Protective effectiveness of anise against testicular ischemia and reperfusion injury: An experimental study in rats.

Testicular torsion is a frequently encountered clinical condition that requires urgent treatment. The aim of this study is to investigate the efficacy of Anise (Pimpinella anisum L.) in treating the pathological condition due to ischemia and reperfusion injury by using biochemical, histopathological and immunohistochemical methods. A total of 6 groups were formed with 8 male Wistar Albino rats in each group. Group 1 (n=8): control group, Group 2 (n=8): Anise aqueous solution was given orally 5 ml/kg by gavage for 30 days. Group 3 (n=8): Ischemia and Reperfusion (I/R) group, bilateral testicles were rotated 270° and reperfused after 30 minutes of ischemia. Group 4 (n=8): I/R+ Anise group, Group 5 (n=8): Anise+ I/R group and Group 6 (n=8): Anise+ I/R+ Anise group. The results of the Anise group and the Control group were similar. However, the damage in the I/R group was considerably more severe than in any of the other study groups. While it was observed that spermatogenic cells started to regenerate in the I/R+Anise group, edema and congestion were observed in the Anise+I/R group. In the Anise+I/R+Anise group, all histological findings and biochemical parameters were similar to those of the control group. It was observed that anise had protective effects in ischemia and reperfusion injury in rat testicles.

In vitro and in vivo assessment of direct effects of simulated solar and galactic cosmic radiation on human hematopoietic stem/progenitor cells.

Future deep space missions to Mars and near-Earth asteroids will expose astronauts to chronic solar energetic particles (SEP) and galactic cosmic ray (GCR) radiation, and likely one or more solar particle events (SPEs). Given the inherent radiosensitivity of hematopoietic cells and short latency period of leukemias, space radiation-induced hematopoietic damage poses a particular threat to astronauts on extended missions. We show that exposing human hematopoietic stem/progenitor cells (HSC) to extended mission-relevant doses of accelerated high-energy protons and iron ions leads to the following: (1) introduces mutations that are frequently located within genes involved in hematopoiesis and are distinct from those induced by γ-radiation; (2) markedly reduces in vitro colony formation; (3) markedly alters engraftment and lineage commitment in vivo; and (4) leads to the development, in vivo, of what appears to be T-ALL. Sequential exposure to protons and iron ions (as typically occurs in deep space) proved far more deleterious to HSC genome integrity and function than either particle species alone. Our results represent a critical step for more accurately estimating risks to the human hematopoietic system from space radiation, identifying and better defining molecular mechanisms by which space radiation impairs hematopoiesis and induces leukemogenesis, as well as for developing appropriately targeted countermeasures.

Ultrastructural changes in the kidney cortex of rats treated with lead acetate / Cambios ultraestructurales en la corteza renal de ratas tratadas con acetato de plomo

The purpose of this study was to investigate the ultrastructural effects of lead on the kidney cortex of rats. Wistar Albino rats (180-200g body weight) were divided into a controlled and lead acetate-exposed group. Rats received lead acetate at 500 ppm in their drinking water for 60 days. Both groups were fed with the same standard food, but lead acetate was added to the drinking water. During the experimental period, blood samples were taken from the abdominal aorta of the anesthetised animals. At the end of exposure, body weight and blood lead levels were measured. The kidney tissue samples were prepared and analyzed by light and transmission electron microscopy. Cortical renal tubules show various degenerative changes with focal tubular necrosis invaded by inflammatory cells. The ultrastructural alterations found in lead acetate-treated rats were a diminution in the amount of filtration slits, increased fusion of foot processes in epithelial cells of the glomeruli, increase of lysosomal structures and pinocytic vesicles as well as large mitochondria in proximal tubule cells.

El propósito de este estudio fue investigar los efectos ultraestructurales del plomo en la corteza renal. Ratas Wistar albinas (180-200g de peso corporal) fueron divididas en grupo control y grupo experimental. Las ratas recibieron 500 ppm de acetato de plomo en el agua potable durante 60 días. Ambos grupos fueron alimentados con el mismo alimento estándar, pero acetato de plomo se le añadió al agua potable al grupo experimental. Durante el período experimental, se tomaron bajo anestesia muestras sanguíneas desde la parte abdominal de la aorta. Al final de la exposición, fueron medidos el peso corporal y los niveles de plomo en la sangre. Fueron preparadas las muestras de tejido renal y se analizaron mediante microscopía de luz y electrónica de transmisión. Los túbulos renales corticales mostraron varios cambios degenerativos con necrosis tubular focal invadida por células inflamatorias. Las alteraciones ultraestructurales encontradas en las ratas tratadas con acetato de plomo correspondieron a una disminución en la cantidad de ranuras de filtración, aumento de la fusión de los procesos podales en las células epiteliales de los glomérulos, aumento de la estructura lisosomal y las vesículas pinocíticas, así como grandes mitocondrias en las células del túbulo proximal.

