Serosal penetration is an important prognostic factor for gastrointestinal stromal tumors

Predicting the malignant potential of gastrointestinal stromal tumors (GISTs) remains difficult. We assessed the value of serosal penetration, an established prognostic factor in solid tumors, to determine the clinical outcome in patients with GISTs. From 1996-2002, 25 consecutive patients with GIST underwent surgical resection at our Department. The histopathological presence of serosal penetration was assessed to predict clinical outcome. In addition, the established histopathological classification system by Franquemont (modified by using the Ki-67 proliferation index), was applied to each study patient. A Ki-67 index > or =5% (p<0.001) and a mitotic rate > or =5/50 high-power fields (p<0.047) significantly correlated with a shorter survival, whereas a tumor size >5 cm (p=0.07) tended towards a worse prognosis. The survival of patient groups defined by Franquemont (p=0.03) were of prognostic relevance. The presence of serosal penetration significantly correlated (p<0.01) with a shorter survival. Our data suggest that the presence of serosal penetration is a negative prognostic factor for GISTs. Serosal penetration may become a useful additional parameter for the classification of the malignant potential of GISTs. Since our data are merely hypothesis-generating, serosal penetration should be evaluated in large prospective databases.

Epitope mapping of mAbs to denatured human testicular ACE (CD143)

Angiotensin I-converting enzyme (ACE; CD143) has two homologous enzymatically active domains (N and C) and plays a crucial role in blood pressure regulation and vascular remodeling. A wide spectrum of monoclonal antibodies (mAbs) to different epitopes on the N and C domains of human ACE have been used to study different aspects of ACE biology. In this study, we characterized a set of nine mAbs, developed against the C domain of human ACE, which recognize the denatured forms of ACE and thus are suitable for the detection and quantification of somatic ACE (sACE) and testicular ACE (tACE) using Western blotting and immunohistochemistry on paraffin-embedded human tissues. The epitopes for these mAbs were defined using species cross-reactivity, phage display library screening, Western blotting and ACE mutagenesis. Most of the mAbs recognized common/overlapping region(s) on both somatic and testicular forms of human ACE, whereas mAb 4E10 was relatively specific for the testicular isoform and mAb 5B9 mainly recognized the glycan attached to Asn 731. This set of mAbs is useful for identifying even subtle changes in human ACE conformation because of denaturation. These mAbs are also sensitive tools for the detection of human sACE and tACE in biological fluids and tissues using proteomic approaches. Their high reactivity in paraffin-embedded tissues provides opportunities to study changes in the pattern of ACE expression and glycosylation (particularly with mAb 5B9) in different tissues and cells.

Clinicopathological significance of MMP-2 and its specific inhibitor TIMP-2 in gastric cancer

Matrix metalloproteinases (MMPs) can degrade type IV collagen of extracellular matrices and basal membranes and thus play a key role in the migration of malignant cells. In vivo, MMPs are inhibited by tissue inhibitors of metalloproteinases (TIMPs). Since in a previous study we showed that the expression of MMP-2 correlates with clinicopathological parameters in gastric cancer, we have now investigated a possible correlation of MMP-2 and TIMP-2 expression with survival in gastric cancer, as well as the possible association of TIMP-2 with clinicopathological parameters. Tissue samples were obtained from 116 gastric cancer patients who underwent gastrectomy with extended lymphadenectomy. MMP-2 and TIMP-2 expression was analysed using immunohistochemical staining and was graded semiquantitatively (score 0 - 3). High epithelial MMP-2 immunoreactivity was significantly associated with tumor stage and poor survival using the Kaplan-Meier log-rank statistical method (log-rank statistics). However, using Cox regression analysis, high epithelial MMP-2 immunoreactivity was not an independent prognostic factor. TIMP-2 showed no association with survival in gastric cancer, but the intensity of TIMP-2 staining in tumor cells correlated significantly with tumor differentiation based on the WHO and Lauren and Ming classifications, as well as with presence of distant metastasis. Our results show that high epithelial MMP-2 expression in gastric cancer is associated with poor survival, although it is not an independent prognostic factor, and that aggressive forms of gastric cancer are associated with low TIMP-2 expression.

Clinicopathologic and prognostic factors of young and elderly patients with esophageal adenocarcinoma: is there really a difference?

