Therapeutic angiogenesis induced by human hepatocyte growth factor gene in rat hindlimb of ischemia

Objective To investigate the effect of plasmid pEGFP-hepatocyte growth factor (HGF)-Cl on rat acute ischemia of hindlimb. Methods The eukaryotic expressed plasmid pEGFP-HGF-Cl carrving human HGF cDNA was constructed. The transfection efficiency and the expression level of HGF were evaluated     

Vascular endothelial growth factor stimulates angiogenesis without improving collateral blood flow following hindlimb ischemia in rabbits

This study was designed to test the ability of adenovirus-delivered vascular endothelial growth factor (Ad-VEGF) to stimulate angiogenesis and arteriogenesis in the rabbit hindlimb following the induction of ischemia and to evaluate the functional changes in the collateral circulation. Ten days after the surgical induction of hindlimb ischemia, either a control virus (1 × 10⁹pfu) or an adenovirus containing the gene for VEGF₁₆₅ (1 × 10⁶, 1 × 10⁷, 1 × 10⁸, or 1 × 10⁹pfu) was administered intramuscularly into the ischemic limb. Thirty days after administration of the adenoviral vectors, skeletal muscle capillary density was assessed and angiography was performed as markers of angiogenesis and arteriogenesis, respectively. Hindlimb blood flow was directly measured and hyperemic tests were performed to evaluate the functional improvements in collateral blood flow. Animals treated with Ad-VEGF at 1 × 10⁸ and 1 × 10⁹pfu showed elevated levels of circulating VEGF and dose-dependent hindlimb edema. These doses also led to a robust angiogenic response (i.e., increase in capillary density), but failed to improve collateral blood flow. Consistent with the lack of a functional response, there was no angiographic evidence of enhanced arteriogenesis with any dose of Ad-VEGF. Following the induction of hindlimb ischemia, administration of Ad-VEGF stimulated capillary sprouting (i.e., angiogenesis), but did not increase the growth and development of larger conduit vessels (i.e., arteriogenesis) or improve collateral blood flow. These results support the concept that VEGF may not be expected to have therapeutic utility for the treatment of peripheral or myocardial ischemia.     

Hyperhomocysteinemia impairs angiogenesis in response to hindlimb ischemia

Hyperhomocysteinemia (HH) is an independent risk factor for atherosclerosis, including peripheral arterial occlusive disease (PAOD). Because angiogenesis and collateral vessel formation are important self-salvage mechanisms for ischemic PAOD, we examined whether HH modulates angiogenesis in vivo in a rat model of hindlimb ischemia. Rats were divided into 3 groups: the control group was given tap water, the HH group was given water containing L-methionine (1 g x kg(-1) x d(-1)), and the HH+L-arg group was given water containing methionine (1 g x kg(-1) x d(-1)) and l-arginine (2.25 vol%). At day 14 of the dietary modifications, the left femoral artery and vein were excised, and the extent of angiogenesis and collateral vessels in the ischemic limb were examined for 4 weeks. Plasma homocysteine levels significantly increased (P:<0.001), and plasma and tissue contents of nitrite+nitrate as well as tissue cGMP levels significantly decreased in the HH group compared with the control group (P:<0.01). Laser Doppler blood flowmetry (LDBF) revealed a significant decrease in the ischemic/normal limb LDBF ratio in the HH group at days 7, 14, 21, and 28 (P:<0.01 versus control). Angiography revealed a significant decrease in the angiographic score in the HH group at day 14 (P:<0.001 versus control). Immunohistochemistry of ischemic tissue sections showed a significant reduction in the capillary density in the HH group (P:<0. 001 versus control). Oral l-arginine supplementation in rats with HH (HH+L-arg) restored the decreased plasma and tissue nitrite+nitrate and cGMP contents (P:<0.05) as well as angiogenesis, as assessed by LDBF (P:<0.05 versus HH), angiographic score (P:<0.01 versus HH), and capillary density (P:<0.001 versus HH). In summary, HH impaired ischemia-induced angiogenesis and collateral vessel formation in a rat model of hindlimb ischemia in vivo. The mechanism of the HH-induced impairment of angiogenesis might be mediated in part by a reduced bioactivity of endogenous NO in the HH state.     