Ab initio calcineurin inhibitor-based monotherapy immunosuppression after liver transplantation reduces the risk for Pneumocystis jirovecii pneumonia.

At the Tor Vergata University of Rome, ab initio calcineurin inhibitor-based monotherapy immunosuppression (IS) is the standard of treatment after liver transplantation (LT). As the net state of IS determines the onset of Pneumocystis jirovecii pneumonia (PCP), we hypothesized that, in the presence of weak impairment of the immune function, as determined by the above-mentioned IS, the host is not overexposed to the risk for PCP and consequently the specific anti-PCP prophylaxis is unnecessary. In a single-cohort descriptive study, we retrospectively investigated the incidence of PCP in 203 LT patients who did not receive anti-PCP prophylaxis because they were under monotherapy IS. The primary endpoint of the study was the incidence of PCP during the first 12 months following LT; secondary endpoints were the incidence of acute rejection requiring additional IS and of CMV infection. No cases of PCP were recorded. The incidence of CMV and acute rejection was 3.9% and 0.9%, respectively. Our data suggest that monotherapy IS after LT may nullify the risk for PCP even in the absence of any specific prophylaxis.

Unilateral vernal keratoconjunctivitis: a case report.

PURPOSE: A rare case of unilateral vernal keratoconjunctivitis is presented. METHODS: A 5-year-old boy had itching, foreign body sensation, redness, and ptosis in his left eye. Impression cytology specimens were taken from both upper eyelid tarsal conjunctiva. RESULTS: On slit-lamp biomicroscopy, unilateral cobblestone papillae and a shield ulcer were found in the left eye. On impression cytology examination, there was a significant increase in inflammation, presence of a honeycomb pattern, plasma cells, and mucus strands in the upper tarsal conjunctiva of the specimens. CONCLUSIONS: Giant papillary conjunctivitis must be considered in differential diagnosis of unilateral vernal conjunctivitis. Impression cytology method may be combined with the clinical findings in vernal keratoconjunctivitis diagnosis.

Alterations in angiogenic growth factors and neuronal nitric oxide synthase expression in chronic cavernosal ischemia.

Our aim was to study anatomical and molecular changes at varying time points after the induction of cavernosal ischemia (CI) in a rabbit model of arteriogenic erectile dysfunction. Tissue structure and the expression of angiogenic and neurogenic genes were examined using immunostaining and reverse transcription-polymerase chain reaction (RT-PCR) analyses. We found a progressive increase of erectile connective tissue together with a decrease in smooth muscle cell content as the duration of CI increased. Immunohistochemical staining showed an increase in vascular endothelial growth factor (VEGF) levels at the early stages and a decrease at the later stages of ischemia. RT-PCR analysis of VEGF and neuronal nitric oxide synthase (nNOS) confirmed these results and showed nearly a two-fold increase in VEGF and nNOS mRNA levels in the early stages of CI with a decrease at the later stages of CI. On the other hand, mRNA levels of VEGF receptor, KDR, decreased approximately by 50% over the course of CI. Our studies showed that the cellular and molecular responses of the erectile tissue to short-term ischemia are different than those seen after long-term ischemia. The dramatic reduction in KDR expression suggests that the cavernosal endothelium is very sensitive to ischemia. The similar changes in VEGF and nNOS expression over the course of CI suggest a tissue-defensive mechanism to CI via the VEGF and NO pathways. Taken together, this study suggests that supplementation of VEGF at earlier stages of ischemia may restore the damaged endothelial cells of the corpus cavernosum and support tissue perfusion.

Functional small-diameter neovessels created using endothelial progenitor cells expanded ex vivo.

