SOXF transcription factors in cardiovascular development

Cardiovascular development during embryogenesis involves complex changes in gene regulatory networks regulated by a variety of transcription factors. In this review we discuss the various reported roles of the SOXF factors: SOX7, SOX17 and SOX18 in cardiac, vascular and lymphatic development. SOXF factors have pleiotropic roles during these processes, and there is significant redundancy and functional compensation between SOXF family members. Despite this, evidence suggests that there is some specificity in the transcriptional programs they regulate which is necessary to control the differentiation and behaviour of endothelial subpopulations. Furthermore, SOXF factors appear to have an indirect role in regulating cardiac mesoderm specification and differentiation. Understanding how SOXF factors are regulated, as well as their downstream transcriptional target genes, will be important for unravelling their roles in cardiovascular development and related diseases.

Vascular endothelial growth factor (VEGF)-C, VEGF-D, VEGFR-3 and D2-40 expressions in primary breast cancer: Association with lymph node metastasis

BACKGROUND

Two members of the vascular endothelial growth factor (VEGF) family, VEGF-C and -D, are known as lymphangiogenic growth factors and play an important role in tumor lymphangiogenesis via activation of the VEGF receptor (VEGFR)-3, which is expressed in lymphatic endothelial cells. D2-40 is a specific antibody for lymphatic vessel density (LVD).

OBJECTIVES

In the present study, we have aimed to evaluate whether intraand peri-tumoral D2-40-positive lymphatic vessels affect lymph node metastasis and to investigate the relationship between LVD and lymph node metastasis in breast cancer.

MATERIAL AND METHODS

We have evaluated the relationships between lymph node metastasis and VEGF-C, VEGF-D, VEGFR-3 and D2-40 expressions in breast cancer cells using immunohistochemistry. VEGF-C, VEGF-D and VEGFR-3 expression were found in tumor cells in the majority of the cases (83.75, 97.5 and 95%, respectively).

RESULTS

There was a significant positive relationship between VEGF-D expression and lymph node metastasis (p < 0.05) however no significant association was found in VEGF-C and VEGFR-3 expressions. It was found that patients with high-expression of VEGF-D have a high level of both periand intra-tumoral LVD compared to those with low expression of VEGF-D (p < 0.05).

CONCLUSIONS

Our results support that examination of VEGF-D expression in breast cancer cells may be beneficial in the identification of lymph node metastasis.

Quantitative measurement of lymphatic function in mice by noninvasive near-infrared imaging of a peripheral vein

Optical imaging methods have been developed to measure lymphatic function in skin; however, the lymphatic system of many organs is not accessible to this technology. Since lymphatic transport of macromolecules from any organ proceeds to the blood circulation, we aimed to develop a method that can measure lymphatic function by monitoring the fluorescence in a superficial vein of an interstitially injected tracer. We selected a 40-kDa PEGylated near-infrared dye conjugate, as it showed lymphatic system-specific uptake and extended circulation in blood. Lymphatic transport to blood from subcutaneous tissue required a transit time before signal enhancement was seen in blood followed by a steady rise in signal over time. Increased lymphatic transport was apparent in awake mice compared with those under continuous anesthesia. The methods were validated in K14-VEGFR-3-Fc and K14-VEGF-C transgenic mice with loss and gain of lymphatic function, respectively. Reduced lymphatic transport to blood was also found in aged mice. The technique was also able to measure lymphatic transport from the peritoneal cavity, a location not suitable for optical imaging. The method is a promising, simple approach for assessment of lymphatic function and for monitoring of therapeutic regimens in mouse models of disease and may have potential for clinical translation.

Modulating the Biologic Activity of Mesenteric Lymph after Traumatic Shock Decreases Systemic Inflammation and End Organ Injury

Introduction

Trauma/hemorrhagic shock (T/HS) causes the release of pro-inflammatory mediators into the mesenteric lymph (ML), triggering a systemic inflammatory response and acute lung injury (ALI). Direct and pharmacologic vagal nerve stimulation prevents gut barrier failure and alters the biologic activity of ML after injury. We hypothesize that treatment with a pharmacologic vagal agonist after T/HS would attenuate the biologic activity of ML and prevent ALI.

Methods

ML was collected from male Sprague-Dawley rats after T/HS, trauma-sham shock (T/SS) or T/HS with administration of the pharmacologic vagal agonist CPSI-121. ML samples from each experimental group were injected into naïve mice to assess biologic activity. Blood samples were analyzed for changes in STAT3 phosphorylation (pSTAT3). Lung injury was characterized by histology, permeability and immune cell recruitment.

