PECAM-1 (CD31) cloning and relation to adhesion molecules of the immunoglobulin gene superfamily

Identification of protein targets in cerebral endothelial cells for brain arteriovenous malformation (AVMs) molecular therapies

Background

To develop a new molecular targeted treatment for brain (AVMs), identification of membrane proteins that are localised on the AVM endothelium is crucial. Current treatment methods are surgery and radiosurgery. However, complete occlusion post radiosurgery are achieved within 3 years, while patient remain at risk of haemorrhage. This study aims to identify potential protein targets in AVM endothelial cells that discriminate these vessels from normal vessels; these proteins targets will be investigated for the molecular therapy of brain AVMs to promote rapid thrombosis after radiosurgery.

Methods

We employed in vitro biotinylation that we developed, and mass spectrometry to detect cell surface-exposed proteins in cultures of murine cerebral endothelial cells (bEnd.3). Two forms of mass spectrometry were applied (iTRAQ-MS and MS^E) to identify and quantify membrane protein expression at various time-points following irradiation which simulates a radiosurgical treatment approach. Immunocytochemistry was used to confirm the expression of selected membrane proteins. ProteinPilot V4.0 software was used to analyse the iTRAQ-MS data and the MS^E data was analysed using ProteinLynx Global Server version 2.5 software.

Results

The proteomics data revealed several differentially expressed membrane proteins between irradiated and non-irradiated cells at specific time points, e.g. PECAM-1, cadherin-5, PDI, EPCR and integrins. Immunocytochemistry data confirmed the expression of these proteins.

Conclusion

Cell surface protein biotinylation and proteomics analysis successfully identified membrane proteins from murine brain endothelial cells in response to irradiation. This work suggests potential target protein molecules for evaluation in animal models of brain-AVM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12014-017-9151-3) contains supplementary material, which is available to authorized users.

ITIM receptors: more than just inhibitors of platelet activation

Since their discovery, immunoreceptor tyrosine-based inhibition motif (ITIM)-containing receptors have been shown to inhibit signaling from immunoreceptor tyrosine-based activation motif (ITAM)-containing receptors in almost all hematopoietic cells, including platelets. However, a growing body of evidence has emerged demonstrating that this is an oversimplification, and that ITIM-containing receptors are versatile regulators of platelet signal transduction, with functions beyond inhibiting ITAM-mediated platelet activation. PECAM-1 was the first ITIM-containing receptor identified in platelets and appeared to conform to the established model of ITIM-mediated attenuation of ITAM-driven activation. PECAM-1 was therefore widely accepted as a major negative regulator of platelet activation and thrombosis for many years, but more recent findings suggest a more complex role for this receptor, including the facilitation of α_IIbβ₃-mediated platelet functions. Since the identification of PECAM-1, several other ITIM-containing platelet receptors have been discovered. These include G6b-B, a critical regulator of platelet reactivity and production, and the noncanonical ITIM-containing receptor TREM-like transcript-1, which is localized to α-granules in resting platelets, binds fibrinogen, and acts as a positive regulator of platelet activation. Despite structural similarities and shared binding partners, including the Src homology 2 domain-containing protein-tyrosine phosphatases Shp1 and Shp2, knockout and transgenic mouse models have revealed distinct phenotypes and nonredundant functions for each ITIM-containing receptor in the context of platelet homeostasis. These roles are likely influenced by receptor density, compartmentalization, and as-yet unknown binding partners. In this review, we discuss the diverse repertoire of ITIM-containing receptors in platelets, highlighting intriguing new functions, controversies, and future areas of investigation.

Viable Stem Cells Are in the Injury Effusion Fluid and Arthroscopic Byproducts From Knee Cruciate Ligament Surgery: An In Vivo Analysis

PURPOSE

To examine the number of viable stem cells contained in the postinjury effusion fluid and the waste byproducts of arthroscopic cruciate ligament surgery.

METHODS

This study included patients older than 18 years of age with acute (<5 weeks old) cruciate ligament injuries requiring arthroscopic surgery. The postinjury effusion fluid (effusion fluid), fat pad and cruciate ligament stump debridement tissue (byproduct tissue), and arthroscopic fluid collected during fat pad and/or stump debridement (byproduct fluid) were collected at the time of surgery from 30 individuals. Specimens were analyzed, investigating cell viability, nucleated cell counts, cell concentrations, colony-forming unit assays, and flow cytometry. Samples from the first 20 individuals were collected in small specimen containers, and samples from the last 10 individuals were collected in larger specimen containers.

RESULTS

Cells of the injury effusion exhibited the greatest viability (86.4 ± 1.31%) when compared with the small volume harvest byproduct tissue (50.2 ± 2.5%, P = .0001), small volume harvest byproduct fluid (48.8 ± 1.88%, P = .0001), large volume harvest byproduct tissue (70.1 ± 5.6%, P = .0001), and large volume harvest byproduct fluid (60.3 ± 3.41%, P = .0001). The culture analysis of fibroblast colony-forming units found on average 1916 ± 281 progenitor cells in the effusion fluid, 2488 ± 778 progenitor cells in the byproduct tissue, and 2357 ± 339 progenitor cells in the byproduct fluid. Flow cytometry confirmed the presence of immature cells and the presence of cells with markers typically expressed by known stem cell populations.

CONCLUSIONS

Viable stem cells are mobilized to the postinjury effusion at the time of cruciate ligament injury and can be found in the byproduct waste of cruciate ligament surgery.

CLINICAL RELEVANCE

The methodology around effusion fluid and byproduct tissue capture during cruciate ligament surgery should be investigated further. Cell amounts available from these tissues with current technologies are not sufficient for immediate evidence-based clinical application.

Endothelial cell markers from clinician's perspective

Endothelial cell markers are membrane-bound or cytoplasmic molecules expressed by endothelial cells, which help their easier identification and discrimination from other cell types. During vasculogenesis, endothelial cells differentiate from hemangioblasts to form new blood vessels. With the discovery of endothelial progenitor cells (EPC) and their ability to form new blood vessels, the term vasculogenesis is not only reserved for the embryonic development. Possibility of de novo blood vessel formation from EPC is now widely explored in different ischemic conditions, especially in cardiovascular medicine. Numerous clinical trials have tested enhancing tissue vascularization by delivering hematopoietic cells that expressed endothelial markers. This therapeutic approach proved to be challenging and promising, particularly for patients who have exhausted all conventional therapeutic modalities. Angiogenesis, which refers to the formation of new blood vessels from existing vasculature, is indispensable process during tumor progression and metastasis. Blockage of tumor angiogenesis by targeting and inhibiting endothelial cell has emerged as novel safe and efficacious method to control many advanced malignant diseases. Numerous clinical studies are currently testing new antiangiogenic drugs which target and inhibit endothelial cell markers, receptors or molecules which transmit receptor-mediated signals, therefore inhibiting endothelial cell proliferation, migration and vascular tube formation. Many of these drugs are now widely used in clinical settings as first- or second-line chemotherapy in advanced malignant conditions. So far, these therapeutic approaches gave modest, yet encouraging clinical improvements, prolonging survival and improving functional capacity and quality of life for many terminally ill patients. Here we present the most commonly used endothelial cell markers along with their applicability in contemporary clinical practice.

Isolation of luteal endothelial cells and functional interactions with T lymphocytes

The objectives of this study were to optimize the isolation of luteal endothelial cells (LEC) and examine their functional interactions with autologous T lymphocytes. Analysis by flow cytometry showed that the purity of LEC isolated by filtration was nearly 90% as indicated by Bandeiraea simplicifolia (BS)-1 lectin binding. LEC expressed mRNA for progesterone receptor (PGR), prostaglandin receptors (PTGFR, PTGER2 and 4, and PTGIR), tumor necrosis factor receptors (TNFRSF1A&B) and interleukin (IL) 1B receptors (IL1R1&2). LEC were pretreated with either vehicle, progesterone (P₄; 0-20 µM), prostaglandin (PG) E₂ or PGF_2α (0-0.2 µM), and further treated with or without TNF and IL1B (50 ng/mL each). LEC were then incubated with autologous T lymphocytes in an adhesion assay. Fewer lymphocytes adhered to LEC after exposure to high compared to low P₄ concentrations (cubic response; P < 0.05). In contrast, 0.2 µM PGE₂ and PGF_2α each increased T lymphocyte adhesion in the absence of cytokines (P < 0.05). LEC induced IL2 receptor alpha (CD25) expression and proliferation of T lymphocytes. In conclusion, filtration is an effective way of isolating large numbers of viable LEC. It is proposed that PGs and P₄ modulate the ability of endothelial cells to bind T lymphocytes, potentially regulating extravasation, and that LEC activate T lymphocytes migrating into or resident in the CL.

