Expression Of Vascular Markers Research Articles

Myeloid sarcoma with RBM15::MRTFA (MKL1) mimicking vascular neoplasm.

Extramedullary involvement of acute myeloid leukemia (AML), aka myeloid sarcoma, is a rare phenomenon in acute megakaryoblastic leukemia with RBM15:: MRTFA(MKL1) fusion, which might mimic non-hematologic malignancies. A 7-month-old infant presented with leukocytosis, hepatosplenomegaly, multiple lymphadenopathies, and a solid mass in the right thigh. Initially, the patient was diagnosed with a malignant vascular tumor regarding the expression of vascular markers from the biopsy of the right thigh lesion that was performed after the inconclusive bone marrow biopsy. The second bone marrow biopsy, which was performed due to the partial response to sarcoma treatment, showed hypercellular bone marrow with CD34 and CD61-positive spindle cell infiltration and > 20% basophilic blasts with cytoplasmic blebs. RNA sequencing of soft tissue biopsy revealed the presence of RBM15::MRTFA(MKL1) fusion. Based on these findings, myeloid sarcoma/AML with RBM15::MRTFA(MKL1) fusion diagnosis was made. AML with RBM15::MRTFA(MKL1) fusion can initially present as extramedullary lesions and might cause misdiagnosis of non-hematologic malignancies.

Single-stage transplantation combined with epidermal stem cells promotes the survival of tissue-engineered skin by inducing early angiogenesis

BackgroundThe composite transplantation of a split-thickness skin graft (STSG) combined with an acellular dermal matrix (ADM) is a promising repair method for full-thickness skin defects. Due to delayed vascularization of the ADM, no currently available engineered skin tissue is able to permanently cover full-thickness skin defects via a single-stage procedure. Epidermal stem cells (EpSCs) have been found to promote angiogenesis in the wound bed. Whether EpSCs can induce early angiogenesis of dermal substitutes and promote the survival of single-stage tissue-engineered skin transplantation needs to be further studied.MethodsIn vitro, rat vascular endothelial cells (RVECs) were treated with the supernatant of EpSCs cultured in ADM and stimulated for 48 h. RVECs were analysed by RNA sequencing and tube formation assays. For the in vivo experiment, 75 rats were randomly divided into five groups: ADM, ADM + EpSCs (AE), STSG, ADM + STSG (AS), and ADM + STSG + EpSCs (ASE) groups. The quality of wound healing was estimated by general observation and H&E and Masson staining. The blood perfusion volume was evaluated using the LDPI system, and the expression of vascular markers was determined by immunohistochemistry (IHC).ResultsThe active substances secreted by EpSCs cultured in ADM promoted angiogenesis, as shown by tube formation experiments and RNA-seq. EpSCs promoted epithelialization of the ADM and vascularization of the ADM implant. The ASE group showed significantly increased skin graft survival, reduced skin contraction, and an improved cosmetic appearance compared with the AS group and the STSG control group.ConclusionsIn summary, our findings suggest that EpSCs promote the formation of new blood vessels in dermal substitutes and support one-step transplantation of tissue-engineered skin, and thereby provide new ideas for clinical application.

Impact of Exogenous Nitric Oxide Treatment on Vascularization of a Subcutaneous Device for Cell Transplantation

Subcutaneous polymer scaffolds have shown potential for creating an optimal transplantation site in cellular replacement therapy, e.g., when transplanting insulin-producing cells to cure type 1 diabetes. Imperative for these scaffolds is a high degree of vascularization to guarantee long-term functional cellular survival. In this study, the effect of the nitric oxide (NO) donor S-nitroso-N-acetyl-dl-penicillamine (SNAP) on the vascularization degree of a subcutaneous poly(d,l-lactide-co-ε-caprolactone) (PDLLCL) scaffold was investigated. To this end, scaffolds were implanted under the skin of C57BL/6 mice. Each mouse received a control scaffold and a scaffold containing SNAP. At day 7, 14, and 28, the oxygen percentage within the scaffolds was measured and at day 28, the vascularization degree was determined with lectin infusion and gene expression analysis. We measured lower oxygen percentages within the scaffolds containing the NO-donor up to day 14 compared to the control scaffolds, but no differences were found at day 28. Although blood vessels in the scaffolds were well perfused, no differences between the groups were found in the lectin staining and gene expression of vascular markers, such as CD31, CD105, and VEGFa. To conclude, in this biomaterial setting, addition of a NO-donor did not improve the vascularization degree of the subcutaneous scaffold.