Results

T/HS lymph injected in naïve mice caused a systemic inflammatory response characterized by hypotension and increased circulating monocyte pSTAT3 activity. Injection of T/HS lymph also resulted in ALI, confirmed by histology, lung permeability and increased recruitment of pulmonary macrophages and neutrophils to lung parenchyma. CPSI-121 attenuated T/HS lymph-induced systemic inflammatory response and ALI with stable hemodynamics and similar monocyte pSTAT3 levels, lung histology, lung permeability and lung immune cell recruitment compared to animals injected with lymph from T/SS.

Conclusion

Treatment with CPSI-121 after T/HS attenuated the biologic activity of the ML and decreased ALI. Given the superior clinical feasibility of utilizing a pharmacologic approach to vagal nerve stimulation, CPSI-121 is a potential treatment strategy to limit end organ dysfunction after injury.

Effects of Melatonin, Aluminum Oxide, and Polymethylsiloxane Complex on the Expression of LYVE-1 in the Liver of Mice with Obesity and Type 2 Diabetes Mellitus

The effects of melatonin, aluminum oxide, and polymethylsiloxane complex on the expression of LYVE-1 (lymphatic vessel endothelial hyaluronan receptor) in the liver were studied in db/db mice with experimental obesity and type 2 diabetes mellitus. The complex or placebo was administered daily by gavage from week 8 to week 16 of life. The animals receiving the complex exhibited enhanced, in comparison with the placebo group, immunohistochemical LYVE-1+ staining of endothelial cells in sinusoids. Enhanced expression of LYVE-1 was associated with less pronounced dilatation of interlobular arteries, veins, and lymphatic vessels. Thee findings suggest a protective effect of the complex towards structural changes in the liver of mice with obesity and type 2 diabetes.

Morphological and Molecular Characterization of Human Dermal Lymphatic Collectors

Millions of patients suffer from lymphedema worldwide. Supporting the contractility of lymphatic collectors is an attractive target for pharmacological therapy of lymphedema. However, lymphatics have mostly been studied in animals, while the cellular and molecular characteristics of human lymphatic collectors are largely unknown. We studied epifascial lymphatic collectors of the thigh, which were isolated for autologous transplantations. Our immunohistological studies identify additional markers for LECs (vimentin, CCBE1). We show and confirm differences between initial and collecting lymphatics concerning the markers ESAM1, D2-40 and LYVE-1. Our transmission electron microscopic studies reveal two types of smooth muscle cells (SMCs) in the media of the collectors with dark and light cytoplasm. We observed vasa vasorum in the media of the largest collectors, as well as interstitial Cajal-like cells, which are highly ramified cells with long processes, caveolae, and lacking a basal lamina. They are in close contact with SMCs, which possess multiple caveolae at the contact sites. Immunohistologically we identified such cells with antibodies against vimentin and PDGFRα, but not CD34 and cKIT. With Next Generation Sequencing we searched for highly expressed genes in the media of lymphatic collectors, and found therapeutic targets, suitable for acceleration of lymphatic contractility, such as neuropeptide Y receptors 1, and 5; tachykinin receptors 1, and 2; purinergic receptors P2RX1, and 6, P2RY12, 13, and 14; 5-hydroxytryptamine receptors HTR2B, and 3C; and adrenoceptors α2A,B,C. Our studies represent the first comprehensive characterization of human epifascial lymphatic collectors, as a prerequisite for diagnosis and therapy.

Optical tracer size differences allow quantitation of active pumping rate versus Stokes-Einstein diffusion in lymphatic transport

Lymphatic uptake of interstitially administered agents occurs by passive convective–diffusive inflow driven by interstitial concentration and pressure, while the downstream lymphatic transport is facilitated by active propulsive contractions of lymphatic vessel walls. Near-infrared fluorescence imaging in mice was used to measure these central components of lymphatic transport for the first time, using two different-sized molecules––methylene blue (MB) and fluorescence-labeled antibody immunoglobulin G (IgG)-IRDye 680RD. This work confirms the hypothesis that lymphatic passive inflow and active propulsion rates can be separated based upon the relative differences in Stokes–Einstein diffusion coefficient. This coefficient specifically affects the passive-diffusive uptake when the interstitial volume and pressure are constant. Parameters such as mean time-to-peak signal, overall fluorescence signal intensities, and number of active peristaltic pulses, were estimated from temporal imaging data. While the mean time to attain peak signal representative of diffusion-dominated flow in the lymph vessels was 0.6±0.2??min for MB and 8±6??min for IgG, showing a size dependence, the active propulsion rates were 3.4±0.8??pulses/min and 3.3±0.5??pulses/min, respectively, appearing size independent. The propulsion rates for both dyes decreased with clearance from the interstitial injection-site, indicating intrinsic control of the smooth muscles in response to interstitial pressure. This approach to size-comparative agent flow imaging of lymphatic function can enable noninvasive characterization of diseases related to uptake and flow in lymph networks.