Evidence suggests a significant difference in the incidence, presentation, and outcome of young and elderly patients with esophageal adenocarcinoma. We aimed to compare clinicopathologic and prognostic factors of young and elderly patients with esophageal adenocarcinoma at a surgical department in Europe. From 1996 to 2006, 223 patients with a resectable esophageal adenocarcinoma were analyzed and divided in three groups: (i) patients <or=50 years (n = 40); (ii) patients between 50 and 70 years (n = 131); and (iii) patients >70 years (n = 52). Clinicopathological and prognostic factors were compared between these groups. The total number of patients with esophageal adenocarcinoma increased significantly. Although the total number of patients <or=50 years increased over the years, the proportion of young patients with esophageal adenocarcinoma was rather constant. The number of patients with a pT1-tumor was similar among all groups. Young patients had a significantly lower comorbidity and received more often a neoadjuvant radio-chemotherapy. The 5-year survival rate of young patients was significantly higher compared with elderly patients. In this European population, the total number of patients with adenocarcinoma of the esophagus increased dramatically in recent years, but the number of young patients remained rather constant. The better prognosis of young patients is mainly caused by less comorbidity and more frequent use of neoadjuvant therapy.

Long gap esophageal atresia and arterial circle of Willis variant leading to ischemic stroke during gastric transposition

In children, strokes occur with a frequency of 2 to 13 per 100,000. Risk factors include hematological, embolic and anatomical anomalies. But often the exact cause of strokes in pediatric patients remains unclear. We report here on a patient with long gap esophageal atresia, who suffered an ischemic stroke during gastric transposition. Postoperative assessment revealed a cerebral vascular variant of the circle of Willis. Follow-up clinical controls showed a favorable course. Today, at the age of 14 months, almost no neurological deficits are evident. To the best of our knowledge, no description of vascular cerebral complications combined with esophageal atresia can be found in the literature.

C-kit receptor in the human vas deferens: distinction of mast cells, interstitial cells and interepithelial cells

The molecular mechanisms underlying the regulation of vas deferens (VD) motility and semen emission are still poorly understood. Interstitial cells of Cajal (ICC), which harbour the c-kit receptor (CD117), provide the basis of coordinated gut motility. We investigated whether c-kit receptor-positive cells also exist in the normal human VD. Enzyme and fluorescence immunohistochemical techniques were applied on serial sections of human proximal, middle, and distal VD segments (n=49) employing 13 different monoclonal and polyclonal antibodies recognizing the c-kit receptor. The c-kit receptor was detected in either round- or spindle-shaped cells. On account of their antigenic profile, the round- and oval-shaped c-kit receptor-positive cells were identified as mast cells (MC) occurring in all layers of the VD except the epithelium. In contrast, two distinct populations of exclusively c-kit receptor-positive spindle-shaped cells were found within the lamina propria and, rarely, in the inner and outer smooth muscle layers, as well as within the epithelium. Different shaped c-kit receptor-positive MC and IC were present in all layers of the human VD. Our findings demonstrate the presence of different c-kit receptor-positive cells also in the human VD. Their rather ubiquitous distribution within the lamina propria and muscle layers suggests that IC and MC may modulate the neuromuscular transmission and the propagation of electrical signals in multiple systems involved in the draining of fluids. The importance of the c-kit receptor-positive interepithelial cells remains unclear.

The CCN3 gene coding for an extracellular adhesion-related protein is transcriptionally activated by the p53 tumor suppressor

The CCN3 protein (Nov, Nephroblastoma overexpressed) is a member of the CCN family (Cyr61, CTGF, Nov) of growth regulators and exerts antiproliferative properties. We show here that the tumor suppressor p53 transcriptionally upregulates the CCN3 gene. p53 is an important transcription factor contributing to cell cycle arrest and apoptosis after cell damage through the regulation of numerous target genes. We show that CCN3 mRNA and protein are upregulated following p53 expression. A DNA binding-deficient p53 mutant fails to regulate CCN3. CCN3 protein is located in the perinuclear space after induction and is also exported to the extracellular matrix. Furthermore, the CCN3 promoter is inducible by p53 and the response element is located in the first exon of the CCN3 gene. Chromatin immunoprecipitations show that p53 binds to the CCN3 promoter in vivo. As CCN3 was shown to inhibit cell growth, transcriptional induction by p53 may serve as an antiproliferative signal in the extracellular matrix. Furthermore, CCN3 depletion was also reported to reduce collagen type IV-dependent adhesion of melanocytes. Thus, elevated levels of CCN3 protein regulated by p53 might influence cell adhesion.

