Total Vascular Area Research Articles

Granulated metrial gland cells in the murine uterus: localization, kinetics, and the functional role in angiogenesis during pregnancy.

Granulated metrial gland (GMG) cells are a major immune cell population in the murine pregnant uterus, and contribute to the maintenance of pregnancy by functioning as uterus-specific natural killer (NK) cells. In order to reveal their kinetics, activation, and functional roles in pregnancy, we conducted quantitative and immunohistochemical analyses in normal and immuno-modulator-treated mice. Under a light microscope, GMG cells were identified by red cytoplasmic granules in periodic-acid-Schiff (PAS)-stained sections. They progressively increased in number and size with the peak at day 12-14 of pregnancy in the decidua and metrial gland. New vessel formation was most prominent around day 8, and the total vascular area reached the peak at day 13. GMG cells were often located near the blood vessels, and expressed vascular endothelial growth factor (VEGF), suggesting their possible inducing role in angiogenesis during the development of decidua/metrial gland. While blood vessels in the non-pregnant uterus were negative for vascular cell adhesion molecule (VCAM)-1, those in the pregnant one were positive. Treatment with neutralizing antibody against VCAM-1, however, did not decrease the number of GMG cells. On the other hand, mitosis of GMG cells was frequently observed. These data suggest that the increment of GMG cells during pregnancy may largely result from local proliferation in the uterus rather than an increased influx of precursor cells. Although we attempted to induce in vivo activation of GMG cells by administration of interleukin-12 (IL-12) or alpha-galactosylceramide, a potent activator for natural killer-T (NK-T) cells, the number of GMG cells did not appreciably increase. The present study has demonstrated that GMG cells locally proliferate in the pregnant uterus, not being related to VCAM-1 expression by the uterine vasculature or systemic activation of NK cells and NK-T cells, and seem to be involved in angiogenesis in the pregnant uterus through VEGF production.

Bimodal Distribution of the Blood Supply to Lower Abdominal Fat: Histological Study of the Microcirculation of the Lower Abdominal Wall

Fat necrosis is a common postoperative complication in transverse rectus abdominis muscle flap breast reconstruction. A histological quantification of the blood supply to the lower abdominal fat was undertaken to define this problem further. One hundred eighty sections, 1.5 cm(2) in size, were studied from one half of the lower abdomen in 10 fresh cadavers. These represent three different depths of fat (superficial, middle, deep) and six different anatomic areas (upper, middle, and lower sectors of the medial and lateral parts of the hemiabdomen). The average diameter, number of blood vessels, and the total vascular area were measured in each section. The average diameter of the blood vessels was greater in the superficial compared with the mid fat layer (p = 0.02). The total vascular area was greater in the deep compared with the mid fat layer (p = 0.01) and the superficial fat layer (p = 0.05). The number of blood vessels was also significantly higher in the deep fat layer compared with the mid fat layer (p = 0.001) and the superficial fat layer (p = 0.01). The lower medial area of the lower anterior abdominal wall contained the largest number and average diameter of blood vessels whereas the mid lateral area contained the smallest number and average diameter; however, this did not reach significance (p = 0.1 and 0.2). The results of this study are in keeping with the bimodal vascular supply to the subcutaneous fat of the anterior abdominal wall. The deep and the superficial fat layers are supplied more richly with vessels with a larger diameter whereas the intermediate fat layer is supplied from the terminal branches of these vessels.

Mechanisms of restenosis after coronary intervention: Difference between plain old balloon angioplasty and stenting

Background: Restenosis after coronary intervention remains an unsolved and important clinical problem. We histologically examined the mechanism of restenosis after both balloon injury and stenting. Methods: Coronary arteries of swine were subjected to balloon injury and stenting. Next, just after stenting or at 7, 14, or 28 days, the animals were sacrificed for the evaluation by morphometric analysis, histological observation, and immunostaining. Results: The neointimal area peaked at 14 days in the balloon injury group (BG) and increased linearly up to 28 days in the stent group (SG). At 28 days, the total vascular area in the BG was reduced to 78% of the control values. In the SG, the total vascular area remained enlarged. According to the phenotypic analysis, the vascular smooth muscle cells (VSMCs) in the neointimal area at 28 days were the contractile type in the BG and the synthetic type in the SG. Proliferating cell nuclear antigen (PCNA) and macrophage-positive cells were not observed in neointima in the BG at 28 days, whereas they were observed around the stent struts in the SG. In addition, numerous inflammatory cells, such as neutrophils and eosinophils, were also present in the SG. Conclusions: Restenosis after balloon injury consisted of arterial remodeling and neointimal hyperplasia, whereas that after stenting consisted mostly of neointimal hyperplasia. The neointimal area in the SG lasted longer than that in the BG. Continuous inflammation may be an important factor in the restenosis of stenting.

