An improved procedure to quantify tumour vascularity using true colour image analysis. Comparison with the manual hot-spot procedure in a human melanoma xenograft model

Blood Vessel Detection Algorithm for Tissue Engineering and Quantitative Histology

Immunohistochemistry for vascular network analysis plays a fundamental role in basic science, translational research and clinical practice. However, identifying vascularization in histological tissue images is time consuming and markedly depends on the operator’s experience. In this study, we present “blood vessel detection—BVD”, an automatic algorithm for quantitative analysis of blood vessels in immunohistochemical images. BVD is based on extraction and analysis of low-level image features and spatial filtering techniques, which do not require a training phase. BVD algorithm performance was comparatively evaluated on histological sections from three different in vivo experiments. Collectively, 173 independent images were analyzed, and the algorithm's results were compared to those obtained by human operators. The developed BVD algorithm proved to be a robust and versatile tool, being able to quantify number, area, and spatial distribution of blood vessels within all three considered histologic datasets. BVD is provided as an open-source application working on different operating systems. BVD is supported by a user-friendly graphical interface designed to facilitate large-scale analysis.

The impact of allergies and smoking status on nasal mucosa of hypertrophied turbinates - an immunohistologic analysis

Background: Allergies and smoking are common reasons for nasal mucosa inflammations, which in turn, cause nasal obstructions. Nevertheless, the impact of coexisting allergies and smoking on nasal mucosa inflammation has not been studied.Objectives: To study the impact of smoking with relation to allergies on nasal mucosa histology and to characterize an immunologic profile using immunohistochemical (IHC) staining.Methods: A cross-sectional study. Nasal biopsies of inferior turbinates from smokers with different allergic statuses were compared. Demographics, comorbidities, histologic, and immunohistochemical (IHC) staining of CD3, CD68, CD 20, and CD138 receptors were compared and analyzed.Results: A total of 53 patients were included, of which 20 (37.7%) were smokers, and 20 (37.7%) had allergic backgrounds. Smokers, both allergic and non-allergic, demonstrated reduced edema compared to the control group (p Value = 0.034) and significantly lower eosinophil density in the stroma compared to the allergic nonsmokers' group (p Value = 0.04). Smokers had a significant negative correlation between the number of cigarettes per day and the expression of CD20 in the stroma (-0.452, p Value = 0.045) and the epithelium (-0.432, p Value = 0.057) in IHC staining. Allergic smokers had a negative correlation (-0.705, p Value = 0.023) between the number of cigarettes per day and the CD68 marked cell expression in the epithelium.Conclusion: The coexistence of an allergic background and smoking alters known immunologic responses within the nasal mucosa. Smoking may have an immunosuppressive role in the nasal mucosa in both innate and humoral immune systems.

Prognostic value of the area and density of lymphatic vessels in cutaneous squamous cell carcinoma

BACKGROUND AND OBJECTIVES

Cutaneous squamous cell carcinoma (SCC) is known for its capacity to metastasize via lymphatic vessels. In recent studies, the level of lymphangiogenesis has been reported as a potential prognostic factor for several skin tumors. The aim of this study was to quantify lymphangiogenesis in SCC using either computer-assisted image analysis or the Chalkley count technique. Vascular parameters were evaluated and compared with respect to their predictive power for tumor metastasis.

PATIENT AND METHODS

In this case-control study, clinical and histological data of 15 metastatic and 15 nonmetastatic SCC patients were retrospectively analyzed. SCC samples were immunostained for the lymphatic endothelial marker D2-40 and the panvascular marker CD31, and analyzed using computer-assisted morphometric image analyses within hot spots as well as the digitalized Chalkley counting method.

RESULTS

Lymphatic vessel density, relative lymphatic vessel area, and lymphatic Chalkley count were significantly elevated in metastatic SCC. Tumor thickness was significantly higher in metastatic SCC, and had the highest predictive power for metastatic disease. Tumor thickness was a significant predictor of lymphangiogenic parameters.

CONCLUSIONS

Lymphangiogenesis is elevated in metastatic SCC but its extent is influenced by tumor thickness. Tumor thickness remains the most reliable predictive factor for metastatic disease.

Saliency-Based Bleeding Localization for Wireless Capsule Endoscopy Diagnosis

Stomach bleeding is a kind of gastrointestinal disease which can be diagnosed noninvasively by wireless capsule endoscopy (WCE). However, it requires much time for physicians to scan large amount of WCE images. Alternatively, computer-assisted bleeding localization systems are developed where color, edge, and intensity features are defined to distinguish lesions from normal tissues. This paper proposes a saliency-based localization system where three saliency maps are computed: phase congruency-based edge saliency map derived from Log-Gabor filter bands, intensity histogram-guided intensity saliency map, and red proportion-based saliency map. Fusing the three maps together, the proposed system can detect bleeding regions by thresholding the fused saliency map. Results demonstrate the accuracy of 98.97% for our system to mark bleeding regions.

