The role of vascular endothelial growth factor in Langerhans cell histiocytosis

In angiogenesis, new blood vessels are generated from pre-existing ones. It plays a major role in tumor growth and metastasis. The main pro-angiogenic factor is the vascular endothelial growth factor (VEGF). VEGF displays high specificity for vascular endothelial cells and also elicits a pronounced angiogenic response in a variety of in vivo models. VEGF withdrawal has been shown to result in regression of vasculature in tumors. The pathogenic and the angiogenic processes of Langerhans cell histiocytosis (LCH) are not yet clear. The purpose of this study was to investigate the extent of the angiogenic response in LCH tumors. The authors examined tissue sections from LCH patients with single lesion (5 patients) or multisystem disease (5 patients). The preparations were examined by using monoclonal anti-VEGF antibody, CD34, and factor VIII-like antigen. VEGF was expressed in 70% of the cases examined. All the multisystem lesions were positive, as were two of the five single-lesion tumors. LCH cells expressed VEGF. The blood vessel density was significantly higher within the lesion than in normal margins. The findings that VEGF was expressed in LCH cells and that all multisystem lesions were VEGF producers raise the possibility of using anti-angiogenic drugs to treat these patients. Further studies to explore the role of angiogenesis in LCH are warranted.     

Urothelial mesh--a new technique of cell culture on biomaterials.

INTRODUCTION: Urogenital malformations, trauma or tumours may demand surgical reconstruction in children. Cell culture is an important technology in biomaterial research and tissue engineering. Tissue-engineering of urothelial organs is of interest in children, because the number of complications and re-operations may be reduced. Actually, monolayer cultures of urothelium are used for tissue engineering and biocompatibility testing. A culture system that more closely mimics the physiologic environment of the urothelium would be of interest. The aim of this study was to determine the biological and mechanical characteristics of urothelial mesh cultured in vitro. METHODS: Meshes containing urothelium, lamina propria, and submucosal tissue were generated using a skin mesh graft cutter. Meshes were cultured in 6-well plates, on collagen I/III, polydioxanone/polylactic acid and silicone matrices. Cell morphology was examined by inversion microscopy, histology, and scanning electron microscopy. It was compared to urothelium cultured by methods reported in the literature. To define the basic mechanical properties, meshes were extended longitudinally by a servohydraulic testing machine and strain diagrams generated. RESULTS: Urothelium was reproducibly cultured from meshes. Cell growth could be induced onto fibrillary collagen, polydioxanone-polylactic acid matrices and shaped polyurethane surfaces. Cells formed confluent layers of flat cells, resembling native urothelium. The meshes have unique mechanical properties, allowing for stable fixation, surgical handling and mechanical stimulation. CONCLUSIONS: Meshes can be used for cell culture on biomaterials. They maintain epithelial-stromal integrity and mechanic stability. The small size of tissue bridges allows in vitro culture for long periods with many potential advantages for tissue engineering and biologic research. Applications are possible both in vitro and in vivo.     

Endothelial effects of 3-hydroxyglutaric acid: implications for glutaric aciduria type I

Infants with glutaric aciduria type 1 (GA1) are subject to intracranial vascular dysfunction. Here, we demonstrate that the disease-specific metabolite 3-hydroxyglutaric acid (3-OH-GA) inhibits basal and vascular endothelial growth factor (VEGF)-induced endothelial cell migration. 3-OH-GA affects the morphology of VEGF-induced endothelial tubes in vitro because of partial disintegration of endothelial cells. These effects correlate with Ve-cadherin loss. Remarkably, 3-OH-GA treatment of human dermal microvascular endothelial cells leads to disruption of actin cytoskeleton. Local application of 3-OH-GA alone or in combination with VEGF in chick chorioallantoic membrane induces abnormal vascular dilatation and hemorrhage in vivo. The study demonstrates that 3-OH-GA reduces endothelial chemotaxis and disturbs structural vascular integrity in vitro and in vivo. These data may provide insight in the mechanisms of 3-OH-GA-induced vasculopathic processes and suggest N-methyl-D-aspartate receptor-dependent and -independent pathways in the pathogenesis of GA1.     

