Changes in the hydrodynamic resistance of collaterals after ligation of the femoral artery

After ligation of the femoral artery in 12 dogs anatomical changes of the collaterals 1 month after the operation are accompanied with 18-fold decrease of hydrodynamic resistance in them as compared to the initial one. The shifts observed in 96% are the results of dilatation occurring in the intramuscular interarterial anastomoses. Dilatation of the intramuscular arteries, situating more distally to the anastomosis zone and experiencing a decreased arterial pressure, is also observed, as it is in proximal vessels, situating in the zone of an increased blood pressure. Despite the essential shifts, the blood flow capacity of the collaterals even 1 month after the operation is still 500 times as small as that of the intact femoral artery.     

Identification of differentially expressed genes like cofilin2 in growing collateral arteries

Arteriogenesis, the growth of pre-existing collateral arteries, can be induced in rabbits by occlusion of the femoral artery. In order to analyze the differential gene expression in arteriogenesis, cDNA of collateral arteries 24h after femoral occlusion or sham operation was subjected to suppression subtractive hybridization (SSH). We demonstrated an upregulation of the U6 snRNA binding protein Lsm5, cytochrome b, an expressed sequence tag, and the actin-depolymerizing factor cofilin2 mRNA in collateral arteries 24h after femoral ligation. For cofilin2, we also detected an increase in the protein level and a localization predominantly in smooth muscle cells of collaterals. Simultaneously with the upregulation of cofilin2 we found a downregulation of the alpha-smooth muscle actin mRNA in growing collateral arteries. In summary, our data showed an augmented expression level of genes contributing to different fundamental processes of arteriogenesis.     

Femoral artery occlusion augments TRPV1-mediated sympathetic responsiveness

Muscle metabolic by-products stimulate thin fiber muscle afferent nerves and evoke reflex increases in blood pressure and sympathetic nerve activity. Previous studies reported that chemically sensitive transient receptor potential vanilloid type 1 (TRPV1) channels present on sensory muscle afferent neurons have an important impact on sympathetically mediated cardiovascular responses. The reflex-mediated reduction in blood flow to skeletal muscle leads to limited exercise capacity in patients with peripheral arterial occlusive disease. Thus, in this study, we tested the hypothesis that the expression of enhanced TRPV1 receptor and its responsiveness in primary afferent neurons innervating muscles initiate exaggerated reflex sympathetic responses after vascular insufficiency to the muscle. Muscle vascular insufficiency was induced by the femoral artery ligation in rats for 24 h. Our data show that 1) the ligation surgery leads to the upregulation of TRPV1 expression in the dorsal root ganglion; 2) the magnitude of the dorsal root ganglion neuron TRPV1 response induced by capsaicin is greater in vascular insufficiency (4.0 +/- 0.31 nA, P < 0.05 vs. sham-operated control) than that in sham-operated control (2.9 +/- 0.23 nA); and 3) renal sympathetic nerve activity and mean arterial pressure responses to capsaicin (0.5 microg/kg body wt) are also enhanced by vascular insufficiency (54 +/- 11%, 9 +/- 2 mmHg in sham-operated controls vs. 98 +/- 13%, 33 +/- 5 mmHg after vascular insufficiency, P < 0.05). In conclusion, sympathetic nerve responses to the activation of metabolite-sensitive TRPV1 receptors are augmented in rats with the femoral artery occlusion compared with sham-operated control animals, due to alterations in the expression of TRPV1 receptor and its responsiveness in sensory neurons.     