Segmentation of digitized histological sections for quantification of the muscularized vasculature in the mouse hind limb

Immunohistochemical tissue staining enhances microvasculature characteristics, including the smooth muscle in the medial layer of the vessel walls that is responsible for regulation of blood flow. The vasculature can be imaged in a comprehensive fashion using whole-slide scanning. However, since each such image potentially contains hundreds of small vessels, manual vessel delineation and quantification is not practically feasible. In this work, we present a fully automatic segmentation and vasculature quantification algorithm for whole-slide images. We evaluated its performance on tissue samples drawn from the hind limbs of wild-type mice, stained for smooth muscle using 3,3'-Diaminobenzidine (DAB) immunostain. The algorithm was designed to be robust to vessel fragmentation due to staining irregularity, and artefactual staining of nonvessel objects. Colour deconvolution was used to isolate the DAB stain for detection of vessel wall fragments. Complete vessels were reconstructed from the fragments by joining endpoints of topological skeletons. Automatic measures of vessel density, perimeter, wall area and local wall thickness were taken. The segmentation algorithm was validated against manual measures, resulting in a Dice similarity coefficient of 89%. The relationships observed between these measures were as expected from a biological standpoint, providing further reinforcement of the accuracy of this system. This system provides a fully automated and accurate means of measuring the arteriolar and venular morphology of vascular smooth muscle.

Assessing Tumor Angiogenesis in Histological Samples

Tumor neovascularization acquires their vessels through a number of processes including angiogenesis, vasculogenesis, vascular remodeling, intussusception, and possibly vascular mimicry in certain tumors. The end result of the tumor vasculature has been quantified by counting the number of immunohistochemically identified microvessels in areas of maximal vascularity, so-called hot spot. Other techniques have been developed such as Chalkley counting and the use of image analysis systems that are robust and reproducible as well as being more objective. Many of the molecular pathways that govern tumor neovascularization have been identified and many reagents are now available to study these tissue sections. These include angiogenic growth factors and their receptors and cell adhesion molecules, proteases, and markers of activated, proliferating, cytokine-stimulated, or angiogenic vessels, such as CD105. It is also possible to differentiate quiescent from active vessels. Other reagents that can identify proteins involved in microenvironmental influences such as hypoxia have also been generated. Although the histological assessment of tumor vascularity is used mostly in the research context, it may also have clinical applications if appropriate methodology and trained observers perform the studies.

TMA vessel segmentation based on color and morphological features: application to angiogenesis research

Given that angiogenesis and lymphangiogenesis are strongly related to prognosis in neoplastic and other pathologies and that many methods exist that provide different results, we aim to construct a morphometric tool allowing us to measure different aspects of the shape and size of vascular vessels in a complete and accurate way. The developed tool presented is based on vessel closing which is an essential property to properly characterize the size and the shape of vascular and lymphatic vessels. The method is fast and accurate improving existing tools for angiogenesis analysis. The tool also improves the accuracy of vascular density measurements, since the set of endothelial cells forming a vessel is considered as a single object.

Differential TIMP3 expression affects tumor progression and angiogenesis in melanomas through regulation of directionally persistent endothelial cell migration

The angiogenic potential of solid tumors, or the ability to initiate neovasculature development from pre-existing host vessels, is facilitated by soluble factors secreted by tumor cells and involves breaching of extracellular matrix barriers, endothelial cell (EC) proliferation, migration and reassembly. We evaluated the angiogenic potential of human melanoma cell lines differing in their degree of aggressiveness, based on their ability to regulate directionally persistent EC migration. We observed that conditioned-medium (CM) of the aggressive melanoma cell line BLM induced a high effective migratory response in ECs, while CMs of Mel57 and 1F6 had an inhibitory effect. Further, the melanoma cell lines exhibited a varied expression profile of tissue inhibitor of metalloproteinase-3 (TIMP3), detectable in the CM. TIMP3 expression inversely correlated with aggressiveness of the melanoma cell line, and ability of the respective CMs to induce directed EC migration. Interestingly, TIMP3 expression was found to be silenced in the BLM cell line, concurrent with its role as a tumor suppressor. Treatment with recombinant human TIMP3 and CM of modified, TIMP3 expressing, BLM cells mitigated directional EC migration, while CM of TIMP3 silenced 1F6 cells induced directed EC migration. The functional implication of TIMP3 expression on tumor growth and angiogenic potential in melanoma was evaluated in vivo. We observed that TIMP3 expression reduced tumor growth, angiogenesis and macrophage infiltration of BLM tumors while silencing TIMP3 increased tumor growth and angiogenesis of 1F6 tumors. Taken together, our results demonstrate that TIMP3 expression correlates with inhibition of directionally persistent EC migration and adversely affects the angiogenic potential and growth of melanomas.

The correlation between extracellular resistance by electrical biopsy and the ratio of optical low staining area in irradiated intestinal tissues of rats

BACKGROUND

Electrical biopsy illustrates a tissue's electrical properties by electrical impedance spectroscopy. However, electrical biopsy parameters are different from conventional morphological-based examinations. The correlation between electrical biopsy and the morphological observation has not been checked. Considering the tissue responses to injury, extracellular resistance should be most sensitive with the accumulation of fluid in tissue, and it is expected to increase the ratio of optical low staining area on histological images. In this study, we calculated the ratio of optical low staining area of sampled histological images and compared with the results of electrical biopsy to verify the hypothesis of that the extracellular resistance of electrical biopsy most highly correlates with the ratio of optical low staining area on histological images.

METHODS

The irradiated intestinal tissues of rats after different latent period were used for study. The sampled tissues were measured by electrical impedance spectroscopy for electrical biopsy and the microscopic images were acquired. The sampled histological images were transformed into the Hue-Saturation-Density (HSD) colour model to decouple the stain density. The ratio of optical low staining area on histological images was computed to quantify the morphological changes. The results were related to the parameters from electrical biopsy according to three element circuit model by Spearman's rank correlation test.