Puffball spores improve wound healing in a diabetic rat model.

Persistent chronic oxidative stress is a primary pathogenic characteristics of diabetic foot ulcers. Puffball spores are a traditional Chinese medicine used to treat diabetic foot ulcers infections and bedsores. However, their effects against diabetic wounds and the mechanism underlying these effects remain largely unknown. The present study explored the effectiveness of puffball spores in diabetic wound treatment and the mechanisms underlying their effects. Sprague-Dawley rats with streptozotocin (STZ)-induced diabetes were treated with puffball spores to ascertain whether they accelerated wound healing.Real-time quantitative PCR, western blotting, hematoxylin-eosin and Masson’s trichrome staining, immunohistochemistry analysis, and immunofluorescence assays were performed. As indicated by wound and serum histology and biochemical analyses, the puffball spores accelerated wound healing by activating Akt/Nrf2 signaling and promoting the expression of its downstream antioxidant genes, markedly stimulating antioxidant activity and enhanceing angiogenesis and collagen deposition. Our findings showed that puffball spores could accelerate diabetic wound healing, enhance antioxidant ability, promote the expression of vascular markers, and suppress inflammation, thus providing a theoretical basis for the treatment of diabetic and refractory wounds.

Inhibition of EZH2 suppresses peritoneal angiogenesis by targeting a VEGFR2/ERK1/2/HIF-1α-dependent signaling pathway.

The catalytic subunit of polycomb repressive complex 2 (PRC2), enhancer of zeste homolog 2 (EZH2), has been reported to be involved in angiogenesis in some tumors and autoimmune diseases. However, the mechanisms by which EZH2 regulates peritoneal angiogenesis remain unclear. We detected the expression of EZH2 in clinical samples and the peritoneal tissue of a mouse peritoneal fibrosis model induced by chlorhexidine gluconate (CG). In addition, we further investigated the mechanisms by which inhibition of EZH2 by 3-deazaneplanocin A (3-DZNeP) alleviated the CG-induced peritoneal fibrosis mouse model in vivo and 3-DZNeP or EZH2 siRNA treatment in cultured human peritoneal mesothelial cells (HPMCs) and human umbilical vein endothelial cells (HUVECs). The expression of EZH2 in the peritoneum of long-term peritoneal dialysis (PD) patients and the CG-induced peritoneal fibrosis mouse model was remarkably increased and this was positively associated with higher expression of vascular markers (CD31, CD34, VEGF, p-VEGFR2). Peritoneal injection of 3-DZNeP attenuated angiogenesis in the peritoneum of CG-injured mice; improved peritoneal membrane function; and decreased phosphorylation of STAT3, ERK1/2, and activation of Wnt1/β-catenin. In in vitro experiments, we demonstrated that inhibition of EZH2 by 3-DZNeP or EZH2 siRNA decreased tube formation and the migratory ability of HUVECs via two pathways: the Wnt1/β-catenin pathway and the IL-6/STAT3 pathway. Suppression of the Wnt1/β-catenin pathway and the IL-6/STAT3 pathway subsequently reduced VEGF production in HPMCs. Using specific inhibitors of VEGFR2, ERK1/2, and HIF-1α, we found that a VEGFR2/ERK1/2/HIF-1α axis existed and contributed to angiogenesis in vitro. Moreover, phosphorylation of VEGFR2 and activation of the ERK1/2 pathway and HIF-1α in HUVECs could be suppressed by inhibition of EZH2. Taken together, the results of this study suggest that EZH2 may be a novel target for preventing peritoneal angiogenesis in PD patients. © 2022 The Pathological Society of Great Britain and Ireland.

Angiosarcoma-like Kaposi Sarcoma: A Distinctive Histomorphologic Variant Representing an Important Diagnostic Pitfall.

