MMP1 and limb ischemia: 600 ng/mL Tb4 improves endothelial dysfunction through enhancing dia-hiPSC-EC viability and proliferation, reducing senescence and endothelin-1 and MMP-1 secretion, and improving reparative potency of dia-hiPSC-ECs for treatment of ischemic limb disease in mice with T2DM.