How Do Meningeal Lymphatic Vessels Drain the CNS?

The many interactions between the nervous and the immune systems, which are active in both physiological and pathological states, have recently become more clearly delineated with the discovery of a meningeal lymphatic system capable of carrying fluid, immune cells, and macromolecules from the central nervous system (CNS) to the draining deep cervical lymph nodes. However, the exact localization of the meningeal lymphatic vasculature and the path of drainage from the cerebrospinal fluid (CSF) to the lymphatics remain poorly understood. Here, we discuss the potential differences between peripheral and CNS lymphatic vessels and examine the purported mechanisms of CNS lymphatic drainage, along with how these may fit into established patterns of CSF flow.

[The fatty acids, triglycerides, chylomicrons, endoplasmic net, paracrine regulated cells' cenosises and becoming of lymph flow system in phylogenesis]

According phylogenetic theory of general pathology, necessity in supply of cells in vivo with exogenous fatty acids-substrates for gaining energy and physical-chemical parameters of fatty acids resulted in development (initially in single paracrine regulated cenosis of cells) of system of fatty acids transfer through hydrophilic inter-cellular medium in form of triglycerides in composition of hydrophobic chylomicrons -from enterocytes where they were developed to cells into which they were deposited. It is assumed that system of transfer of hydrophobic chylomicrons through aqueous inter-cellular medium was developed by anatomic combination of tubules of endoplasmic reticulum of enterocytes and the same tubules of cells of areolar tissue in paracrine regulated cenosis of cells of enterocytes with development of the most early in phylogenesis system of directed transfer, lymph flow. This occurrence became a prototype of lymphatic system; its first biological predestination is transferring of fatty acids to all cells escaping hydrophilic inter-cellular medium. With time, the lymphatic system all paracrin regulated cenosis of cells in vivo united in single system and became the foundation of development of organs and systems. The unification of epithelial and connective tissue cells of areolar tissue in single structure turned out to become the basis that at later stages of phylogenesis the lymphatic system began, under expressed convolution of its structure (development of lymphatic nodes), to combine: a) implementation ofprimary biological function of trophology (function of nutrition) with biological function of adaptation; b) later biological reactions of inherited and acquired immune defense at stages of phylogenesis and, probably, c) participation in hydrodynamics of distal sections of closed systemic blood circulation. The mechanisms of osmotic “pushing" of lymph have a lot of common with initiation of stream of cerebrospinal fluid of central nervous system and flow of primary urine in tubules of nephron.

Limited versus total epithelial debridement ocular surface injury: Live fluorescence imaging of hemangiogenesis and lymphangiogenesis in Prox1-GFP/Flk1::Myr-mCherry mice

BACKGROUND

Immunohistochemical staining experiments have shown that both hemangiogenesis and lymphangiogenesis occur following severe corneal and conjunctival injury and that the neovascularization of the cornea often has severe visual consequences. To better understand how hemangiogenesis and lymphangiogenesis are induced by different degrees of ocular injury, we investigated patterns of injury-induced corneal neovascularization in live Prox1-GFP/Flk1::myr-mCherry mice, in which blood and lymphatic vessels can be imaged simultaneously in vivo.

METHODS

The eyes of Prox1-GFP/Flk1::myr-mCherry mice were injured according to four models based on epithelial debridement of the: A) central cornea (a 1.5-mm-diameter circle of tissue over the corneal apex), B) total cornea, C) bulbar conjunctiva, and D) cornea+bulbar conjunctiva. Corneal blood and lymphatic vessels were imaged on days 0, 3, 7, and 10 post-injury, and the percentages of the cornea containing blood and lymphatic vessels were calculated.

RESULTS

Neither central corneal nor bulbar conjunctival debridement resulted in significant vessel growth in the mouse cornea, whereas total corneal and corneal+bulbar conjunctival debridement did. On day 10 in the central cornea, total cornea, bulbar conjunctiva, and corneal+bulbar conjunctival epithelial debridement models, the percentage of the corneal surface that was occupied by blood vessels (hemangiogenesis) was 1.9±0.8%, 7.14±2.4%, 2.29±1%, and 15.05±2.14%, respectively, and the percentage of the corneal surface that was occupied by lymphatic vessels (lymphangiogenesis) was 2.45±1.51%, 4.85±0.95%, 2.95±1.27%, and 4.15±3.85%, respectively.

CONCLUSIONS

Substantial corneal debridement was required to induce corneal neovascularization in the mouse cornea, and the corneal epithelium may therefore be partially responsible for maintaining corneal avascularity.

GENERAL SIGNIFICANCE

Our study demonstrates that GFP/Flk1::myr-mCherry mice are a useful model for studying coordinated hemangiogenic and lymphangiogenic responses.