Kaposi sarcoma (KS) is a rare low-grade angioproliferative neoplasm associated with human herpesvirus 8 (HHV-8) infection with multiple clinical subtypes and varying histopathologic patterns. Histologically, many different variants of KS have been reported, yet all can be difficult to recognize and must be differentiated from other vascular tumors. In this report, we studied fourteen cases of a newly described variant of KS reminiscent of a well-differentiated angiosarcoma (angiosarcoma-like KS). All cases showed a diffuse, ill-defined infiltrative dermal-based lesion composed of numerous anastomosing vascular channels of varying caliber lined by a single layer of endothelium with minimal pleomorphism. The vascular proliferation ramified through the dermis and dissected the collagen bundles along with infiltration into the subcutaneous fat and around skin appendages. All cases showed expression of vascular markers (CD31, CD34, and ERG) and were positive for HHV-8. None showed the classic histopathology associated with KS. Without clinical guidance these tumors can be difficult to recognize as KS, creating significant diagnostic challenges. Our study expands on a rare histologic variant of KS that ought to be considered in the differential diagnosis of any cutaneous well-differentiated angiosarcoma. Awareness of this variant of KS is of important for proper diagnosis and management of these patients; thus, careful attention to the histomorphology and clinical history can help lead the pathologist to the correct diagnosis.

Hepatic epithelioid hemangioendothelioma: Clinical characteristics, diagnosis, treatment, and prognosis.

BACKGROUNDHepatic epithelioid hemangioendothelioma (HEHE) is a rare hepatic vascular tumor with unpredictable malignant potential. The etiology, characteristics, diagnosis, treatment, and prognosis of HEHE are not well-understood, and large-scale retrospective studies are required to understand better this disease.AIMTo determine the characteristics of HEHE and identify its optimal treatments and prognostic factors.METHODSThe clinical data of two patients diagnosed with HEHE at the Fourth Hospital of Hebei Medical University and 258 previously reported cases retrieved from the China National Knowledge Infrastructure and PubMed databases between 1996 and 2021 were combined and summarized. All cases were pathologically identified as HEHE. Information such as clinical features, laboratory examination findings, imaging findings, pathological characteristics, treatment, and survival periods was reviewed. Kaplan-Meir curves were used for survival analysis. Prognostic factors were identified by Cox regression analysis.RESULTSHEHE primarily affected middle-aged women. The typical manifestations included epigastric pain, hepatosplenomegaly, inappetence, distension, weight loss, and fatigue. Tumor markers were expressed normally. The incidence of extrahepatic metastasis was 34.5% at the time of diagnosis. The most common sites of extrahepatic involvement were the lungs (22.3%), lymph nodes (5.6%), peritoneum (3.6%), bones (6.6%), and spleen (5.1%). Furthermore, “capsular retraction”, “target sign”, and “lollipop sign” were the characteristic features of HEHE on imaging. The immunohistochemical profile for HEHE (expression of vascular markers, such as factor VIII-related antigen, CD31, and CD34; expression levels of D2-40) can facilitate and ensure an accurate diagnosis. The management options for patients with HEHE include liver resection (29.7%), liver transplantation (16.1%), palliative treatments (12.7%), transhepatic arterial chemotherapy and embolization (TACE, 10.2%), chemotherapy (11.0%), antiangiogenic therapy (15.3%), and other treatments (5.1%); the mean survival time was 158.6, 147.3, 4.2, 90.8, 71.4, 83.1, and 55.0 mo, respectively. The survival time of patients who underwent surgical treatment was longer than that of patients who did not. TACE and antiangiogenic therapy tended to prolong survival compared with other nonsurgical treatments. The 1-, 5-, and 10-year survival rates were 82%, 71%, and 64%, respectively. Multivariate analysis showed that liver function (P = 0.045), intrahepatic metastasis (P = 0.029), and treatment (P = 0.045) were independent prognostic factors. The presence of extrahepatic metastases was not an independent risk factor for poor prognosis (P = 0.558).CONCLUSIONThe clinical course of HEHE is rare and variable, and patients with intrahepatic metastases and liver dysfunction may have a poorer prognosis than those without. Surgical intervention, whether liver resection or transplantation, might be warranted regardless of extrahepatic metastasis. For patients without the option for surgery, clinicians should consider the use of TACE with antiangiogenic drugs in the treatment of HEHE.

Histological Profiling of the Human Umbilical Cord: A Potential Alternative Cell Source in Tissue Engineering.