The bromodomain inhibitor JQ1 triggers growth arrest and apoptosis in testicular germ cell tumours in vitro and in vivo

Type II testicular germ cell cancers (TGCT) are the most frequently diagnosed tumours in young men (20–40 years) and are classified as seminoma or non‐seminoma. TGCTs are commonly treated by orchiectomy and chemo‐ or radiotherapy. However, a subset of metastatic non‐seminomas (embryonal carcinomas) displays only incomplete remission or relapse and requires novel treatment options. Recent studies have shown effective application of the small‐molecule inhibitor JQ1 in tumour therapy, which interferes with the function of ‘bromodomain and extraterminal (BET)’ proteins. JQ1‐treated TGCT cell lines display up‐regulation of genes indicative for DNA damage and cellular stress response and induce cell cycle arrest. Embryonal carcinoma (EC) cell lines, which presented as JQ1 sensitive, display down‐regulation of pluripotency factors and induction of mesodermal differentiation. In contrast, seminoma‐like TCam‐2 cells tolerated higher JQ1 concentrations and were resistant to differentiation. ECs xenografted in vivo showed a reduction in tumour size, proliferation rate and angiogenesis in response to JQ1. Finally, the combination of JQ1 and the histone deacetylase inhibitor romidepsin allowed for lower doses and less frequent application, compared with monotherapy. Thus, we propose that JQ1 in combination with romidepsin may serve as a novel therapeutic option for (mixed) TGCTs.

Fluid shear stress induces upregulation of COX-2 and PGI2 release in endothelial cells via a pathway involving PECAM-1, PI3K, FAK, and p38

Vascular endothelial cells play an important role in the regulation of vascular function in response to mechanical stimuli in both healthy and diseased states. Prostaglandin I₂ (PGI₂) is an important antiatherogenic prostanoid and vasodilator produced in endothelial cells through the action of the cyclooxygenase (COX) isoenzymes COX-1 and COX-2. However, the mechanisms involved in sustained, shear-induced production of COX-2 and PGI₂ have not been elucidated but are determined in the present study. We used cultured endothelial cells exposed to steady fluid shear stress (FSS) of 10 dyn/cm² for 5 h to examine shear stress-induced induction of COX-2/PGI₂ Our results demonstrate the relationship between the mechanosensor platelet endothelial cell adhesion molecule-1 (PECAM-1) and the intracellular mechanoresponsive molecules phosphatidylinositol 3-kinase (PI3K), focal adhesion kinase (FAK), and mitogen-activated protein kinase p38 in the FSS induction of COX-2 expression and PGI₂ release. Knockdown of PECAM-1 (small interference RNA) expression inhibited FSS-induced activation of α₅β₁-integrin, upregulation of COX-2, and release of PGI₂ in both bovine aortic endothelial cells (BAECs) and human umbilical vein endothelial cells (HUVECs). Furthermore, inhibition of the PI3K pathway (LY294002) substantially inhibited FSS activation of α₅β₁-integrin, upregulation of COX-2 gene and protein expression, and release of PGI₂ in BAECs. Inhibition of integrin-associated FAK (PF573228) and MAPK p38 (SB203580) also inhibited the shear-induced upregulation of COX-2. Finally, a PECAM-1^-/- mouse model was characterized by reduced COX-2 immunostaining in the aorta and reduced plasma PGI₂ levels compared with wild-type mice, as well as complete inhibition of acute flow-induced PGI₂ release compared with wild-type animals.NEW & NOTEWORTHY In this study we determined the major mechanotransduction pathway by which blood flow-driven shear stress activates cyclooxygenase-2 (COX-2) and prostaglandin I₂ (PGI₂) release in endothelial cells. Our work has demonstrated for the first time that COX-2/PGI₂ mechanotransduction is mediated by the mechanosensor platelet endothelial cell adhesion molecule-1 (PECAM-1).

Endothelial functions of platelet/endothelial cell adhesion molecule-1 (CD31)

PURPOSE OF REVIEW

The purpose of this article is to describe the function of the vascular cell adhesion and signaling molecule, platelet/endothelial cell adhesion molecule-1 (PECAM-1), in endothelial cells, with special emphasis on its role in maintaining and restoring the vascular permeability barrier following disruption of the endothelial cell junction.

RECENT FINDINGS

In addition to its role as an inhibitory receptor in circulating platelets and leukocytes, PECAM-1 is highly expressed at endothelial cell-cell junctions, where it functions as an adhesive stress-response protein to both maintain endothelial cell junctional integrity and speed restoration of the vascular permeability barrier following inflammatory or thrombotic challenge.

SUMMARY

Owing to the unique ability of antibodies that bind the membrane proximal region of the extracellular domain to trigger conformational changes leading to affinity modulation and homophilic adhesion strengthening, PECAM-1 might be an attractive target for treating vascular permeability disorders.

Structural Basis for Human PECAM-1-Mediated Trans-homophilic Cell Adhesion

Cell adhesion involved in signal transduction, tissue integrity and pathogen infection is mainly mediated by cell adhesion molecules (CAM). One CAM member, platelet–endothelial-cell adhesion molecule-1 (PECAM-1), plays an important role in tight junction among endothelia cells, leukocyte trafficking, and immune response through its homophilic and heterophilic binding patterns. Both kinds of interactions, which lead to endogenous and exogenous signal transmission, are derived from extracellular immunoglobulin-like (IgL) domains and cytoplasmic immunoreceptor tyrosine-based inhibitory motifs (ITIMs) of PECAM-1. To date, the mechanism of trans-homophilic interaction of PECAM-1 remains unclear. Here, we present the crystal structure of PECAM-1 IgL1-2 trans-homo dimer. Both IgL 1 and 2 adopt the classical Ig domain conformation comprised of two layers of β-sheets possessing antiparallel β-strands with each being anchored by a pair of cysteines forming a disulfide bond. The dimer interface includes hydrophobic and hydrophilic interactions. The Small-Angle X-ray Scattering (SAXS) envelope of PECAM-1 IgL1-6 supported such a dimer formation in solution. Cell adhesion assays on wildtype and mutant PECAM-1 further characterized the structural determinants in cell junction and communication.

The lymphatic vascular system of the mouse head

Histological studies of the lymphatic vascular system in adult mice are hampered because bones cannot be sectioned properly. Here, we decalcified the heads of 14-day-old mice, embedded them in paraffin and stained resultant serial sections with the lymphendothelial-specific antibodies Lyve-1 and Podoplanin. We show that the tissues with the highest lymphatic vascular density are the dermis and the oral mucous membranes. In contrast, the nasal mucous membrane is devoid of lymphatics, except for its most basal parts below the vomeronasal organ. The inferior nasal turbinate contains numerous lymphatics and is connected to the nasolacrimal duct (NLD), which is ensheathed by a dense network of lymphatics. The lymphatics of the eye lids and conjunctiva are connected to those of the inferior nasal turbinate. We suggest that cerebro-spinal fluid (CSF) can drain via the optic nerve and NLD lymphatics, whereas CSF drained via the Fila olfactoria into the nasal mucous membrane is used for moisturization of the respiratory air. Tongue, palatine and buccal mucous membranes possess numerous lymphatics, whereas the dental pulp has none. Lymphatics are present in the maxillary gland and close to the temporomandibular joint, suggesting the augmentation of lymph flow by chewing and yawning. Lymphatics can also be found in the dura mater and in the dural septae entering into deeper parts of the brain. Our findings are discussed with regard to CSF drainage and potential routes for ocular tumor dissemination.