Arterial conduits are increasingly preferred for surgical bypass because of inherent functional properties conferred by arterial endothelial cells, especially nitric oxide production in response to physiologic stimuli. Here we tested whether endothelial progenitor cells (EPCs) can replace arterial endothelial cells and promote patency in tissue-engineered small-diameter blood vessels (4 mm). We isolated EPCs from peripheral blood of sheep, expanded them ex vivo and then seeded them on decellularized porcine iliac vessels. EPC-seeded grafts remained patent for 130 days as a carotid interposition graft in sheep, whereas non-seeded grafts occluded within 15 days. The EPC-explanted grafts exhibited contractile activity and nitric-oxide-mediated vascular relaxation that were similar to native carotid arteries. These results indicate that EPCs can function similarly to arterial endothelial cells and thereby confer longer vascular-graft survival. Due to their unique properties, EPCs might have other general applications for tissue-engineered structures and in treating vascular diseases.

Vascular endothelial growth factor-mediated autocrine stimulation of prostate tumor cells coincides with progression to a malignant phenotype.

Vascular endothelial growth factor (VEGF), which is often produced at high levels by tumor cells, is a well-known mediator of tumor angiogenesis. VEGF receptor tyrosine kinases, KDR/Flk-1 and Flt-1, have been thought to be expressed exclusively by endothelial cells. In this study, we have used a prostate tumor progression series comprised of a differentiated rat prostate epithelial cell line, NbE-1, and its highly motile clonal derivative, FB2. Injection of NbE-1 cells into the inferior vena cava of syngeneic rats indicated that these cells are nontumorigenic. Using the same model, FB2 cells generated rapidly growing and well-vascularized tumors in the lungs. NbE-1 expressed marginal levels of VEGF, whereas high levels of VEGF protein were detected in FB2-conditioned medium and in FB2 tumors in vivo. Analysis of (125)I-VEGF(165) binding to NbE-1 and FB2 cells indicated that only motile FB2 cells expressed the VEGF receptor Flt-1. Consistent with this finding, physiological concentrations of VEGF induced chemotactic migration in FB2 but not in NbE-1 cells. This is the first documentation of a functional Flt-1 receptor in prostate tumor cells. Our results suggest two roles for VEGF in tumor progression: a paracrine role as an angiogenic factor and a previously undescribed role as an autocrine mediator of tumor cell motility.

Tissue specific regulation of VEGF expression during bone development requires Cbfa1/Runx2.

Vascular endothelial growth factor (VEGF) is a critical regulator of angiogenesis during development, but little is known about the factors that control its expression. We provide the first example of tissue specific loss of VEGF expression as a result of targeting a single gene, Cbfa1/Runx2. During endochondral bone formation, invasion of blood vessels into cartilage is associated with upregulation of VEGF in hypertrophic chondrocytes and increased expression of VEGF receptors in the perichondrium. This upregulation is lacking in Cbfa1 deficient mice, and cartilage angiogenesis does not occur. Finally, over-expression of Cbfa1 in fibroblasts induces an increase in their VEGF mRNA level and protein production by stimulating VEGF transcription. The results demonstrate that Cbfa1 is a necessary component of a tissue specific genetic program that regulates VEGF during endochondral bone formation.

Peptides encoded by exon 6 of VEGF inhibit endothelial cell biological responses and angiogenesis induced by VEGF.

VEGF induces pathological angiogenesis and is an important target for the development of novel antiangiogenic molecules. In this study, we tested synthetic peptides based on the sequence of VEGF(189) for their ability to inhibit VEGF receptor binding and biological responses. We identified 12-amino acid peptides derived from exon 6 that inhibited VEGF binding to HUVECs, VEGF-stimulated ERK activation, and prostacyclin production. These peptides inhibited VEGF-induced mitogenesis, migration, and VEGF-dependent survival of endothelial cells, but caused no increase in apoptosis in the absence of VEGF. Exon 6-encoded peptides also caused a marked inhibition of VEGF-induced angiogenesis in vitro. Studies of effects of peptides on cross-linking of VEGF to its receptors and on binding of VEGF to porcine aortic endothelial cells expressing either KDR or neuropilin-1 showed that exon 6-encoded peptides effectively blocked the interaction of VEGF with both receptors. Exon 6-derived peptides caused release of bFGF from endothelial cells but inhibited bFGF-dependent ERK activation, cell proliferation and angiogenesis. Our findings indicate that VEGF exon 6-encoded peptides inhibit VEGF-induced angiogenesis, at least in part through inhibition of VEGF binding to KDR. In addition, exon 6-encoded peptides are also effective inhibitors of bFGF-mediated angiogenesis.