The embryonic development of the human umbilical cord (hUC) is complex, and different regions can be identified in this structure. The aim of this work is to characterize the hUC at in situ and ex vivo levels to stablish their potential use in vascular regeneration. Human umbilical cords were obtained and histologically prepared for in the situ analysis of four hUC regions (intervascular—IV, perivascular—PV, subaminoblastic—SAM, and Wharton’s jelly—WH), and primary cell cultures of mesenchymal stem cells (hUC-MSC) isolated from each region were obtained. The results confirmed the heterogeneity of the hUC, with the IV and PV zones tending to show the higher in situ expression of several components of the extracellular matrix (collagens, proteoglycans, and glycosaminoglycans), vimentin, and MSC markers (especially CD73), although isolation and ex vivo culture resulted in a homogeneous cell profile. Three vascular markers were positive in situ, especially vWF, followed by CD34 and CD31, and isolation and culture revealed that the region associated with the highest expression of vascular markers was IV, followed by PV. These results confirm the heterogeneity of the hUC and the need for selecting cells from specific regions of the hUC for particular applications in tissue engineering.

Ets1 functions partially redundantly with Etv2 to promote embryonic vasculogenesis and angiogenesis in zebrafish

ETS transcription factors play an important role in the specification and differentiation of endothelial cells during vascular development. Despite previous studies, the role of the founding member of the ETS family, Ets1, in vascular development in vivo is only partially understood. Here, we generated a zebrafish ets1 mutant by TALEN genome editing and tested functional redundancy between Ets1 and a related ETS factor Etv2/Etsrp/ER71. While zebrafish ets1−/− mutants have a normal functional vascular system, etv2−/−;ets1-/embryos had more severe angiogenic defects and lower expression levels of kdr and kdrl, the two zebrafish homologs of the mammalian Vascular Endothelial Growth Factor Receptor 2 VEGFR2/Flk1, than etv2−/−embryos. Expression of constitutively active Mitogen-Activated Protein Kinase1 (MAP2K1) within endothelial cells partially rescued this angiogenic defect. Interestingly, ets1−/− embryos displayed extensive apoptosis within the trunk vasculature despite exhibiting normal vascular patterning. Loss of Ets1 combined with a partial knockdown of Etv2 function resulted in a decrease in endothelial cell numbers in the axial vasculature, which argues for a role of Ets1 in promoting vasculogenesis. We also demonstrate that although both Ets1 and Etv2 can induce ectopic vascular marker expression in zebrafish embryos, Ets1 activity is dependent on MAPK-mediated phosphorylation of its Thr30 and Ser33 residues, while Etv2 activity is not. Together, our results identify a novel function of Ets1 in regulating endothelial cell survival during vasculogenesis in vivo. Based on these findings, we propose a revised model of how Ets1 and Etv2 play unique and partially redundant roles to promote vascular development.

Epithelioid haemengioendothelioma: A report of two cases

Epithelioid hemangioendothelioma (EHE), is a rare vascular tumor, described for the first time in 1975 by Dail and Liebow as an aggressive bronchoalveolar-cell carcinoma. The aetiology is still a dilemma to this day. Studies about suggestive hypothesis are ongoing. Most of the times, it affects lung, liver, and bones, but can arise from any part of the body. It has a very low prevalence of one in one million. Because of its heterogeneous presentation and rarity - represents <1% of all the vascular tumours, it is often misdiagnosed and not suitably treated, leading to a poor prognosis in some cases. Over 50%–76% of the patients are asymptomatic in the early stage of the disease. A small number of them complain of respiratory symptoms. Bone metastases might cause pathological fractures or cord compression if they arise in vertebrae. Imaging is necessary to determine extend of spread, the involvement of surrounding tissues, and potentially the cleavage plan. It is important to recognize the expression of vascular markers (Fli-1 and CD31 are endothelial-specific markers), and the microscopic evidence of vascular differentiation to make a correct diagnosis, as many pulmonary diseases show multiple nodular lesions. Because of its rarity, there is no standard treatment for EHE.

