title: Sustained delivery of sphingosine-1-phosphate using poly(lactic-co-glycolic acid)-based microparticles stimulates Akt/ERK-eNOS mediated angiogenesis and vascular maturation restoring blood flow in ischemic limbs of mice.
abstract: Therapeutic angiogenesis is a promising strategy for treating ischemia. The lysophospholipid mediator sphingosine-1-phosphate (S1P) acts on vascular endothelial cells to stimulate migration and tube formation, and plays the critical role in developmental angiogenesis. We developed poly(lactic-co-glycolic-acid) (PLGA)-based S1P-containing microparticles (PLGA-S1P), which are biodegradable and continuously release S1P, and studied the effects of PLGA-S1P on neovascularization in murine ischemic hindlimbs. Intramuscular injections of PLGA-S1P stimulated blood flow in C57BL/6 mice dose-dependently, with repeated administrations at a 3-day interval, rather than a single bolus or 6-day interval, over 28 days conferring the optimal stimulating effect. In Balb/c mice that exhibit limb necrosis and dysfunction due to retarded blood flow recovery, injections of PLGA-S1P stimulated blood flow with alleviation of limb necrosis and dysfunction. PLGA-S1P alone did not induce edema in ischemic limbs, and rather blocked vascular endothelial growth factor-induced edema. PLGA-S1P not only increased the microvessel densities in ischemic muscle, but promoted coverage of vessels with smooth muscle cells and pericytes, thus stabilizing vessels. PLGA-S1P stimulated Akt and ERK with increased phosphorylation of endothelial nitric oxide synthase in ischemic muscle. The effects of the nitric oxide synthase inhibitor, Nomega-nitro-L-arginine methylester, showed that PLGA-S1P-induced blood flow stimulation was partially dependent on nitric oxide. Injections of PLGA-S1P also increased the expression of angiogenic factors and the recruitment of CD45-, CD11b- and Gr-1-positive myeloid cells, which are implicated in post-ischemic angiogenesis, into ischemic muscle. These results indicate that PLGA-based, sustained local delivery of S1P is a potentially useful therapeutic modality for stimulating post-ischemic angiogenesis.
authors.affiliation: Department of Physiology, Kanazawa University Graduate School of Medicine, 13-1 Takara-machi, Kanazawa, Ishikawa 920-8640, Japan.
authors.forename: Xun
authors.initials: X
authors.lastname: Qi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Tomomi
authors.initials: T
authors.lastname: Murakawa
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Osamu
authors.initials: O
authors.lastname: Oyama
authors.forename: Ryunosuke
authors.initials: R
authors.lastname: Ohkawa
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Yoshioka
authors.forename: Wa
authors.initials: W
authors.lastname: Du
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Sugimoto
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yatomi
authors.forename: Noriko
authors.initials: N
authors.lastname: Takuwa
authors.forename: Yoh
authors.initials: Y
authors.lastname: Takuwa
mesh_terms: D000818:Animals; D003692:Delayed-Action Preparations / Q000008:administration & dosage; D004195:Disease Models, Animal; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology*; D006614:Hindlimb / Q000098:blood supply / Q000187:drug effects; D007511:Ischemia / Q000188:drug therapy* / Q000201:enzymology / Q000503:physiopathology*; D019344:Lactic Acid / Q000008:administration & dosage*; D008246:Lysophospholipids / Q000008:administration & dosage*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008863:Microspheres; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000201:enzymology / Q000503:physiopathology; D018919:Neovascularization, Physiologic / Q000187:drug effects* / Q000502:physiology; D052250:Nitric Oxide Synthase Type III / Q000502:physiology*; D011100:Polyglycolic Acid / Q000008:administration & dosage*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D011897:Random Allocation; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D013110:Sphingosine / Q000008:administration & dosage / Q000031:analogs & derivatives*
chemical_list: D003692:Delayed-Action Preparations; D008246:Lysophospholipids; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; C060506:sphingosine 1-phosphate; D019344:Lactic Acid; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D013110:Sphingosine