Alpha-smooth Muscle Actin-positive Cells Research Articles

Endothelial Fli1 Deficiency Impairs Vascular Homeostasis: A Role in Scleroderma Vasculopathy

Systemic sclerosis or scleroderma (SSc) is a complex autoimmune connective tissue disease characterized by obliterative vasculopathy and tissue fibrosis. The molecular mechanisms underlying SSc vasculopathy are largely unknown. Friend leukemia integration factor 1 (Fli1), an important regulator of immune function and collagen fibrillogenesis, is expressed at reduced levels in endothelial cells in affected skin of patients with SSc. To develop a disease model and to investigate the function of Fli1 in the vasculature, we generated mice with a conditional deletion of Fli1 in endothelial cells (Fli1 CKO). Fli1 CKO mice showed a disorganized dermal vascular network with greatly compromised vessel integrity and markedly increased vessel permeability. We show that Fli1 regulates expression of genes involved in maintaining vascular homeostasis including VE-cadherin, platelet endothelial cell adhesion molecule 1, type IV collagen, matrix metalloproteinase 9, platelet-derived growth factor B, and S1P(1) receptor. Accordingly, Fli1 CKO mice are characterized by down-regulation of VE-cadherin and platelet endothelial cell adhesion molecule 1, impaired development of basement membrane, and a decreased presence of alpha-smooth muscle actin-positive cells in dermal microvessels. This phenotype is consistent with a role of Fli1 as a regulator of vessel maturation and stabilization. Importantly, vascular characteristics of Fli1 CKO mice are recapitulated by SSc microvasculature. Thus, persistently reduced levels of Fli1 in endothelial cells may play a critical role in the development of SSc vasculopathy.

Variable expression of tenascin‐C, osteopontin and fibronectin in inflammatory myofibroblastic tumour of the lung

The aim of this study was to analyse the expression of tenascin-C, osteopontin and fibronectin in inflammatory myofibroblastic tumour of the lung, which is a rare tumour of unknown aetiology. Nine patients with an inflammatory myofibroblastic tumour of lung were studied by immunohistochemistry for the presence of tenascin-C, osteopontin, fibronectin and alpha-smooth muscle actin, which is a common marker for myofibroblasts. The ultrastructure of myofibroblasts was confirmed by transmission electron microscopy. The expression of tenascin-C, osteopontin, fibronectin and alpha-smooth muscle actin was also studied by immunoelectron microscopy. All cases displayed all of the studied extracellular matrix proteins and also alpha-smooth muscle actin-positive spindle-shaped fibroblastic cells that were undoubtedly myofibroblasts. The immunoelectron microscopic studies demonstrated labelling for alpha-smooth muscle actin in intracellular filament bundles within myofibroblasts, for fibronectin in the extracellular filaments of the fibronexus and for tenascin-C extracellularly often adjacent to myofibroblasts. Labels for osteopontin were observed within myofibroblasts and plasma cells. These results demonstrate that tenascin-C, osteopontin and fibronectin were expressed in all three kinds of subtypes of inflammatory myofibroblastic tumours of the lung and further, variable amounts of myofibroblasts could be observed by light and transmission electron microscopy as well as by immunoelectron microscopic techniques.

Liver Fibrosis in an Extremely Small Infant for Gestational Age

Premature infants with intrauterine growth restriction (IUGR) are at greater risk for an adverse perinatal outcome. IUGR affects hepatocyte function, but the histopathological changes in the postnatal liver are not well known. We report a male infant with severe IUGR. His mother was transferred to our hospital at 26 weeks of gestation because of preterm labor and severe IUGR. An emergency cesarean section was carried out because of a non-reassuring fetal status. The birth weight of the infant was 332 g. He showed congestive heart failure and marked hepatomegaly from birth. After 1 week, blood examinations showed hyperbilirubinemia with high direct bilirubin. Because of liver dysfunction, he received the minimal total parenteral nutrition for 7 days. After 1 month, he progressively developed ascites and coagulopathy, and died 3 months after birth. Liver autopsy showed diffuse perisinusoidal fibrosis. Fibrosis was also prominent around the central vein. Immunohistochemical study revealed many alpha-smooth muscle actin-positive cells, which represent activated hepatic stellate cells, and a few transforming growth factor-beta1-positive cells in the perisinusoidal fibrotic area. These results indicate that the infant developed chronic (end stage) liver failure by 3 months of age. We excluded congenital infection, metabolic syndrome and citrin deficiency. It is therefore conceivable that intrauterine cardiac failure may be responsible for liver fibrosis. Early detection of liver dysfunction soon after birth is a key to predict the prognosis of severe IUGR in preterm infants.