The function of Nsdhl during vascular development in zebrafish

Genetic conrol of vascular development and patterning in vertebrates is not fully understood. We used zebrafish as a model organism to identify transcription factors Islet2 (Isl2) and Nr2f1b required for the growth of intersegmental vessels (ISV) and caudal vein plexus (CVP). We further identify NAD(P)H steroid dehydrogenase‐like (Nsdhl) gene is positively regulated by Ist2 /Nr2f1b. Nsdhl is a dehydrogenase that participates in sterol production in cholesterol biosynthesis. Excess cellular cholesterol often leads to abnormal proliferation and migration. In addition, recent study showed cholesterol efflux related to angiogenesis control.Here, we show Nsdhl is highly conserved in all species. Nsdhl mRNA is expressed in vessels, suggesting its roles in vascular development. Knockdown of Nsdhl expression by Morpholino (MO) disrupts the growth of ISV and CVP, suggesting the role of Nsdhl in controlling ISV and CVP growth. Consist with the defects in vascular development, we examined the expression of vascular markers flk1, mrc1, stabilin, flt4 and ephrinb2 and we found the remodeling the expression of vascular markers in nsdhlMO. To address whether the cell death contributes to the ISV and CVP defects in nsdhlMO, we performed AO staining and TUNEL assay. The data showed that vascular defects do not caused by cell death, but likely due to the impairment of proliferation and migration. We also revealed the relationship between Nsdhl and VEGF/BMP signals. Together, we showed that Nsdhl plays important role for vascular development in zebrafish.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Promotion of Vascular Morphogenesis of Endothelial Cells Co-Cultured with Human Adipose-Derived Mesenchymal Stem Cells Using Polycaprolactone/Gelatin Nanofibrous Scaffolds.

New blood vessel formation is essential for tissue regeneration to deliver oxygen and nutrients and to maintain tissue metabolism. In the field of tissue engineering, in vitro fabrication of new artificial vessels has been a longstanding challenge. Here we developed a technique to reconstruct a microvascular system using a polycaprolactone (PCL)/gelatin nanofibrous structure and a co-culture system. Using a simple electrospinning process, we fabricated three-dimensional mesh scaffolds to support the sprouting of human umbilical vein endothelial cells (HUVECs) along the electrospun nanofiber. The co-culture with adipose-derived mesenchymal stem cells (ADSCs) supported greater sprouting of endothelial cells (ECs). In a two-dimensional culture system, angiogenic cell assembly produced more effective direct intercellular interactions and paracrine signaling from ADSCs to assist in the vascular formation of ECs, compared to the influence of growth factor. Although vascular endothelial growth factor and sphingosine-1-phosphate were present during the culture period, the presence of ADSCs was the most important factor for the construction of a cell-assembled structure in the two-dimensional culture system. On the contrary, HUVECs co-cultured on PCL/gelatin nanofiber scaffolds produced mature and functional microvessel and luminal structures with a greater expression of vascular markers, including platelet endothelial cell adhesion molecule-1 and podocalyxin. Furthermore, both angiogenic factors and cellular interactions with ADSCs through direct contact and paracrine molecules contributed to the formation of enhanced engineered blood vessel structures. It is expected that the co-culture system of HUVECs and ADSCs on bioengineered PCL/gelatin nanofibrous scaffolds will promote robust and functional microvessel structures and will be valuable for the regeneration of tissue with restored blood vessels.

Silibinin from Silybum marianum Stimulates Embryonic Stem Cell Vascular Differentiation via the STAT3/PI3-K/AKT Axis and Nitric Oxide.