营养动脉结扎和液氮冷冻对股骨头内局部氧分压的影响

目的：观察营养动脉结扎和液氮冷冻对股骨头内局部氧分压的影响,为后期制作极度低氧股骨头缺血坏死模型打下基础。方法：9只雄性大耳白兔随机平均分为对照组、液氮冷冻组和动脉结扎＋液氮冷冻组,对照组动物不做任何处理,液氮冷冻组动物行股骨头液氮冷冻使其发生缺血坏死,动脉结扎＋液氮冷冻组动物先结扎旋股内外侧动脉,再对股骨头进行液氮冷冻。造模后立刻活体观察股骨头内氧分压变化。结果：液氮冷冻组股骨头内氧分压较对照组下降一半左右,2组比较有显著性差异（P〈0．05）;动脉结扎＋液氮冷冻组动物股骨头内氧分压进一步下降到对照组的1／8左右,与其他2组相比有显著性差异（P〈0．05）。结论：液氮冷冻和旋股内、外侧动脉结扎均可明显降低股骨头内氧分压,两者合用具有重叠效应,可共同促使股骨头内氧分压下降。     

DR和CT对人鼠股动脉结扎诱导的侧支血管显像能力的对比研究

目的：探讨数字化X线摄影（digital radiography,DR）和电子计算机断层扫描成像（Computed Tomography,CT）对大鼠股动脉结扎诱导的侧支血管显像能力的对比,方法：28只健康SD大鼠,右侧行股动脉结扎,存活1w,采用明胶一四氧化三铅混合物行血管造影观察大鼠后肢侧支血管形成情况并分别采用DR及CT进行摄片,观察DR及cT对侧支血管的显像能力结果：DR及CT均显示在股动脉结扎处血管连续性中断,并出现不同数量的侧支血管;DR对新生侧支血管的显影分辨率和清晰度明显高于CT,且远端股动脉显影较CT清晰,CT横断面成像具有放射状伪影结论：经DR拍摄的侧支血管的显像能力较CT清晰,利用DR可以直观清晰的将其显像     

Bronchial collateral vessel micropuncture pressure in postobstructive pulmonary vasculopathy.

Postobstructive pulmonary vasculopathy, produced by chronic ligation of one pulmonary artery, markedly increases bronchial blood flow. Previously, using arterial and venous occlusion, we determined that bronchial collaterals enter the pulmonary circuit at the distal end of the arterial segment. In this study, we tested the hypothesis that pressure in bronchial collaterals (Pbr) closely approximates that at the downstream end of the arterial segment (Pao). We pump perfused [111 +/- 10 (SE) ml/min] left lower lobes of seven open-chest live dogs 3-15 mo after ligation of the left main pulmonary artery. Bronchial blood flow was 122 +/- 16 ml/min. We measured pulmonary arterial and venous pressures and, by arterial and venous occlusion, respectively, Pao and the pressure at the upstream end of the venous segment (Pvo). Pbr was obtained by micropuncture of 34 pleural surface bronchial vessels 201 +/- 16 microns in diameter. We found that Pbr (14.4 +/- 1.0 mmHg) was similar to Pao (15.0 +/- 0.8 mmHg) but differed significantly (P < 0.01) from Pvo (11.3 +/- 0.5 mmHg). In addition, Pbr was independent of systemic arterial pressure and bronchial vessel diameter. Light and electron microscopy revealed that, in the lobes with the ligated pulmonary artery, the new bronchial collaterals entered the thickened pleura from the parenchyma via either bronchovascular bundles or interlobular septa and had sparsely muscularized walls. We conclude that, in postobstructive pulmonary vasculopathy, bronchial collateral pressure measured by micropuncture is very close to the pressure in precapillary pulmonary arteries and that most of the pressure drop in the bronchial collaterals occurs in vessels > 350 microns in diameter.     

Catecholamines augment collateral vessel growth and angiogenesis in hindlimb ischemia