Proteolytic activation defines distinct lymphangiogenic mechanisms for VEGFC and VEGFD

Lymphangiogenesis is supported by 2 homologous VEGFR3 ligands, VEGFC and VEGFD. VEGFC is required for lymphatic development, while VEGFD is not. VEGFC and VEGFD are proteolytically cleaved after cell secretion in vitro, and recent studies have implicated the protease a disintegrin and metalloproteinase with thrombospondin motifs 3 (ADAMTS3) and the secreted factor collagen and calcium binding EGF domains 1 (CCBE1) in this process. It is not well understood how ligand proteolysis is controlled at the molecular level or how this process regulates lymphangiogenesis, because these complex molecular interactions have been difficult to follow ex vivo and test in vivo. Here, we have developed and used biochemical and cellular tools to demonstrate that an ADAMTS3-CCBE1 complex can form independently of VEGFR3 and is required to convert VEGFC, but not VEGFD, into an active ligand. Consistent with these ex vivo findings, mouse genetic studies revealed that ADAMTS3 is required for lymphatic development in a manner that is identical to the requirement of VEGFC and CCBE1 for lymphatic development. Moreover, CCBE1 was required for in vivo lymphangiogenesis stimulated by VEGFC but not VEGFD. Together, these studies reveal that lymphangiogenesis is regulated by two distinct proteolytic mechanisms of ligand activation: one in which VEGFC activation by ADAMTS3 and CCBE1 spatially and temporally patterns developing lymphatics, and one in which VEGFD activation by a distinct proteolytic mechanism may be stimulated during inflammatory lymphatic growth.

CHD4-regulated plasmin activation impacts lymphovenous hemostasis and hepatic vascular integrity

The chromatin-remodeling enzyme CHD4 maintains vascular integrity at mid-gestation; however, it is unknown whether this enzyme contributes to later blood vessel or lymphatic vessel development. Here, we addressed this issue in mice harboring a deletion of Chd4 specifically in cells that express lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1), which include lymphatic endothelial cells (LECs) and liver sinusoidal endothelial cells. Chd4 mutant embryos died before birth and exhibited severe edema, blood-filled lymphatics, and liver hemorrhage. CHD4-deficient embryos developed normal lymphovenous (LV) valves, which regulate the return of lymph to the blood circulation; however, these valves lacked the fibrin-rich thrombi that prevent blood from entering the lymphatic system. Transcripts of the urokinase plasminogen activator receptor (uPAR), which facilitates activation of the fibrin-degrading protease plasmin, were upregulated in Chd4 mutant LYVE1+ cells, and plasmin activity was elevated near the LV valves. Genetic reduction of the uPAR ligand urokinase prevented degradation of fibrin-rich thrombi at the LV valves and largely resolved the blood-filled lymphatics in Chd4 mutants. Urokinase reduction also ameliorated liver hemorrhage and prolonged embryonic survival by reducing plasmin-mediated extracellular matrix degradation around sinusoidal blood vessels. These results highlight the susceptibility of LV thrombi and liver sinusoidal vessels to plasmin-mediated damage and demonstrate the importance of CHD4 in regulating embryonic plasmin activation after mid-gestation.

Antitumor and Antimetastatic Activity of Synthetic Hydroxystilbenes Through Inhibition of Lymphangiogenesis and M2 Macrophage Differentiation of Tumor-associated Macrophages

An increase in tumor-associated macrophages (TAMs) around the tumor microenvironment has been closely associated with a poor prognosis in patients with cancer, and M2 TAMs promote tumor growth and tumor metastasis by stimulating angiogenesis or lymphangiogenesis in tumors. We herein examined the effects of nine synthetic hydroxystilbenes on M2 macrophage activation and differentiation, and three selected dihydroxystilbenes on vascular endothelial cell growth factor (VEGF)-C-induced tube formation in human lymphatic endothelial cells (HLECs) (in vitro). We also investigated the antitumor and antimetastatic effects of three synthetic dihydroxystilbenes in LM8-bearing mice in vivo. The three selected synthetic stilbenes (at concentrations of 5, 10, 25, and 50 μM) inhibited the production of interleukin-10 and monocyte chemoattractant protein-1 in M2 macrophages, but promoted that of transforming growth factor-β1. The three dihydroxystilbenes (at concentrations of 10-50 μM) inhibited the phosphorylation of signal transducer and activator of transcript 3 without affecting its expression in the differentiation of M2 macrophages. Furthermore, the 2,3- and 4,4'-dihydroxystilbene inhibited VEGF-C-induced lymphangiogenesis in HLECs. Both 2,3- and 4,4'-dihydroxystilbene (at 10 and 25 mg/kg, twice daily) inhibited tumor growth and metastasis to the lung in mice. These results suggested that the antitumor and antimetastatic effects of 2,3- and 4,4'-dihydroxystilbene were partly due to anti-lymphangiogenesis, and the regulation of M2 macrophage activation and differentiation.