缺氧诱导因子-1α在婴幼儿血管瘤及血管畸形中的表达与意义

目的 本研究拟通过检测缺氧诱导因子-1α(hypoxia inducible factor-1α,HIF-1α)、血管内皮生长因子(vascular endothelial growth factor,VEGF)、细胞增殖核抗原Ki-67、血管内皮标志抗原CD34在婴幼儿血管瘤不同时期、血管畸形和儿童正常皮肤中的表达,探讨缺氧在血管瘤血管生成、细胞增殖中的作用.方法 采用免疫组织化学S-P染色法,检测CD34、HIF-1α、VEGF和Ki-67在小儿血管瘤、血管畸形及正常皮肤组织中的表达,并计算微血管密度(MVD).结果 不同时期血管瘤之间,血管瘤与血管畸形、正常皮肤之间HIF-1α、VEGF、Ki-67、MVD均有显著性差异(P<0.05).血管瘤中HIF-1α表达分别与VEGF、Ki-67、MVD表达呈正相关;而血管畸形HIF-1α与VEGF表达不存在相关关系.结论 缺氧是不同时期血管瘤的普遍现象.HIF-1α能促进血管瘤血管生成.而在血管畸形中可能不存在缺氧的微环境,是"血管内皮细胞生长正常的血管形态异常",因此在血管畸形中不会发生内皮细胞的增殖,也不存在类似血管瘤那样出现增生期和消退期.     

Percutaneous Pulmonary Artery Gene Transfer in Pigs Using Naked Plasmid DNA Delivered During Angioplasty

Gene transfer techniques are increasingly being used to study blood vessel biology and develop models for gene therapy. To date, there are no reports of pulmonary vascular gene transfer performed either without adjunctive agents or during angioplasty. We sought to demonstrate the feasibility of recombinant gene transfer to the pulmonary artery of juvenile pigs using naked plasmid DNA delivered via percutaneous angioplasty techniques. Plasmid DNA directing the expression of β-galactosidase was used to transfect one pulmonary artery while the contralateral vessel served as an untreated control. One delivery technique used a standard angioplasty balloon coated with a DNA–heparin mixture. The second involved infusion of DNA between an angioplasty balloon and a surrounding, microporous balloon. Vessels were harvested 3 or 4 days following gene delivery. Protein expression was demonstrated by immunohistochemical staining in transfected but not control vessels in 9/9 pigs. Vascular wall expression was limited to endothelial cells. Pulmonary artery gene transfer using naked plasmid DNA delivered via percutaneous angioplasty techniques is feasible. Using naked plasmid DNA removes the potential for toxicity associated with adjunctive agents. The described techniques provide novel methods for studying pulmonary vascular biology in vivo and for developing future gene therapies.     

Stem cell and regenerative science applications in the development of bioengineering of renal tissue

A rising number of patients with acute and chronic renal failure worldwide have created urgency for clinicians and investigators to search out alternative therapies other than chronic renal dialysis and/or organ transplantation. This review focuses on the recent achievements in this area, and discusses the various approaches in the development of bioengineering of renal tissue including recent discoveries in the field of regenerative medicine research and stem cells. A variety of stem cells, ranging from embryonic, bone marrow, endogenous, and amniotic fluid, have been investigated and may prove useful as novel alternatives for organ regeneration both in vitro and in vivo. Tissue engineering, developmental biology, and therapeutic cloning techniques have significantly contributed to our understanding of some of the molecular mechanisms involved in renal regeneration and have demonstrated that renal tissue can be generated de novo with similar physiologic functions as native tissue. Ultimately all of these emerging technologies may provide viable therapeutic options for regenerative medicine applications focused on the bioengineering of renal tissue for the future.     