The Role of Sialylated Glycans in Human Platelet Endothelial Cell Adhesion Molecule 1 (PECAM-1)-mediated Trans Homophilic Interactions and Endothelial Cell Barrier Function

Platelet Endothelial Cell Adhesion Molecule 1 (PECAM-1) is a major component of the endothelial cell intercellular junction. Previous studies have shown that PECAM-1 homophilic interactions, mediated by amino-terminal immunoglobulin homology domain 1, contribute to maintenance of the vascular permeability barrier and to its re-establishment following inflammatory or thrombotic insult. PECAM-1 glycans account for ∼30% of its molecular mass, and the newly solved crystal structure of human PECAM-1 immunoglobulin homology domain 1 reveals that a glycan emanating from the asparagine residue at position 25 (Asn-25) is located within the trans homophilic-binding interface, suggesting a role for an Asn-25-associated glycan in PECAM-1 homophilic interactions. In support of this possibility, unbiased molecular docking studies revealed that negatively charged α2,3 sialic acid moieties bind tightly to a groove within the PECAM-1 homophilic interface in an orientation that favors the formation of an electrostatic bridge with positively charged Lys-89, mutation of which has been shown previously to disrupt PECAM-1-mediated homophilic binding. To verify the contribution of the Asn-25 glycan to endothelial barrier function, we generated an N25Q mutant form of PECAM-1 that is not glycosylated at this position and examined its ability to contribute to vascular integrity in endothelial cell-like REN cells. Confocal microscopy showed that although N25Q PECAM-1 concentrates normally at cell-cell junctions, the ability of this mutant form of PECAM-1 to support re-establishment of a permeability barrier following disruption with thrombin was significantly compromised. Taken together, these data suggest that a sialic acid-containing glycan emanating from Asn-25 reinforces dynamic endothelial cell-cell interactions by stabilizing the PECAM-1 homophilic binding interface.

Recent updates in experimental protocols for endothelial cells

Scleroderma (systemic sclerosis, SSc) is a multisystem autoimmune disease of unknown etiology. The disease is characterized by vascular disorder, activation of the immune system, and excessive deposition of matrix proteins in the skin and involved organs. The vascular disorder is believed to play a crucial role in disease pathogenesis. Endothelial injury and dysfunction, subsequent capillary loss and arteriolar wall thickness, are well documented in all involved organs. The resulting tissue hypoxia and ischemia fail to initiate new vessel formation leading to progressive loss of vasculature with no apparent replenishment. Issues related to endothelial injury/activation, dysfunction and failure of angio/vasculogenesis are central to the understanding of SSc vasculopathy. Isolation of endothelial cells and cells involved in the genesis of new vessels is enormously important in the investigation of mechanisms involved in SSc vasculopathy. Nevertheless, this goal has been difficult to achieve in view of the charac­teristic slow growth of endothelial cells, the high demand for growth factors and rapid growth of contaminating cells and the scarcity of circulating cells involved in angio/vasculogenesis hampered this line of investigation. Nonetheless, recent technologic progress in the last decade provided us with the tools to isolate vascular cells with an acceptable purity based on unique cell surface markers using immunoselection methods. The purpose of this review is to update the readers on current technical state-of-the-art methods of isolation and propagation of vascular cells. We wish that this review will spark interest in more investigations of this crucial phase of SSc pathogenesis.

Transcriptional Profiling of Cultured, Embryonic Epicardial Cells Identifies Novel Genes and Signaling Pathways Regulated by TGFβR3 In Vitro

The epicardium plays an important role in coronary vessel formation and Tgfbr3^-/- mice exhibit failed coronary vessel development associated with decreased epicardial cell invasion. Immortalized Tgfbr3^-/- epicardial cells display the same defects. Tgfbr3^+/+ and Tgfbr3^-/- cells incubated for 72 hours with VEH or ligands known to promote invasion via TGFβR3 (TGFβ1, TGFβ2, BMP2), for 72 hours were harvested for RNA-seq analysis. We selected for genes >2-fold differentially expressed between Tgfbr3^+/+ and Tgfbr3^-/- cells when incubated with VEH (604), TGFβ1 (515), TGFβ2 (553), or BMP2 (632). Gene Ontology (GO) analysis of these genes identified dysregulated biological processes consistent with the defects observed in Tgfbr3^-/- cells, including those associated with extracellular matrix interaction. GO and Gene Regulatory Network (GRN) analysis identified distinct expression profiles between TGFβ1-TGFβ2 and VEH-BMP2 incubated cells, consistent with the differential response of epicardial cells to these ligands in vitro. Despite the differences observed between Tgfbr3^+/+ and Tgfbr3^-/- cells after TGFβ and BMP ligand addition, GRNs constructed from these gene lists identified NF-ĸB as a key nodal point for all ligands examined. Tgfbr3^-/- cells exhibited decreased expression of genes known to be activated by NF-ĸB signaling. NF-ĸB activity was stimulated in Tgfbr3^+/+ epicardial cells after TGFβ2 or BMP2 incubation, while Tgfbr3^-/- cells failed to activate NF-ĸB in response to these ligands. Tgfbr3^+/+ epicardial cells incubated with an inhibitor of NF-ĸB signaling no longer invaded into a collagen gel in response to TGFβ2 or BMP2. These data suggest that NF-ĸB signaling is dysregulated in Tgfbr3^-/- epicardial cells and that NF-ĸB signaling is required for epicardial cell invasion in vitro. Our approach successfully identified a signaling pathway important in epicardial cell behavior downstream of TGFβR3. Overall, the genes and signaling pathways identified through our analysis yield the first comprehensive list of candidate genes whose expression is dependent on TGFβR3 signaling.

PECAM-1 gene polymorphism (rs668) and subclinical markers of carotid atherosclerosis in patients with type 2 diabetes mellitus

The platelet endothelial cell adhesion molecule 1 (PECAM-1) plays an important role in many inflammatory processes, including the development of atherosclerosis. Polymorphism rs668 of the PECAM-1 gene (373C/G) is functional, and it was reported to be associated with increased serum levels of PECAM-1. We investigated the association between the rs668 polymorphism of PECAM-1 and subclinical markers of carotid atherosclerosis in subjects with type 2 diabetes mellitus (T2DM). Five hundred and ninety-five T2DM subjects and 200 control subjects were enrolled. The carotid intima-media thickness (CIMT) and plaque characteristics (presence and structure) were assessed ultrasonographically. Biochemical analyses were performed using standard biochemical methods. Geno-typing of the PECAM-1 gene polymorphism (rs668) was performed using KASPar assays. The control examinations were performed 3.8 ± 0.5 years after the initial examination. Higher CIMT was found in patients with T2DM in comparison with subjects without T2DM. Statistically sig-nificantly faster progression of the atherosclerotic markers was shown in subjects with T2DM in comparison with the control group. When adjusted to other risk factors, the rs668 GG genotype was associated with an increased risk of carotid plaques in subjects with T2DM. We concluded that our study demonstrated a minor effect of the rs668 PECAM-1 on markers of carotid atherosclerosis in subjects with T2DM.

Comparison of Endothelial Cell Proliferation in Normal Liver and Adipose Tissue in B6C3F1 Mice, F344 Rats, and Humans

Peroxisome proliferator-activated receptor gamma (PPARγ) and dual PPARα and γ agonists have been developed for use in the treatment of diabetes and hyperlipidemias. Vascular tumors were increased in mice treated with some PPAR agonists, but not in rats. Spontaneous hemangiosarcomas are common in several strains of mice, uncommon in rats, and rarely occur in humans. The objective of this study was to determine the endothelial cell proliferation rate in liver and adipose tissue of B6C3F1 mice, F344 rats, and humans to aid in investigations of the genesis and development of hemangiosarcoma formation, and to determine the relevance of the increased endothelial cell proliferation rate in drug-treated rodents in assessing the risk of these drugs in humans. We determined the endothelial cell labeling index (LI) in untreated mice, rats, and humans, in normal liver, brown fat (rats and mice only) and white fat by dual immunohistochemistry of CD31 and Ki-67. The LI, highest in mice and lowest in humans, was statistically significantly greater in the mouse compared to the human and rat. The increased rate of spontaneous or PPAR agonist-induced hemangiosarcoma formation in mice may be related to the higher background endothelial cell proliferation rate compared to rats and humans.