Catecholamine stimulation of alpha1-adrenoceptors exerts growth factor-like activity, mediated by generation of reactive oxygen species, on arterial smooth muscle cells and adventitial fibroblasts and contributes to hypertrophy and hyperplasia in models of vascular injury and disease. Adrenergic trophic activity also contributes to flow-mediated positive arterial remodeling by augmenting proliferation and leukocyte accumulation. To further examine this concept, we studied whether catecholamines contribute to collateral growth and angiogenesis in hindlimb insufficiency. Support for this hypothesis includes the above-mentioned studies, evidence that ischemia augments norepinephrine release from sympathetic nerves, and proposed involvement of reactive oxygen species in angiogenesis and collateral growth. Mice deficient in catecholamine synthesis [by gene deletion of dopamine beta-hydroxylase (DBH-/-)] were studied. At 3 wk after femoral artery ligation, increases in adductor muscle perfusion were similar in DBH-/- and wild-type mice, whereas recovery of plantar perfusion and calf microsphere flow were attenuated, although not significantly. Preexisting collaterals in adductor of wild-type mice showed increases in lumen diameter (60%) and medial and adventitial thickness (57 and 119%, P < 0.05 here and below). Lumen diameter increased similarly in DBH-/- mice (52%); however, increases in medial and adventitial thicknesses were reduced (30 and 65%). Leukocyte accumulation in the adventitia/periadventitia of collaterals was 39% less in DBH-/- mice. Increased density of alpha-smooth muscle actin-positive vessels in wild-type adductor (45%) was inhibited in DBH-/- mice (2%). Although both groups experienced similar atrophy in the gastrocnemius (approximately 22%), the increase in capillary-to-muscle fiber ratio in wild-type mice (21%) was inhibited in DBH-/- mice (7%). These data suggest that catecholamines may contribute to collateral growth and angiogenesis in tissue ischemia.     

The role of the pericytes of the adventitial microcirculation in the arterial intimal thickening

Segments of rat femoral arteries, with one collateral each, occluded between ligatures and dissected from surrounding tissue, developed intimal thickening, with or without ligation of their collaterals. Numerous newly-formed capillaries from the surrounding arterial microcirculation growing into the adventitia, tunica media and intimal thickening were demonstrated by means of serial longitudinal sections, predominantly in the ostium of the collateral. When the ligatures were applied without damaging the microcirculation surrounding the artery and the normal continuity of the adventitial vessels was unchanged, earlier presence of intimal thickening was observed. When the fibrous layers of the adventitia were removed at the moment of the arterial ligation, the continuity between newly-formed vessels of the neoadventitia and those growing into the media and neointima was much more evident. It was then noted that the pericytes constituted a major component of the intimal thickening. The introduction of contrast material in microcirculation confirmed the connections between newly-formed adventitial and intimal vessels. At the beginning of the experiment, autoradiographic studies showed an increased DNA synthesis in the cells of preformed postcapillary venules and capillaries of surrounding arterial microcirculation and later in those of the newly-formed vessels growing into the arterial wall. These results indicate that newly-formed capillaries derived from surrounding arterial microcirculation penetrate the wall of the occluded arterial segments and contribute to the intimal thickening formation. It is likely that the pericytes and endothelial cells (EC) of these ingrowing vessels are sources of myointimal cells at the intimal thickening and of endothelium at the luminal surface, respectively.     

Glyoxalase-1 overexpression partially prevents diabetes-induced impaired arteriogenesis in a rat hindlimb ligation model

We hypothesize that diabetes-induced impaired collateral formation after a hindlimb ligation in rats is in part caused by intracellular glycation and that overexpression of glyoxalase-I (GLO-I), i.e. the major detoxifying enzyme for advanced-glycation-endproduct (AGE) precursors, can prevent this. Wild-type and GLO-I transgenic rats with or without diabetes (induced by 55 mg/kg streptozotocin) were subjected to ligation of the right femoral artery. Laser Doppler perfusion imaging showed a significantly decreased blood perfusion recovery after 6 days in the diabetic animals compared with control animals, without any effect of Glo1 overexpression. In vivo time-of-flight magnetic resonance angiography at 7-Tesla showed a significant decrease in the number and volume of collaterals in the wild-type diabetic animals compared with the control animals. Glo1 overexpression partially prevented this decrease in the diabetic animals. Diabetes-induced impairment of arteriogenic adaptation can be partially rescued by overexpressing of GLO-I, indicating a role of AGEs in diabetes-induced impaired collateral formation.     

