Department of Physiology, Kanazawa University Graduate School of Medicine, 13-1 Takara-machi, Kanazawa, Ishikawa 920-8640, Japan.
Eur J Pharmacol. 2010 May 25;634(1-3):121-31. doi: 10.1016/j.ejphar.2010.02.038. Epub 2010 Mar 3.
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.
治疗性血管生成是治疗缺血的一种很有前途的策略。溶血磷脂介质 1-磷酸鞘氨醇（S1P）作用于血管内皮细胞，刺激迁移和管腔形成，并在发育性血管生成中发挥关键作用。我们开发了基于聚（乳酸-共-乙醇酸）（PLGA）的含有 S1P 的微粒（PLGA-S1P），其具有生物降解性且可连续释放 S1P，并研究了 PLGA-S1P 对小鼠缺血后肢新生血管形成的影响。PLGA-S1P 的肌肉内注射以剂量依赖性方式刺激 C57BL/6 小鼠的血流，以 3 天的间隔重复给药，而不是单次推注或 6 天的间隔，在 28 天内产生最佳的刺激效果。在由于血流恢复延迟而导致肢体坏死和功能障碍的 Balb/c 小鼠中，PLGA-S1P 的注射刺激了血流，缓解了肢体坏死和功能障碍。PLGA-S1P 本身不会在缺血肢体中引起水肿，而是阻断血管内皮生长因子诱导的水肿。PLGA-S1P 不仅增加了缺血肌肉中的微血管密度，而且促进了平滑肌细胞和周细胞对血管的覆盖，从而稳定了血管。PLGA-S1P 刺激了缺血肌肉中的 Akt 和 ERK，使内皮型一氧化氮合酶的磷酸化增加。一氧化氮合酶抑制剂 Nomega-硝基-L-精氨酸甲酯的作用表明，PLGA-S1P 诱导的血流刺激部分依赖于一氧化氮。PLGA-S1P 的注射还增加了血管生成因子的表达和 CD45-、CD11b-和 Gr-1 阳性髓样细胞的募集，这些细胞与缺血后血管生成有关，进入缺血肌肉。这些结果表明，基于 PLGA 的 S1P 的持续局部递送是刺激缺血后血管生成的一种很有前途的治疗方法。