Comparative analysis of four histopathological classification systems to discriminate benign and malignant behaviour in gastrointestinal stromal tumors

The prognostic value of the four most common histopathological classification systems in gastrointestinal stromal tumors (GISTs) was evaluated retrospectively.

PATIENTS AND METHODS

Twenty-five consecutive patients with resected GIST and a follow-up of five years or more for surviving patients were included in this analysis. All the tumors were c-KIT (CD117) positive and were additionally re-evaluated for the number of mitoses per 50 high-power fields (HPF) and Ki-67 proliferation index. The four most commonly applied histopathological classification systems of the WHO, Franquemont (modified by using the Ki-67 proliferation index), Fletcher and Miettinen were applied to each patient.

RESULTS

The survival of patient groups classified by Franquemont (p = 0.03) and the WHO (p = 0.031) were of prognostic relevance, while the grouping of patients by classifications according to both, Fletcher and Miettinen did not show a significant prognostic value.

CONCLUSION

The classification systems of Franquemont (modified) or WHO appear to be advantageous for the evaluation of malignant potential and clinical outcome in patients with GISTs. Our data are merely hypothesis generating and should be validated in larger clinical studies.

Lack of Thy1 (CD90) expression in neuroblastomas is correlated with impaired survival

Neuroblastoma (NBL) is the most common solid tumor in children. Tumors in advanced stage or with positive risk factors still have a poor prognosis. Thy1 (CD90) is a membrane glycoprotein expressed in thymus, retinal ganglionic cells, and several types of stem cells. The aim of this study was to assess Thy1 expression in NBL and analyze the correlation with clinical outcome. Sixty-three specimens of NBL were stained for Thy1 on a tissue microarray by immunohistochemistry. Fresh frozen tumor tissues were used for RNA isolation, and RT-PCR analysis for Thy1-mRNA expression was performed. Patients' survival data were correlated with Thy1 status using a log rank test and a Cox regression multivariate analysis. Thy1 was expressed on 51 (81%) of the tumors. Kaplan-Meier survival analysis showed a significantly impaired survival in patients with NBL missing Thy1 (P < 0.005 by log-rank test). A multivariate Cox regression showed an independent prognostic value of Thy1 status for overall survival (P < 0.05). In addition, the frequency of events and deaths was significantly higher in the group of patients with Thy1 negative tumors, as assessed by ANOVA analysis (P < 0.05 by F-test). The data showed that Thy1-negative NBL patients have a significantly impaired overall survival compared with Thy1-positive NBL patients. Thus, Thy1 seemed to be a marker with a specific prognostic value in NBL patients. Future studies are aiming at the biological role of this marker in the tumor cell differentiation.

Alterations of tumor and normal tissue of human lung cancer resection specimens after isolation perfusion

The isolation perfusion model, including transbronchial ventilation of human lung, offers the possibility to study pharmacological interactions under physiological conditions. In view of the increasing importance of targeted therapy of lung diseases, this model of perfusion might attract major interest, particularly, in lung cancer. Our study investigated physiological, histological, and immunohistochemical alterations of lung and tumor tissue during isolated perfusion of lung lobectomy specimens to explore potential limitations of this model. Right after resection, 16 human lung resection specimens for primary lung cancer were isolated, ventilated, and perfused under physiological conditions with a modified Krebs-Henseleit solution over a period of 10, 60, 90, 120, and 240 min. Perfusion pressure, pH, lung weight gain, and histological edema formation were measured continuously before and during perfusion. After perfusion, lung and tumor tissue was investigated by hematoxylin-and-eosin stained sections. Immunohistochemistry of NADH, PECAM-1, angiotensin-converting-enzyme and NF-kappabeta were performed to determine lung tissue viability and changes at the endothelial layer. We found that perfusion up to 120 min could be performed with completely stable physiological conditions. Beyond that time span, edema formation and weight gain of the resection specimen started and were followed by an increase in inspiratory pressure and pulmonary artery pressure. Perfusion of more than 4 h led to a significant edema formation in lung tissue accompanied by loss of viability and significant histological alterations. We conclude that isolated ventilation and perfusion of human lung resections within the setup chosen is reliable for pharmacological studies up to a period of 120 min. Thereafter, edema formation and endothelial damage develop and limit the interpretation and reliability of drug delivery studies.