RESULTS

The ratio of optical low staining area varied as well as the tissue's electrical parameters. The extracellular resistance (Re) and intracellular resistance (Ri) by electrical biopsy tended to increase with the ratio of low staining area decreasing. The membrane capacitance (Cm) by electrical biopsy tended to increase with the ratio of optical low staining area increasing. The extracellular resistance (Re) of electrical biopsy was the parameter most highly correlated with the ratio of optical low staining area with a correlation coefficient of -0.757 (p < 0.001).

CONCLUSIONS

The results of this report confirm the hypothesis and support the idea that electrical biopsy results reflect the changes in tissues seen in conventional histological findings in a sense of conventional histological knowledge, and this approach may have a great potential for augmenting the pathological diagnosis of tissues.

Diffusion-weighted and dynamic contrast-enhanced MRI of prostate cancer: correlation of quantitative MR parameters with Gleason score and tumor angiogenesis

OBJECTIVE

The objective of our study was to investigate whether quantitative parameters derived from diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI (DCE-MRI) correlate with Gleason score and angiogenesis of prostate cancer.

MATERIALS AND METHODS

Seventy-three patients who underwent preoperative MRI and radical prostatectomy were included in our study. A radiologist and pathologist located the dominant tumor on the MR images based on histopathologic correlation. For each dominant tumor, the apparent diffusion coefficient (ADC) value and quantitative DCE-MRI parameters (i.e., contrast agent transfer rate between blood and tissue [K(trans)], extravascular extracellular fractional volume [v(e)], contrast agent backflux rate constant [k(ep)], and blood plasma fractional volume on a voxel-by-voxel basis [v(p)]) were calculated and the Gleason score was recorded. The mean blood vessel count, mean vessel area fraction, and vascular endothelial growth factor (VEGF) expression of the dominant tumor were determined using CD31, CD34, and VEGF antibody stains. Spearman correlation analysis between MR and histopathologic parameters was conducted.

RESULTS

The mean tumor diameter was 15.2 mm (range, 5-28 mm). Of the 73 prostate cancer tumors, five (6.8%) had a Gleason score of 6, 46 (63%) had a Gleason score of 7, and 22 (30.1%) had a Gleason score of greater than 7. ADC values showed a moderate negative correlation with Gleason score (r = -0.376, p = 0.001) but did not correlate with tumor angiogenesis parameters. Quantitative DCE-MRI parameters did not show a significant correlation with Gleason score or VEGF expression (p > 0.05). Mean blood vessel count and mean vessel area fraction parameters estimated from prostate cancer positively correlated with k(ep) (r = 0.440 and 0.453, respectively; p = 0.001 for both).

CONCLUSION

There is a moderate correlation between ADC values and Gleason score and between k(ep) and microvessel density of prostate cancer. Although the strength of the correlations is insufficient for immediate diagnostic utility, these results warrant further investigation on the potential of multiparametric MRI to facilitate noninvasive assessment of prostate cancer aggressiveness and angiogenesis.

An immunohistochemical study of metroplastic surgical specimens from patients with a septate uterus

Purpose

To elucidate the etiology of recurrent pregnancy loss in patients with congenital uterine anomalies, an immunohistochemical technique was used to quantitatively evaluate the vascular arrangement of septate uteri with respect to vascular density and morphology.

Methods

Nine specimens obtained from patients who had undergone metroplastic surgery for the treatment of a septate uterus and 10 control specimens from patients who had undergone a hysterectomy because of cervical carcinoma were used in this study. Formalin-fixed paraffin-embedded uterine specimens were then immunostained for CD34, which is specifically expressed in vascular endothelial cells.

Results

The mean blood vessel count (mean ± SD) for the myometrium was 149.7 ± 22.7/field in the septate uteri and 162.2 ± 36.4/field in the control uteri; these values were not significantly different. However, the total vessel cross-sectional areas, as evaluated quantitatively using the KS400 image analysis system, were 10350.4 ± 1024.3 μm²/field for the septate uteri and 12002.9 ± 2232.3 μm²/field for the control uteri; these values were significantly different (p < 0.05). The vessel morphology expressed by vessel irregularity and deformity showed a characteristic change in the septate uterus.

Conclusions

A significant difference in the distribution of the blood vessels existed between the septate and control uteri, presumably impairing blood flow in the myometrium and the adverse pregnancy outcome.

An automatic algorithm for the segmentation and morphological analysis of microvessels in immunostained histological tumour sections

A fully automatic segmentation and morphological analysis algorithm for the analysis of microvessels from CD31 immunostained histological tumour sections is presented. Development of the algorithm exploited the distinctive hues of stained vascular endothelial cells, cell nuclei and background, to provide the seeds for a 'region-growing' method for object segmentation in the 3D hue, saturation, value (HSV) colour model. The segmented objects, identified as microvessels by CD31 immunostaining, were post-processed with three morphological tasks: joining separate objects that were likely to belong to a single vessel, closing objects that had a narrow gap around their periphery, and splitting objects with multiple lumina into individual vessels. The automatic segmentation was validated against a hand-segmented set of 44 images from three different SW1222 human colorectal carcinomas xenografted into mice. 96.3 ± 0.9% of pixels were found to be correctly classified. Automated segmentation was carried out on a further 53 images from three histologically distinct mouse fibrosarcomas (MFs) for morphological comparison with the SW1222 tumours. Four morphometric measurements were calculated for each segmented vessel: vascular area (VA), ratio of lumen area to vascular area (lu/VA), eccentricity (e), and roundness (ro). In addition, the total vascular area relative to tumour tissue area (rVA) was calculated. lu/VA, e and ro were found to be significantly smaller in MF tumours than in SW1222 tumours (p < 0.05; unpaired t-test). The algorithm is available through the website http://www.caiman.org.uk where images can be uploaded, processed and sent back to users. The output from CAIMAN consists of the original image with boundaries of segmented vessels overlaid, the calculated parameters and a Matlab file, which contains the segmentation that the user can use to derive further results.