Silibinin, the bioactive compound of milk thistle (Silybum marianum), exerts tissue protective and regenerative effects that may include stem cell differentiation toward vascular cells. The purpose of the present study was to investigate whether silibinin stimulates blood vessel formation from mouse embryonic stem (ES) cells and to unravel the underlying signaling cascade. Vascular branching points were assessed by confocal laser scanning microscopy and computer-assisted image analysis of CD31-positive cell structures. Protein expression of vascular markers and activation of protein kinases were determined by western blot. Nitric oxide (NO) generation was investigated by use of the fluorescent dye 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate. Silibinin dose-dependently increased CD31-positive vascular branching points in embryoid bodies cultivated from ES cells. This was paralleled by increase of protein expression levels for the endothelial-specific markers vascular endothelial cadherin (VE-cadherin), vascular endothelial growth factor receptor 2, and hypoxia-inducible factor-1α. Moreover, silibinin increased activation of endothelial nitric oxide synthase (eNOS), which boosted generation of NO in embryoid bodies and enhanced phosphorylation of signal transducer and activator of transcription 3 (STAT3) as well as phosphoinositide 3-kinase (PI3-K) and AKT. Vasculogenesis, VE-cadherin expression, STAT3 and AKT phosphorylation, NO generation, and eNOS phosphorylation were inhibited by the small molecule STAT3 inhibitor Stattic, AKT inhibitor VIII, the PI3-K inhibitor LY294002, or the NOS inhibitor Nω-Nitro-L-arginine methyl ester hydrochloride. In conclusion, our findings indicate that silibinin induces vasculogenesis of ES cells via activation of STAT3, PI3-K, and AKT, which regulate NO generation by eNOS.

Coral-Derived Natural Marine Compound GB9 Impairs Vascular Development in Zebrafish.

Blood vessels in vertebrates are established and genetically controlled in an evolutionarily-conserved manner during embryogenesis. Disruption of vascular growth by chemical compounds or environmental hormones may cause developmental defects. This study analyzed the vascular impacts of marine compound GB9 in zebrafish. GB9 was isolated from the marine soft coral Capnella imbricata and had shown anti-neuroinflammatory and anti-nociceptive activities. However, the role of GB9 on vascular development has not been reported. We first tested the survival rate of embryos under exogenous 5, 7.5, 10, and 15 μM GB9 added to the medium and determined a sub-lethal dosage of 10 μM GB9 for further assay. Using transgenic Tg(fli:eGFP) fish to examine vascular development, we found that GB9 treatment impaired intersegmental vessel (ISV) growth and caudal vein plexus (CVP) patterning at 25 hours post-fertilization (hpf) and 30 hpf. GB9 exposure caused pericardial edema and impaired circulation at 48–52 hpf, which are common secondary effects of vascular defects and suggest the effects of GB9 on vascular development. Apoptic cell death analysis showed that vascular defects were not caused by cell death, but were likely due to the inhibition of migration and/or proliferation by examining ISV cell numbers. To test the molecular mechanisms of vascular defects in GB9-treated embryos, we examined the expression of vascular markers and found the decreased expression of vascular specific markers ephrinb2, flk, mrc1, and stabilin. In addition, we examined whether GB9 treatment impairs vascular growth due to an imbalance of redox homeostasis. We found an enhanced effect of vascular defects during GB9 and H2O2 co-treatment. Moreover, exogenous N-acetyl-cysteine (NAC) treatment rescued the vascular defects in GB9 treated embryos. Our results showed that GB9 exposure causes vascular defects likely mediated by the imbalance of redox homeostasis.

Expression of CD34 and CD146 vascular markers contributes to the immunological function of the human palatine tonsil.

The fundamental function of the palatine tonsil is the immune response to airborne and foodborne pathogenic agents. Small blood vessels have an important role in the provision of a special microenvironment in which the immune response occurs. In this study, we investigated the expression of vascular markers CD34 and CD146 and basal lamina marker - type IV collagen - in the small blood vessels of the human palatine tonsil in the context of their role in the immunological function of the tonsil. The tonsils were collected after tonsillectomy from ten patients with chronic tonsillitis, aged 18-28 years. Five-µm-thick paraffin sections were routinely stained with haematoxylin and eosin, while the studied markers (CD34, CD146 and type IV collagen) were detected immunohistochemically using LSAB2/HRP method. CD34 was expressed equally in the capillaries within and below the crypt epithelium, in lymphoid follicles and in high endothelial venules localized para- and interfollicularly. CD146 molecule was expressed on the luminal surface of endothelial cells in the capillaries of the crypt epithelium, while its expression in high endothelial venules was seen on the luminal and lateral surfaces of the cuboidal endothelial cells. In contrast to the basal lamina of intraepithelial capillaries, where collagen IV-immunopositivity is mostly seen as a continuing line, the basal lamina of high endothelial venules was seen as a two- or three-layered structure beneath the cuboidal endothelial cells. The specifics of expression of CD34, CD146, and type IV collagen confirm the morphofunctional specialization of endothelium in crypt epithelium capillaries, and also in endothelium of high endothelial venules, which is directly associated with the role of these vessels in the immune function of the tonsil.