Association of COX-2 expression with corresponding active and chronic inflammatory reactions in Barrett's metaplasia and progression to cancer

AIMS

Risk reduction for Barrett's cancer in individuals taking non-steroidal anti-inflammatory drugs has been reported. Cyclooxygenase (COX)-2, one of the inhibited enzymes, is putatively involved in Barrett's cancer pathogenesis. The aim of this study was to examine a possible association between COX-2 protein expression and the development and progression of the Barrett's metaplasia-dysplasia-carcinoma sequence and the type and degree of associated inflammatory reaction.

METHODS AND RESULTS

Squamous epithelium, metaplastic, low-grade, high-grade dysplastic lesions and tumour tissue of 49 resection specimens from patients with Barrett's adenocarcinoma were immunohistochemically analysed. Active and chronic inflammatory reactions were classified according to the Updated Sydney System. Within the Barrett's sequence, a significant progressive increase in COX-2 expression was identified (P < 0.0001). The most significant differences were detected between squamous epithelium and Barrett's metaplasia (P < 0.001) and from low- to high-grade dysplasia (P < 0.0001). Active and chronic inflammation were significantly different between squamous epithelium and Barrett's metaplasia (P < 0.0001), but not during further progression in the sequence.

CONCLUSIONS

Increasing COX-2 expression in Barrett's metaplasia is significantly associated with a change in the local inflammatory reaction, but not during further progression through dysplasia to cancer. This supports the potential of a chemoprevention strategy using COX-2 inhibitors independent of the extent and type of the inflammatory reaction in Barrett's oesophagus.

First Report of Pythium intermedium Causing Root Rot on Rosa canina Rootstock in France

Old cultivars of roses (Rosa spp.) established on Rosa canina as rootstock are grown in field collections in the repository at Gaillard in eastern France, close to the Swiss border. During June 2005 and July 2006, several rose plants in full vegetation were severely wilted, leading ultimately to plant death. Necrotic lesions were present on the roots, and marginal tissue was excised and incubated in the dark at 20°C on PARP V8 agar plates (1). Similar isolates were obtained in both years, which were inoculated within 4 days on V8 agar medium and incubated at 25°C. The pathogen colonies grew approximately 30 mm daily on V8 agar. Colonies on corn meal agar (CMA) (1) were submerged, with or without a vague radiate pattern on potato carrot agar. Main hyphae were as much as 7 μm wide. Sporangia and zoospores were not produced. Hyphal swellings as much as 25 μm in diameter were abundant, terminal, and sometimes intercalary, often forming regular, dense chains in basipetal succession at hyphal tips and readily liberated. The morphological characters matched those described for Pythium intermedium (2). DNA sequencing of the ITS rDNA (ITS1, ITS2, and 5.8S rDNA) was generated using primers ITS5 and ITS4 in primary PCR (35 cycles: 96°C for 1 min, 55°C for 1 min, and 72°C for 2 min) and sequencing reactions (1). All isolates yielded identical ITS sequences, which were identical to the ex-type strain of P. intermedium, CBS 266.38 (GenBank Accession No. AY598647). The ITS sequence was deposited as GenBank Accession No. EF078693 (National Center for Biotechnology Information, NCBI, Bethesda, MD). Pathogenicity testing was performed on 3-year-old Rosa canina rootstocks from clonal propagation in 25 cm in diameter and 40 cm deep pots of compost 297 (Ricoter, Aarberg, Switzerland). Five-day-old mycelial plugs of our isolates grown on CMA (1) were inoculated in two pots, and roots were mechanically wounded. Sterile plugs were used on two control plants set aside. All plants were kept for 2 weeks at 20°C in a glasshouse with sufficient watering. Extensive necrotic lesions developed on inoculated roots, and severe wilting and leaves drying out were also observed. The controls showed no symptoms. P. intermedium was reisolated from margins of root lesions, thus fulfilling the postulates of Koch. P. intermedium was originally isolated from dead plant material (2) but is known as a typical soil inhabitant. It also has been isolated from water and living material from numerous plant species, but never from the genus Rosa until now. To our knowledge, this is the first record of P. intermedium on Rosa spp. grafted on Rosa canina in France. References: (1) L. Belbahri et al. FEMS Microbiol Lett 255:209, 2006. (2) A. J. van der Plaats-Niterink. Stud. Mycol. 21:1, 1981.