Canine classical seminoma: a specific malignant type with human classifications is highly correlated with tumor angiogenesis

Background

Human seminoma is classified as classical seminoma (SE) and spermatocytic seminoma (SS). Human SE is known to be more malignant and metastasizing more frequently than SS. Tumor angiogenesis is highly related with tumor progression and metastasis, with microvessel density (MVD) being an important parameter of metastatic potential. Canine seminoma is not yet well-established as SE or SS type including correlation with angiogenesis. We classified canine SE and SS, and then compared them to tumor associated vessels.

Methods

Twenty-three cases of canine seminomas (2 intratubular, 9 diffuse, and 12 intratubular/diffuse seminomas showing both intratubular and diffuse patterns) were classified as SE or SS by immunohistochemistry (IHC) using monoclonal antibody against PLAP and by PAS stain. The histopathological data were then compared to see if there was a correlation with SE or SS. Angiogenesis of seminomas were evaluated by immunohistochemical assay using polyclonal antibody against Von Willebrand factor (vWF) and by calculating the means of MVD, vessels area and perimeters using computerized image analysis. Statistical Package for Social Sciences (SPSS) program was used for various statistical analyses.

Results

The numbers of PLAP+/PAS+ canine SEs were 8/23 (34.8%) and PLAP-/PAS- SSs were 15/23 (61.2%). All SE cases (8/8, 100%) were intratubular/diffuse types. SS types included 2 intratubular (2/15, 13.3%), 9 diffuse (9/15, 60%), and 4 intratubular/diffuse (4/15, 26.7%) types. MVD and vascular parameters in SEs were significantly higher than in SSs, showing the highest value in the intratubular/diffuse type. Seminomas observed with neoplastic cells invasion of vessels presented higher perimeter and area values than seminomas without conformed neoplastic cells invasion.

Conclusion

In this study, we demonstrated a positive relationship between canine SE and tumor angiogenesis. Furthermore, we also showed that a tumor cells invasion of vessels were a correlated vascular parameter. Although metastasis of canine seminomas has rarely been reported, our results support that canine SE could have high metastatic potential similar to the human counterpart. Further studies are required to clarify the relationship between canine SE and clinical data with metastatic factors.

Computerized whole slide quantification shows increased microvascular density in pT2 prostate cancer as compared to normal prostate tissue

BACKGROUND

Contrast enhanced imaging enables powerful, non-invasive diagnostics, important for detection and staging of early prostate cancer. The uptake of contrast agent is increased in prostate cancer as compared to normal prostate tissue. To reveal the underlying physiological mechanisms, quantification of tissue components in pathology specimens may yield important information. Aim of this study was to investigate whether microvascularity is increased in prostate confined cancer (pT2).

METHODS

Radical prostatectomy specimens of 26 patients were selected for organ confined peripheral zone tumors which were restricted to one side of the prostate. Microvessels were visualized by immunohistochemistry against CD31. Specimens were scanned using a computer controlled microscope and scanning stage and vessels were recognized automatically. Pseudocolor mappings were produced showing number of vascular profiles (MVD), vascular area (MVA) and perimeter (MVP) in an overview of the entire prostate transection. MVD is a common measure for vascularity, whereas MVA represents the 3D vascular volume and MVP the perfused surface area. Mean, coefficient of variation and 75th percentile of these parameters were calculated automatically in manually indicated areas, consisting of the entire tumor area and the corresponding normal area in the contra lateral side of the prostate.

RESULTS

The mappings clearly indicate areas of increased vascularity in prostate transections. In tumor tissue an increase was found compared to normal tissue of 81%, 49%, and 62% for mean MVD, mean MVA and mean MVP, respectively (P < 0.001 for all comparisons). In contrast, the heterogeneity in tumor vasculature was significantly decreased as compared to normal prostate (P < 0.001).

CONCLUSIONS

Characteristics of microvasculature deviated significantly in pT2 prostate tumor as compared to normal tissue.

Assessing tumor angiogenesis in histological samples

Tumor neovascularization acquires vessels through a number of processes, including angiogenesis, vasculogenesis, vascular remodelling, intussusception, and possibly vascular mimicry in certain tumors. The end result of the tumor vasculature has been quantified by counting the number of immunohistochemically identified microvessels in areas of maximal vascularity so-called hot spots. Other techniques have been developed, such as Chalkley counting and the use of image analysis systems that are robust and reproducible as well as more objective. Many of the molecular pathways that govern tumor neovascularization have been identified, and many reagents are now available to study these tissue sections. These include angiogenic growth factors and their receptors, cell adhesion molecules, proteases, and markers of activated, proliferating, cytokine-stimulated, or angiogenic vessels, such as CD105. It is also possible to differentiate quiescent from active vessels. Other reagents that can identify proteins involved in microenvironmental influences such as hypoxia have also been generated. Although the histological assessment of tumor vascularity is used mostly in the research context, it may also have clinical applications if appropriate methodology and trained observers perform the studies.