Isolation and culture of fibroblasts, vascular smooth muscle, and endothelial cells from the fetal rat ductus arteriosus

The ductus arteriosus (DA), a fetal arterial shunt vessel between the proximal descending aorta and the pulmonary artery, closes shortly after birth. Initial functional closure as a result of the DA's smooth muscle contraction is followed by definite anatomical closure. The latter involves several complex mechanisms like endothelial cushion formation and smooth muscle cell migration resulting in fibrosis and sealing of the vessel. These complex steps indicate highly specialized functions of the DA vascular smooth muscle cells (VSMCs), endothelial cells, and fibroblasts. Herein, we describe a new reproducible method for isolating VSMCs, endothelial cells, and fibroblasts of high viability from fetal rat DA using immunomagnetic cell sorting. Purity of the different cell cultures was assessed by immunohistochemistry and flow cytometry and ranged between 85 and 94%. The capability of the VSMCs to react to hypoxic stimuli was assessed by intracellular calcium and ATP measurements and by VEGF mRNA expression analysis. VSMCs respond to hypoxia with decreases in intracellular calcium concentrations and ATP levels, whereas VEGF mRNA expression increased 3.2-fold. The purified vessel-specific different cell types are suitable for subsequent gene expression profiling and functional studies and provide important tools for improving our understanding of the complex processes involved in the closure of the DA.     

Tissue engineered vessels: Cells to telomeres

Vascular diseases continue to affect people of all ages, and therapies are continually being improved. Cardiovascular tissue engineering is becoming an established field that will enable the replacement or modification of diseased tissues. Although commonly thought to affect older populations, cardiac disease afflicts many pediatric patients who come with a different set of needs. Particularly, with congenital defects, an engineered construct must be able to grow with the patient to avoid costly, repeated surgeries. Of the wide variety of congenital cardiac defects observed today, many concern the vessels in and around the heart. The selection of a proper cell source and attention to cellular lifespan are important factors that dictate the success of a vascular graft. Engineered blood vessels have been constructed from both synthetic and biological materials, using cells from human, bovine, and porcine species. Smooth muscle and endothelial cells taken from vessel explants, as well as cells derived from bone marrow, have been utilized to generate extracellular matrix components needed for conduit construction. The limited lifespan of these cells, especially after weeks in culture, has been addressed with the use of the telomerase enzyme. The catalytic subunit of telomerase, hTERT, has been used to maintain telomere length and consequently extend cellular lifespan. This review looks at current research that is expanding the vessel tissue engineering field by implementing novel use of cells and telomerase.     

Determining the origin of cells in tissue engineered skin substitutes: a pilot study employing in situ hybridization

Background  

Definitive and high-quality coverage of large and, in particular, massive skin defects remains a significant challenge in burn as well as plastic and reconstructive surgery because of donor site shortage. A novel and promising approach to overcome these problems is tissue engineering of skin. Clearly, before eventual clinical application, engineered skin substitutes of human origin must be grafted and then evaluated in animal models. For the various tests to be conducted it is indispensable to be able to identify human cells as such in culture and also to distinguish between graft and recipient tissue after transplantation. Here we describe a tool to identify human cells in vitro and in vivo.     

Human tracheal chondrocytes as a cell source for augmenting stenotic tracheal segments: the first feasibility study in an in vivo culture system

INTRODUCTION: Construction of engineered respiratory tract using tissue-engineered cartilage has not yet been reported. In order to generate artificial trachea using human chondrocytes obtained from tracheal cartilage, we investigated whether human tracheal chondrocytes can act as a cell source to fabricate engineered airway patches to augment stenotic parts of the trachea. MATERIALS AND METHODS: After informed consent, chondrocytes were obtained from five patients who needed tracheal surgery. A small piece of resected tracheal cartilage was digested by collagenase type 2 for 3-4 h. This yielded chondrocytes, which were expanded in vitro and seeded onto biodegradable scaffolds; these were then implanted subcutaneously in athymic mice. The implanted constructs were retrieved 8 weeks later for histologic and biochemical analysis. RESULTS: In monolayer cultures, chondrocytes proliferated well, showing a 100- to 1,000-fold increase in 1 month. Once expanded, the cells lost their original morphological and biologic characteristics, but the engrafted scaffold showed histologic and biochemical characteristics of cartilage. Viable chondrocytes and extracellular matrix were detected, and glycosaminoglycan (GAG) in vivo was present. CONCLUSIONS: Here we show that a small piece of human tracheal cartilage can generate sufficient chondrocytes in vitro and form tracheal cartilage architecture in an in vivo environment.     