脉冲电磁场对糖尿病大鼠急性下肢缺血模型血管再生的作用

目的:探讨脉冲电磁场(PEMF)对糖尿病大鼠急性下肢缺血模型血管再生的作用。方法:60只SD大鼠按照60 mg/kg腹腔注射链脲菌素(STZ),建立糖尿病大鼠模型后,再根据文献Kawasaki等[2]的方法建立大鼠急性下肢缺血模型,并随机分为实验组和对照组,每组30只。实验组术后第1天,即给予PEMF治疗(每天2 h,共28 d),对照组不做任何处理。于术后当天及术后7、14、28 d,运用激光多普勒技术检测血流。并在术后7、14、28 d处死动物(每组每次处死10只),分离缺血后肢的肌肉,采用免疫组织化染色法检测CD31的表达;采用Western-blot法检测VEGF、FGF-2、VEGFR2、FGFR1、ERK1/2、P-ERK1/2、P38及P-P38的表达。结果:激光多普勒检查显示,实验组在术后14、28 d,血流的恢复(0.64±0.02、0.85±0.02)明显高于对照组(0.48±0.02、0.61±0.02,P0.01)。实验组术后14、28 d,CD31的表达(677.4±15.6)/mm2和(837.2±25.6)/mm2明显高于对照组(495.2±25.3)/mm2和(619.4±19.2)/mm2(P0.01)。Western blot法检测在各个时间段的FGF-2和FGFR1的表达实验组均高于对照组(P0.05);而VEGF及其受体的表达无明显差异。实验组P-ERK1/2与T-ERK1/2的比值在各个时间段均高于对照组(P0.05),两组P-P38与T-P38的比值无显著性差异。结论:PEMF可促进糖尿病大鼠急性下肢缺血的血管新生,机制可能为通过刺激血管内皮细胞释放FGF-2,并与ERK1/2有关,因ERK1/2是FGF-2促进血管增生的重要信号转导途径。     

联合促血管生成素-1及血管内皮细胞生长因子基因治疗对大鼠新生血管通透性的影响

目的　探讨联合转染促血管生成素 1(angoipoietin 1,Ang 1)及血管内皮细胞生长因子(vascularendothelialgrowthfactor,VEGF)基因对大鼠下肢新生血管通透性的影响 ,并观察不同基因剂量配比的差异。方法　制造大鼠下肢血管闭塞病理模型 ,按不同剂量配比肌肉内电转pcD2 Ang 1和 或pcD2 VEGF基因。应用逆转录聚合酶链反应、免疫组化染色检测外源基因在骨骼肌中的表达 ,通过伊文思蓝灌注观察其对新生血管通透性的影响。结果　逆转录聚合酶链反应及免疫组化染色均能检测到外源基因的表达。随着转入pcD2 VEGF剂量的增加 ,血管通透性逐渐增加 ;而随着转入pcD2 Ang 1剂量的增加 ,血管通透性逐渐下降。其中pcD2 VEGF 10 0 μg pcD2 Ang 12 0 0 μg组通透性与正常对照最为接近 [( 8 5 7± 0 74 )ng mlvs ( 8 4 2± 0 82 )ng ml,P >0 0 5 ]。结论　联合转pcD2 Ang 1基因可逆转pcD2 VEGF基因增加血管通透性的副作用 ,其中pcD2 VEGF与pcD2 Ang 1比例为 1 2时血管通透性最接近生理状态。与单基因治疗相比 ,适当配比的联合转基因可能成为治疗闭塞性血管病更安全、更有效的新方法。     

The role of vascular endothelial growth factor in angiogenesis and diabetic retinopathy

Diabetic retinopathy (DR), a DM microvascular complication, is the leading cause of blindness. Angiogenic factors such as vascular endothelial growth factor (VEGF) are involved in the pathogenesis of DR. VEGF-A is a potent, multifunctional cytokine that acts through the receptors VEGFR-1 and VEGFR-2 expressed in the vascular endothelium and causing increased vascular permeability and neovascularization stimulation in both physiological and pathological processes. The expression of VEGFR-1 is upregulated by hypoxia and is less responsive to VEGF compared to VEGFR-2 which is the main mediator mitogenic, angiogenic, and increased vascular permeability. VEGF polymorphisms have been studied in DR susceptibility and progression. Significant association between the polymorphism 634C / G and the presence of RD is reported mainly in relation to allele C. The homozygous CC is associated to proliferative RD and to increased vitreous and serum levels of VEGF suggesting that the presence of the C allele is an independent risk factor for RD. The knowledge of VEGF lead to the development of anti-VEGF drugs (pegaptanib, ranibizumab and bevacizumab) aiming to prevent pathological neovascularization. The anti-VEGF therapy is a reality in practice medical treatment of DR.     