Involvement of neuronal NO synthase in collateral artery growth

To evaluate the role of neuronal nitric oxides synthase (nNOS) in collateral artery growth (arteriogenesis), we analyzed the expression pattern of nNOS at distinct time points on RNA and protein levels in a rabbit and a murine model of peripheral arteriogenesis. In the rabbit model, Northern blot analyses revealed a significant upregulation of nNOS at 6 h (1.6-fold), 12 h (2.2-fold) and 24 h (2.0-fold) after induction of arteriogenesis via femoral artery ligation, when compared to the sham operated side. In mice, an upregulation of nNOS was also detected using Northern blot (at 6 h, 12 h) and qRT-PCR (12 h: 2.4-fold). On the protein level, nNOS was found to be upregulated 24 h after femoral artery ligation. Immunohistochemical staining showed that nNOS was localized in endothelial and smooth muscle cells of collateral arteries, as well as in skeletal muscle and nerves. In summary, our data provide evidence that nNOS is not constitutively expressed, but is induced during arteriogenesis, playing a role in supplying reactive oxygen species such as H2O2 and low levels of NO.     

Vascular ligation response is independent of p107: stressing the role of the related p130

Recent studies have revealed the role of the pRb family members pRb and p130 in the response to vascular injury. We evaluated the arterial injury response in the absence of p107, a protein that shares a high degree of homology with the injury-controlling p130. Carotid artery ligation and perivascular electric injury of the femoral artery were applied to p107 knockout (p107 -/-) mice, and morphometric analysis was performed 3 wk after ligation and electric injury. Arterial vessels of p107 -/- mice were indistinguishable from controls under basal conditions. After carotid artery ligation the p107 -/- mice (n = 7) did not display an enhanced ligation response compared with controls (n = 9), which was studied over a distance of approximately 450 microm proximal and approximately 200 microm distal from the ligation site, with regard to vessel wall area, neointima area, and lumen area. Corresponding with this, morphometric data obtained from the perivascular electric injury of the femoral artery confirmed the lack of enhanced ligation and injury response in the absence of p107. We conclude that the pRb family member p107 is not a key regulator in vascular injury response. These data, in conjunction with previously reported results, indicate that the control of vascular injury response is not a redundant feature of pRb proteins but primarily specific for p130. Further studies on functional domains of p130 and p107 will help to resolve the pathways in vascular injury response.     

MR angiography of collateral arteries in a hind limb ischemia model: comparison between blood pool agent Gadomer and small contrast agent Gd-DTPA

The objective of this study was to compare the blood pool agent Gadomer with a small contrast agent for the visualization of ultra-small, collateral arteries (diameter<1 mm) with high resolution steady-state MR angiography (SS-MRA) in a rabbit hind limb ischemia model. Ten rabbits underwent unilateral femoral artery ligation. On days 14 and 21, high resolution SS-MRA (voxel size 0.49×0.49×0.50 mm³) was performed on a 3 Tesla clinical system after administration of either Gadomer (dose: 0.10 mmol/kg) or a small contrast agent (gadopentetate dimeglumine (Gd-DTPA), dose: 0.20 mmol/kg). All animals received both contrast agents on separate days. Selective intra-arterial x-ray angiograms (XRAs) were obtained in the ligated limb as a reference. The number of collaterals was counted by two independent observers. Image quality was evaluated with the contrast-to-noise ratio (CNR) in the femoral artery and collateral arteries. CNR for Gadomer was higher in both the femoral artery (Gadomer: 73±5 (mean ± SE); Gd-DTPA: 40±3; p<0.01) and collateral arteries (Gadomer: 18±4; Gd-DTPA: 9±1; p = 0.04). Neither day of acquisition nor contrast agent used influenced the number of identified collateral arteries (p = 0.30 and p = 0.14, respectively). An average of 4.5±1.0 (day 14, mean ± SD) and 5.3±1.2 (day 21) collaterals was found, which was comparable to XRA (5.6±1.7, averaged over days 14 and 21; p>0.10). Inter-observer variation was 24% and 18% for Gadomer and Gd-DTPA, respectively. In conclusion, blood pool agent Gadomer improved vessel conspicuity compared to Gd-DTPA. Steady-state MRA can be considered as an excellent non-invasive alternative to intra-arterial XRA for the visualization of ultra-small collateral arteries.     