脂肪间充质干细胞的体外诱导和成血管作用

目的 研究在体外诱导脂肪间充质干细胞(ADMSCs)向内皮细胞分化、在立体培养基上的血管形成情况.方法 将传至第三代的ADMSCs用内皮细胞诱导液、Matrigel三维培养基进行诱导培养,对ADMSCs和诱导细胞选用CD31、CD44细胞表面抗原在流式细胞仪检测表达情况,用HE染色、FⅧ-RAg免疫组织化学染色及倒置显微镜、透射电镜等进行观察鉴定.结果流式细胞仪上检测ADMSCs的表达为CD44阳性、CD31阴性,诱导的细胞CD31阳性、CD44阴性.诱导细胞14d倒置显微镜下呈铺路石样形态,FⅧ-RAg染色细胞呈阳性,透射电镜下在细胞浆内见到内皮细胞特有标志物Weibel-Palade小体。ADMSCs在Matrigel三维培养基上诱导,24h细胞迁徙成团、有伪足伸出,诱导7d伸出的细胞形成交叉网格状,13d形成较长血管,20d较长血管粗而多、出现小分叉,30d长血管、分叉血管变粗厚;FⅧ-RAg染色后诱导血管亦呈阳性.结论 脂肪间充质干细胞在体外经诱导能向内皮细胞分化、能形成血管,可作为促进组织工程移植物血管化的良好的种子细胞.

Abstract：

Objective To study in vitro induction of adipose-derived mesenchymal stem cells (ADMSCs) into endothelial cells and blood vessel formation on three-dimensional (3D) media． Methods The 3rd passage ADMSCs were induced in vitro into endothelial cells on conditional medium and grew on Matrigel medium． The cell surface antigens CD31 and CD44 were detected with flow cytometric analysis before and after induction． HE staining, FⅧ-RAg immunohistochemical staining, inverted microscope and transmission electron microscope were used for morphological study.Results The expression of CD44 was positive and CD31 negative in ADMSCs in flow cytometric analysis.After induction,CD31 became positive while CD44 was negative． Paving-stone-like cell appearance was seen under inverted microscope 14 days after induction.The cells were FⅧ-RAg positively stained with immunohistological method,and Weibel-Palade body was observed under transmission electron microscope.On Matrigel media,the induced cells migrated in lumping with pseudopodia protrusion after 24 hours,and formed grid structure on the 7th day.Long vasculature was observed on the 13th day,and the vessels branched on the 20th to 30th day.The vessels stained positive for FⅧ-Rag． Conclusions ADMSCs have the potential to give rise to endothelial cells with in vitro induction and to form vessel structure in 3D media.ADMSCs have potential role in vascularized tissue engineering grafting．     

Blood and blood-vessels. Hemorrhages in scurvy

In scurvy there is, according to the results of previous investigators, a deficient regeneration of crythrocytes and polymorphous leukocytes, an initial hyperemia and a weakness of the vascular wall. This weakness is explained by the present author as a defective formation of the collagen connective tissue of the vessel and the lack of sufficient support from the atrophic tissue outside the vessel     

Antiangiogenic strategies in medulloblastoma: reality or mystery

Medulloblastoma is the most common malignant brain tumor of childhood. Surgery, radiation therapy, and chemotherapy successfully cure many patients, but survivors can suffer long-term toxicities affecting their neurocognitive and growth potential; furthermore, there is no curative therapy in up to 30% of cases, mainly because of our incomplete understanding of many of the underlying molecular and cellular processes. Angiogenesis is a hallmark of the progression of medulloblastoma and, over the last years, investigators have sought to develop effective and less toxic antiangiogenic strategies, including the inhibition or destruction of abnormal blood vessels using either antiangiogenic or vascular disrupting agents. However, the results are conflicting principally because of the complex biology of tumor vasculature and the irregular geometry of the vascular system in real space. In addition, current targets of antiangiogenic therapy, such as vascular endothelial growth factor (VEGF), are thought to be critical for both physiologic and pathologic angiogenesis, and clinical side effects of anti-VEGF therapy are beginning to emerge. We here review the state-of-the-art concerning antiangiogenic targets for medulloblastoma treatment, and discuss the complexity of the vascular system that intrinsically limits the efficacy of current strategies.     