Three-dimensional (3D) reconstruction and quantitative analysis of the microvasculature in medulloblastoma and ependymoma subtypes

In the World Health Organisation (WHO) classification of tumours of the nervous system, four main histopathological subtypes of medulloblastomas (classic medulloblastoma, desmoplastic medulloblastoma, medulloblastoma with extensive nodularity and advanced neuronal differentiation and large cell/anaplastic medulloblastoma) as well as of ependymal tumours (low-grade ependymoma, anaplastic ependymoma, myxopapillary ependymoma and subependymoma) are recognised. Under the hypothesis that the microvascular architecture of tumours is a reflection of the histopathological subtype, we performed three-dimensional reconstructions of the microvasculature in these subtypes of medulloblastomas and ependymal tumours using computerised image analysis. In addition, we quantitatively assessed three microvascular parameters (number, area, perimeter) in these neoplasms. Three-dimensional reconstructions showed a dense pattern of irregular vessels in classic and large cell medulloblastoma. In desmoplastic medulloblastoma and medulloblastoma with extensive nodularity, the vessels were more unevenly distributed and organised around the nodular areas. Classic medulloblastoma and large cell medulloblastoma had on average the largest vessel area and perimeter. The highest number of vessels was seen in classic medulloblastoma and medulloblastoma with extensive nodularity. Three-dimensional analysis of ependymal tumours showed that low-grade ependymoma had larger but fewer vessels compared to anaplastic ependymoma, while myxopapillary ependymoma had a complex, heterogeneous pattern of vessels and subependymoma few but regular vessels. In ependymal tumours, the highest values for vessel number, vessel area and vessel perimeter were found in anaplastic ependymoma and the lowest values in subependymoma. We conclude that our three-dimensional reconstructions shed unprecedented light on the tumour vasculature in medulloblastomas and ependymal tumours and expect that such reconstructions are helpful tools for further studies on tumour angiogenesis.

Expression of WT1 is down-regulated in eutopic endometrium obtained during the midsecretory phase from patients with endometriosis

OBJECTIVE

To investigate whether WT1 protein expression is altered in eutopic endometrium of endometriosis patients.

DESIGN

Prospective study.

SETTING

University hospital.

PATIENT(S)

Patients with endometriosis and fertile women with macroscopically normal pelvic cavities.

INTERVENTION(S)

During surgery, endometrial tissues were obtained from 59 patients with deep infiltrating endometriosis, ovarian endometriosis, or only superficial peritoneal endometriosis. Control endometrial tissue samples were obtained from 40 fertile women who underwent laparoscopic tubal ligation or reversal of tubal sterilization.

MAIN OUTCOME MEASURE(S)

The percentage of nuclear surface positively immunostained for WT1 (PI) and WT1-positive microvessel density.

RESULT(S)

The PI was significantly lower in endometrial stromal cells from patients with deep infiltrating endometriosis than in stroma from control subjects during the midsecretory phase, whereas there was no significant difference between the two populations during the proliferative, early secretory, and late secretory phases. The PI was also significantly lower during the midsecretory phase in endometrial stromal cells from patients with ovarian endometriosis and superficial peritoneal endometriosis compared with control subjects.

CONCLUSION(S)

During the midsecretory phase, PI in endometrial stromal cells is down-regulated in patients with deep infiltrating endometriosis, ovarian endometriosis, and superficial peritoneal endometriosis compared with endometrium from healthy control subjects.

Development of the tumor vascular bed in response to hypoxia-induced VEGF-A differs from that in tumors with constitutive VEGF-A expression

Tumors arise initially as avascular masses in which central hypoxia induces expression of vascular endothelial growth factor-A (VEGF-A) and subsequently tumor vascularization. However, VEGF-A can also be constitutively expressed as a result of genetic events. VEGF-A is alternatively spliced to yield at least 6 different isoforms. Of these, VEGF-A(121) is freely diffusible whereas basically charged domains in the larger isoforms confer affinity for cell surface or extracellular matrix components. We previously reported that in a mouse brain metastasis model of human melanoma, VEGF-A(121) induced a qualitatively different tumor vascular phenotype than VEGF-A(165) and VEGF-A(189): in contrast to the latter ones, and VEGF-A(121) did not induce a neovascular bed but rather led to leakage and dilatation of preexistent brain vessels. Here, we correlate vascular phenotypes with spatial VEGF-A expression profiles in clinical brain tumors (low grade gliomas; n = 6, melanoma metastases; n = 4, adenocarcinoma metastases; n = 4, glioblastoma multiforme; n = 3, sarcoma metastasis; n = 1, renal cell carcinoma metastasis; n = 1). We show that tumors that constitutively express VEGF-A present with different vascular beds than tumors in which VEGF-A is expressed as a response to central hypoxia. This phenotypic difference is consistent with a model where in tumors with constitutive VEGF-A expression, all isoforms exert their effects on vasculature, resulting in a classical angiogenic phenotype. In tumors where only central parts express hypoxia-induced VEGF-A, the larger angiogenic isoforms are retained by extracellular matrix, leaving only freely diffusible VEGF-A(121) to exert its dilatation effects on distant vessels.

The quantification of angiogenesis in relation to metastasis in oral cancer: a review

Tumours need vessels to grow into clinically significant dimensions, and to metastasize. Varying results have been reported for the relation between angiogenic activity in oral carcinomas, and the occurrence of metastasis. Quantification of microvessels in tissue sections is mostly used to assess angiogenesis, but appears subject to biases as reflected in contradicting reports. Especially the choice of immunohistochemical staining technique appears pivotal. Although microvessel density measurements (MVD) appear promising for other tumour types, in oral carcinomas no unambiguous relation could be established. Furthermore, MVD assessment appears more elaborate than expected. New, more time efficient techniques may replace MVD as we know it.