Survivin expression in esophageal cancer: Association with histomorphological response to neoadjuvant therapy and prognosis

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Background: The poor prognosis associated with locally advanced esophageal cancer prompted an evaluation of combined modality treatments including neoadjuvant radiochemotherapy in combination with surgery. However, it has been well established that only patients with a complete pathological response to neoadjuvant therapy will have a significant survival benefit. Therefore, predictive markers to allow a tailored radiochemotherapy are needed. The aim of this study was to examine the association of the protein expression of survivin, an inhibitor of apoptosis, with histopathologic response to neoadjuvant radiochemotherapy and prognosis of patients with locally-advanced esophageal cancer. Methods: 59 patients with esophageal cancer (cT2–4, Nx, M0) received neoadjuvant radiochemotherapy (cisplatin, 5-FU, 36 Gy) followed by esophagectomy. Histomorphologic regression was defined as major response when resected specimens contained less than 10 % and as minor response when resected specimens contained more than 10 % of residual vital tumor cells. Pre- and post-therapeutic intratumoral protein expression of survivin was determined and correlated with clinicopathologic parameters. Results: The pre-therapeutic intratumoral survivin protein expression was not associated with any clinicopathologic factor, including histopathologic response and prognosis. Survivin protein expression was significantly reduced during neoadjuvant therapy, showing lower levels in post-therapeutic tumor samples (p<0.01). Higher postoperative survivin levels were significantly associated with a higher ypT-stage (p<0.009), a poorer histopathologic response (p<0.01) and a shorter overall survival (p<0.028). Conclusions: The intratumoral protein expression of survivin was significantly down-regulated during neoadjuvant therapy, whereas a higher survivin level after pre-operative therapy was significantly associated with a worse histopathologic response and prognosis. Therapeutic strategies which are able to reduce survivin expression or to block survivin mediated pathways might increase the histopathologic response rate and prognosis in the multimodal therapy of patients with locally-advanced esophageal cancer.

No significant financial relationships to disclose.

Immunotargeting of catalase to lung endothelium via anti-angiotensin-converting enzyme antibodies attenuates ischemia-reperfusion injury of the lung in vivo

Limitation of reactive oxygen species-mediated ischemia-reperfusion (I/R) injury of the lung by vascular immunotargeting of antioxidative enzymes has the potential to become a promising modality for extension of the viability of banked transplantation tissue. The preferential expression of angiotensin-converting enzyme (ACE) in pulmonary capillaries makes it an ideal target for therapy directed toward the pulmonary endothelium. Conjugates of ACE monoclonal antibody (MAb) 9B9 with catalase (9B9-CAT) have been evaluated in vivo for limitation of lung I/R injury in rats. Ischemia of the right lung was induced for 60 min followed by 120 min of reperfusion. Sham-operated animals (sham, n = 6) were compared with ischemia-reperfused untreated animals (I/R, n = 6), I/R animals treated with biotinylated catalase (CAT, n = 6), and I/R rats treated with the conjugates (9B9-CAT, n = 6). The 9B9-CAT accumulation in the pulmonary endothelium of injured lungs was elucidated immunohistochemically. Arterial oxygenation during reperfusion was significantly higher in 9B9-CAT (221 +/- 36 mmHg) and sham (215 +/- 16 mmHg; P < 0.001 for both) compared with I/R (110 +/- 10 mmHg) and CAT (114 +/- 30 mmHg). Wet-dry weight ratio of I/R (6.78 +/- 0.94%) and CAT (6.54 +/- 0.87%) was significantly higher than of sham (4.85 +/- 0.29%; P < 0.05), which did not differ from 9B9-CAT (5.58 +/- 0.80%). The significantly lower degree of lung injury in 9B9-CAT-treated animals compared with I/R rats was also shown by decreased serum levels of endothelin-1 (sham, 18 +/- 9 fmol/mg; I/R, 42 +/- 12 fmol/mg; CAT, 36 +/- 11 fmol/mg; 9B9-CAT, 26 +/- 9 fmol/mg; P < 0.01) and mRNA for inducible nitric oxide synthase (iNOS) [iNOS-GAPDH ratio: sham, 0.15 +/- 0.06 arbitrary units (a.u.); I/R, 0.33 +/- 0.08 a.u.; CAT, 0.26 +/- 0.05 a.u.; 9B9-CAT, 0.14 +/- 0.04 a.u.; P < 0.001]. These results validate immunotargeting by anti-ACE conjugates as a prospective and specific strategy to augment antioxidative defenses of the pulmonary endothelium in vivo.