Vascular effects of sphingolipids

The sphingomyelin metabolites ceramide, sphingosine 1-phosphate (S1P) and sphingosylphosphorylcholine (SPC) are emerging modulators of vascular tone. While ceramide appears to act primarily intracellularly, S1P and SPC appear to mainly work via specific receptors, although those for SPC have not yet been defined unequivocally. Each of the sphingomyelin metabolites can induce both vasoconstriction and vasodilatation and, in some cases--ceramide on the one hand, and S1P and SPC on the other hand--have opposite effects on vascular tone. The differences in effects between vessels may relate to the relative roles of endothelial and smooth muscle cells in mediating them, as well as to the distinct expression patterns of S1P receptors among vascular beds and among endothelial and smooth muscle cells. Recent evidence suggests that vascular tone is not only modulated by sphingomyelin metabolites which are exogenously added or reach the vessel wall via the bloodstream but also by those formed locally by cells in the vessel wall. Such local formation can be induced by known vasoactive agents such as angiotensin II and may serve a signalling function. CONCLUSION: We conclude that sphingomyelin metabolites are important endogenous modulators of vascular function, which may contribute to the pathophysiology of some diseases and be targets for therapeutic interventions.     

Methods for analyzing the density,distribution, origin,and phenotypes of restored cell populations in vivo and post-explant

Key challenges in the development of a tissue engineered heart valve (TEHV) include the creation of appropriate scaffold substrates and the selection of phenotypically appropriate cells for seeding or, conversely, the selection of progenitor cells that will appropriately proliferate and differentiate in vivo. Mesenchymal stem cells (MSCs) have come to the forefront as prime contenders for in vivo seeding due to their multilineage potential. However, because MSCs have the innate ability to differentiate into numerous cell types (e.g. osteoblasts, myocytes, adipocytes), methods must be established to accurately characterize the in vitro and in vivo cellular characteristics (cellular origin, phenotype and distribution; gene expression). Such methods can include gene expression analysis, proteomics, traditional quantitative morphology and morphometry, and cellular imaging. Through real-time quantitative PCR, RNA sequencing and microarray technology, the phenotype of differentiated repopulated cells in explanted tissue can be compared to cultured MSCs. Additionally, such methods are useful in tissues or cells harvested from animal models where a lack of specific antibodies for phenotype markers precludes the widespread use of immunoassays. Similarly, while ELISAs and western blots are useful to study the protein products of target genes, alternative methods exist for use in poorly validated animal models (e.g. mass spectrometry, differential gel electrophoresis). Finally, conventional histology is essential to the evaluation of cusp architecture in the TEHV and when coupled with immunohistochemistry or sophisticated cell tracking methods, the ultimate phenotype of repopulated cells can be evaluated.     

新法制备动脉脱细胞基质的实验研究

目的 建立一种新的动脉血管脱细胞基质制备方法.方法 取犬动脉,应用自行设计的胰酶、SDS和反复冻融的多步骤法制备犬动脉脱细胞基质.电镜、病理及力学检测脱细胞效果及力学特性.将猪内皮祖细胞种植于脱细胞基质,构建组织工程血管并移植到骨髓供体猪颈动脉或肺动脉.结果 应用胰酶消化、SDS漂洗及反复冻融处理后,保持了犬动脉的管形,细胞成分完全去除,最大断裂负荷、拉伸长度与自体动脉类似.种植内皮祖细胞后形成完整的内皮细胞层.移植到颈动脉后出现狭窄、堵塞.移植到肺动脉后血管通畅.结论 胰酶、SDS和反复冻融结合制备血管脱细胞基质,能够完全去除细胞成分,保留血管支架结构.     