Image analysis system for assessment of immunohistochemically stained proliferative marker (MIB-1) in oesophageal squamous cell carcinoma

The prognosis of oesophageal cancer patients is related to the portion of MIB-1 positively stained tumour nuclei. In this study, an image analysis system was developed based on LEICA Image Processing and Analysis System to reduce the subjective, tedious and inaccurate manual counting of nuclei staining. Representative oesophageal cancer tissues were collected and immunohistochemical preparations of MIB-1 were made. The MIB-1 positive nuclei in these tumours were assessed by quantitative counting, semi-quantitative counting, and three computer assessment methods using LEICA QWIN PRO. Our results showed that computer assessment methods were reliable and consistent. The procedure using the system could be accomplished within 15 min. Overlapped or missed counting of nuclei by the observer were eliminated. The image analysis system can really assist experts in obtaining reliable data for the prognosis of oesophageal cancer patients quickly.

Computer assisted analysis of the microvasculature in metastasized and nonmetastasized squamous cell carcinomas of the tongue

BACKGROUND

Quantification of microvessels in solid malignancies is regarded as a potential test to predict their clinicobiologic behavior. However, discordant results have been reported for head and neck cancer that may be explained by varying methods.

METHODS

In this retrospective study, we therefore quantified the microvasculature in 20 nonmetastasized and 20 metastasized squamous cell carcinomas of the tongue, using recently developed methods. For immunohistochemical visualization of the vessels, we used anti-CD34 with a signal amplification step based on the catalyzed deposition of biotinylated tyramine. This protocol results in enhanced staining quality compared with standard protocols. For each tumor, a representative tissue section was systematically sampled with 40 to 60 standardized test fields. True color image analysis system was used to measure microvessel density (MVD) and to obtain additional information with regard to size categories of vessels.

RESULTS

Remarkably, in the group of nonmetastasized tumors, the MVD was greater than in the metastasized tumors (p =.007). However, the microvessels with a diameter in the range of 10 to 15 microm predominated in the group of metastasized tongue carcinomas (p =.03). A logistic regression model based on the percentage of vessels smaller than 5 microm, classified 85% of patients with a metastasized tumor correctly and 75% of patients with a nonmetastasized tumor, independently of the clinical stage of the tumor.

CONCLUSIONS

These results suggest that only vessels with a diameter larger than 10 microm, consistent with functional vessels, play a role in the process of metastasis. Further research more specifically into structural and functional characterization of blood and lymphatic vessels might help provide more insight into the relationship between microvasculature and the pathogenesis of metastasis in tongue carcinomas.

Relevance of biologic markers in colorectal carcinoma: a comparative study of a broad panel

BACKGROUND

Although pathologic stage is currently the main prognostic indicator for patients with colorectal carcinoma (CRC), mounting evidence suggests that, in its current form, it is insufficient to predict clinical outcome. To assess biologic markers of primary CRC that may improve clinical staging and provide useful information for the application of novel therapeutic strategies, the authors investigated a panel of markers that included transforming growth factor alpha (TGF alpha), epithelial growth factor receptor (EGF-R; the protein product of the c-erb B2/HER-2 oncogene), matrix metalloproteinase 2 (MMP-2), insulin-like growth factor II (IGF-II), vascular endothelial growth factor (VEGF), and angiogenesis, as evaluated by microvessel density (MVD).

METHODS

Two groups of CRC were studied: 1) surgical samples from patients who achieved a disease free survival of at least 6 years (CRC-M0) and 2) surgical specimens of both primary tumors and synchronous or metachronous liver metastases (CRC-M1).

RESULTS

Chi-square analysis revealed that expression levels of TGF-alpha, c-erb B2/HER-2, MMP-2, IGF-II, VEGF, and MVD (but not EGF-R) were significantly higher in CRC-M1 samples compared with CRC-M0 samples (P < 0.001, P < 0.05, P < 0.001, P < 0.001, P < 0.01, and P < 0.001, respectively). Logistic regression analysis showed that TGF-alpha, IGF-II, and MMP-2 had significantly greater expression in CRC-M1 samples independent of the other variables (including tumor classification, histologic grade, and patient age). If all three markers had > or = 25% expression, then the probability of developing liver metastasis was 99.5%.

CONCLUSIONS

Based on the evidence of this study, TGF-alpha MMP-2, and IGF-II seem suitable candidates for a selective panel of markers designed to provide significant additional information with respect to the current pathologic staging system for patients with colorectal carcinoma.

The angiopoietin-like factor cornea-derived transcript 6 is a putative morphogen for human cornea

The human cornea-specific protein cornea-derived transcript 6 (CDT6) is a member of the angiopoietin gene family. We report the structural and functional characterization of CDT6. We demonstrate that CDT6 is a secreted protein that folds into disulfide-linked homotetramers by coiled-coil interactions. The finding that CDT6 is expressed at high levels in the avascular corneal stromal layer suggested that the protein, similar to certain angiopoietins, acts as a negative regulator of angiogenesis. To test this hypothesis and to assay the effect of the protein on a growing tissue with high vascular density, CDT6 was expressed in a mouse xenograft model. Expression of CDT6 led to a reduction in tumor growth and aberrant blood vessel formation by inducing massive fibrosis. Interestingly, expression of CDT6 also resulted in the deposition of extracellular matrix components typical for the mature corneal stromal layer. These observations strongly suggest a role as morphogen for CDT6 in inducing a corneal phenotype in vivo.

Expression of L-type amino acid transporter 1 (LAT1) and 4F2 heavy chain (4F2hc) in liver tumor lesions of rat models

BACKGROUND AND OBJECTIVES

It has been said that amino acid transporters play an important role in supplying nutrition to cells and for cell proliferation. In this study, we examined whether LAT1 and 4F2hc are closely related to tumor growth.