Endothelial Cell Response to Fusobacterium nucleatum

Vascular response is an essential aspect of an effective immune response to periodontal disease pathogens, as new blood vessel formation contributes to wound healing and inflammation. Gaining a greater understanding of the factors that affect vascular response may then contribute to future breakthroughs in dental medicine. In this study, we have characterized the endothelial cell response to the common bacterium Fusobacterium nucleatum, an important bridging species that facilitates the activity of late colonizers of the dental biofilm. Endothelial cells were infected with Fusobacterium nucleatum (strain 25586) for periods of 4, 12, 24, or 48 h. Cell proliferation and tube formation were analyzed, and expression of adhesion molecules (CD31 and CD34) and vascular endothelial growth factor (VEGF) receptors 1 and 2 was measured by fluorescence-activated cell sorter (FACS) analysis. Data indicate that F. nucleatum impaired endothelial cell proliferation and tube formation. The findings suggest that the modified endothelial cell response acts as a mechanism promoting the pathogenic progression of periodontal diseases and may potentially suggest the involvement of periodontopathogens in systemic diseases associated with periodontal inflammation.

Polymorphism rs5498 of the ICAM-1 gene affects the progression of carotid atherosclerosis in patients with type 2 diabetes mellitus

Background

Adhesion molecules are involved in the development of atherosclerosis. An increased level of the ICAM 1 molecule is associated with numerous inflammatory diseases including atherosclerosis of carotid arteries. The rs5498 (K469E) polymorphism of the ICAM-1 gene leads to an increase in the level of serum ICAM. We investigated the association between the rs5498 (K469E) polymorphism of the ICAM-1 gene and the progression of carotid atherosclerosis in subjects with type 2 diabetes mellitus (T2DM).

Methods

The study included 595 patients with T2DM and 200 subjects in the control group without T2DM. The control examination was made 3.8 years after the initial examination. Indicators of atherosclerosis (carotid intima-media thickness (CIMT), total plaque sum and sum of the plaques thickness) were detected by ultrasound examination. Genetic analyses of the polymorphism rs5498 of the ICAM-1 gene were made by RT-PCR.

Results

The distribution of genotypes and frequencies of rs5498 polymorphism was not significantly different between the group with type 2 diabetes ( T2DM) and the control group. Genotype EE K469E polymorphism is associated with a statistically significant annual plaques growth.

Conclusion

The EE genotype of the rs5498 of the ICAM-1 gene was associated with a more rapid progression of carotid atherosclerosis in patients with T2DM in comparison with other genotypes.

Microparticles in sputum of COPD patients: a potential biomarker of the disease?

Background

Microparticles (MPs) are small membrane vesicles of 0.1–1 µm which are released by cells following chemical, physical, and apoptotic stimuli. MPs represent more than a miniature version of the cell. Their composition and function depend not only on cellular origin, but also on stimuli. Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by nearly irreversible lung destruction which results in airway limitation.

Purpose

We investigated the presence and source of MPs in sputum of COPD patients to evaluate if changes in MP number and origin may reflect the pathophysiological conditions of disease and may serve as potential biomarkers for diagnostic and prognostic use.

Methods

Induced sputum samples were collected from 18 male subjects and liquefied with Sputasol. MPs obtained were immunolabeled for leukocyte (CD11a), granulocyte (CD66b), monocyte-macrophage (CD11b), platelets and megakaryocytic cells (CD41), endothelial cells (CD31), and red blood cells (CD235ab) and analyzed by cytofluorimetry.

Results

There was a negative correlation between CD31-MPs and forced expiratory volume in 1 second (R=−53, P<0.05) and CD66b-MP level was correlated with worse performance index of COPD such as the Body mass index airflow Obstruction, Dyspnea, and Exercise capacity (BODE); they were negatively correlated with 6-minute walking test: 0.65 and −0.64, respectively (P<0.05). CD235ab-MPs showed a negative correlation with body mass index (R=−0.86, P<0.05), while there was a positive correlation with dyspnea index (R=0.91, P<0.05).

Conclusion

The main finding of this study was that MPs were detected in the sputum of patients affected by COPD. The phenotype of some of them was related to the main COPD parameters. These results suggest that MPs could be implicated in the pathogenesis of COPD.

Overexpression of Vascular Endothelial Growth Factor A in Invasive Micropapillary Colorectal Carcinoma

BACKGROUND

Invasive micropapillary carcinoma (IMPC) is a rare variant of colorectal cancer with an adverse prognosis. "Retraction artifact" around tumor cells is a feature of IMPC. The aim of this study was to assess the nature of the retractions around the tumor cells and to describe the histopathological features of a group of 18 cases of IMPC.

METHODS

A pathology review of 128 consecutive colorectal cancers identified 18 cases of histologically proven IMPC using 5% of the total tumor volume comprised of a micropapillary component as the diagnostic criterion. Immunostains for D2-40, CD31, CD34, vascular endothelial growth factor A (VEGF-A), and mucin 1 (MUC-1) were performed using the avidin-biotin complex method.

RESULTS

Cases of IMPC were characterized by pseudomicropapillae surrounded by lacunar-like clear spaces. These structures exhibited the inside-out growth pattern as highlighted by MUC-1 staining. The lining of the lacunar spaces was immunoreactive to CD31 but not CD34 or D2-40, indicating that they are neovascular structures. Furthermore, the tumor cells strongly and diffusely expressed VEGF-A.

CONCLUSIONS

The strong coexpression of VEGF-A and CD31 suggests a prominent role of neoangiogenesis in these tumors.

Targeted Recycling of the Lateral Border Recycling Compartment Precedes Adherens Junction Dissociation during Transendothelial Migration

Leukocyte transendothelial migration (TEM) requires two major events: local dissociation of adherens junctions manifested as gaps in vascular endothelial (VE)-cadherin staining at the site of TEM and targeted trafficking of the lateral border recycling compartment (LBRC) to the site of TEM. However, the association between LBRC recycling and VE-cadherin gaps remains unknown. We found that when targeting of the LBRC is selectively inhibited using established methods, such as a function blocking anti-platelet endothelial cell adhesion molecule 1 antibody, depolymerizing microtubules, or microinjection of an antibody that inhibits kinesin, VE-cadherin gaps do not form around the blocked leukocyte. This is the first time that the LBRC has been implicated in this process. We obtained similar results for neutrophils and monocytes and in studies using live cell imaging microscopy conducted under fluid shear conditions. Depolymerizing microtubules did not affect the ability of leukocytes to induce tyrosine phosphorylation of VE-cadherin. A VE-cadherin double mutant (Y658F, Y731F) expressed in endothelial cells acted as a dominant negative and inhibited VE-cadherin gap formation and TEM, yet targeting of the LBRC still occurred. These data suggest that targeting of the LBRC to the site of TEM precedes VE-cadherin clearance. Recruitment of the LBRC may play a role in clearing VE-cadherin from the site of TEM.

An in vitro model of hemogenic endothelium commitment and hematopoietic production

Adult-type hematopoietic stem and progenitor cells are formed during ontogeny from a specialized subset of endothelium, termed the hemogenic endothelium, via an endothelial-to-hematopoietic transition (EHT) that occurs in the embryonic aorta and the associated arteries. Despite efforts to generate models, little is known about the mechanisms that drive endothelial cells to the hemogenic fate and about the subsequent molecular control of the EHT. Here, we have designed a stromal line-free controlled culture system utilizing the embryonic pre-somitic mesoderm to obtain large numbers of endothelial cells that subsequently commit into hemogenic endothelium before undergoing EHT. Monitoring the culture for up to 12 days using key molecular markers reveals stepwise commitment into the blood-forming system that is reminiscent of the cellular and molecular changes occurring during hematopoietic development at the level of the aorta. Long-term single-cell imaging allows tracking of the EHT of newly formed blood cells from the layer of hemogenic endothelial cells. By modifying the culture conditions, it is also possible to modulate the endothelial cell commitment or the EHT or to produce smooth muscle cells at the expense of endothelial cells, demonstrating the versatility of the cell culture system. This method will improve our understanding of the precise cellular changes associated with hemogenic endothelium commitment and EHT and, by unfolding these earliest steps of the hematopoietic program, will pave the way for future ex vivo production of blood cells.