Antioxidant and cytotoxic effects of bilirubin on neonatal erythrocytes

Bilirubin, the breakdown product of heme from erythrocytes, accumulates in the neonate in the first days of life. In recent years, the antioxidant properties of bilirubin have been demonstrated in vitro and in vivo, yet it is clear that bilirubin can be toxic to cells. To study the range in which bilirubin exerts its beneficial effect, we used erythrocytes derived from cord blood and incubated them with 0-60 mg/dL bilirubin combined with 3 g/dL BSA (bilirubin/BSA) to mimic physiologic and pathologic conditions. Oxidative stress was induced by incubating the erythrocytes with a solution of 0.6 mM H2O2 and 0.15 M CuSO4 to generate hydroxyl radical mediated injury. The loss of fluorescence of cis-parinaric acid and the degree of protein oxidation of erythrocyte membranes were assessed. Additionally, we determined erythrocyte membrane integrity, glucose-6 phosphate dehydrogenase activity, and adenosine triphosphatase activity before and after incubation with bilirubin/BSA. Incubation with bilirubin/BSA at concentrations up to 60 mg/dL and a bilirubin/BSA molar ratio of two was associated with dose-dependent protection of erythrocytes against lipid peroxidation. However, concentrations of bilirubin equal to or exceeding 30 mg/dL and a bilirubin:BSA ratio of one were associated with increased protein oxidation, decreased erythrocyte glucose-6 phosphate dehydrogenase and adenosine triphosphatase activity, and altered cell membrane integrity. We conclude that bilirubin, at physiologic concentrations, protects neonatal red blood cells against oxidative stress in the presence of physiologic concentrations of BSA but that bilirubin concentrations of 30 mg/dL or higher and a bilirubin:BSA ratio of greater than one are associated with significant cytotoxicity.     

Three-dimensional co-culture model of enterocytes and primary enteric neuronal tissue

Aim The aim of this study was to establish a three-dimensional model of the innervated mucosal barrier using a co-culture of an enterocyte cell line and enteric glial and nerve cells. Such a model might form the basis for further studies of interactions between the single compartments of the bowel wall, as well as of extrinsic influences on intestinal development and plasticity.Methods Isolated and dissociated myenteric plexus was resuspended in either collagen or extracellular matrix (ECM) solutions. After incubation at 37°C the solution gelled and formed stable plugs where neurons and glial cells reaggregated to form secondary neuronal networks. HT-29-enterocytes were seeded on top of the gels either immediately (collagen, ECM), or after adding a thin layer of collagen II (ECM).Results While the neuronal tissue formed complex networks within the gel, the enterocytes on top of the gels grew differently depending on the substrate and innervation. So enterocytes on ECM gels did not grow to confluence, while on collagen gels or on ECM plus collagen larger patches and increasing confluence could be observed. In general HT-29 grew better on innervated gels than on gels with no neuronal tissue.Conclusions With the presented model of different compartments of the bowel wall, various parameters of intercellular dependencies and influences can be observed in vitro. Moreover, the first results are also steps towards developing an innervated gut wall in vitro which might be able to restore functional capacity in infants with short bowel syndrome or other disorders that severely impair bowel function.S. Bainczyk and C. Hagl contributed equally to the study     

Stem cell plasticity: a new image of the bone marrow stem cell

The central tenet of stem cell biology is that within tissues there reside stem cells with the capacity for both self-renewal and terminal differentiation to the multiple lineages of that tissue. Over the last few years, numerous studies have challenged this paradigm by showing that tissue stem cells can differentiate to unexpected cell lineages, suggesting an enormous plasticity of differentiation. The hematopoietic stem cell, which resides within bone marrow and gives rise to all blood cells, has been the focal point of these efforts. However, recent studies have disputed the notion of hematopoietic stem cell plasticity. In truth, stem cell plasticity, strictly defined, has yet to be rigorously proven. Both animal models to carefully address outstanding issues and pilot clinical trials to explore the therapeutic potential will be key elements to advance science for the benefit of patients.