Therapeutic angiogenesis by local sustained release of microRNA-126 using poly lactic-co-glycolic acid nanoparticles in murine hindlimb ischemia

Objective: Recent studies demonstrate that microRNAs show promising potential, including angiogenesis, in therapeutic intervention. MicroRNA-126 (miR-126) is reported to regulate angiogenesis by blocking Sprouty-related EVH1 domain-containing protein 1 (SPRED1), an endogenous inhibitor of vascular endothelial cell growth factor. In this study, we investigated the angiogenic effects of the sustained release of miR-126 loaded with poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) in a murine hindlimb ischemia model. Methods: We induced mice hindlimb ischemia through femoral artery excision. We randomly assigned the mice to two groups and performed an intramuscular injection of miR-126-loaded PLGA NPs (miR-126) or scrambled miR-loaded PLGA NPs (control) shortly after induction of ischemia. Results: The miR-126 expression levels in the ischemic limb at 3 days after treatment were significantly higher in mice treated with miR-126-loaded PLGA NPs than in those with scrambled miR, indicating the fair efficiency of local miR transduction (control vs miR-126: 0.33 +/- 0.12 vs 0.74 +/- 0.42; P < .05; n = 6). Laser Doppler perfusion imaging revealed that limb blood flow in mice treated with miR-126-loaded PLGA NPs was significantly higher at 14 days after treatment (sham vs control vs miR-126: 0.62 +/- 0.09 vs 0.58 +/- 0.05 vs 0.72 +/- 0.07; P < .001; n = 12). Immunohistochemical analysis indicated that CD31-positive cell density and a-smooth muscle actin-positive vessel density were significantly higher in miR-126-treated mice (control vs miR-126: 0.33 +/- 0.12 vs 0.74 +/- 0.42; P <.05; n = 6). SPRED1 messenger RNA expression levels were significantly lower in miR-126-treated mice (control vs miR-126: 1.00 +/- 0.05 vs 0.81 +/- 0.07; P <.05; n = 6). Western blotting indicated that protein levels of pERK/ERK mediated by SPRED1 were significantly higher in miR-126-treated mice (control vs miR-126: 0.29 +/- 0.10 vs 0.54 +/- 0.21; P <.05; n = 6). Conclusions: This study suggests that sustained release of miR-126-loaded PLGA NPs might be an effective method in therapeutic angiogenesis for hindlimb ischemia. Clinical Relevance: Severe clinical limb ischemia resistant to conventional treatments, including medication, percutaneous angioplasty, and bypass surgery, remains a serious health care problem. Therapeutic angiogenesis that induces angiogenesis at the ischemic site could be a novel and effective approach for this severe condition. Here, we developed a therapeutic approach combining microRNA-126 and a drug delivery system using poly lactic-co-glycolic acid nanoparticles, which showed novel therapeutic potential on a mouse hindlimb ischemia model. This therapeutic approach could be a promising new strategy after verification of the safety and long-term therapeutic effects in clinical studies in the future.