宫颈多重缝扎术联合子宫动脉上行支结扎治疗难治性出血的效果

目的:探究宫颈多重缝扎术联合子宫动脉上行支结扎治疗难治性出血的效果及安全性。方法:选取2014年9月～2018年10月我院收治的剖宫产术后难治性出血患者70例进行回顾性分析,根据术中止血方式不同分为两组,对照组(35例)患者行宫腔纱布填塞联合双侧子宫动脉上行支结扎术,观察组(35例)患者行宫颈多重缝扎术联合双侧子宫动脉上行支结扎术。比较两组患者的止血效果、术中和术后出血量、术后恢复情况及并发症的发生情况。结果:治疗后,观察组患者的止血有效率显著高于对照组(P0.05);观察组患者术中和术后2 h、12 h和24 h的出血量显著低于对照组(P0.05);两组患者月经量和子宫复旧情况相比无统计学差异(P0.05),观察组患者住院时间、恶露持续时间、月经恢复时间均显著短于对照组(P0.05);两组患者不良反应发生率相比无统计学差异(P0.05)。结论:宫颈多重缝扎术联合子宫动脉上行支结扎可显著降低术中和术后出血量,止血效果较好,可促进患者术后恢复,且不增加并发症的发生率。     

Changes in hemodynamics of tibial diaphysis in case of blood flow disorder in superficial femoral artery

Changes in tibial hemodynamics have been studied experimentally after applying a clamp (n=41) and resection of superficial femoral artery (n=22) in 63 adult dogs. It has been revealed with the help ofrheovasography that, in case of blood flow disorders in the superficial femoral artery, anastomoses with deep femoral artery branches contribute to maintenance of blood circulation in tibia, and in this connection the parameters of tibial blood flow may significantly differe from those of circulation in the leg soft tissues. Preservation of intraosseous pressure all along tibial diaphyseal cavity demonstrates a possibility of using its driving force to compensate for the circulatory insufficiency in the leg soft tissues and, moreover, in that part of the bone the environment of which in ischemia is involved.     

The role of the renin-angiotensin system and oxidative stress in spontaneously hypertensive rat mesenteric collateral growth impairment

Recent clinical and animal studies have shown that collateral artery growth is impaired in the presence of vascular risk factors, including hypertension. Available evidence suggests that angiotensin-converting enzyme inhibitors (ACEI) promote collateral growth in both hypertensive humans and animals; however, the specific mechanisms are not established. This study evaluated the hypothesis that collateral growth impairment in hypertension is mediated by excess superoxide produced by NAD(P)H oxidase in response to stimulation of the ANG II type 1 receptor. After ileal artery ligation, mesenteric collateral growth did not occur in untreated, young, spontaneously hypertensive rats. Significant luminal expansion occurred in collaterals of spontaneously hypertensive rats treated with the superoxide dismutase mimetic tempol, the NAD(P)H oxidase inhibitor apocynin, and the ACEI captopril, but not ANG II type 1 (losartan) or type 2 (PD-123319) receptor blockers. The ACEI enalapril produced equivalent reduction of arterial pressure as captopril but did not promote luminal expansion. This suggests the effects of captopril on collateral growth might result from its antioxidant properties. RT-PCR demonstrated that ANG II type 1 receptor and angiotensinogen expression was reduced in collaterals of untreated rats. This local suppression of the renin angiotensin system provides a potential explanation for the lack of effect of enalapril and losartan on collateral growth. The results demonstrate the capability of antioxidant therapies, including captopril, to reverse impaired collateral artery growth and the novel finding that components of the local renin angiotensin system are naturally suppressed in collaterals.     