Prognostic implications of microvessel morphometry in diffuse astrocytic neoplasms.

Astrocytic brain tumours, particularly malignant astrocytomas, are recognized to be highly vascular neoplasms with potent angiogenic activity. Recent research has shown that quantification of microvessel density (MVD), as a measure of the degree of angiogenesis, constitutes a strong prognostic indicator in patients with astrocytomas. However, the significance of other morphometric aspects of microvessel network has not been tested so far. In this report, histological sections from 70 astrocytomas (grades II to IV), immunostained for CD34, were evaluated by image analysis for the quantification of MVD, total vascular area (TVA), and microvascular branching, as well as several morphometric parameters related to vessel size or shape. Minor axis length increased with grade (P = 0.045) but MVD and TVA presented a peak in grade III (P = 0.033 and P < 0.001, respectively). Size and shape related parameters affected survival in univariate analysis of grade IV and grades II/III, respectively. In multivariate analysis, only branching counts, along with age and grade, were the independent predictors of survival. Although MVD, TVA and branching counts were adversely related to disease-free survival in grades II and III (univariate analysis), only TVA remained statistically significant in multivariate analysis. It is concluded that TVA and branching counts are prognostically more informative than MVD for patients with diffuse astrocytic tumours.

Endothelial vasodilator production by uterine and systemic arteries. IX. eNOS gradients in cycling and pregnant ewes.

The follicular phase (FOL) and pregnancy exhibit increases in uterine blood flow (UBF), estrogen levels, and uterine artery (UA) endothelial nitric oxide synthase (eNOS) expression. UA branching within the mesometrium increases the total vascular cross-sectional area, which reduces the vascular perfusion pressure gradient, thus locally decreasing the blood flow velocity. Shear stress (SS) activates eNOS and may be associated with UBF elevations during FOL and pregnancy. We hypothesized that regional differences in eNOS responses are observed with both decreases in vessel diameter and during the ovarian cycle and pregnancy. Endothelial isolated proteins were collected from renal (RA) and internal iliac arteries (II) as well as from primary (UA 1 degrees ), secondary (UA 2 degrees), and tertiary (UA 3 degrees) UA branches of nonpregnant luteal phase (LUT; n = 6) and FOL (n = 6) as well as midpregnant (MP; 82 +/- 1 days gestation, n = 6) and late pregnant (LP; 127 +/- 3 days gestation, n = 6) ewes (term = 145 +/- 3 days gestation) for Western blot analysis. LUT RA, II, and UA 1 degrees eNOS levels were similar. There was a 60.7 +/- 9.8% reduction in eNOS expression in UA 2 degrees and UA 3 degrees. A similar decreasing eNOS regional expression gradient was observed in LP ewes. No eNOS regional expression gradient was observed in FOL or MP ewes because eNOS increased in UA 2 degrees and UA 3 degrees. In UA 2 degrees and UA 3 degrees, MP > LP = FOL > LUT. Thus, with increasing UBF, FOL and pregnancy rises in SS may regulate eNOS protein expression in smaller diameter UAs. A decrease in LUT and LP UA 2 degrees and UA 3 degrees endothelial eNOS suggest a possible negative feedback mechanism due to downregulation of eNOS if SS is normalized.

Antitumor effect of TNP-470 is not associated to decrease of angiogenesis in an experimental malignant neuroectodermic tumor.