SiRNA targeting SHP-1 accelerates angiogenesis in a rat model of hindlimb ischemia

Vascular endothelial growth factor (VEGF) receptor-2 (KDR/flk-1) has a tyrosine kinase domain, and once activated, induces the autophosphorylation of the tyrosine residues, which is essential for angiogenesis. SHP-1, a cytoplasmic protein tyrosine phosphatase, plays a negative regulatory role in signal transduction pathways by dephosphorylation of the receptors to which it binds. Thus, therapeutic angiogenesis designed to inhibit expression of SHP-1 would be beneficial in hindlimb ischemia. In in vitro, the inhibition of SHP-1 by SHP-1 siRNA impaired the ability of TNF to block the tyrosine phosphorylation of KDR/flk-1 induced by VEGF and showed an increase in endothelial cell growth. In in vivo, SHP-1 mRNA, SHP-1 protein levels and VEGF were increased in a rat model of hindlimb ischemia. Upon injection to the ischemic adductor muscle, vector-based siRNA reduced SHP-1, increased phosphorylation of KDR/flk-1, and markedly increased capillary density. Our data demonstrated in vivo the potential use of siRNA targeting SHP-1 as therapy for peripheral ischemic diseases.     

PET/SPECT imaging of hindlimb ischemia: focusing on angiogenesis and blood flow

Peripheral artery disease (PAD) is a result of the atherosclerotic narrowing of blood vessels to the extremities, and the subsequent tissue ischemia can lead to the up-regulation of angiogenic growth factors and formation of new vessels as a recovery mechanism. Such formation of new vessels can be evaluated with various non-invasive molecular imaging techniques, where serial images from the same subjects can be obtained to allow the documentation of disease progression and therapeutic response. The most commonly used animal model for preclinical studies of PAD is the murine hindlimb ischemia model, and a number of radiotracers have been investigated for positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging of PAD. In this review article, we summarize the PET/SPECT tracers that have been tested in the murine hindlimb ischemia model as well as those used clinically to assess the extremity blood flow.     

Therapeutic angiogenesis for critical limb ischemia: design of the hepatocyte growth factor therapeutic angiogenesis clinical trial

The objective of the HGF-STAT clinical trial is to determine whether perfusion can be improved by gene transfer with a plasmid DNA containing hepatocyte growth factor (HGF) in the affected limb of patients with unreconstructable critical limb ischemia (CLI). CLI results in a high rate of limb loss and impaired quality of life. The current therapeutic strategies, including bypass surgery and percutaneous interventions, are only successful in treating a subset of patients. Therapeutic angiogenesis is an investigational method that seeks to favorably impact tissue perfusion in CLI. HGF-STAT is a double-blind, parallel-group, placebo-controlled, dose-response study in 100 patients with unreconstructable CLI. Eligible subjects will be randomized 1:1:1:1 to receive saline placebo or one of three dose/regimens of HGF plasmid DNA. The selection of outcome measures, including the primary endpoint, and changes in transcutaneous oxygen pressure (TcPO2) from baseline to 3 months will be discussed. In conclusion, this study will help to determine whether therapeutic angiogenesis with HGF is a viable option in the treatment of patients with CLI.     

New therapeutic approach for impaired arteriogenesis in diabetic mouse hindlimb ischemia.

