Synectin/syndecan-4 regulate coronary arteriolar growth during development.

Syndecan-4 and its cytoplasmic binding partner, synectin, are known to play a role in FGF-2 signaling and vascular growth. To determine their roles in coronary artery/arteriolar formation and growth, we compared syndecan-4 and synectin null mice with their wild-type counterparts. Image analysis of arterioles visualized by smooth muscle alpha-actin immunostaining revealed that synectin (-/-) mice had lower arteriolar length and volume densities than wild-type mice. As shown by electron microscopic analysis, arterioles from the two did not differ in morphology, including their endothelial cell junctions, and the organization and distribution of smooth muscle. Using micro-computer tomography, we found that the size and branching patterns of coronary arteries (diameters > 50 microm) were similar for the two groups, a finding that indicates that the growth of arteries is not influenced by a loss of synectin. Syndecan-4 null male mice also had lower arteriolar length densities than their gender wild-type controls. However, female syndecan-4 null mice were characterized by higher arteriolar length and volume densities than their gender-matched wild-type controls. Thus, we conclude that both synectin and syndecan-4 play a role in arteriolar development, a finding that is consistent with previous evidence that FGF-2 plays a role in coronary arterial growth. Moreover, our data reveal that gender influences the arteriolar growth response to syndecan-4 but not to synectin.     

Syndecan-4 proteoliposomes enhance fibroblast growth factor-2 (FGF-2)-induced proliferation, migration, and neovascularization of ischemic muscle

Ischemia of the myocardium and lower limbs is a common consequence of arterial disease and a major source of morbidity and mortality in modernized countries. Inducing neovascularization for the treatment of ischemia is an appealing therapeutic strategy for patients for whom traditional treatment modalities cannot be performed or are ineffective. In the past, the stimulation of blood vessel growth was pursued using direct delivery of growth factors, angiogenic gene therapy, or cellular therapy. Although therapeutic angiogenesis holds great promise for treating patients with ischemia, current methods have not found success in clinical trials. Fibroblast growth factor-2 (FGF-2) was one of the first growth factors to be tested for use in therapeutic angiogenesis. Here, we present a method for improving the biological activity of FGF-2 by codelivering the growth factor with a liposomally embedded coreceptor, syndecan-4. This technique was shown to increase FGF-2 cellular signaling, uptake, and nuclear localization in comparison with FGF-2 alone. Delivery of syndecan-4 proteoliposomes also increased endothelial proliferation, migration, and angiogenic tube formation in response to FGF-2. Using an animal model of limb ischemia, syndecan-4 proteoliposomes markedly improved the neovascularization following femoral artery ligation and recovery of perfusion of the ischemic limb. Taken together, these results support liposomal delivery of syndecan-4 as an effective means to improving the potential of using growth factors to achieve therapeutic neovascularization of ischemic tissue.     

猪后肢动脉生成过程中血管内皮细胞eNOS的表达

目的:研究猪后肢动脉生成过程中内皮型一氧化氮合酶(eNOS)表达及其活性.方法:猪股动脉行单侧结扎术,另一侧行假手术,两周后处死动物.应用免疫荧光组织化学技术检测侧支血管中eNOS表达,用抗磷酸化的eNOS抗体(P-eNOS)检测eNOS的活性.用Leica激光共聚焦显微镜观察并拍照,图片用Silicon Graphics Octane进行处理.结果:在正常小动脉血管中eNOS的表达非常低,呈弱阳性;在生长的侧支血管中eNOS的表达显著上调,呈强阳性.在正常血管和生长的侧支血管中eNOS的表达都定位于内皮细胞.在生长的侧支血管中,P-eNOS表达水平非常高,免疫双重染色证实eNOS和P-eNOS的表达共同定位于内皮细胞.结论:侧支血管发育过程中,eNOS的表达被上调,并具有生物活性,高水平和具有活性的eNOS可能通过调节内皮细胞的增殖、移动及对炎症的控制,从而对侧支血管的生长发挥重要作用.     

等长收缩训练促进犬慢性心肌缺血侧支动脉生成的机制

目的:观察等长收缩训练对慢性心肌缺血犬血压、血管壁剪切力及血流灌注的影响,探索等长收缩训练促进缺血心肌侧支动脉生成的机制。方法:制备犬慢性冠状动脉狭窄模型,随机分为假手术组,单纯心肌缺血组,被动等长收缩训练组。实验终点时,所有犬在DSA检查后检测血管壁剪切力(wall shear stress,WSS)及记录收缩压、舒张压的数值,记为基础值;PIE组除了测定基础值外,还使用电刺激诱发IE运动,测定IE开始前30s、开始后30s及停止后30s的收缩压、舒张压及WSS的值。检测缺血心肌冠状动脉侧支循环血流量(collateral blood flow,CBF)、单核细胞(mononuclear phagocyte,MP)及平滑肌细胞(smooth muscle cell,SMC)的数量。结果:6周IE后:(1)WSS:实验终点经过DSA造影发现,PIE组WSS的基础数值最高(P0.05)。PIE组实验犬在DSA造影过程中行IE运动不同时间点的WSS值相比较,IE开始后30s的WSS值最高(P0.05)。(2)血压:实验终点时基础血压值相比较,SO组的SBP值最低(P0.05);PIE组的DBP值最高(P0.05)。PIE组实验犬在DSA造影过程中IE运动不同时间点的SBP、DBP相比较,IE开始后30s的SBP值最高(P0.05)。(3)心肌局部血流量及细胞学检测:PIE组的CBF、平滑肌数量、单核细胞数量最高(P0.05)。(6)相关性分析发现:WSS与CBF呈中度正相关;WSS与SMC呈高度正相关;WSS与MP呈高度正相关。实验终点时PIE组犬不同时间点的WSS与SBP、DBP的相关性分析发现,WSS与SBP呈高度正相关;WSS与DBP呈中度正相关。结论:等长收缩训练可以通过升高血压,提高血管壁剪切力水平从而促进缺血心肌血流灌注。     