Monoclonal antibodies targeting CD38 in hematological malignancies and beyond

CD38 is a multifunctional cell surface protein that has receptor as well as enzyme functions. The protein is generally expressed at low levels on various hematological and solid tissues, while plasma cells express particularly high levels of CD38. The protein is also expressed in a subset of hematological tumors, and shows especially broad and high expression levels in plasma cell tumors such as multiple myeloma (MM). Together, this triggered the development of various therapeutic CD38 antibodies, including daratumumab, isatuximab, and MOR202. Daratumumab binds a unique CD38 epitope and showed strong anti-tumor activity in preclinical models. The antibody engages diverse mechanisms of action, including complement-dependent cytotoxicity, antibody-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis, programmed cell death, modulation of enzymatic activity, and immunomodulatory activity. CD38-targeting antibodies have a favorable toxicity profile in patients, and early clinical data show a marked activity in MM, while studies in other hematological malignancies are ongoing. Daratumumab has single agent activity and a limited toxicity profile, allowing favorable combination therapies with existing as well as emerging therapies, which are currently evaluated in the clinic. Finally, CD38 antibodies may have a role in the treatment of diseases beyond hematological malignancies, including solid tumors and antibody-mediated autoimmune diseases.

Regulation of Blood Stem Cell Development

Understanding how the blood system is formed is an ongoing fundamental research challenge. Developmental biology has provided many insights into the molecules and processes that affect the formation of the blood tissues, both in health and disease. It is of particular interest for clinical transplantation therapies to understand how hematopoietic stem cells (HSCs)-the self-renewing purveyors of the adult blood system that produce over 10 different functionally specialized cell lineages and over 10(11) cells daily-are generated during embryonic stages. Recent successes to reprogram the fate of adult differentiated cells to pluripotency and to other cell lineages now highlight the importance of identifying the cells and molecules that affect the in vivo developmental initiation of rare and robust transplantable HSCs. The close association of the developing hematopoietic and vascular system, hematopoietic cell mobility through the circulation, and the essential role of the embryonic hematopoietic system in adult hematopoietic cell development make this a formidable study. This chapter reviews the advances, controversies, and current state of our knowledge of the growing field of hematopoietic development, with a special focus on the regulation of the natural transdifferentiation of endothelial cells to HSCs within the developing embryo.

Adrenomedullin in the growth modulation and differentiation of acute myeloid leukemia cells

Adrenomedullin (ADM) is a regulatory peptide endowed with multiple biological effects, including the regulation of blood pressure, cell growth and innate host defence. In the present study, we demonstrated that ADM signaling could be involved in the impaired cellular differentiation of myeloid leukemia cells to mature granulocytes or monocytes by modulating RAMPs/CRLR expression, PI3K/Akt cascade and the ERK/MAPK signaling pathway. When exogenously administered to in vitro cultures of HL60 promyelocytic leukemia cells, ADM was shown to exert a strong proliferative effect with minimal upregulation in the expression level of monocyte antigen CD14. Notably, the experimental inhibition of ADM signaling with inhibitor ADM22-52 promoted a differentiative stimulation towards monocytic and granulocytic lineages. Moreover, based on the expression of CD31 relative to CD38, we hypothesized that an excess of ADM in bone marrow (BM) niche could increase the transendothelial migration of leukemia cells while any inhibitory event of ADM activity could raise cell retention in hyaluronate matrix by upregulating CD38. Taken into consideration the above evidence, we concluded that ADM and ADM22-52 could differently affect the growth of leukemia cells by autocrine/paracrine mechanisms and may have clinical relevance as biological targets for the intervention of tumor progression.

Thalidomide Improves the Intestinal Mucosal Injury and Suppresses Mesenteric Angiogenesis and Vasodilatation by Down-Regulating Inflammasomes-Related Cascades in Cirrhotic Rats

Background and Aims

By blocking TNFα-related effects, thalidomide not only inhibits hepatic fibrogenesis but improves peripheral vasodilatation and portal hypertension in cirrhotic rats. Nonetheless, the investigation of thalidomide's effects on splanchnic and collateral microcirculation has been limited. Our study explored the roles of intestinal and mesenteric TNFα along with inflammasome-related pathway in relation to cirrhosis and the splanchnic/collateral microcirculation.

Methods

Using in vivo and in vitro approaches, mechanisms of the effects of thalidomide on intestinal and mesenteric inflammatory, vasodilatory and angiogenic cascades-related abnormalities were explored in cirrhotic rats that had received 1-month thalidomide (C-T) treatment.

Results

In cirrhotic rats, high tumor necrosis factor (TNF)α, vascular endothelial growth factor (VEGF) and nitric oxide (NO)x levels were associated with the NOD-like receptors protein 3 (NLRP3), IL-1β and caspase-1 inflammasome over-expression in splenorenal shunt and mesenteric tissues. The thalidomide-related inhibition of mesenteric and splenorenal shunt inflammasome expression was accompanied by a significantly decreased intestinal mucosal injury and inflammasome immunohistochemical staining expression. Suppression of various angiogenic cascades, namely VEGF-NOS-NO, was paralleled by a decrease in mesenteric angiogenesis as detected by CD31 immunofluorescence staining and by reduced portosystemic shunting (PSS) in C-T rats. The down-regulation of the mesenteric and collateral vasodilatory VEGF-NOS-NO cascades resulted in a correction of vasoconstrictive hypo-responsiveness and in an attenuation of vasodilatory hyper-responsiveness when analyzed by in situ perfusion of the superior mesenteric arterial (SMA) and portosystemic collaterals. There was also a decrease in SMA blood flow and an increase in SMA resistance in the C-T rats. Additionally, acute incubation with thalidomide abolished TNFα-augmented VEGF-mediated migration of and tube formation of human umbilical vein endothelial cells, which was accompanied by corresponding changes in inflammatory and angiogenic substances release.

Conclusions

The suppression of inflammasome over-expression by chronic thalidomide treatment ameliorates inflammatory, angiogenic and vasodilatory cascades-related pathogenic changes in the splanchnic and collateral microcirculation of cirrhotic rats. Thalidomide seems to be a promising agent that might bring about beneficial changes to the disarrangements of peripheral, hepatic, splanchnic and collateral systems in cirrhosis.

Recombinant Resilin-Based Bioelastomers for Regenerative Medicine Applications

The outstanding elasticity, excellent resilience at high-frequency, and hydrophilic capacity of natural resilin have motivated investigations of recombinant resilin-based biomaterials as a new class of bio-elastomers in the engineering of mechanically active tissues. Accordingly, here the comprehensive characterization of modular resilin-like polypeptide (RLP) hydrogels is presented and their suitability as a novel biomaterial for in vivo applications is introduced. Oscillatory rheology confirmed that a full suite of the RLPs can be rapidly cross-linked upon addition of the tris(hydroxymethyl phosphine) cross-linker, achieving similar in situ shear storage moduli (20 k ± 3.5 Pa) across various material compositions. Uniaxial stress relaxation tensile testing of hydrated RLP hydrogels under cyclic loading and unloading showed negligible stress reduction and hysteresis, superior reversible extensibility, and high resilience with Young's moduli of 30 ± 7.4 kPa. RLP hydrogels containing MMP-sensitive domains are susceptible to enzymatic degradation by matrix metalloproteinase-1 (MMP-1). Cell culture studies revealed that RLP-based hydrogels supported the attachment and spreading (2D) of human mesenchymal stem cells and did not activate cultured macrophages. Subcutaneous transplantation of RLP hydrogels in a rat model, which to our knowledge is the first such reported in vivo analysis of RLP-based hydrogels, illustrated that these materials do not elicit a significant inflammatory response, suggesting their potential as materials for tissue engineering applications with targets of mechanically demanding tissues such as vocal fold and cardiovascular tissues.

Isolation and Culture of Human Endothelial Cells from Micro- and Macro-vessels

The endothelium from different vascular beds exhibits a high degree of phenotypic heterogeneity. Endothelial cells (EC) can be harvested easily from large vessels by mechanical removal or collagenase digestion. In particular, the human umbilical vein has been used due to its wide availability, and the study of ECs derived from it has undoubtedly greatly advanced our knowledge of vascular biology. However, the majority of the body's endothelium (>95 %) forms the microvasculature, and it is these cells providing the interface between the blood and tissues that play a critical role in the development of new blood vessels. This has led to the establishment of techniques for the isolation of microvascular ECs (MEC) from different tissues to provide more physiologically relevant in vitro models of angiogenesis and EC function.In this chapter the use of superparamagnetic beads (Dynabeads) coated with anti-PECAM-1 (CD31) antibodies (PECA-beads) to culture MECs from human adipose tissue is described along with the standard methods used to characterize them. Adipose tissue is an ideal source of MECs as it is composed mainly of adipocytes with a very rich microvasculature and is easy to disaggregate. Furthermore, it can be obtained in large quantities during plastic surgery procedures. Adipose obtained at reduction mammoplasty or abdominoplasty is first dissected free of the connective tissue, minced finely, and subjected to collagenase type II digestion. The adipocytes are removed by centrifugation to obtain a microvessel rich pellet, which is further disaggregated with trypsin/EDTA solution. Following filtration to remove fragments of the connective tissue, the pellet is incubated with PECA-beads and microvessel fragments/ECs and washed and harvested using a magnet. In addition, the adaptation of this basic technique for the isolation of the human lung and stomach MECs is also described along with common methods for the preparation of large vessel endothelial cells.