The hypothesis that tumor growth depends on neovascularization has been broadly used in oncology research. TNP-470 is a fumagillin synthetic analog that is isolated from Aspergillus fumigatus, and experimental studies suggested that it shows antitumor effect mediated by its strong antiangiogenic effect. Because limited experience exists about the antitumoral effect of TNP-470 in cerebral tumors, we have carried out a study in order to evaluate the effect of TNP-470 on tumor growth and the vascular area in an experimental malignant neuroectodermic tumor growing in the subcutaneous space of immunocompetent Wistar rats. Our results showed a significant tumor growth inhibition in animals treated with TNP-470 when compared to those in the control group (intratumoral injections were administered in 30 mg/kg dose, three times a week on alternate days during four consecutive weeks). Since the quantitative analysis of tumor vascular parameters--number of microvessels and total intratumor vascular area--in the experimental groups did not show significant statistical differences, we conclude that TNP-470 has a significant antitumor effect on our neuroectodermic tumor, but this effect is mediated by other antineoplastic mechanisms that are independent of its previously described angiostatic capacity.

Prognostic evaluation of the microvascular network in myelodysplastic syndromes.

Considering the recently stated suggestion of neovascularization being implicated in myelodysplastic syndromes (MDS) pathogenesis, we evaluated multiple morphometric microvascular characteristics in MDS, in relation to clinicopathologic factors and prognosis. Trephines from 50 newly diagnosed MDS patients were immunostained for factor VIII and compared to those from 20 controls, 10 chronic myelomonocytic leukemia (CMML) and 12 acute myeloid leukemia (AML) patients. Quantitation of microvessel density (MVD), area, total vascular area (TVA), major and minor axis length, perimeter, compactness, shape factor, Feret diameter, and the number of branching vessels was performed by image analysis. Overall, the MDS group had significantly higher MVD, TVA, minor axis and shape factor values and significantly lower compactness than the control group. AML was characterized by increased vascularity compared to MDS and CMML, as well as by the presence of flattened microvessels (lower values of shape factor). Hypercellular MDS showed higher MVD. RA/RARS displayed larger caliber vessels than RAEB, which explains the favorable prognostic effect of increased size-related parameters on progression and/or survival. Moreover, decreased compactness and MVD were independent predictors of longer progression-free survival. It is concluded that angiogenesis is involved in the conversion of normal marrow to MDS and ultimately to AML and that disease progression within MDS is accompanied by qualitative alterations of the microvascular network. Furthermore, size-related parameters affect survival, while shape-related parameters and MVD are more influential with regard to progression-free survival.

Quantification of the ionising radiation effect over angiogenesis in the chick embryo and its chorioallantoic membrane by computerised analysis of angiographic images.

We evaluated, in vivo, the effect of ionising radiation on the angiogenesis process in the chick embryo and its chorioallantoic membrane (CAM) using digital subtraction angiography (DSA) in conjunction with computer-assisted image analysis. Information regarding the ionising effect on endothelial cells during radiation treatment was extracted. Two series of fertilized eggs were irradiated with a single ionising radiation dose of 10 Gy on days 9 and 13 of embryonic development. Angiography was carried out 24 h after irradiation. The angiographic images were digitized and subsequently processed. A set of specific morphological parameters was defined to allow an analytical characterization of the vascularity status. Vessels were classified into three categories according to their diameters (> or = 200 microm, 100-200 microm and 50-100 microm). The data were normalized and statistically evaluated. On day 10, total vascular area and total vascular length presented a 15.6+/-1.2% and 18.4+/-2.4% reduction, respectively, while vascular diameters increased 3.3+/-0.5%. The vessel area and length of the first category > or = 200 microm) increased 9.8+/-1.1% and 8.1+/-0.9%, respectively, while these morphometric parameters for each of the remaining two categories decreased 44.3+/-2.9%, 38.7+/-4.2% and 45+/-3.8%, 30.7+/-3.4%, respectively. On day 14 insignificant changes were observed. Computerised analysis of angiographic images showed that the antiangiogenic effect of irradiation during the various phases of CAM development is larger on the 10th day than that observed on day 14 and it depends on the vessel size.