BACKGROUND: The combined treatment of sustained-release basic fibroblast growth factor (Sr-bFGF) and a 5-hydroxytryptamine(2A) blocker, sarpogrelate, was evaluated to see whether it reversed the impaired collateral circulation in diabetic (DM) mouse hindlimb ischemia. METHOD AND RESULTS: Diabetic and normal mice with ischemic hindlimb were randomly assigned to 1 of 5 experimental groups (no treatment, sarpogrelate 50 mg . kg(-1) . day(-1), 20 microg or 50 microg Sr-bFGF and a combined treatment of 20 microg Sr-bFGF and sarpogrelate), and treated for 4 weeks. Tissue blood perfusion (TBP), vascular density (angiogenesis) and the number of mature vessels (arteriogenesis) were checked by the use of standard methods. Although angiogenesis was comparable (161+/-14 vs 154+/-12 vessels/mm(2)), the laser Doppler perfusion image index (LDPII) (0.43+/-0.11 (SD) vs 0.63+/-0.08, p<0.05) and arteriogenesis (8+/-3 vs 12+/-4 vessels/mm(2), p<0.05) were significantly lower in DM mice than those in normal mice. The dose of Sr-bFGF for the sufficient number of mature vessels (>or=45 vessels/mm(2)) and LDPII (>or=0.9) was 20 microg for the normal mice, and 50 microg for the DM mice, which was reduced with the aid of sarpogrelate. Conclusions A combined therapy of Sr-bFGF and sarpogrelate is effective for neovascularization to reverse the impaired arteriogenesis and TBP in DM mice.     

2型糖尿病大鼠急性心肌缺血对心肌新生血管的影响

目的探讨糖尿病急性心肌缺血对心肌新生血管生成的影响及其机制。方法清洁级健康雄性8周龄sD大鼠52只,任意选取其中20只以高脂喂养联合小剂量链脲佐菌素建立糖尿病大鼠模型;以糖尿病建模成功的大鼠与16只正常大鼠以结扎冠状动脉前降支制作急性心肌梗死模型;另外16只大鼠只开胸不造模、不给药作为假手术组。心肌梗死造模术后2周,处死各组动物,取左心室梗死区及相邻区域心肌,采用免疫组化方法检测各组大鼠缺血周边区微血管密度（MVD）,Western blotting法检测血管内皮生长因子（VEGF）及其信号转导蛋白[磷酸化蛋白激酶B（p-Akt）、内皮型一氧化氮合酶（eNOS）、磷酸化eNOS（p-eNOS）]、内皮抑素蛋白的表达。组间数据比较采用单因素方差分析,样本均数间两两比较采用q检验,两组计量资料比较采用t检验。结果3组成活大鼠分别为：糖尿病心肌梗死组12只,非糖尿病心肌梗死组（对照组）13只,假手术组14只。与对照组相比,糖尿病组缺血心肌新生血管明显减少（19．7±3．8比14．2±3．6,q=2．98,P〈0．05）。糖尿病组、假手术组VEGF表达显著低于对照组（分别为0．89±0．12、0．65±0．23和1．53±0．20,F=6．52,P〈0．01）。糖尿病组和对照组p-Akt和eNOS蛋白表达差异无统计学意义（t值分别为3．02、2．78,P〉0．05）,但糖尿病组p-eNOS蛋白表达显著减少（0．49±0．09比1．16±0．12,t=5．68,P〈0．05）。糖尿病组内皮抑素表达显著高于对照组（4．6±0．6比2．3±0．4,t=8．63,P〈0．05）。结论糖尿病大鼠急性缺血心肌的新生血管生成低下,VEGF转导通路在多个水平上参与其中,并与内皮抑素共同作用。     

Combined treatment with sustained-release basic fibroblast growth factor and heparin enhances neovascularization in hypercholesterolemic mouse hindlimb ischemia.

BACKGROUND: Whether the combined treatment with sustained-release basic fibroblast growth factor (bFGF) and heparin enhances neovascularization in hypercholesterolemic mouse hindlimb ischemia was investigated. METHODS AND RESULTS: Wild-type C57BL/6 and low density lipoprotein receptor-deficient mice were assigned to 1 of the following 4 experimental groups and treated for 2 weeks after femoral artery extraction: group N, no treatment; group H, daily subcutaneous injection of heparin calcium; group F, single intramuscular injection of the sustained-release bFGF microspheres; and group FH, combined treatment with sustained-release bFGF and heparin. Among the wild-type mice at 4 weeks after femoral artery extraction, the laser Doppler perfusion image index (LDPII) in groups H, F, and FH was significantly higher than that in group N. The vascular density in group FH was the highest among the 4 groups. The maturation index in the 3 treated groups was significantly higher than that in group N. Among the hypercholesterolemic mice, the LDPII in group FH was significantly higher than that in the other 3 groups. The vascular density and maturation index in group FH were the highest among the 4 groups. CONCLUSIONS: Combined treatment with sustained-release bFGF and heparin enhanced neovascularization in the hypercholesterolemic hindlimb ischemia model.