METHODS

Rat colon cancer cells (RCN-9) were injected into the spleen of 12 male rats (inbred F344/DuCrj). In each rat, liver samples including tumor lesions were immunostained with anti-LAT1 and anti-4F2hc antibodies. The staining area of LAT1 and 4F2hc tumor lesions was calculated by computer analysis.

RESULTS

Sixty-eight tumor nodules were observed in 12 livers. Out of the 68 tumor nodules, 36 nodules (52.9%) indicated a positive staining of LAT1 and 32 (47.1%) had a negative staining of LAT1. However, the LAT1 expression was scarcely detected in non-tumor areas. In terms of the 4F2hc expression, there were 56 nodules (82.4%) with 4F2hc positive and 12 (17.6) with 4F2hc negative. In addition, the expression of 4F2hc in non-tumor areas was almost the same as the expression of 4F2hc in tumor lesions. The average tumor size of the group with LAT1 positive and 4F2hc positive (n = 31) was 0.845 +/- 0.232 mm(2), which was significantly larger than that of the group with LAT1 negative and 4F2hc negative group (n = 7) (0.090 +/- 0.028 mm(2)) or the group with LAT1 positive and 4F2hc negative (n = 5) (0.097 +/- 0.025 mm(2)), respectively (P = 0.0017, P = 0.007).

CONCLUSION

LAT1 was related to tumor growth. We think that LAT1 can possibly enhance its ability to promote tumor growth in cooperation with 4F2hc.

In vivo detection of small subsurface melanomas in athymic mice using noninvasive fiber optic confocal imaging

Fiber optic confocal imaging, following intravenous administration of fluorescently labeled antibodies and Texas Red-dextran, enabled in vivo detection of melanoma and surrounding blood vessels in athymic mice. Human melanoma cells (three cell lines) and cultured normal human skin cells were implanted intradermally into the haunch skin of anesthetized athymic BALB/C mice and allowed to grow to a maximum size of 2 mm diameter. Using three different fluorescein-isothiocyanate-labeled antimelanoma antibodies, single channel confocal images of melanoma cells were obtained in vivo. Using noninvasive techniques, the overall in vivo melanoma detection rate for tumors within 0.2 mm of the skin surface was 84% (27 of 32 tumors). Normal cultured human skin cells were found to have little or no fluorescence after administration of the fluorescein-isothiocyanate-labeled antibodies and tumors were not labeled by an isotype control antibody. Dual channel imaging of the implanted melanoma tumor and surrounding dermal vasculature in vivo showed increased blood vessel density at the melanoma site. Conventional immunoperoxidase histology confirmed that fiber optic confocal imaging was able to detect melanoma tumors up to 0.2 mm below the skin surface, in vivo.

Whole-body and intravital optical imaging of angiogenesis in orthotopically implanted tumors

The development of drugs for the control of tumor angiogenesis requires a simple, accurate, and economical assay for tumor-induced vascularization. We have adapted the orthotopic implantation model to angiogenesis measurement by using human tumors labeled with Aequorea victoria green fluorescent protein for grafting into nude mice. The nonluminous induced capillaries are clearly visible against the very bright tumor fluorescence examined either intravitally or by whole-body luminance in real time. The orthotopic implantation model of human cancer has been well characterized, and fluorescence shadowing replaces the laborious histological techniques for determining blood vessel density. Intravital images of orthotopically implanted human pancreatic tumors clearly show angiogenic capillaries at both primary and metastatic sites. A quantitative time course of angiogenesis was determined for an orthotopically growing human prostate tumor periodically imaged intravitally in a single nude mouse over a 19-day period. Whole-body optical imaging of tumor angiogenesis was demonstrated by injecting fluorescent Lewis lung carcinoma cells into the s.c. site of the footpad of nude mice. The footpad is relatively transparent, with comparatively few resident blood vessels, allowing quantitative imaging of tumor angiogenesis in the intact animal. Capillary density increased linearly over a 10-day period as determined by whole-body imaging. Similarly, the green fluorescent protein-expressing human breast tumor MDA-MB-435 was orthotopically transplanted to the mouse fat pad, where whole-body optical imaging showed that blood vessel density increased linearly over a 20-week period. These powerful and clinically relevant angiogenesis mouse models can be used for real-time in vivo evaluation of agents inhibiting or promoting tumor angiogenesis in physiological microenvironments.

Evaluation of angiogenesis in canine mammary tumors by quantitative platelet endothelial cell adhesion molecule immunohistochemistry

Angiogenesis was evaluated by immunohistochemistry for platelet endothelial cell adhesion molecule (CD31) in a series of benign and malignant canine mammary neoplasms. Computer image analysis was used to measure the intratumoral microvessel density (number of microvessels per square millimeter) and the area and perimeter of immunolabeled vascular structures. A higher intratumoral microvessel density and lower values for area and perimeter were found in malignant neoplasms compared with benign tumors and among the malignant tumors, in less differentiated phenotypes and in more anaplastic histological types (solid and squamous carcinomas), most of which had metastasized. These findings are consistent with an increase in angiogenesis in multistage neoplasia. Therefore, in more anaplastic malignant neoplasms, numerous but small and often malformed new vessels can be identified. The correlation of angiogenesis data with differentiation grade and histological type of mammary neoplasms is consistent with the findings in human medicine and demonstrates that angiogenesis can also have a prognostic value in veterinary medicine.