Structural basis for PECAM-1 homophilic binding

Platelet endothelial cell adhesion molecule-1 (PECAM-1) is a 130-kDa member of the immunoglobulin gene superfamily (IgSF) that is present on the surface of circulating platelets and leukocytes, and highly expressed at the junctions of confluent endothelial cell monolayers. PECAM-1-mediated homophilic interactions, known to be mediated by its 2 amino-terminal immunoglobulin homology domains, are essential for concentrating PECAM-1 at endothelial cell intercellular junctions, where it functions to facilitate diapedesis, maintain vascular integrity, and transmit survival signals into the cell. Given the importance of PECAM-1-mediated homophilic interactions in mediating each of these cell physiological events, and to reveal the nature and orientation of the PECAM-1-PECAM-1 homophilic-binding interface, we undertook studies aimed at determining the crystal structure of the PECAM-1 homophilic-binding domain, which is composed of amino-terminal immunoglobulin homology domains 1 and 2 (IgD1 and IgD2). The crystal structure revealed that both IgD1 and IgD2 exhibit a classical IgSF fold, having a β-sandwich topology formed by 2 sheets of antiparallel β strands stabilized by the hallmark disulfide bond between the B and F strands. Interestingly, despite previous assignment to the C2 class of immunoglobulin-like domains, the structure of IgD1 reveals that it actually belongs to the I2 set of IgSF folds. Both IgD1 and IgD2 participate importantly in the formation of the trans homophilic-binding interface, with a total buried interface area of >2300 Å(2). These and other unique structural features of PECAM-1 allow for the development of an atomic-level model of the interactions that PECAM-1 forms during assembly of endothelial cell intercellular junctions.

Non-Triple Helical Form of Type IV Collagen α1 Chain

Type IV collagen with a triple-helical structure composed of three α chains is a major component of basement membrane. Previously, we reported that non-triple helical form of type IV collagen α1 chain (NTHα1(IV)) was isolated from human placenta and the culture media of human cells. In the present study, we report on the localization of NTH α1(IV) with a monoclonal antibody #370, exclusively reactive for the nascent chain, in the rabbit tissues. The staining was found on the basement membrane of blood vessels, of endomysium, of nerve, and of kidney but not on epithelial basement membrane. In a rabbit angiogenic model, #370 antibody staining was exclusively observed in neovascular tip region of endothelial cells, where no staining with anti-type IV collagen antibody was seen. Distinct localizations suggest that NTHα1(IV) is produced and stably deposited in endothelial cells and the surroundings under physiological conditions with some physiological roles in relation to the dynamics of vascular system.

Advances in our understanding of mechanisms of venous thrombus resolution

Traditionally, venous thrombosis has been seen as the consequence of a regulated cascade of proteolytic steps leading to the polymerization of fibrinogen and fibrin crosslinking that is facilitated by platelets. A new view of thrombosis is providing a more integrated concept, with components of the vascular wall contributing to the vascular remodeling of thrombosis. Angiogenesis and inflammation are two key mechanisms that safeguard venous thrombus resolution and restitution of vascular patency after thrombosis. Disturbance of these processes leads to thrombus persistence and has potentially severe consequences for affected patients. Examples for clinical conditions associated with recurrent or persisting venous thrombosis are post-thrombotic syndrome or chronic thromboembolic pulmonary hypertension. Recently, studies using animal models of venous thrombosis have contributed to a better understanding of thrombus non-resolution that will eventually lead to modification of current treatment concepts. For example, recent data suggest that innate immunity is involved in the modification of thrombosis.

Effects of hyperthyroidism on expression of vascular endothelial growth factor (VEGF) and apoptosis in fetal adrenal glands

This study investigated the expression of vascular endothelial growth factor (VEGF), vascular density, and apoptosis in fetal rat adrenal glands with hyperthyroidism in late gestation. Twelve mature female Wistar albino rats with the same biological and physiological features were used for this study. Rats were divided into two groups: control and hyperthyroidism. Hyperthyroidism was induced by daily subcutaneous injections of L-thyroxine (250 µg/kg) before pregnancy for 21 days and during pregnancy. Rats in the control and hyperthyroidism groups were caged according to the number of male rats. Zero day of pregnancy (Day 0) was indicated when the animals were observed to have microscopic sperm in vaginal smears. Pregnant rats were sacrificed on the 20th day of pregnancy; blood from each animal was collected to determine the concentrations of maternal adrenocorticotropic hormone and thyroxine. Rat fetuses were then quickly removed from the uterus, and the adrenal glands of the fetuses were dissected. VEGF expression, vascular density, and apoptosis were analyzed in fetal rat adrenal glands. Maternal serum levels of the ACTH and free thyroxine were significantly higher in the hyperthyroidism group than in the control group. Immunohistochemistry revealed that the number of VEGF positive cells and vessel density significantly increased in the hyperthyroidism rat fetal adrenal group compared with the control group. Hyperthyroidism did not change the fetal and placental weights and the number of fetuses. This study demonstrates that hyperthyroidism may have an effect on the development of rat adrenal glands mediated by VEGF expression, angiogenesis, and apoptosis.

The regulation of transendothelial migration: new knowledge and new questions

Leucocyte transendothelial migration (TEM) involves a co-operative series of interactions between surface molecules on the leucocyte and cognate counter-ligands on the endothelial cell. These interactions set up a cascade of signalling events inside the endothelial cell that both allow for the junctions to loosen and for membrane to be recruited from the lateral border recycling compartment (LBRC). The LBRC is thought to provide an increased surface area and unligated receptors to the leucocyte to continue the process. The relative importance of the individual adhesion/signalling molecules that promote transmigration may vary depending on the type of leucocyte, the vascular bed, the inflammatory stimulus, and the stage of the inflammatory response. However, the molecular interactions between leucocyte and endothelial cell activate signalling pathways that disengage the adherens and tight junctions and recruit the LBRC to the site of transmigration. With the exception of disengaging the junctions, similar molecules and mechanisms promote transcellular migration as paracellular migration of leucocytes. This review will discuss the molecular interactions and signalling pathways that regulate transmigration, and the common themes that emerge from studying TEM of different leucocyte subsets under different inflammatory conditions. We will also raise some unanswered questions in need of future research.

PECAM-1 isoforms, eNOS and endoglin axis in regulation of angiogenesis

Vascular development and maintenance of proper vascular function through various regulatory mechanisms are critical to our wellbeing. Delineation of the regulatory processes involved in development of the vascular system and its function is one of the most important topics in human physiology and pathophysiology. Platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31), a cell adhesion molecule with proangiogenic and proinflammatory activity, has been the subject of numerous studies. In the present review, we look at the important roles that PECAM-1 and its isoforms play during angiogenesis, and its molecular mechanisms of action in the endothelium. In the endothelium, PECAM-1 not only plays a role as an adhesion molecule but also participates in intracellular signalling pathways which have an impact on various cell adhesive mechanisms and endothelial nitric oxide synthase (eNOS) expression and activity. In addition, recent studies from our laboratory have revealed an important relationship between PECAM-1 and endoglin expression. Endoglin is an essential molecule during angiogenesis, vascular development and integrity, and its expression and activity are compromised in the absence of PECAM-1. In the present review we discuss the roles that PECAM-1 isoforms may play in modulation of endothelial cell adhesive mechanisms, eNOS and endoglin expression and activity, and angiogenesis.