Neuropilin in the midst of cell migration and retraction.

Neuropilin (NRP) is a 140 kDa membrane protein, with a large extracellular domain and a short cytoplasmic tail, that was isolated in 1987 from the optic tactum of Xenopus laevis. About 10 years after its isolation, NRP was identified as a receptor for semaphorin, a family of axonal chemorepellent proteins and for vascular endothelial growth factor (VEGF), a family of potent angiogenic factors. In the nervous system, NRP forms a high affinity semaphorin-binding complex with a receptor tyrosine kinase, plexin, that mediates semaphorin-induced growth cone collapse. On the endothelium, NRP is expressed together with KDR, a VEGF receptor tyrosine kinase. We have shown that NRP potentiated KDR-mediated endothelial cell migration and proliferation. Some tumor cells can express high levels of NRP, which is typically their only VEGF receptor, but do not seem to respond to VEGF directly. Possible use of NRP as a target for VEGF antagonists, in the context of antiangiogenic therapy, are described.

Neuropilin-1 expression by tumor cells promotes tumor angiogenesis and progression.

Neuropilin-1 (NRP1) is a VEGF(165) and semaphorin receptor expressed by vascular endothelial cells (EC) and tumor cells. The function of NRP1 in tumor cells is unknown. NRP1 was overexpressed in Dunning rat prostate carcinoma AT2.1 cells using a tetracycline-inducible promoter. Concomitant with increased NRP1 expression in response to a tetracycline homologue, doxycycline (Dox), basal cell motility, and VEGF(165) binding were increased three- to fourfold in vitro. However, induction of NRP1 did not affect tumor cell proliferation. When rats injected with AT2.1/NRP1 tumor cells were fed Dox, NRP1 synthesis was induced in vivo and AT2.1 cell tumor size was increased 2.5- to 7-fold in a 3-4 wk period compared to controls. The larger tumors with induced NRP1 expression were characterized by markedly increased microvessel density, increased proliferating EC, dilated blood vessels, and notably less tumor cell apoptosis compared to noninduced controls. It was concluded that NRP1 expression results in enlarged tumors associated with substantially enhanced tumor angiogenesis.

Prospective evaluation of the argon laser treatment of trachomatous trichiasis.

PURPOSE: To evaluate the effectiveness of argon laser photocoagulation for the treatment of trachomatous trichiasis. METHODS: This report presents a prospective, non-masked study of 22 patients (36 eyelids) with trachomatous trichiasis treated with the argon laser. Each abnormal lash was treated with a beam of 50- to 200-micron spot size, for 0.2 seconds, and 1 to 1.2 watts power. In 30 lids (83.3%) infiltration anesthesia was used and in 6 lids (16.7%) no anesthesia was used. RESULTS: Successful treatment with no evidence of recurrence was achieved in 55.5% of lids after one laser session. The remaining 44.5% of the lids required two or three sessions. The final success rate of the method was 88.9%. No complications were observed. The mean follow-up time was 10.6 months. CONCLUSION: Argon laser photocoagulation is an effective and safe method for the treatment of trachomatous trichiasis.

Mitomycin C primary trabeculectomy with releasable sutures in primary glaucoma.

PURPOSE: To evaluate the effects of mitomycin C and a releasable suture technique on outcomes of primary trabeculectomy in primary glaucoma patients. METHODS: A prospective analysis of patients who underwent primary trabeculectomy with a mitomycin C concentration of 0.2 mg/mL for 2 minutes. For closing the scleral flap, releasable sutures were used in 18 patients (17 eyes), Group 1, or permanent sutures in 18 patients (20 eyes), Group 2. Clinical outcome factors including postoperative intraocular pressure (IOP), visual acuity, and incidence of complications were determined. RESULTS: The mean follow-up periods were 8.1 +/- 1.3 months in Group 1 and 8.3 +/- 1.3 months in Group 2. The postoperative reduction in IOP was highly significant (P <.0001) at all time intervals in both groups. In all measurement of IOP before the second week, mean IOP in Group 2 was found significantly lower than the mean IOP in Group 1 (P =.01). No statistically significant differences were found between the groups at later mean IOP measurements. At the last visit, the complete success rate was 88.8% in Group 1 and 85.0% in Group 2. No serious complications such as hypotonous maculopathy were observed in any patient. CONCLUSION: Primary trabeculectomy with mitomycin C in eyes with primary glaucoma showed effective IOP pressure reduction. There were no cases of serious complications. In the early postoperative period IOP was controlled better in the releasable suture group.