Angiogenic balance in human melanoma: expression of VEGF, bFGF, IL-8, PDGF and angiostatin in relation to vascular density of xenografts in vivo

Tumor angiogenesis, a major requirement for tumor outgrowth and metastasis formation, is regulated by pro- and anti-angiogenic factors. We have studied the expression of a panel of angiogenic factors, and of the angiogenesis inhibitor angiostatin, in a panel of human melanoma cell lines giving rise to xenografts with different vascular densities. Angiogenic-factor expression was analyzed in vitro (cell lines) and in vivo (xenografts), both at mRNA (RT-PCR and Northern blot) and at protein level (ELISA and Western blot). In vitro angiostatin generation was assessed by Western-blot analysis. Expression of bFGF and VEGF was clearly correlated with a high degree of vascularization, confirming the importance of these factors for tumor angiogenesis. In addition, there was exclusive or elevated in vitro expression of angiogenic factors IL-8, PDGF-AB, and, to a lesser extent, midkine in cell lines that formed highly vascularized tumors. A similar angiogenic-factor-expression pattern was found in the corresponding xenografts, with the exception of VEGF. In most cell lines, this factor had low expression in vitro which was strongly enhanced in vivo. Although all 8 melanoma cell lines were able to excise the angiostatin fragment from the plasminogen parent molecule in vitro, cell lines BLM and M14 showed the most potent angiostatin generation. In vitro angiostatin generation by cell lysates prepared from melanoma xenografts was comparable in all xenograft types. Thus, in our model system we found no correlation between angiostatin generation and vascular density. Our study has limited the number of pro-angiogenic factors that may be involved in melanoma angiogenesis, and provides evidence for the notion that regulation of tumor angiogenesis is dependent on multiple factors. Inhibition of angiogenesis for therapeutic purposes, therefore, should preferably not concentrate on a single factor.

Immunohistochemical measurement of tumor vascular endothelial growth factor in breast cancer. A more reliable predictor of tumor stage than microvessel density or serum vascular endothelial growth factor

Microvessel density counting is commonly proposed as a method of assessing angiogenesis. However, results have been difficult to reproduce because of many methodological inconsistencies. Vascular endothelial growth factor (VEGF), an angiogenic regulator, is also a poor prognostic indicator in breast cancer, correlating in many studies with microvessel density. In this study, VEGF and microvessel density counting were examined as methods of assessing angiogenesis in breast cancer and correlated with tumor stage. A representative tumor section was stained with anti-CD34 and anti-VEGF. Microvessel density was evaluated using the manual "hot-spot" procedure and a semiquantitative image analysis system. Serum VEGF levels were available from an additional nine patients. Results were analyzed using Kendall's tau correlation. Tumor stage correlated with tumor VEGF, but not with microvessel "hot-spot" or vessel counts. There was no correlation between scores obtained from the manual or semiquantitative methods. Serum VEGF did not correlate with either tumor VEGF or tumor stage. The prognostic importance of VEGF in invasive breast cancer is associated with tumor stage. Measurement of tumor VEGF, as an indicator of angiogenesis, is more reliable prognostically than measurement of microvessel density or serum VEGF. Routine measurement of microvessel density in breast cancer is less reliable.

Fully automated microvessel counting and hot spot selection by image processing of whole tumour sections in invasive breast cancer

BACKGROUND

Manual counting of microvessels is subjective and may lead to unacceptable interobserver variability, which may explain conflicting results.

AIMS

To develop and test an automated method for microvessel counting and objective selection of the hot spot, based on image processing of whole sections, and to compare this with manual selection of a hot spot and counting of microvessels.

METHODS

Microvessels were stained by CD31 immunohistochemistry in 10 cases of invasive breast cancer. The number of microvessels was counted manually in a subjectively selected hot spot, and also in the same complete tumour sections by interactive and automated image processing methods. An algorithm identified the hot spots from microvessel maps of the whole tumour section.

RESULTS

No significant difference in manual microvessel counts was found between two observers within the same hot spot, and counts were significantly correlated. However, when the hot spot was reselected, significantly different results were found between repeated counts by the same observer. Counting all microvessels manually within the entire tumour section resulted in significantly different hot spots than manual counts in selected hot spots by the same observer. Within the entire tumour section no significant differences were found between the hot spots of the manual and automated methods using an automated microscope. The hot spot was found using an eight connective path search algorithm, was located at or near the border of the tumour, and (depending on the size of the hot spot) did not always contain the field with the largest number of microvessels.

CONCLUSIONS

The automated counting of microvessels is preferable to the manual method because of the reduction in measurement time when the complete tumour is scanned, the greater accuracy and objectivity of hot spot selection, and the possibility of visual inspection and relocation of each measurement field afterwards.

Quality control of immunohistochemical evaluation of tumour-associated plasminogen activators and related components. European BIOMED-1 Concerted Action on Clinical Relevance of Proteases in Tumour Invasion and Metastasis

The plasminogen activation (PA) system is involved in the breakdown and remodelling of the extracellular matrix. In the case of cancer, this is a prerequisite for invasion and metastasis. The expression of urokinase-type plasminogen activator and plasminogen activator inhibitor type 1 in particular have been reported to be of clinical and prognostic value. This has primarily been proven in the case of breast carcinoma and colon carcinoma, using the enzyme-linked immunosorbent assay (ELISA) as a quantitative assay to determine the level of expression. Immunohistochemistry is another technique to investigate the presence of PA components. It allows assessment in a semiquantitative way and informs in addition on the specific distribution within the tissue. To take full advantage of the benefits of immunohistochemistry, it is important to aim at optimal quality in all steps influencing the final judgement of the staining results. These various steps are highlighted and discussed in this paper.