QUANTIFICATION OF THE IONISING RADIATION EFFECT OVER ANGIOGENESIS IN THE CHICK EMBRYO AND ITS CHORIOALLANTOIC MEMBRANE BY COMPUTERISED ANALYSIS OF ANGIOGRAPHIC IMAGES

We evaluated, in vivo, the effect of ionising radiation on the angiogenesis process in the chick embryo and its chorioallantoic membrane (CAM) using digital subtraction angiography (DSA) in conjunction with computer-assisted image analysis. Information regarding the ionising effect on endothelial cells during radiation treatment was extracted. Two series of fertilized eggs were irradiated with a single ionising radiation dose of 10 Gy on days 9 and 13 of embryonic development. Angiography was carried out 24 h after irradiation. The angiographic images were digitized and subsequently processed. A set of specific morphological parameters was defined to allow an analytical characterization of the vascularity status. Vessels were classified into three categories according to their diameters (> or = 200 microm, 100-200 microm and 50-100 microm). The data were normalized and statistically evaluated. On day 10, total vascular area and total vascular length presented a 15.6+/-1.2% and 18.4+/-2.4% reduction, respectively, while vascular diameters increased 3.3+/-0.5%. The vessel area and length of the first category > or = 200 microm) increased 9.8+/-1.1% and 8.1+/-0.9%, respectively, while these morphometric parameters for each of the remaining two categories decreased 44.3+/-2.9%, 38.7+/-4.2% and 45+/-3.8%, 30.7+/-3.4%, respectively. On day 14 insignificant changes were observed. Computerised analysis of angiographic images showed that the antiangiogenic effect of irradiation during the various phases of CAM development is larger on the 10th day than that observed on day 14 and it depends on the vessel size.

Morphometric microvascular characteristics predict prognosis in superficial and invasive bladder cancer.

Recent research has shown that neovascularization, quantitated by microvessel density (MVD), constitutes a strong prognostic indicator in patients with invasive urothelial carcinomas. These studies, however, have focused only on MVD as the only factor reflecting angiogenesis in transitional-cell carcinomas (TCCs). The objective of this report was to evaluate multiple morphometric microvascular characteristics besides MVD in superficial and muscle-invasive TCCs separately, to provide a better approach to the relationship between angiogenesis, clinicopathological parameters, and prognosis. Histologic sections from 115 TCCs [35 superficial (T1) and 80 muscle-invasive] were immunostained for CD31 and evaluated using image analysis for the quantitation of MVD, area, total vascular area, major axis length, minor axis length, perimeter, compactness, shape factor, and Feret diameter. Patients were followed-up until death (n=31) or for an average of 42.2 months (median 38.5 months). MVD increased with progressing T category (P=0.049) but area (P=0.033), major axis length (P=0.022), perimeter (P=0.043), and Feret diameter (P=0.042) were highest in T2 tumors. Area was the single independent predictor of adverse significance in T1 TCCs, whereas for muscle-invasive tumors, survival was independently predicted by MVD. Regarding disease-free survival in superficial tumors, the single significant independent parameter was compactness, whereas area was an independent favorable indicator of disease-free survival for patients with invasive TCCs. It is concluded that the prognostic significance of neovascularization is better assessed by area and shape-related morphometric characteristics, whereas MVD becomes influential only with regard to overall survival of patients with invasive tumors.

Endothelial NO synthase overexpression inhibits lesion formation in mouse model of vascular remodeling.

NO produced by endothelial NO synthase (eNOS) plays important roles in the regulation of vascular tone and structure. The purpose of this study was to clarify the role of eNOS-derived NO on vascular remodeling by use of eNOS-transgenic (eNOS-Tg) mice. The common carotid artery was ligated just proximal to the carotid bifurcation. Four weeks later, the proximal carotid artery of the ligation site was histologically examined. In this vascular remodeling model, the endothelium remains uninjured, but neointimal and medial thickening occurs in combination with a reduction in vascular diameter at the proximal portion of the ligation. At 4 weeks after ligation, the respective neointimal and medial areas in wild-type mice were 17 200+/-1100 and 24 300+/-1500 microm(2), whereas both were reduced to 8000+/-1900 (P:<0.01) and 18 400+/-700 microm(2) (P:<0.01) in eNOS-Tg mice (n=8). Total vascular area was not different between the 2 genotypes. N:(G)-Nitro-L-arginine methyl ester treatment increased neointimal and medial areas to the same extent in both genotypes. Leukocyte infiltration was observed in the luminal side of the vessel, but the number of infiltrating cells was significantly attenuated in eNOS-Tg mice compared with wild-type mice. This reduction of leukocyte infiltration in eNOS-Tg mice was associated with reduced expressions of intracellular adhesion molecule-1 and vascular cellular adhesion molecule-1 on the endothelium. In conclusion, chronic eNOS overexpression in the endothelium reduced leukocyte infiltration and inhibited neointimal formation and medial thickening. Our data provide the evidence for the regulatory role of NO from the endothelium on vascular structure integrity.