Voltage-gated sodium channels contribute to action potentials and spontaneous contractility in isolated human lymphatic vessels

Voltage-gated sodium channels (VGSC) play a key role for initiating action potentials (AP) in excitable cells. VGSC in human lymphatic vessels have not been investigated. In the present study, we report the electrical activity and APs of small human lymphatic collecting vessels, as well as mRNA expression and function of VGSC in small and large human lymphatic vessels. The VGSC blocker TTX inhibited spontaneous contractions in six of 10 spontaneously active vessels, whereas ranolazine, which has a narrower VGSC blocking profile, had no influence on spontaneous activity. TTX did not affect noradrenaline-induced contractions. The VGSC opener veratridine induced contractions in a concentration-dependent manner (0.1-30 μm) eliciting a stable tonic contraction and membrane depolarization to -18 ± 0.6 mV. Veratridine-induced depolarizations and contractions were reversed ∼80% by TTX, and were dependent on Ca(2+) influx via L-type calcium channels and the sodium-calcium exchanger in reverse mode. Molecular analysis determined NaV 1.3 to be the predominantly expressed VGSC isoform. Electrophysiology of mesenteric lymphatics determined the resting membrane potential to be -45 ± 1.7 mV. Spontaneous APs were preceded by a slow depolarization of 5.3 ± 0.6 mV after which a spike was elicited that almost completely repolarized before immediately depolarizing again to plateau. Vessels transiently hyperpolarized prior to returning to the resting membrane potential. TTX application blocked APs. We have shown that VGSC are necessary for initiating and maintaining APs and spontaneous contractions in human lymphatic vessels and our data suggest the main contribution from comes NaV 1.3. We have also shown that activation of these channels augments the contractile activity of the vessels.

Systemic Targeting of Lymph Node Metastasis through the Blood Vascular System by Using Size-Controlled Nanocarriers

Occult nodal metastases increase the risk of cancer recurrence, demoting prognosis and quality of life of patients. While targeted drug delivery by using systemically administered nanocarriers can potentially control metastatic disease, lymph node metastases have been mainly dealt by locally injecting nanocarriers, which may not always be applicable. Herein, we demonstrated that sub-50 nm polymeric micelles incorporating platinum anticancer drugs could target lymph node metastases in a syngeneic melanoma model after systemic injection, even after removing the primary tumors, limiting the growth of the metastases. By comparing these micelles with clinically used doxorubicin-loaded liposomes (Doxil) having 80 nm, as well as a 70 nm version of the micelles, we found that the targeting efficiency of the nanocarriers against lymph node metastases was associated with their size-regulated abilities to extravasate from the blood vasculature in metastases and to penetrate within the metastatic mass. These findings indicate the potential of sub-50 nm polymeric micelles for developing effective conservative treatments against lymph node metastasis capable of reducing relapse and improving survival.

Simultaneous in vivo imaging of blood and lymphatic vessel growth in Prox1-GFP/Flk1::myr-mCherry mice

The ability to visually observe angiogenesis and lymphangiogenesis simultaneously and repeatedly in living animals would greatly enhance our understanding of the inter-dependence of these processes. To generate a mouse model that allows such visualization via in vivo fluorescence imaging, we crossed Prox1-GFP mice with Flk1::myr-mCherry mice to generate Prox1-GFP/Flk1::myr-mCherry mice, in which lymphatic vessels emit green fluorescence and blood vessels emit red fluorescence. Corneal neovascularization was induced in these mice using three injury models: implantation of a vascular endothelial growth factor (VEGF) pellet, implantation of a basic fibroblast growth factor (bFGF) pellet, and alkali burn injury. Vessel growth was observed in vivo by stereomicroscopy on days 0, 3, 7 and 10 after pellet implantation or alkali injury as well as in flat-mounted corneas via confocal microscopy after the final in vivo imaging time point. We observed blood and lymphatic vessel growth in all three models, with the most significant growth occurring from days 0-7. Upon VEGF stimulation, the growth kinetics of blood and lymphatic vessels were similar. Blood vessels exhibited similar growth patterns in VEGF- and bFGF-stimulated corneas. Alkali burn injury induced robust angiogenesis and lymphangiogenesis. The intrinsic fluorescence of blood and lymphatic endothelial cells in Prox1-GFP/Flk1::myr-mCherry mice permitted simultaneous in vivo imaging of angiogenesis and lymphangiogenesis. This allowed us to differentiate the processes as well as observe their inter-dependence, and will be valuable in development of therapies targeting angiogenesis and/or lymphangiogenesis.