Gentian violet solution for staining the anterior capsule.

PURPOSE: To evaluate the histopathological changes after injecting gentian violet solution into the anterior chamber of rats and to describe a technique that uses gentian violet to allow a clear view of the anterior capsule during continuous curvilinear capsulorhexis (CCC) in human eyes with white mature cataract. SETTING: Department of Ophthalmology, University of Dicle, Diyarbakir, Turkey. METHODS: In this masked, experimental study (first stage), 0.05 mL of gentian violet 0.01% or 0.001% solution or balanced salt solution (BSS) (control group) was injected into the anterior chamber of 30 eyes of 30 Wistar albino rats. One, 24, and 48 hours after injection, 4 eyes in each group and 2 eyes in the control group were enucleated, and histopathological examination was performed. In the second stage, these solutions were used for staining the anterior capsule in the 18 human eyes with white mature cataract. The success rate of CCC and intraoperative and postoperative complications were evaluated. RESULTS: Histopathological examination revealed no pathology in any group. A CCC was completed in all cases. No intraoperative or postoperative complications were observed in human eyes except mild corneal edema and mild inflammatory reaction in the anterior chamber that improved within 1 week. Mean follow-up was 3.4 months. Visualization of the anterior capsule was better with gentian violet 0.01% solution. CONCLUSIONS: Gentian violet solutions at 0.01% and 0.001% concentrations had no evident toxic effect that caused significant histopathological changes. The staining technique was practical and helped the surgeon visualize the anterior capsule. However, gentian violet may have adverse effects that lead to corneal edema.

Overexpression of VEGF 121 in immortalized endothelial cells causes conversion to slowly growing angiosarcoma and high level expression of the VEGF receptors VEGFR-1 and VEGFR-2 in vivo.

Vascular endothelial growth factor (VEGF or vascular permeability factor) is an important angiogenic factor that is up-regulated in numerous benign and malignant disorders, including angiosarcoma, hemangiomas, and solid tumors. To determine the functional role of VEGF in the development of endothelial tumors, we expressed primate VEGF 121 in an endothelial cell line, MS1, derived from primary murine cells by immortalization with a temperature-sensitive SV40 large T antigen. This cell line expresses the VEGFR-2 (Flk-1/Kdr) receptor for VEGF. Expression of VEGF 121 led to the development of slowly growing endothelial tumors, which were histologically well-differentiated angiosarcomas. The angiosarcomas generated from MS1 VEGF cells demonstrated up-regulation of the VEGF receptors VEGFR-2 and VEGFR-1 (Flt-1) in vivo compared with benign hemangiomas generated from MS1 cells. Treatment of these cells with the VEGFR-2 tyrosine kinase inhibitor SU 1498 led to decreased expression of ets-1, a transcription factor which has been shown to be stimulated by VEGF. These results suggest that high level expression of VEGF in endothelial cells may result in malignant transformation. This transformation process likely involves both autocrine and paracrine pathways.

Systems for therapeutic angiogenesis in tissue engineering.

The goals in tissue engineering include the replacement of damaged, injured, or missing body tissues with biologically compatible substitutes. To overcome initial tissue-mass loss, improved vascularization of the regenerated tissue is essential. Two pathways of tissue neovascularization are known: vasculogenesis, the in situ assembly of capillaries from undifferentiated endothelial cells (EC), and angiogenesis, the sprouting of capillaries from preexisting blood vessels. Recent advances in our understanding of the process of bloodvessel growth have provided significant tools for the neovascularization of bioengineered tissues. Several growth factors serve as stimuli for EC proliferation and migration as well as the formation of new blood vessels. They convey their effects via specific receptors expressed on the surface of EC. Vascular epithelial growth factor (VEGF) is a major regulator of neovascularization. VEGF plays a major role in the early development of blood-cell progenitors. Basic fibroblast growth factor (bFGF) was identified as the first angiogenic factor. It is a potent inducer of EC proliferation and blood-vessel growth in vitro and in vivo. VEGF and bFGF have been injected into undervascularized ischemic tissues, resulting in new blood-vessel formation and tissue perfusion. Gene-therapy approaches using VEGF cDNA injection into ischemic tissues have augmented the formation of collateral vessels. Angiogenic factors such as VEGF and bFGF have also been incorporated into bioengineered tissues and have facilitated blood-vessel growth. Other approaches such as prevascularization of the matrix prior to cell seeding and incorporation of EC into the bioengineered tissues have produced encouraging results. This article reviews the process of blood-vessel growth and tissue vascularization, placing emphasis on strategies that can be employed for efficient vascularization of engineered tissues in vitro and in vivo.

