to mitochondrial fusion and fission. RNA sequencing revealed the THBS1/PI3K/AKT axis may play a central role in mediating the therapeutic effects of TMP. Molecular docking predicted a potential interaction between TMP and THBS1, identifying THBS1 as a candidate target of TMP. In vitro and in vivo experiments confirmed TMP treatment reduced THBS1 expression and increased PI3K and AKT phosphorylation. CONCLUSION: Our findings demonstrate that TMP may reverse dysregulated expression of mitochondrial fusion-fission proteins and enhance angiogenesis in T1DM-HLI by inhibiting THBS1 and activating the PI3K/AKT pathway, supporting TMP as a therapeutic candidate for diabetic hindlimb ischemia.