Fine-tune regulation of carboxypeptidase N1 controls vascular patterning during zebrafish development

Vascular development is regulated by complicated signals and molecules in vertebrates. In this study, we characterized a novel function of carboxypeptidase N1 (Cpn1) in the vasculature. We show that cpn1 mRNA is expressed in developing vessels. The knockdown of cpn1 by morpholino injection impairs the growth of intersegmental vessels (ISV) and caudal vein plexus (CVP), suggesting the role of cpn1 in vascular development. We showed that vascular defects are not caused by cell death but are due to the impairment of migration and proliferation. Consistent with vascular growth defects, loss of cpn1 affects the expression of the vascular markers flt4, mrc1, flk, stabilin, and ephrinb2. Furthermore, the overexpression of cpn1 impaired the growth of ISV and CVP, but the remodeling expression of vascular markers was different from the knockdown of cpn1, indicating the differential regulation mechanisms in cpn1-overexpressing embryos. We examine the interaction between cpn1 and multiple signals and observed that cpn1 is regulated by Notch/VEGF signals for ISV growth and likely regulates BMP signals for CVP patterning. In conclusion, we demonstrate that cpn1 has a critical role in the vascular development of zebrafish. We also reveal a fine-tune regulation of cpn1 that controls vascular patterning mediated by multiple signals.

Prdx1-encoded peroxiredoxin is important for vascular development in zebrafish.

Genetic signaling and redox homeostasis are required for proper growth of blood vessels. Here, we report a novel function of peroxiredoxin1 (Prdx1) in vascular development in zebrafish. Knockdown of prdx1 impairs the growth of intersegmental vessel and caudal vein plexus (CVP), and reduces the expression of vascular markers, thus suggesting a role for prdx1 in vasculature and indicating that the antioxidant function of prdx1 is important. We found that H2 O2 -treated embryos also have CVP defects and observed synergistic effects when prdx1 knockdown was combined with H2 O2 treatment. Moreover, N-acetyl-cysteine treatment rescues the vascular defects in prdx1 morphants. These results suggest that oxidative stress disturbs vascularization. Furthermore, we show that the regulation of prdx1 is mediated by Notch and BMP signals.

Biomimetic, ultrathin and elastic hydrogels regulate human neutrophil extravasation across endothelial-pericyte bilayers.

The vascular basement membrane—a thin, elastic layer of extracellular matrix separating and encasing vascular cells—provides biological and mechanical cues to endothelial cells, pericytes, and migrating leukocytes. In contrast, experimental scaffolds typically used to replicate basement membranes are stiff and bio-inert. Here, we present thin, porated polyethylene glycol hydrogels to replicate human vascular basement membranes. Like commercial transwells, our hydrogels are approximately 10μm thick, but like basement membranes, the hydrogels presented here are elastic (E: 50-80kPa) and contain a dense network of small pores. Moreover, the inclusion of bioactive domains introduces receptor-mediated biochemical signaling. We compare elastic hydrogels to common culture substrates (E: >2GPa) for human endothelial cell and pericyte monolayers and bilayers to replicate postcapillary venules in vitro. Our data demonstrate that substrate elasticity facilitates differences in vascular phenotype, supporting expression of vascular markers that are increasingly replicative of venules. Endothelial cells differentially express vascular markers, like EphB4, and leukocyte adhesion molecules, such as ICAM-1, with decreased mechanical stiffness. With porated PEG hydrogels we demonstrate the ability to evaluate and observe leukocyte recruitment across endothelial cell and pericyte monolayers and bilayers, reporting that basement membrane scaffolds can significantly alter the rate of vascular migration in experimental systems. Overall, this study demonstrates the creation and utility of a new and accessible method to recapture the mechanical and biological complexity of human basement membranes in vitro.

Ftr82 Is Critical for Vascular Patterning during Zebrafish Development.