Modular Small Diameter Vascular Grafts with Bioactive Functionalities

We report the fabrication of a novel type of artificial small diameter blood vessels, termed biomimetic tissue-engineered blood vessels (bTEBV), with a modular composition. They are composed of a hydrogel scaffold consisting of two negatively charged natural polymers, alginate and a modified chitosan, N,O-carboxymethyl chitosan (N,O-CMC). Into this biologically inert scaffold two biofunctionally active biopolymers are embedded, inorganic polyphosphate (polyP) and silica, as well as gelatin which exposes the cell recognition signal, Arg-Gly-Asp (RGD). These materials can be hardened by exposure to Ca(2+) through formation of Ca(2+) bridges between the polyanions, alginate, N,O-CMC, and polyP (alginate-Ca(2+)-N,O-CMC-polyP). The bTEBV are formed by pressing the hydrogel through an extruder into a hardening solution, containing Ca(2+). In this universal scaffold of the bTEBV biomaterial, polycations such as poly(L-Lys), poly(D-Lys) or a His/Gly-tagged RGD peptide (three RGD units) were incorporated, which promote the adhesion of endothelial cells to the vessel surface. The mechanical properties of the biopolymer material (alginate-Ca(2+)-N,O-CMC-polyP-silica) revealed a hardness (elastic modulus) of 475 kPa even after a short incubation period in CaCl2 solution. The material of the artificial vascular grafts (bTEBVs with an outer size 6 mm and 1.8 mm, and an inner diameter 4 mm and 0.8 mm, respectively) turned out to be durable in 4-week pulsatile flow experiments at an alternating pressure between 25 and 100 mbar (18.7 and 75.0 mm Hg). The burst pressure of the larger (smaller) vessels was 850 mbar (145 mbar). Incorporation of polycationic poly(L-Lys), poly(D-Lys), and especially the His/Gly-tagged RGD peptide, markedly increased the adhesion of human, umbilical vein/vascular endothelial cells, EA.HY926 cells, to the surface of the hydrogel. No significant effect of the polyP samples on the clotting of human plasma is measured. We propose that the metabolically degradable polymeric scaffold bTEBV is a promising biomaterial for future prosthetic vascular grafts.

Regional and stage-specific effects of prospectively purified vascular cells on the adult V-SVZ neural stem cell lineage

Adult neural stem cells reside in specialized niches. In the ventricular-subventricular zone (V-SVZ), quiescent neural stem cells (qNSCs) become activated (aNSCs), and generate transit amplifying cells (TACs), which give rise to neuroblasts that migrate to the olfactory bulb. The vasculature is an important component of the adult neural stem cell niche, but whether vascular cells in neurogenic areas are intrinsically different from those elsewhere in the brain is unknown. Moreover, the contribution of pericytes to the neural stem cell niche has not been defined. Here, we describe a rapid FACS purification strategy to simultaneously isolate primary endothelial cells and pericytes from brain microregions of nontransgenic mice using CD31 and CD13 as surface markers. We compared the effect of purified vascular cells from a neurogenic (V-SVZ) and non-neurogenic brain region (cortex) on the V-SVZ stem cell lineage in vitro. Endothelial and pericyte diffusible signals from both regions differentially promote the proliferation and neuronal differentiation of qNSCs, aNSCs, and TACs. Unexpectedly, diffusible cortical signals had the most potent effects on V-SVZ proliferation and neurogenesis, highlighting the intrinsic capacity of non-neurogenic vasculature to support stem cell behavior. Finally, we identify PlGF-2 as an endothelial-derived mitogen that promotes V-SVZ cell proliferation. This purification strategy provides a platform to define the functional and molecular contribution of vascular cells to stem cell niches and other brain regions under different physiological and pathological states.

Concomitant inhibition of oxidative stress and angiogenesis by chronic hydrogen-rich saline and N-acetylcysteine treatments improves systemic, splanchnic and hepatic hemodynamics of cirrhotic rats

AIM

In cirrhosis, increased oxidative stress leads to systemic and splanchnic hyperdynamic circulation, splanchnic angiogenesis, portosystemic collateral formation, hepatic endothelial dysfunction, increased intrahepatic resistance and the subsequent portal hypertension. Like N-acetylcysteine, hydrogen-rich saline is a new documented antioxidant with the potential to treat the complications of liver diseases.

METHODS

In this study, hemodynamics, splanchnic angiogenesis and hepatic endothelial dysfunction were measured in common bile duct ligation (BDL)-cirrhotic rats receiving 1-month treatment of vehicle, N-acetylcysteine and hydrogen-rich saline immediately after BDL. Additionally, acute effects of N-acetylcysteine and hydrogen-rich saline on vascular endothelial growth factor (VEGF)-induced tubule formation and migration of human umbilical vein endothelial cells (HUVEC) were also evaluated.

RESULTS

The data indicate that 1-month treatment of N-acetylcysteine or hydrogen-rich saline significantly ameliorated systemic and splanchnic hyperdynamic circulation, corrected hepatic endothelial dysfunction, and decreased intrahepatic resistance and mesenteric angiogenesis by inhibiting inflammatory cytokines, nitric oxide, VEGF and reducing mesenteric oxidative stress in cirrhotic rats. In vivo studies revealed that acute co-incubation of N-acetylcysteine or hydrogen-rich saline with VEGF effectively suppressed VEGF-induced angiogenesis and migration of HUVEC accompanied by decreasing of oxidative stress and inflammatory cytokines.

CONCLUSION

Both hydrogen-rich saline and N-acetylcysteine alleviate portal hypertension, the severity of portosystemic collaterals, mesenteric angiogenesis, hepatic endothelial dysfunction and intrahepatic resistance in cirrhotic rats. N-Acetylcysteine and the new antioxidant, hydrogen-rich saline are potential treatments for the complications of cirrhosis.

Caffeine ameliorates hemodynamic derangements and portosystemic collaterals in cirrhotic rats

Portal hypertension (PH), a pathophysiological derangement of liver cirrhosis, is characterized by hyperdynamic circulation, angiogenesis, and portosystemic collaterals. These may lead to lethal complications, such as variceal bleeding. Caffeine has been noted for its effects on liver inflammation, fibrogenesis, and vasoreactiveness. However, the relevant influences of caffeine in cirrhosis and PH have not been addressed. Spraque-Dawley rats with common bile duct ligation-induced cirrhosis or sham operation received prophylactic or therapeutic caffeine treatment (50 mg/kg/day, the first or 15th day since operation, respectively) for 28 days. Compared to vehicle (distilled water), caffeine decreased cardiac index, increased systemic vascular resistance, reduced portal pressure (PP), superior mesenteric artery flow, mesenteric vascular density, portosystemic shunting (PSS), intrahepatic angiogenesis, and fibrosis without affecting liver and renal biochemistry. The beneficial effects were reversed by selective adenosine A1 agonist N6-cyclopentyladenosine (CPA) or A2A agonist GCS21680. Both prophylactic and therapeutic caffeine treatment decreased portal resistance and PP in thioacetamide (200mg/kg, thrice-weekly for 8 weeks)-induced cirrhotic rats. Caffeine down-regulated endothelial nitric oxide synthase, vascular endothelial growth factor (VEGF), phospho-VEGFR2, and phospho-Akt mesenteric protein expression. Caffeine adversely affected viability of hepatic stellate and sinusoidal endothelial cells, which was reversed by CPA and GCS21680. On the other hand, caffeine did not modify vascular response to vasoconstrictors in splanchnic, hepatic, and collateral vascular beds.

CONCLUSIONS

Caffeine decreased PP, ameliorated hyperdynamic circulation, PSS, mesenteric angiogenesis, hepatic angiogenesis, and fibrosis in cirrhotic rats. Caffeine may be a feasible candidate to ameliorate PH-related complications in cirrhosis.