Efficacy of Electrocautery in Different Media: Air, Perfluorodecalin, Glycerine, Glycine, and Electrolyte Solution

BACKGROUND

Electrocautery during fetoscopic surgery is impossible in the electrolyte-containing amniotic fluid. Intrauterine insufflation of carbon dioxide may cause lethal hypercapnia and acidosis in the fetus. Therefore, other media must be considered.

OBJECTIVE

To evaluate the efficacy of electrocautery in different media that have been described for fetoscopic surgery.

MATERIALS AND METHODS

Using bipolar electrocautery, lesions were made in 16 skin/cartilage specimens from the ears of New Zealand White rabbits in 5 different media: air, 85% glycerine, 1.5% glycine, electrolyte solution, and perfluorodecalin. The efficacy of electrocautery in the different media was compared by calculating mean necrosis indices--the quotient of native to necrosed tissue thickness--and assessing the qualitative histologic changes.

RESULTS

In all media except the electrolyte solution, the cauterized areas showed clear sequellae of electrocautery such as thinning, loss of tissue architecture, increased stromal staining, and nuclear disintegration. Mean necrosis indices were 1.38 +/- 0.24 for air, 1.37 +/- 0.28 for glycerine, 1.32 +/- 0.23 for perfluorodecalin, 1.31 +/- 0.14 for glycine, and 1.05 +/- 0.10 for electrolyte solution (P < 0.01 for electrolyte solution compared to all other media). No significant differences were detected between the nonconductive substances.

CONCLUSION

In our tests, air, glycine, glycerine, and perfluorodecalin allowed similarly effective electrocauterization. As expected, bipolar electrocautery in electrolyte solution is ineffective. The perfluorocarbon perfluorodecalin may have other potential advantages as a medium in endosurgery, such as low surface tension, biologic inertia, optical clarity, and insolubility of blood.

Tumor model for laparoscopy in pediatric oncology: subperitoneal inoculation of human hepatoblastoma cells in nude rats

BACKGROUND

Minimally invasive surgery (MIS) for diagnostic or even ablative purposes in pediatric oncology is gradually evolving, but little is known about its biological consequences and surgical complications. Especially for hepatoblastoma (HB), no study on the influence of laparoscopy is available yet. A special tumor model could facilitate a variety of investigations. The present study introduces a laparoscopic technique to create subperitoneal metastases of human HB.

METHODS

7 immuno-incompetent (rnu/rnu) rats (mean weight 198 g) received a stab incision in the lower abdomen to insert a 4 mm scope. Under laparoscopic guidance (CO2 pressure of 1 mmHg, flow of 0.2 l/min) an 18 G needle was introduced, to inject several subperitoneal deposits of the tumor cell suspension (HuH6, 3 x 10 (6) in 1 ml of RPMI-1640 medium). Tumor growth was allowed for 6 - 7 weeks and finally the animals were laparoscopically evaluated for peritoneal metastases. Each suspicious lesion was harvested for histology.

RESULTS

One animal was investigated after 6 weeks without evidence of tumor growth. After 7 weeks, in 4 out of 6 animals at least one lesion could be detected. Histology revealed HB in all specimens.

CONCLUSION

Subperitoneal inoculation of human HB cells in nude rats achieves intraabdominal tumor growth. The present model allows a variety of laparoscopic strategies and their oncological impact to be studied. Thus it may contribute to the development of distinct oncological concepts for MIS in children with HB.

Laparoscopic fluorescence diagnosis of peritoneal metastases from human hepatoblastoma in nude rats

AIM

Fluorescence diagnosis is gaining clinical importance for the detection of malignancies in various medical disciplines. The technique relies on the specific metabolic capacity of a lesion to produce a fluorescent compound. It is still unknown whether pediatric solid tumors like hepatoblastoma (HB) are susceptible to this technique as well.

METHODS

Human HB (3 x 10(6)) cells were laparoscopically injected (4 mm scope, 18-G needle) underneath the peritoneum of 7 nude rats (mean weight, 198 g). Tumor growth was allowed for 7 weeks. Photosensitization was induced by peritoneal lavage with aminolevulinic acid (3%). After 3 hours, the animals were investigated with white light laparoscopy (WL) and laparoscopic fluorescence diagnosis (LFD), applying the Storz PDD system. Every suspicious lesion was analyzed by spectrometry and harvested for histology.