Mosaic blood vessels in tumors: frequency of cancer cells in contact with flowing blood.

The presence of "mosaic" vessels in which both endothelial cells and tumor cells form the luminal surface has profound implications for metastasis, drug delivery, and antivascular therapy. Yet little is known of the frequency, and thus importance, of mosaic vessels in tumors. Using CD31 and CD105 to identify endothelial cells and endogenous green fluorescent protein labeling of tumor cells, we show that approximately 15% of perfused vessels of a colon carcinoma xenografted at two different sites in mice were mosaic vessels having focal regions where no CD31/CD105 immunoreactivity was detected and tumor cells appeared to contact the vessel lumen. These regions occupied approximately 25% of the perimeter of the mosaic vessels, or approximately 4% of the total vascular surface area in these colon carcinomas. In addition, we found similar numbers of mosaic vessels in human colon carcinoma biopsies. Our results are consistent with the observation that approximately 10(6) cells are shed daily per g of tumor. More importantly, our data offer a possible explanation for the antivascular effects of cytotoxic agents and suggest potential strategies for targeting the tumor vasculature.

Relation between vascular morphologic changes during stent implantation and the magnitude of in-stent neointimal hyperplasia

Intimal hyperplasia usually occurs after balloon overstretch injury or wire coil stimuli to coronary arteries. We examined whether the degree of vessel wall stretch during coronary stent placement could predict the amount of in-stent neointimal hyperplasia after a 6-month follow-up. Serial (preintervention, postballooning, poststent implantation, and a follow-up after 6 months) intravascular ultrasound (IVUS) was used to study 457 consecutive cross-sectional areas in 28 patients. IVUS imaging, using a motorized pullback system at 0.5 mm/s, allowed 1-mm axial increment measurements of the total vascular, stent, and lumen cross-sectional areas. The mean total vascular area changed from 10.89 ± 2.50 mm 2 before to 11.27 ± 2.49 mm 2 after ballooning, to 12.80 ± 2.59 mm 2 after stenting, and to 12.58 ± 2.41 mm 2 at follow-up (p <0.0001). The mean lumen area changed from 3.36 ± 1.95 mm 2 before to 4.21 ± 1.65 mm 2 after ballooning , to 5.16 ± 1.09 mm 2 after stenting, and to 3.57 ± 1.23 mm 2 at follow-up (p <0.0001). The mean stent area decreased from 5.25 ± 1.17 mm 2 after stenting to 5.09 ± 0.90 mm 2 at follow-up (p <0.0001). Stepwise logistic regression analysis showed that Δ total vascular area (after stent implantation–before intervention) was a strong predictor of the amount of intimal hyperplasia (r = 0.57, p <0.0001). Vascular overstretch caused by the stenting procedure promotes intimal hyperplasia in proportion to the degree of sectional vascular stretch.

Expression of Vascular Endothelial Growth Factor Induces an Invasive Phenotype in Human Squamous Cell Carcinomas

Inhibition of the vascular endothelial growth factor (VEGF) receptor Flk-1 has been shown to prevent invasion of experimental squamous cell carcinomas (SCC). To directly investigate the role of VEGF in tumor invasion, we stably transfected human SCC-13 cells, which are characterized by a noninvasive phenotype in vivo, with expression vectors containing murine VEGF(164) in sense (SCC/VEGF+) or antisense (SCC/VEGF-) orientation or with vector alone (SCC/vec). SCC/vec cells formed slowly growing, well-differentiated tumors with well-defined borders between tumor and stroma, after intradermal or subcutaneous injection. In contrast, SCC/VEGF+ tumors were characterized by rapid tumor growth, with small cell groups and single cells invading into the surrounding tissue, and by admixture of blood vessels and tumor cells in areas of tumor invasion. We detected an increase in tumor vessel density and size in VEGF-overexpressing tumors, resulting in a more than fourfold increase in total vascular areas. In contrast, SCC/VEGF- clones formed noninvasive, sharply circumscribed tumors with reduced vascular density. These findings demonstrate that selective VEGF overexpression was sufficient to induce tumor invasiveness, and they provide further evidence for an active role of the tumor stroma in cancer progression.