Treatment with recombinant lubricin attenuates osteoarthritis by positive feedback loop between articular cartilage and subchondral bone in ovariectomized rats

Osteoarthritis (OA) is a most commonly multifactorial degenerative joint disease along with the aging population, particularly in postmenopausal women. During the onset of OA, articular cartilage and subchondral bone act in concert as a functional unit. This present study is to investigate the effects of early or late treatment with recombinant lubricin on the onset of osteoarthritis (OA) in ovariectomized (OVX) rats. We found that both early and late recombinant lubricin treatments attenuated the onset of OA by positive feedback loop between articular cartilage and subchondral bone, although late treatment contributed to a lesser effect compared with early treatment. Specifically, treatment with recombinant lubricin protected articular cartilage from degeneration, demonstrated by lower proteoglycan loss, lower OARSI scores, less calcification cartilage zone and reduced immunostaining for collagen X (Col X) and matrix metalloproteinase (MMP-13) but increased the expression of lubricin, in comparison with vehicle-treated OVX rat group. Further, chondroprotective effects of lubricin normalized bone remodeling in subchondral bone underneath. It's suggested that treatment with recombinant lubricin inhibited the elevation of TRAP and Osterix positive cells in OVX rats and led to the normalization of subchondral bone microarchitectures with the suppression of subsidence of bone volume ratio (BV/TV) and trabecular thickness (Tb.Th) and the increase of trabecular separation (Tb.Sp) in vehicle-treated OVX rats. What's more, the normalization of subchondral bone in turn attenuated the articular cartilage erosion by inhibiting vascular invasion from subchondral bone to calcified cartilage zone, exemplified by inhibiting the elevation of CD31 positive cells in calcified cartilage and angiography in subchondral bone. Together, these results shed light that both early and late recombinant lubricin treatments attenuate the onset of OA by balancing the interplay between articular cartilage and subchondral bone in OVX rats, while also providing a further rationale for its therapeutic targeting to postmenopausal OA and suggesting that treatment timing is a pivotal factor for better effect acquisition.

The vascular marker CD31 also highlights histiocytes and histiocyte-like cells within cutaneous tumors

OBJECTIVES

While useful in diagnosing angiosarcomas, CD31 can also highlight histiocytes within soft tissue tumors and lead to errors in diagnosis. We sought to determine how often CD31 highlights cutaneous histiocytomas and histiocytoma mimics.

METHODS

We examined eight epithelioid cell histiocytomas (ECHs), 12 xanthogranulomas (XGs), nine cases of Langerhans cell histiocytosis (LCH), eight reticulohistiocytomas, 11 xanthomas, 29 atypical fibroxanthomas, nine granular cell tumors, four cases of angiolymphoid hyperplasia with eosinophilia, nine intradermal Spitz nevi, and nine angiosarcomas with antibodies directed against CD31, CD34, CD163, and factor VIII.

RESULTS

CD31 marked cells in three of 12 XGs, four of nine cases of LCH, one of eight reticulohistiocytomas, one of 11 xanthomas, 10 of 29 atypical fibroxanthomas, four of four cases of angiolymphoid hyperplasia with eosinophilia, nine of nine angiosarcomas, zero of nine granular cell tumors, and zero of eight ECHs. CD34 and factor VIII were negative in all nonvascular cases.

CONCLUSIONS

Our results indicate that CD31 can mark lesional cells and imitate vascular tumors in cutaneous histiocytomas and histiocytoma mimics, an error that can be avoided by using a panel of antibodies.

Tissue non-specific alkaline phosphatase production by human dental pulp stromal cells is enhanced by high density cell culture

The cell surface hydrolase tissue non-specific alkaline phosphatase (TNAP) (also known as MSCA-1) is used to identify a sub-population of bone marrow stromal cells (BMSCs) with high mineralising potential and is found on subsets of cells within the dental pulp. We aim to determine whether TNAP is co-expressed by human dental pulp stromal cells (hDPSCs) alongside a range of BMSC markers, whether this is an active form of the enzyme and the effects of culture duration and cell density on its expression. Cells from primary dental pulp and culture expanded hDPSCs expressed TNAP. Subsequent analyses revealed persistent TNAP expression and co-expression with BMSC markers such as CD73 and CD90. Flow cytometry and biochemical assays showed that increased culture durations and cell densities enhanced TNAP expression by hDPSCs. Arresting the hDPSC cell cycle also increased TNAP expression. These data confirm that TNAP is co-expressed by hDPSCs together with other BMSC markers and show that cell density affects TNAP expression levels. We conclude that TNAP is a potentially useful marker for hDPSC selection especially for uses in mineralised tissue regenerative therapies.

Fat/vessel-derived secretory protein (Favine)/CCDC3 is involved in lipid accumulation

We previously identified a novel gene encoding Favine/CCDC3 (NCBI protein entry NP_083080), a possible secretory factor, the mRNA of which is highly expressed in adipose tissue and the aorta. The Favine mRNA levels are increased in the course of differentiation of rat primary adipocytes and are more elevated in the adipose tissue of genetically obese and diet-induced obese mice than in lean mice. However, its biological function has not yet been elucidated until now. Here, we tested the hypothesis that Favine is involved in lipid metabolism in adipocytes. We found that overexpression of Favine promoted 3T3-L1 adipocyte differentiation. To further investigate the function of Favine in vivo, we generated Favine knock-out (KO) mice. Favine KO mice exhibited a lean phenotype as they aged. The weights of white adipose tissue and liver were less, and adipocyte size was smaller in Favine KO mice compared with wild-type littermates (WT). Expression levels of lipogenic genes, such as fatty-acid synthase (FAS), acetyl-CoA carboxylase α (ACC1), and diacylglycerol O-acyltransferase-2 (Dgat2), were decreased in adipose tissue of Favine KO mice. In 1-year-old mice, Favine deficiency decreased the number of inflammatory cells in white adipose tissue and diminished hepatic steatosis. In vitro, deficiency of Favine attenuated differentiation of primary adipocytes. Taken together, these data demonstrate that Favine has adipogenic and lipogenic effects on adipocytes.

Revisiting cardiovascular regeneration with bone marrow-derived angiogenic and vasculogenic cells

Cell-based therapy has emerged as a promising therapy for cardiovascular disease. Particularly, bone marrow (BM)-derived cells have been most extensively investigated and have shown encouraging results in preclinical studies. Clinical trials, however, have demonstrated split results in post-myocardial infarction cardiac repair. Mechanistically, transdifferentiation of BM-derived cells into cardiovascular tissue demonstrated by earlier studies is now known to play a minor role in functional recovery, and humoral and paracrine effects turned out to be main mechanisms responsible for tissue regeneration and functional recovery. With this advancement in the mechanistic insight of BM-derived cells, new efforts have been made to identify cell population, which can be readily isolated and obtained in sufficient quantity without mobilization and have higher therapeutic potential. Recently, haematopoietic CD31(+) cells, which are more prevalent in bone marrow and peripheral blood, have been revealed to have angiogenic and vasculogenic activities and strong potential for therapeutic neovascularization in ischaemic tissues. This article will cover the recent advances in BM-derived cell-based therapy and implication of CD31(+) cells.

Impact of p53, MIB-1 and PECAM-1 expression on the prognosis of urothelial carcinoma of the renal pelvis

OBJECTIVE

Determine whether the overexpression p53, MIB-1 and PECAM-1 of protein levels is of interest in predicting the prognosis of transitional cell carcinoma of the upper urinary tract (TCC-UUT) with the primary seat in the renal pelvis.

MATERIAL AND METHOD

A univariate and multivariate analysis was conducted for prognosis prediction in a series of 82 patients with TCC-UUT of the renal pelvis who had no metastases at diagnosis (N0/Nx M0) and were treated exclusively with nephroureterectomy. We assessed clinicopathological parameters (age, gender, tumor grade and extent, histological variety, growth pattern, vascular invasion, infiltration of the renal parenchyma, tumor necrosis) and the immunohistochemical expression of p53, MIB-1 (ki-67) and PECAM-1 (CD31) in sections performed with tissue microarray (TMA).

RESULTS

A total of 47.6% of the patients had high-grade lesions according to the USIP-WHO classification. The growth pattern was flat in 15.85%. The distribution by T category was: 3.7% pTa, 51.2% pT1, 11% pT2, 29.3% pT3 and 4.9% pT4. The mean follow-up was 46.8+38.5 (range, 4-172) months. The median survival was reached at 57 (95% CI 44-63) months. The univariate analysis revealed that survival in these patients is associated with tumor size (P=.028), histological variety (P<.0001), growth pattern (P<.0001), grade (P<.0001), pT (P=.01), vascular invasion (P=.025), necrosis (P=.004) and overexpression of p53 (P=.0006), PECAM-1 (P=.0036) and MIB-1 (P=.0038). The Cox regression model showed that high-grade (HR, 4.2; 95% CI 1.28-13.79; P=.018), flat growth pattern (HR, 2.52; 95% CI 1.05-6.03; P=.038) and p53 overexpression (HR, 2.8; 95% CI 1.22-6.44; P=.015) were independent predictors.

CONCLUSION

Histological grade, tumor growth pattern and p53 overexpression were established as the primary predictors of prognosis for primary TCC-UUT of the renal pelvis. The independent value of MIB-1 observed in other studies was not reproduced in this study.