High-mobility group box 1 expression and lymph node metastasis in intrahepatic cholangiocarcinoma

AIM: To evaluate the prognostic value of high-mobility group box 1 (HMGB1) expression in intrahepatic cholangiocarcinoma (IHCC) and the possible underlying mechanism.

METHODS: Tissue microarray was constructed from 65 IHCC patients. Immunohistochemistry was performed to validate expression of HMGB1 and Vascular endothelial growth factor C (VEGF-C). Real-time PCR and Western blot analyses were used to study transcript and protein levels. The interaction between HMGB1 and VEGF-C was evaluated by siRNA, real-time PCR, and enzyme-linked immuno assays. The correlation between HMGB1 expression and other clinicopathologic parameters was analyzed by χ² test, and the univariate as well as multivariate analyses were accomplished by Kaplan-Meier method and Cox-regression model, respectively.

RESULTS: Overall, overexpression of HMGB1 was found in 38/65 (58.8%) IHCCs, whereas VEGF-C overexpression was present in 30/65 (46.2%) cases. Overexpression of HMGB1 was significantly correlated with lymphatic microvessel density (P = 0.031, r = 0.268) and VEGF-C expression (P = 0.041, r = 0.254). With univariate analysis, both HMGB1 (P = 0.001) and VEGF-C (P = 0.004) were identified to be significantly associated with overall survival rate. Multivariate analysis indicated that HMGB1 could be served as an unfavorable independent prognostic factor in IHCCs (P = 0.005). siRNA knockdown of HMGB1 inhibited transforming growth factor-β-induced epithelial-mesenchymal transition (EMT) by elevating E-Cadherin expression and reducing expression of N-Cadherin, Vimentin and Snail in RBE cells. Further in vitro study revealed that HMGB1 silencing significantly decreased the level of VEGF-C, whereas the recombinant HMGB1 increased the VEGF-C level in RBE cells (both P < 0.05), which suggested that HMGB1 could promote lymphatic microvessel density, and subsequently lymphatic invasion, via promoting VEGF-C expression.

CONCLUSION: Our results define an important role of HMGB1 in the progression of cholangiocarcinoma, and HMGB1 may serve as a prognostic marker for IHCC patients.

The mesenteric lymph duct cannulated rat model: application to the assessment of intestinal lymphatic drug transport

The intestinal lymphatic system plays key roles in fluid transport, lipid absorption and immune function. Lymph flows directly from the small intestine via a series of lymphatic vessels and nodes that converge at the superior mesenteric lymph duct. Cannulation of the mesenteric lymph duct thus enables the collection of mesenteric lymph flowing from the intestine. Mesenteric lymph consists of a cellular fraction of immune cells (99% lymphocytes), aqueous fraction (fluid, peptides and proteins such as cytokines and gut hormones) and lipoprotein fraction (lipids, lipophilic molecules and apo-proteins). The mesenteric lymph duct cannulation model can therefore be used to measure the concentration and rate of transport of a range of factors from the intestine via the lymphatic system. Changes to these factors in response to different challenges (e.g., diets, antigens, drugs) and in disease (e.g., inflammatory bowel disease, HIV, diabetes) can also be determined. An area of expanding interest is the role of lymphatic transport in the absorption of orally administered lipophilic drugs and prodrugs that associate with intestinal lipid absorption pathways. Here we describe, in detail, a mesenteric lymph duct cannulated rat model which enables evaluation of the rate and extent of lipid and drug transport via the lymphatic system for several hours following intestinal delivery. The method is easily adaptable to the measurement of other parameters in lymph. We provide detailed descriptions of the difficulties that may be encountered when establishing this complex surgical method, as well as representative data from failed and successful experiments to provide instruction on how to confirm experimental success and interpret the data obtained.

Aberrant lymphatic endothelial progenitors in lymphatic malformation development

Lymphatic malformations (LMs) are vascular anomalies thought to arise from dysregulated lymphangiogenesis. These lesions impose a significant burden of disease on affected individuals. LM pathobiology is poorly understood, hindering the development of effective treatments. In the present studies, immunostaining of LM tissues revealed that endothelial cells lining aberrant lymphatic vessels and cells in the surrounding stroma expressed the stem cell marker, CD133, and the lymphatic endothelial protein, podoplanin. Isolated patient-derived CD133+ LM cells expressed stem cell genes (NANOG, Oct4), circulating endothelial cell precursor proteins (CD90, CD146, c-Kit, VEGFR-2), and lymphatic endothelial proteins (podoplanin, VEGFR-3). Consistent with a progenitor cell identity, CD133+ LM cells were multipotent and could be differentiated into fat, bone, smooth muscle, and lymphatic endothelial cells in vitro. CD133+ cells were compared to CD133− cells isolated from LM fluids. CD133− LM cells had lower expression of stem cell genes, but expressed circulating endothelial precursor proteins and high levels of lymphatic endothelial proteins, VE-cadherin, CD31, podoplanin, VEGFR-3 and Prox1. CD133− LM cells were not multipotent, consistent with a differentiated lymphatic endothelial cell phenotype. In a mouse xenograft model, CD133+ LM cells differentiated into lymphatic endothelial cells that formed irregularly dilated lymphatic channels, phenocopying human LMs. In vivo, CD133+ LM cells acquired expression of differentiated lymphatic endothelial cell proteins, podoplanin, LYVE1, Prox1, and VEGFR-3, comparable to expression found in LM patient tissues. Taken together, these data identify a novel LM progenitor cell population that differentiates to form the abnormal lymphatic structures characteristic of these lesions, recapitulating the human LM phenotype. This LM progenitor cell population may contribute to the clinically refractory behavior of LMs.