Bone Marrow-Derived Cells Promote Liver Regeneration in Mice With Erythropoietic Protoporphyria

Bone marrow transplantation can reverse hepatic protoporphyrin accumulation and prevent the hepatobiliary complications characteristic of erythropoietic protoporphyria. The aim of this study was to assess the recruitment capacity of bone marrow cells in the damaged liver and their possible contribution to the improved or recovered hepatic function in a murine model of erythropoietic protoporphyria (EPP). Lethally irradiated female EPP mice were transplanted with bone marrow cells from healthy male mice and were monitored during 12 or 36 weeks. Two groups of animals killed 12 weeks after transplant were also treated with granulocyte colony-stimulating factor. Cell transplantation decreased porphyrin contents in erythrocytes and liver. Improved hepatic structure and function and reduced hepatic fibrosis were observed, especially 36 weeks after transplant. Bone marrow-derived cells (22%-35%) were identified in the liver of recipient mice by means of fluorescence in situ hybridization (chrY-FISH) or green fluorescent protein staining and were characterized by immunofluorescence staining. The livers of recipients contained 20% to 30% myofibroblasts (alpha-smooth muscle actin-positive cells), 40% CK19-positive cells, and 10% to 28% hepatocytes (albumin-positive cells) derived from the donor bone marrow. Bone marrow-derived cells play a significant role in restoring and regenerating hepatic tissue in EPP mice. Hepatic repair was associated with fibrogenesis, enhanced by granulocyte colony-stimulating factor treatment, and almost normal liver structure and function was observed in the long term (36 weeks posttransplant).

Abstract 5541: Erythropoietin Receptor Signaling Exacerbates Neointimal Hyperplasia in the Rat Carotid Artery After Balloon Injury

Treatment with erythropoietin (EPO) was reported to accelerate reendothelialization, accompanying endothelial progenitor cell (EPC) induction, to result in suppression of neointimal hyperplasia in the carotid artery after balloon injury. We injured the right carotid artery of male SD rats (200 to 250 g) with an oversized balloon. Treatment with recombinant human EPO (1000 IU/kg/day) or asialoerythropoietin (AEPO, 1000 IU/kg/day), a nonerythrogenic derivative of EPO, was started at 1 week after injury when neointimal proliferates and continued for 3 days. The rats were examined 2 weeks after the surgery. The hemoglobin level was significantly increased in the EPO-treated rats but was unchanged in the saline control and AEPO-treated groups. FACS analysis revealed significantly increased circulating EPCs in the EPO-treated group but not in the AEPO-treated group. Reendothelialization was accelerated in both EPO- and AEPO-treated groups. However, the area of neointima was significantly greater in both treatment groups compared with the control group and accordingly the area of neointimal to medial area ratio (%) was significantly greater in the EPO- (150+/−26%) and AEPO-treated (157+/−15%) groups compared with the control group (132+/−7%). Alpha-smooth muscle actin-positive cell population was also greater in both treatment groups. The incidence of proliferating cells labeled with Ki-67 antigen was significantly greater not only in the endothelium but also in the neointima of the EPO- and AEPO-treated groups compared with the control group. In conclusion, EPO receptor signaling can proliferate not only endothelial cells but also intimal smooth muscle-like cells independently of EPC induction, which might have aggravated neointimal hyperplasia when EPO receptor was stimulated at the phase of intimal proliferation after injury. These findings caution an easy use of EPO in patients after vascular intervention.