Quantitative assessment of angiogenesis in the chick embryo and its chorioallantoic membrane by computerised analysis of angiographic images

We studied, in vivo, the angiogenesis process in the chick embryo and its chorioallantoic membrane (CAM) using digital subtraction angiography (DSA) in conjunction with computer-assisted image analysis. In a series of fertilised eggs, angiography was carried out at days 8, 10, 12 and 14 of embryonic development. The angiographic images were digitised and subsequently processed for a specific image analysis. A set of specific morphological parameters has been defined to allow an analytical characterisation of the vascularity status. Vessels were classified into three categories according to their diameter (50–100, 100–200, and >200 μm). The data were normalised and statistically evaluated. Graphs showing the development of angiogenesis were obtained. Total vascular area revealed a continuous rise, whereas, total vascular length increased until day 12 and then it started decreasing. These morphometric parameters in the first two vessel categories progressively increased throughout the entire period of development, whereas in the third category they increased until day 10 and then they started decreasing. By applying a vascular casting technique CAM vessels were visualised and compared with those extracted from the processed angiographic image. The comparison revealed that there is exact matching for the first two vessel categories (diameters higher than 100 μm) while the matching of the third category (diameters between 50 and 100 μm) is approximate.

Suramin treatment of human glioma xenografts; effects on tumor vasculature and oxygenation status.

In this study the effect of suramin on tumor growth, vascularity and oxygenation of a human glioma xenografted in the nude mouse was examined. Vascular parameters and oxygenation status of the xenografts were determined immunohistochemically in frozen sections of the tumors, using the hypoxia marker pimonidazole-hydrochloride to detect hypoxic areas. Tumor vessels in these sections were stained by an endothelial cell marker and perfusion of vessels was visualized by administration of the perfusion marker Hoechst 333342 before harvesting the tumors. The vascular parameters were quantified with an image analysis system. The results show that tumor growth was reduced considerably after suramin treatment. This growth suppression was accompanied by marked changes in vascular architecture. Although the total vascular area and perfused fraction of tumor vessels remained unchanged after suramin treatment, vascular density increased, indicating that more but smaller vessel structures had developed during therapy. These vessel structures were also more homogeneously spread over the tumor area. Control tumors showed extensive areas of hypoxia while in treated tumors hypoxic areas had mostly disappeared. This effect was probably due to the higher density of homogeneously distributed perfused vessel structures in the treated tumors, contributing to an increased oxygenation of the tumor. These observations suggest that suramin therapy can result in marked changes not only in tumor vascularity but also in tumor oxygenation status which may have important consequences for sensitivity of these tumors to other therapies such as radiation treatment.

A Method of Quantifying Microangiograms

SummaryA method is proposed which can quantify the vascularity depicted in microangiograms. Total vascular area depicted in the microangiogram is measured using an image analyser. Vessel diameters and frequency are determined using standard stereological methods. Using the incidence of measured vessel diameters, the measured vascular area, and minimal mathematical manipulation, a distribution curve of possible vascular volumes can be constructed. When combined with sample volume, statistical data relevant to vessel diameters and volumes can be derived. This calculation is not meant as a substitute to stereological methods for quantifying vascularity using thin sections, only as a quantitative adjunct to microangiograms and descriptive microangiography.A method is proposed which can provide statistical data relevant to vessel diameters and volumes depicted in microangiograms.

Adventitial vasa vasorum in balloon-injured coronary arteries: visualization and quantitation by a microscopic three-dimensional computed tomography technique.