[MORPHOLOGICAL CHANGES AFTER THE USE OF MULTIPOTENT STROMAL CELLS OF BONE MARROW ORIGIN TO RESTORE THE LYMPH FLOW IN THE REGION OF THROMBOSED VEIN]

In the male Wag rats aged 6 months with the body mass of 180-200 g the luminescent microscopy was used to examine the possibility of lymphatic vessel formation after injection into thrombosed vein of the thigh of autologous multipotent stromal cells of bone marrow origin (AMSCBMO) transfected with green fluorescent protein gene. Animals were sacrificed 4 days and 1, 2, 3, 4 and 5 weeks after the injection of AMSCBMO. The control group consisted of intact rats, animals with venous thrombosis receiving no injection of AMSCBMO and those injected with AMSCBMO but without the prior modelling of venous thrombosis. In each experimental and control groups at each time point 11-12 animals were used (total number equal to 226). After the main vein ligation with the subsequent injection of thrombin solution, in addition to the thrombosis of the blood vessels, morphological signs of thrombosis of the lymphatic bed and lymphostasis were present: the dilation of lymphatic vessel lumen, thinning of their layers, intense staining of their luminal heterogeneous content. AMSCBMO, injected into thrombosed vein, were found to directly participate in lymphangiogenesis in the connective tissue around vein, its tissue region and in the area of regional lymph nodes. This is indicated by bright specific luminescence of both individual cells in the wall of the lymphatic vessels, and all their tunics together with the valves, when exposed to UV light.

[THE STRUCTURE OF LYMPHATIC CAPILLARIES OF THE CILIARY BODY OF THE HUMAN EYE]

Using light microscopy, immunohistochemistry and electron microscopy, the structural organization of interstitial spaces and vessels of the ciliary body of the human eye (n = 5) were studied. The ciliary body was found to contain wide interstitial spaces--tissue clefts bound by collagen fibers and fibroblasts. Organ-specific lymphatic capillaries were also demonstrated in the ciliary body. According to the present findings and the lymphatic region concept, the first 2 elements of the lymphatic region of the eye were described: tissue clefts--prelymphatics and lymphatic capillaries of the ciliary body. The third element of the lymphatic region are the lymph nodes of the head and neck.

Lymphatic manifestations of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a slowly progressive, low grade, metastasizing neoplasm, associated with cellular invasion and cystic destruction of the pulmonary parenchyma. Although the source of LAM cells that infiltrate the lung is unknown, available evidence indicates that the disease spreads primarily through lymphatic channels, often involving abdominal, axial, and retroperitoneal nodes, suggestive of an origin in the pelvis. LAM cells harbor mutations in tuberous sclerosis genes and produce lymphangiogenic growth factors, which facilitate access to and movement through the lymphatic system and likely play an important role in destructive tissue remodeling in the lung. Lymphatic manifestations of LAM include thoracic duct wall invasion, lymphangioleiomyoma formation, chylous fluid collections in the peritoneal, pleural, and pericardial spaces, chyloptysis, chylocolporrheal chylometrorrhea, chyle leak from the umbilicus, chylous pulmonary congestion, and lower extremity lymphedema. LAM lesions express lymphangiogenic growth factors VEGF-C and VEGF-D; growth factor receptors, VEGFR-2 and VEGFR-3; and markers LYVE-1 and podoplanin, and are laced with chaotic lymphatic channels. Serum VEGF-D is elevated in 70% of patients with LAM and is a clinically useful diagnostic and prognostic biomarker. Molecular targeted therapy with sirolimus stabilizes lung function, is anti-lymphangiogenic, and is highly effective for the lymphatic and chylous complications of LAM. Future trials in patients with LAM who have lymphatic manifestations or elevated serum VEGF-D will likely focus on the VEGF-C/VEGF-D/VEGFR-3 axis.

Rhesus monkey is a new model of secondary lymphedema in the upper limb

OBJECTIVE

This study is to establish the rhesus monkey model of lymphedema in the upper limbs, and assess the suitability of this model.