Cellular components and signaling pathways are required for the proper growth of blood vessels. Here, we report for the first time that a teleost-specific gene ftr82 (finTRIM family, member 82) plays a critical role in vasculature during zebrafish development. To date, there has been no description of tripartite motif proteins (TRIM) in vascular development, and the role of ftr82 is unknown. In this study, we found that ftr82 mRNA is expressed during the development of vessels, and loss of ftr82 by morpholino (MO) knockdown impairs the growth of intersegmental vessels (ISV) and caudal vein plexus (CVP), suggesting that ftr82 plays a critical role in promoting ISV and CVP growth. We showed the specificity of ftr82 MO by analyzing ftr82 expression products and expressing ftr82 mRNA to rescue ftr82 morphants. We further showed that the knockdown of ftr82 reduced ISV cell numbers, suggesting that the growth impairment of vessels is likely due to a decrease of cell proliferation and migration, but not cell death. In addition, loss of ftr82 affects the expression of vascular markers, which is consistent with the defect of vascular growth. Finally, we showed that ftr82 likely interacts with vascular endothelial growth factor (VEGF) and Notch signaling. Together, we identify teleost-specific ftr82 as a vascular gene that plays an important role for vascular development in zebrafish.

Abstract 3371: Genetic, phenotypic and functional characterisation of vasculogenic mimicry in small-cell lung cancer

Abstract Background: Despite a good initial response to chemotherapy, most small cell lung cancer (SCLC) patients relapse with drug resistant disease. Targeting tumor vasculature in SCLC with anti-angiogenic drugs produced disappointing results, therefore angiogenesis-independent tumor vascularisation pathways warrant further investigation. Vasculogenic mimicry (VM) is the ability of tumor cells to mimic endothelial cells by trans-endothelial differentiation, characterised by increased expression of vascular markers including VE-Cadherin. We previously demonstrated that VM correlates with poor Overall Survival in Limited Stage SCLC patients and sought to phenotypically and genetically characterise VM vessels using SCLC Circulating Tumour Cells (CTCs) and CTC-Derived eXplant (CDX) models1 and to explore the functional significance of VE-Cadherin for VM formation in vitro and in vivo.Methods: VM was evaluated using CD31/periodic acid-Schiff (PAS) staining in tumors from 10 CDX models. Laser Capture Microdissection (LCM) and Copy Number Alteration (CNA) analysis was performed on CDX regions with high and low levels of VM. VE-Cadherin expression in SCLC CTCs was evaluated following ISET microfiltration of patients’ blood and Immunofluorescence staining for DAPI, CD45, pan Cytokeratin and VE-Cadherin. VE-Cadherin function was evaluated in vitro by Matrigel network assay using H446 SCLC cells and H446 shRNA VE-Cadherin knockdown (KD) cell lines, and in vivo by growth as xenografts, further treated with Cisplatin. Results: VM was present in CDX models and LCM followed by CNA analysis of VM vessels confirmed their SCLC origin. ISET microfiltration and immunofluorescent staining of CTCs from 37/38 SCLC patients revealed VE-Cadherin as a putative VM biomarker in SCLC CTCs. VE-Cadherin shRNA KD in VM competent H446 SCLC cells abrogated their ability to form VM networks in vitro and in vivo. Cisplatin treatment of mice bearing H446 VE-Cadherin KD tumors resulted in reduced cisplatin binding compared to parental H446 tumors. Conclusions: VM is present in CDX models and co-localises with VE-Cadherin expression. CNA confirms that VM vessels originate from tumour, and these VM-enriched regions bear a unique chromosomal signature compared to the low-VM regions. VE-Cadherin is required for network formation in vitro and VE-Cadherin levels and VM vessel numbers are positively correlated in vivo. Moreover, levels of VM in tumors had significant impact on both tumour growth kinetics and cisplatin delivery which has implications for drug senstivity. Our future research will interrogate the VM signaling pathway in SCLC and its role in chemosensitivity and establish feasibility for therapeutic targeting. Citation Format: Francesca Trapani, Stuart Williamson, Robert L. Metcalf, Hui Sun Leong, Benjamin Abbott, Jenny Antonello, Cassandra Hodgkinson, Lynsey Franklin, Mary J. Hendrix, Richard E b Seftor, Elisabeth Seftor, Dominic Rothwell, Ged Brady, Crispin Miller, Fiona H. Blackhall, Kathryn L. Simpson, Caroline Dive. Genetic, phenotypic and functional characterisation of vasculogenic mimicry in small-cell lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3371.