Tissue engineering skin flaps: which vascular carrier, arteriovenous shunt loop or arteriovenous bundle, has more potential for angiogenesis and tissue generation?

This study was designed to clarify which vascular carrier, the arteriovenous shunt loop or the arteriovenous bundle, has more potential as a vascular carrier for an artificial skin flap in rats. An arteriovenous shunt loop was constructed between the femoral artery and vein using an interpositional artery (group I) or vein (group II) graft. For arteriovenous bundle groups, the femoral artery and vein were used and subdivided into two groups: distal ligation type (group III) and flow-through type (group IV). The vascular pedicle was wrapped with an artificial dermis and implanted beneath the inguinal skin for 4 weeks. For the control group, a folded sheet of artificial dermis without any vascular carrier was embedded. In experiment 1, the volumes of generated tissue within the artificial dermis were measured in the experimental and control groups (n = 5 in each group). In experiment 2, the origin of new blood vessels sprouting from the arteriovenous shunt loop and arteriovenous bundle were evaluated histologically. The volume of generated tissue in the shunt groups was significantly greater than that in the bundle groups (p < 0.01). However, the bundle groups also showed a great potential for producing new tissue. Serial histological studies showed that new capillaries were derived not only from the vasa vasorum of the femoral vessels but directly from the femoral vein in both the shunt and the bundle groups. This "sprouting" was extensively exhibited in the group III. Although the arteriovenous shunt loop showed a greater potential for producing new tissue and capillaries, the distal ligation type of bundle was thought to be an effective and practical vascular carrier for producing a tissue-engineered skin flap.     

Blood monocyte concentration is critical for enhancement of collateral artery growth

Arteriogenesis has been associated with the presence of monocytes/macrophages within the collateral vessel wall. We tested the hypothesis that arteriogenesis is functionally linked to the concentration of circulating blood monocytes. Monocyte concentrations in peripheral blood were manipulated by single injections of the antimetabolite 5-fluorouracil (5-FU), resulting in a marked rebound effect in New Zealand White rabbits. Collateral artery growth was assessed by the use of a model of acute femoral artery ligation. Seven days after ligation, collateral conductance and the number of visible collateral arteries were increased in the rebound group. This increase was accompanied by an increased monocyte accumulation as demonstrated by immunohistology in the thigh 3 days after surgery. In a second animal model (129S2/SvHsd mice), 5-FU treatment caused a remarkable decrease in blood monocyte numbers at day 4, followed by a rebound effect at day 12. Foot blood flow, assessed by laser-Doppler imaging before and at various time points after surgery, increased from day 7 through day 21 in mice from the rebound group. In contrast, ligation during the phase of monocyte depletion resulted in a reduction of blood flow reconstitution. This inhibition could be reversed by an injection of isolated monocytes. In conclusion, we have demonstrated a functional link between the monocyte concentration in the peripheral blood and the enhancement of arteriogenesis.     

An investigation of arterial insufficiency in rat hindlimb. A combined 31P-n.m.r. and bloodflow study.

A small animal model of arterial insufficiency is presented which involves unilateral femoral artery ligation and section. Invoked alterations in metabolism and perfusion of the affected muscle mass have been investigated 12 h, 4, 7 and 14 days post-ligation by 31P-n.m.r. and microsphere infusion, both at rest and during isometric muscle contraction at 1 Hz. At rest, the concentration of phosphocreatine was similar to the mean control value (36.0 +/- 1.0 mM) from 4 days post-ligation, but was significantly lower at 12 h (28.5 +/- 3.6 mM). Inorganic phosphate concentrations were significantly elevated for 7 days post-ligation. No significant differences were noted in intramuscular pH. Upon stimulation of the affected muscle mass, a time-dependent improvement in phosphocreatine utilization was observed such that 14 days post-ligation phosphocreatine utilization was not significantly different from mean control values. A similar amelioration was noted for the contraction-induced fall in intramuscular pH. At rest, no significant differences in bloodflow to the muscles of the ligated limb compared with the unaffected contralateral limb were observed. However, isometric contraction of the affected muscle mass resulted in a markedly reduced hyperaemic response 12 h post-ligation. Thereafter, a time-dependent improvement in tissue perfusion during stimulation was observed which paralleled the improvements in phosphocreatine utilization and intramuscular pH changes. The results presented are discussed with respect to the interrelationship between oxygen delivery, high energy phosphate utilization and force maintenance.     