METHODS

An animal model of lymphedema was established by the combined irradiation and surgical techniques in the upper limbs of these rhesus monkeys. Physical examination, high-resolution MR lymphangiography, bioelectrical impedance analysis (BIA), and immunohistochemical staining were performed to determine the severity of the edema in the upper limbs of the animal model.

RESULTS

Our results from physical examination indicated that the rhesus monkey model present with typical appearance and features of lymphedema. MR lymphangiography further demonstrated pathologically modified lymphatic vessels in our rhesus monkey model. BIA revealed increased water content in the upper limb in these rhesus monkeys, which was in line with the pathology of lymphedema. Immunohistochemical staining showed the curvature of the lymphatic vessels in the rhesus monkey model, typical pathological changes in lymphedema.

CONCLUSION

Rhesus monkey lymphedema model provides a more consistent background to elucidate the pathophysiology of the disease. This new model would help to increase our understanding of acquired upper limb lymphedema, and promote the development of new treatments for this intractable disorder.

Confocal image-based computational modeling of nitric oxide transport in a rat mesenteric lymphatic vessel

The lymphatic system plays important roles in protein and solute transport as well as in the immune system. Its functionality is vital to proper homeostasis and fluid balance. Lymph may be propelled by intrinsic (active) vessel pumping or passive compression from external tissue movement. With regard to the former, nitric oxide (NO) is known to play an important role modulating lymphatic vessel contraction and vasodilation. Lymphatic endothelial cells (LECs) are sensitive to shear, and increases in flow have been shown to cause enhanced production of NO by LECs. Additionally, high concentrations of NO have been experimentally observed in the sinus region of mesenteric lymphatic vessels. A computational flow and mass transfer model using physiologic geometries obtained from confocal images of a rat mesenteric lymphatic vessel was developed to determine the characteristics of NO transport in the lymphatic flow regime. Both steady and unsteady analyses were performed. Production of NO was shear-dependent; basal cases using constant production were also generated. Simulations revealed areas of flow stagnation adjacent to the valve leaflets, suggesting the high concentrations observed here experimentally are due to minimal convection in this region. LEC sensitivity to shear was found to alter the concentration of NO in the vessel, and the convective forces were found to profoundly affect the concentration of NO at a Péclet value greater than approximately 61. The quasisteady analysis was able to resolve wall shear stress within 0.15% of the unsteady case. However, the percent difference between unsteady and quasisteady conditions was higher for NO concentration (6.7%). We have shown high NO concentrations adjacent to the valve leaflets are most likely due to flow-mediated processes rather than differential production by shear-sensitive LECs. Additionally, this model supports experimental findings of shear-dependent production, since removing shear dependence resulted in concentrations that are physiologically counterintuitive. Understanding the transport mechanisms and flow regimes in the lymphatic vasculature could help in the development of therapeutics to treat lymphatic disorders.

Intratumoral but not peritumoral lymphatic vessel density measured by D2-40 expression predicts poor outcome in gastric cancer--ROC curve analysis to find cut-off point

BACKGROUND

Neolymphangiogenesis, a process of lymphatic vessel development in neoplastic tissue, may be a key event in the transmission of cancer cells into lymph nodes. The current study examined the relationship between lymphatic vessel density (LVD) measured by podoplanin (D2-40) expression, clinicopathological parameters and patient survival in gastric cancer.

MATERIALS AND METHODS

D2-40 expression was examined by immunohistochemistry in formalin-fixed paraffin-embedded tissue specimens obtained from 60 patients with gastric cancer. D2-40 immunoreactivity was analyzed in intratumoral and peritumoral compartments of tumors and correlated with tumor grade, type in Lauren's classification, lymph node status, distant metastasis, presence of ulceration, inflammatory infiltration, angio-invasion, lymphangio-invasion and patient survival using a Receiver Operating Characteristic (ROC) curve analysis to find cut-off points that enabled fair decision making in survival analysis.

RESULTS

The mean values of intratumoral and peritumoral LVD were 6.63 and 11.25, respectively. Enhanced intratumoral LVD measured by D2-40 immunoexpression was correlated with the presence of lymph node metastases (p=0.04). Our study revealed a statistically significant correlation between intratumoral LVD measured by D2-40 expression and survival of patients with gastric cancer: an intratumoral LVD higher than 4.68 is significantly correlated with unfavorable prognosis, with a probability of death of approximately 80%. No significant relationship was identified between peritumoral LVD, lymph node status and survival in patients with gastric cancer.

CONCLUSION

A high intratumoral LVD measured by D2-40 expression in specimens from primary tumors is strongly associated with lymph node metastasis and predicts worse clinical outcome. Increased intratumoral D2-40 immunoreactivity is a putative predictor of aggressive gastric cancer behavior.