Differential expression of VEGF isoforms and VEGF(164)-specific receptor neuropilin-1 in the mouse uterus suggests a role for VEGF(164) in vascular permeability and angiogenesis during implantation.

The mechanism(s) by which localized vascular permeability and angiogenesis occur at the sites of implantation is not clearly understood. Vascular endothelial growth factor (VEGF) is a key regulator of vasculogenesis during embryogenesis and angiogenesis in adult tissues. VEGF is also a vascular permeability factor. VEGF acts via two tyrosine kinase family receptors: VEGFR1 (Flt-1) and VEGFR2 (KDR/Flk-1). Recent evidence suggests that neuropilin-1 (NRP1), a receptor involved in neuronal cell guidance, is expressed in endothelial cells, binds to VEGF(165) and enhances the binding of VEGF(165) to VEGFR2. We examined the spatiotemporal expression of vegf isoforms, nrp1 and vegfr2 as well as their interactions in the periimplantation mouse uterus. We observed that vegf(164) is the predominant isoform in the mouse uterus. vegf(164) mRNA accumulation primarily occurred in epithelial cells on days 1 and 2 of pregnancy. On days 3 and 4, the subepithelial stroma in addition to epithelial cells exhibited accumulation of this mRNA. After the initial attachment reaction on day 5, luminal epithelial and stromal cells immediately surrounding the blastocyst exhibited distinct accumulation of vegf(164) mRNA. On days 6-8, the accumulation of this mRNA occurred in both mesometrial and antimesometrial decidual cells. These results suggest that VEGF(164) is available in mediating vascular changes and angiogenesis in the uterus during implantation and decidualization. This is consistent with coordinate expression of vegfr2, and nrp1, a VEGF(164)-specific receptor, in uterine endothelial cells. Their expression was low during the first 2 days of pregnancy followed by increases thereafter. With the initiation and progression of implantation (days 5-8), these genes were distinctly expressed in endothelial cells of the decidualizing stroma. Expression was more intense on days 6-8 at the mesometrial pole, the presumptive site of heightened angiogenesis and placentation. However, the expression was absent in the avascular primary decidual zone immediately surrounding the implanting embryo. Crosslinking experiments showed that (125)I-VEGF(165) binds to both NRP1 and VEGFR2 present in decidual endothelial cells. These results suggest that VEGF(164), NRP1 and VEGFR2 play a role in VEGF-induced vascular permeability and angiogenesis in the uterus required for implantation. genesis 26:213-224, 2000.

Identification of a natural soluble neuropilin-1 that binds vascular endothelial growth factor: In vivo expression and antitumor activity.

Neuropilin-1 (NRP1) is a 130-kDa transmembrane receptor for semaphorins, mediators of neuronal guidance, and for vascular endothelial growth factor 165 (VEGF(165)), an angiogenesis factor. A 2.2-kb truncated NRP1 cDNA was cloned that encodes a 644-aa soluble NRP1 (sNRP1) isoform containing just the a/CUB and b/coagulation factor homology extracellular domains of NRP1. sNRP1 is secreted by cells as a 90-kDa protein that binds VEGF(165), but not VEGF(121). It inhibits (125)I-VEGF(165) binding to endothelial and tumor cells and VEGF(165)-induced tyrosine phosphorylation of KDR in endothelial cells. The 3' end of sNRP1 cDNA contains a unique, 28-bp intron-derived sequence that is absent in full-length NRP1 cDNA. Using a probe corresponding to this unique sequence, sNRP1 mRNA could be detected by in situ hybridization differentially from full-length NRP1 mRNA, for example, in cells of liver, kidney, skin, and breast. Analysis of blood vessels in situ showed that NRP1, but not sNRP1, was expressed. sNRP1 was functional in vivo. Unlike control tumors, tumors of rat prostate carcinoma cells expressing recombinant sNRP1 were characterized by extensive hemorrhage, damaged vessels, and apoptotic tumor cells. These results demonstrate the existence of a naturally occurring, soluble NRP1 that is expressed differently from intact NRP1 and that appears to be a VEGF(165) antagonist.