The objective of this study was to examine the quantitative response of the adventitial vasa vasorum to balloon-induced coronary injury. Recent attention has focused on the role of vasa vasorum in atherosclerotic and restenotic coronary artery disease. However, the three-dimensional anatomy of these complex vessels is largely unknown, especially after angioplasty injury. The purpose of this study was to visualize and quantitate three-dimensional spatial patterns of vasa vasorum in normal and balloon injured porcine coronary arteries. We also studied the spatial growth of vasa vasorum in regions of neointimal formation. A novel imaging technique, microscopic computed tomography, was used for these studies. Four pigs were killed 28 d after coronary balloon injury, and four pigs with uninjured coronary arteries served as normal controls. The coronary arteries were injected with a low-viscosity, radiopaque liquid polymer compound. Normal and injured coronary segments were scanned using a microscopic computed tomography technique. Three-dimensional reconstructed maximum intensity projection and voxel gradient shading images were displayed at different angles and voxel threshold values, using image analysis software. For quantitation, seven to 10 cross-sectional images (40 normal and 32 balloon injured cross-sections) were captured from each specimen at a voxel size of 21 microm. Normal vasa vasorum originated from the coronary artery lumen, principally at large branch points. Two different types of vasa were found and classified as first-order or second-order according to location and direction. In balloon-injured coronary arteries, adventitial vasa vasorum density was increased (3.16+/-0.17/mm2 vs. 1.90+/-0.06/mm2, p = 0.0001; respectively), suggesting neovascularization by 28 d after vessel injury. Also, in these injured arteries, the vasa spatial distribution was disrupted compared with normal vessels, with proportionally more second-order vasa vasorum. The diameters of first-order and second-order vasa were smaller in normal compared with balloon-treated coronary arteries (p = 0.012 first-order; p < 0.001, second-order; respectively). The density of newly formed vasa vasorum was proportional to vessel stenosis (r = 0.81, p = 0.0001). Although the total number of vasa was increased after injury, the total vascular area comprised of vasa was significantly reduced in injured vessels compared with normals (3.83+/-0.20% to 5.42+/-0.56%, p = 0.0185). Adventitial neovascularization occurs after balloon injury. The number of new vessels is proportional to vessel stenosis. These findings may hold substantial implications for the therapy of vascular disease and restenosis.

A morphometric study of neovascularization in colorectal carcinoma

Neovascularization reportedly is correlated with metastasis, recurrence, and prognosis in some types of tumors. Microvessel quantification in so-called "hot spots" has been studied extensively as the only factor reflecting angiogenesis in various malignant tumors. The objective of this report was to evaluate multiple morphometric microvascular characteristics in addition to microvessel density (MVD) in colorectal carcinomas to provide a better approach to examining the relation between angiogenesis and clinicopathologic factors and prognosis. Histologic sections from 106 colorectal adenocarcinomas and 17 adenomas, immunostained for factor VIII, were evaluated by image analysis for the quantification of MVD, total vascular area (TVA), and microvascular branching, as well as several morphometric parameters related to the vessel size or shape. MVD gradually decreased with progressing Dukes stage. The vascular branching counts were significantly higher in carcinomas than in adenomas, and remained unaffected through progressing Dukes stages. Shape-related parameters showed significant differences between carcinomas and adenomas and between different grades of differentiation. Branching counts and TVA were the only factors found to be of prognostic significance. This study provides evidence that neovascularization is an early critical event in colorectal tumorigenesis, reaching a maximum level early in the malignant process. Its prognostic significance is better assessed by quantification of TVA and the branching pattern of microvessels, whereas MVD does not provide significant prognostic information for colorectal carcinoma patients.

Exercise training in swine promotes growth of arteriolar bed and capillary angiogenesis in heart.

Exercise training induces coronary vascular adaptations. The goal of this study was to contrast the effects of training on capillary and arteriolar growth. Minipigs were trained for 1, 3, 8, and 16 wk and compared with controls. Maximal O2 consumption increased continuously throughout the study. Capillary and arteriolar densities and diameters, and proliferation of vascular cells in these vessels, were determined in perfusion-fixed tissue. The arterioles were subdivided into five groups according to diameter: 10-19.9, 20-30, 31-40, 41-70, and 71-120 microgram. The total vascular bed cross-sectional area increased by 37% at 16 wk, mainly because of an increase in the number of the small arterioles and an increase in the diameter of the larger vessels. Capillary density increased at 3 wk and then returned to control levels by 16 wk; concomitantly, the number of arterioles (20-30 microgram) increased at 16 wk. We speculate that the "extra" capillaries observed at 3 wk were the source of the new arterioles.