Pharmacological revascularisation in coronary and peripheral vascular disease

Therapeutic angiogenesis is a novel approach to the treatment of ischaemic or occlusive coronary and peripheral vascular disease. The therapeutic concept is based on the restoration of distal blood flow by the enlargement of existing vessels and tissue perfusion by the induction of new capillaries. Initial studies have focused on the direct application of endothelial growth factors, vascular endothelial growth factor and fibroblast growth factor, or the delivery of genes using either a plasmid or adenoviral vector. Recently, new angiogenic agents such as hypoxia inducible factor-1α, fibroblast growth factor-4, Del-1 and hepatocyte growth factor have entered clinical testing. Moreover, stem-cell therapy or factors mobilising bone marrow progenitor cells have provided evidence for a new avenue for therapeutic angiogenesis. Numerous preclinical studies and several initial clinical trials have provided encouraging data in support of the feasibility of promoting biological revascularisation by the administration of angiogenic factors or cells.     

Formation of the coronary vasculature during development

The formation of the coronary vasculature involves a series of carefully regulated temporal events that include vasculogenesis, angiogenesis, arteriogenesis and remodeling. This review explores these events, which begin with the migration of proepicardial cells to form the epicardium and end with postnatal growth and remodeling. Coronary endothelial, smooth muscle and fibroblast cells differentiate via epithelial–mesenchymal transformation; these cells delaminate from the epicardium. Following the formation of a tubular network by endothelial cells, an aortic ring of endothelial cells penetrates the aorta at the left and right aortic cusps to form the two ostia. Smooth muscle cell recruitment occurs rapidly and the coronary artery network begins forming as blood flow is established. Recent studies have identified a number of regulatory molecules that play key roles in epicardial formation and the transformation of its component cells into mesenchyme. Moreover, we are finally gaining some understanding regarding the interplay of angiogenic growth factors in the complex process of establishing the coronary vascular tree. Understanding coronary embryogenesis is important for interventions regarding adult cardiovascular diseases as well as those necessary to correct congenital defects.     

Angiogenesis and microvascular remodeling: a brief history and future roadmap

Angiogenesis and vessel remodeling determine the integrative control of the architectural structure and functional behaviors of the microcirculation over the lifetime of an organism. Vascular remodeling is the basis of promising therapeutic strategies, including vascularization of ischemic organs. The history of angiogenesis research is long-more than 250 years-and the Microcirculatory Society has been the birthplace of numerous techniques, assays, and scientific concepts that have stimulated massive research endeavors in the pharmaceutical and medical arena. At present, angiogenesis isa dynamic field in which the molecular genetic and proteomic components of the process are still being identified, while integrative systems approaches are once again being recognized as essential to understand microvascular assembly in vivo across multiple scales from cells to whole vessel networks. A short history of people and ideas in this field is presented, followed by discussion of emerging directions receiving intense attention today and major questions that remain unanswered. The primary conclusion is that the need for scientists trained in the integrative approaches nurtured by the Microcirculatory Society over the past 50 years has never been greater, as it is clear that a complete mechanistic understanding of vessel adaptation (based on genomic and proteomic supporting casts) will now require deeper studies of angiogenesis and microvascular remodeling in the exquisite complexity of the native microenvironment-the microcirculation.     

Impact of Arteriogenesis in Plastic Surgery: Choke Vessel Growth Proceeds via Arteriogenic Mechanisms in the Rat Dorsal Island Skin Flap

Objective: We examined the molecular mediators of postoperative choke‐vessel growth. Our focus was the possible overlap between choke‐vessel growth and arteriogenesis. Methods: A rat perforator flap model, encompassing four vascular territories, was used. Flaps were surgically elevated, re‐inset, and allowed to survive for one, three, five, or seven days. Tissue samples for Western and histological analyses were collected from the choke zone along the dorsal midline. Tissue from territories linked by the choke zone was analyzed to distinguish between global and local effects. The proteins examined included CD11b, ICAM‐1, and MMP‐2, three markers associated with arteriogenesis, as well as Hsp70 and vascular endothelial growth factor, markers of physiological stress and hypoxia/ischemia. Results: Arteriogenesis markers, as shown by Western analysis, increased at three and five days after flap elevation, and the increase was localized by immunohistochemistry to the growing arteries and veins. The marker of physiological stress increased at Days 5 and 7. The hypoxia‐ischemia marker did not increase in the choke zone. Conclusions: The growth of choke arteries and veins proceeds in an inflammatory environment that resembles arteriogenesis. Ischemia did not appear to play a role in choke‐vessel changes.