Whole bone marrow transplantation induces angiogenesis following acute ischemia

Several recent studies have shown that purified subsets of bone marrow (BM) cells can differentiate into endothelial, cardiac, and other cell types. During coronary artery bypass graft (CABG) surgery, sternal BM is routinely discarded. To determine if this BM can be used to induce angiogenesis and augment perfusion of the cardiac tissues after CABG, a simplified and more practical approach of using whole BM extract was tried to determine whether it would be adequate for the induction of BM-derived angiogenesis in experimental acute limb ischemia. BM was prepared from FVB/N-TgN(TIE2 lacZ)182 Sato (Tie2-lacZ) or B6.129S7-Gtrosa 26 (Rosa 26) mice that express beta-galactosidase (beta-gal) in endothelial cells and most adult tissues, respectively. Acute limb ischemia was induced in either C57BL6/J or FVB/N mice by double ligation of the left femoral artery just distal to the profunda femoral artery branch. Occlusion of the ligated artery was verified by angiography. The study group (n = 31) received an intramuscular injection of 50 micro l containing 1 x 10(6) BM cells, 5 mm proximal to the site of ligation. Experimental controls (n = 21) had an intramuscular injection of 50 micro l of saline. Angiogenesis in the mice was assessed by histological analysis. BM-derived beta-gal(+) cells were observed to aggregate in the vicinity of the ligated artery and not in the injected musculature BM-derived endothelial cells were incorporated within capillaries and small size blood vessels near the site of ligation. Generation of BM-derived blood vessels in experimental acute limb ischemia does not require purification of specific subset of cells. The elimination of cell purification will enhance the ease of using BM transplantation in generating blood vessels.     

Activation of the integrins α5β1 and αvβ3 and focal adhesion kinase (FAK) during arteriogenesis

Migration and proliferation of smooth muscle cells (SMC) are important events during arteriogenesis, but the underlying mechanism is still only partially understood. The present study investigates the expression of integrins alpha 5 beta 1 and v beta 3 as well as focal adhesion kinase (FAK) and phosphorylated FAK (pY397), key mediators for cell migration and proliferation, in collateral vessels (CV) in rabbit hind limbs induced by femoral ligation or an arteriovenous (AV) shunt created between the distal femoral artery stump and the accompanying femoral vein by confocal immunofluorescence. In addition, the effect of the extracellular matrix components fibronectin (FN), laminin (LN), and Matrigel on expression of these focal adhesion molecules proliferation was studied in cultured SMCs. We found that: (1) in normal vessels (NV), both integrins alpha 5 beta 1 and alpha v beta 3 were mainly expressed in endothelial cells, very weak in smooth muscle cells (SMC); (2) in CVs, both alpha 5 beta 1 and alpha v beta 3 were significantly upregulated (P < 0.05); this was more evident in the shunt-side CVs, 1.5 and 1.3 times higher than that in the ligation side, respectively; (3) FAK and FAK(py397) were expressed in NVs and CVs in a similar profile as was alpha 5 beta 1 and alpha v beta 3; (4) in vitro SMCs cultured on fibronectin (overexpressed in collaterals) expressed higher levels of FAK, FAK (pY397), alpha 5 beta 1, and alpha v beta 3 than on laminin, whereas SMCs growing inside Matrigel expressed little of these proteins and showed no proliferation. In conclusion, our data demonstrate for the first time that the integrin-FAK signaling axis is activated in collateral vessels and that altered expression of FN and LN may play a crucial role in mediating the integrin-FAK signaling pathway activation. These findings explain a large part of the positive remodeling that collateral vessels undergo under the influence of high fluid shear stress.