RESULTS

Every tumor seen in WL also demonstrated strong fluorescence during LFD (100%). One micrometastasis, almost invisible in WL, was obviously illuminating in LFD. Spectrometry demonstrated the specific peak of the aminolevulinic acid metabolite protoporphyrin IX at 635 nm and a 6.34-fold increase of the fluorescence intensity. Histology revealed HB in all specimens.

CONCLUSION

Human HB can be detected with LFD in a rat model. This finding opens a wide spectrum of experimental and clinical investigations to evaluate the impact of fluorescence diagnosis for pediatric oncology.

Selective rat lung endothelial targeting with a new set of monoclonal antibodies to angiotensin I-converting enzyme

We demonstrated previously that monoclonal antibody (mAb) 9B9 to angiotensin-converting enzyme (ACE) accumulates selectively in the rat lung after systemic injection and thus is a powerful tool for immunotargeting therapeutic agents/genes to the lung microvasculature. Bearing in mind the tremendous research and therapeutic potential of lung immunotargeting via ACE, we generated a novel set of mAbs to rat ACE in order to enhance the repertoire of mAbs suitable for targeting drugs/genes to the rat lung. Five new mAbs recognizing different epitopes on rat ACE were examined for their efficacy to bind rat ACE both in vitro and in vivo. Gene delivery into cultured rat lung endothelial cells increased 30-50-fold after coating modified adenoviruses (containing Ig-binding domain) with mAbs to rat ACE. Radiolabeled mAbs specifically accumulated in the lung after systemic injection. mAb 1A2, 4H3 and 2E1 demonstrated the highest efficacy of lung uptake-around 50% of injected dose per gram of tissue; for mAb 1A2, the selectivity of lung uptake (ratio of lung to blood radioactivity) was 205. The effect of the mAbs on ACE shedding was epitope-specific: injection of mAb 1A2 and 4H3 did not change lung ACE activity, whereas injection of mAb 2E1 and 9B9 decreased rat lung ACE activity by 20%. None of the tested mAbs inhibited ACE activity in vitro. A new set of mAbs to rat ACE demonstrated highly efficient and selective lung accumulation and thus have the potential for targeting drugs/genes to the pulmonary vasculature in different rat models of lung diseases.

Monoclonal antibodies to native mouse angiotensin-converting enzyme (CD143): ACE expression quantification, lung endothelial cell targeting and gene delivery

We demonstrated previously that the monoclonal antibody 9B9 to angiotensin-converting enzyme (ACE), which accumulates very selectively into the rat lung after systemic injection, is a powerful tool for immunotargeting of therapeutic agents or genes to the rat lung vascular bed. Bearing in mind a high research and therapeutic potential of lung targeting via ACE, we obtained a new set of rat monoclonal antibodies to different epitopes of mouse ACE in order to expand this approach to mice. Nine new monoclonal antibodies, recognizing epitopes on the N- and C-domains of catalytically active mouse ACE, were obtained and examined for their efficacy to bind ACE both in vitro and in vivo. This set of monoclonal antibodies was proved to be useful for ACE quantification (by flow cytometry and cell enzyme-linked immunosorbent assay) on the surface of different mouse ACE-expressing cells: endothelial cells, monocytes, macrophages, dendritic cells and spermatozoa. Moreover, gene delivery into mouse ACE-expressing cells using adenoviruses increased 40-fold after redirecting of these viruses to ACE (by coating these viruses with anti-ACE monoclonal antibodies). Radiolabelled (I(125)) monoclonal antibodies specifically accumulated in the mouse lung after systemic injection. Monoclonal antibodies 3G8.17, 4B10.5 and 4B10.17 demonstrated the highest level of lung uptake, 40-50% of injected dose, and high selectivity of lung uptake. Influence of monoclonal antibodies on ACE shedding was negligible, except monoclonal antibody 1D10.11. None of the tested monoclonal antibodies inhibited ACE activity in vitro. In conclusion, a new set of rat monoclonal antibodies to mouse ACE was obtained suitable to study ACE biology in mice and for ACE expression quantification on mouse cells in particular. These monoclonal antibodies also demonstrated highly efficient and selective lung accumulation and thus has the potential for targeting drugs/genes to the pulmonary vasculature in different mouse models of human lung diseases, including numerous knockout models.