Sustained Release of Erythropoietin Using Biodegradable Gelatin Hydrogel Microspheres Persistently Improves Lower Leg Ischemia
Longhu Li, MD*,
Hideshi Okada, MD*,
Genzou Takemura, MD*,*,
Masayasu Esaki, MD*,
Hiroyuki Kobayashi, MD*,
Hiromitsu Kanamori, MD*,
Itta Kawamura, MD*,
Rumi Maruyama, PhD*,
Takako Fujiwara, MD ,
Hisayoshi Fujiwara, MD*,
Yasuhiko Tabata, PhD and
Shinya Minatoguchi, MD*
* Division of Cardiology, Gifu University Graduate School of Medicine, Gifu, Japan
Department of Food Science, Kyoto Women's University, Kyoto, Japan
Department of Biomaterials, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
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Figure 1 Blood Perfusion of the Ischemic Hind Limb
(A) Laser Doppler blood perfusion. (B) Blood perfusion in ischemic hind limbs was measured before, just after, on day 3, and at weeks 1, 2, 4, 6, and 8 after right femoral artery ligation. Results are expressed as the ratio of the right (ischemic) to left (nonischemic) limb perfusion. *p < 0.05, EPO or EPO-GHM versus the other groups; #p < 0.05, EPO or EPO-GHM versus saline and GHM. EPO = erythropoietin; EPO-GHM = erythropoietin-immersed gelatin hydrogel microspheres; GHM = gelatin hydrogel microspheres.
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Figure 2 Ischemic Limb Histology in Mice After Ligation of the Femoral Artery
(A) Photomicrographs of immunohistochemical CD31, alpha-smooth muscle actin (SMA), and HHF35 preparations of muscular specimens from the indicated groups at 2 or 8 weeks after ligation. Scale bars: 20 µm. (B) Graphs showing the morphometric data. *p < 0.05 versus the sham group; #p < 0.05 versus the other control groups. E = erythropoietin; EG = erythropoietin-immersed gelatin hydrogel microspheres; G = gelatin hydrogel microspheres; HPF = high-power field; S = saline; other abbreviations as in Figure 1.
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Figure 3 Effects on the Proliferation or Apoptosis of Vessels in Ischemic Limbs
(A) Graphs showing the proliferating or apoptotic index of vessels at 8 weeks after ligation. *p < 0.05 versus the sham group; #p < 0.05 versus the other control groups. (B) Confocal micrographs of the ischemic limb specimen taken from the mice showing the double immunofluorescent labeling of von Willebrand factor (red fluorescence) with Ki-67 (green fluorescence). Scale bars: 20 µm. TUNEL = in situ nick end-labeling; vWF = von Willebrand factor; other abbreviations as in Figures 1 and 2.
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Figure 4 EPC Mobilization in Response to Ischemia and Treatments
(A) Evaluation of CD34+/Flk-1+cell mobilization 7 days after treatments using FACS. (B) Graphs showing the percentages of CD34+/Flk-1+cells, CD34+/CD133+cells, and CD34+/Sca-1+cells in total peripheral blood mononuclear cells (PBMC) on day 3 or 7 after surgery. *p < 0.05 versus the sham group. EPC = endothelial progenitor cell; FACS = fluorescence-activated cell sorter; G-CSF = granulocyte colony-stimulating factor; other abbreviations as in Figure 1.
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Figure 5 Western Analysis for EPO Receptor Expression and Downstream Targets of EPOR Signaling in Ischemic Limbs
(A to C) Graphs showing morphometric data. *p < 0.05 versus the sham group; #p < 0.05 versus the other control groups. EPOR = erythropoietin receptor; ERK = extracellular signal-regulated protein kinase; STAT = signal transducer and activator of transcription; other abbreviations as in Figures 1 and 2.
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Figure 6 Assessment of Angiogenic Factors in Ischemic Limbs
(A) Muscular levels of vascular endothelial growth factor (VEGF) or interleukin-1 beta (IL-1β) (pg/mg protein) determined by enzyme-linked immunosorbent assay. (B) Western analysis for the expression of endothelial nitric oxide synthase (eNOS), p-eNOS, and matrix metalloproteinase (MMP)-2, and -9 in ischemic limbs. Graphs show the morphometric data. *p < 0.05 versus the sham group; #p < 0.05 versus the other control groups. Abbreviations as in Figure 2.
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Figure 7 Effect of EPO and Akt Inhibitor Wortmannin on Cell Proliferation of Cultured Endothelial Cells and Vascular Smooth Muscle Cells
(A) Western analysis for the expression of p-Akt and p-eNOS. (B) Cell proliferation assay. *p < 0.05 versus the untreated group; #p < 0.05 versus the EPO-treated group. EC = endothelial cell; eNOS = endothelial nitric oxide synthase; VSMC = vascular smooth muscle cell; other abbreviations as in Figure 1.
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