Loss of peroxisome proliferator–activated receptor γ in mouse fibroblasts results in increased susceptibility to bleomycin‐induced skin fibrosis

There is increasing evidence that the transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma) plays an important role in controlling cell differentiation, and that PPARgamma ligands can modify inflammatory and fibrotic responses. The aim of the present study was to examine the role of PPARgamma in a mouse model of skin scleroderma, in which mice bearing a fibroblast-specific deletion of PPARgamma were used. Cutaneous sclerosis was induced by subcutaneous injection of bleomycin, while untreated control groups were injected with phosphate buffered saline. Mice bearing a fibroblast-specific deletion of PPARgamma were investigated for changes in dermal thickness, inflammation, collagen content, and the number of alpha-smooth muscle actin-positive cells. The quantity of the collagen-specific amino acid hydroxyproline was also measured. In addition, the effect of PPARgamma deletion on transforming growth factor beta1 (TGFbeta1) signaling in the fibroblasts was investigated. Bleomycin treatment induced marked cutaneous thickening and fibrosis in all treated mice. Deletion of PPARgamma resulted in enhanced susceptibility to bleomycin-induced skin fibrosis, as indicated by increases in all measures of skin fibrosis and enhanced sensitivity of fibroblasts to TGFbeta1 in PPAR-deficient mice. These results indicate that PPARgamma suppresses fibrogenesis. Specific agonists of PPARgamma may therefore alleviate the extent of the development of cutaneous sclerosis.

Loss of β1 integrin in mouse fibroblasts results in resistance to skin scleroderma in a mouse model

Activated adhesive signaling is a hallmark of fibroblasts isolated from the scars of scleroderma (systemic sclerosis) lesions. Beta-1 integrin plays a key role in adhesive signaling. The aim of the present study was to examine the role of beta1 integrin in a mouse model of skin scleroderma using mice bearing a fibroblast-specific deletion of beta1 integrin. Cutaneous sclerosis was induced by subcutaneous injection of bleomycin. Control groups were treated with phosphate buffered saline. Mice bearing a fibroblast-specific deletion of beta1 integrin and control mice were investigated. Dermal thickness, collagen production, and the number of alpha-smooth muscle actin-positive cells were determined. The quantity of the collagen-specific amino acid hydroxyproline was also measured. Bleomycin treatment induced marked cutaneous thickening and fibrosis in control mice. Conversely, the deletion of beta1 integrin resulted in resistance to bleomycin-induced fibrosis. Expression of beta1 integrin by fibroblasts is required for fibrogenesis. Inhibition of beta1 integrin may be a viable method to alleviate the development of cutaneous sclerosis.

Immunohistochemical study of the phenotypic change of the mesenchymal cells during portal tract maturation in normal and fibrous (ductal plate malformation) fetal liver

BackgroundIn adult liver, the mesenchymal cells, portal fibroblasts and vascular smooth muscle cells can transdifferentiate into myofibroblasts, and are involved in portal fibrosis. Differential expression of markers, such as alpha-smooth muscle actin (ASMA), h-caldesmon and cellular retinol-binding protein-1 allows their phenotypic discrimination. The aim of our study was to explore the phenotypic evolution of the mesenchymal cells during fetal development in normal liver and in liver with portal fibrosis secondary to ductal plate malformation in a series of Meckel-Gruber syndrome, autosomal recessive polycystic kidney disease and Ivemark's syndrome.ResultsAt the early steps of the portal tract maturation, portal mesenchymal cells expressed only ASMA. During the maturation process, these cells were found condensed around the biliary and vascular structures. At the end of maturation process, only cells around vessels expressed ASMA and cells of the artery tunica media also expressed h-caldesmon. In contrast, ASMA positive cells persisted around the abnormal biliary ducts in fibrous livers.ConclusionAs in adult liver, there is a phenotypic heterogeneity of the mesenchymal cells during fetal liver development. During portal tract maturation, myofibroblastic cells disappear in normal development but persist in fibrosis following ductal plate malformation.

Improvement of radiation‐induced healing delay by etanercept treatment in rat arteries

Surgical treatment often causes difficulty in the irradiated field because of delayed wound healing, which is mainly due to vascular dysfunction. To overcome this difficulty, we attempted to accelerate the recovery from clamp injury in irradiated superficial epigastric arteries of rats as a model. Etanercept, a soluble receptor of tumor necrosis factor-alpha, was administered four times to rats with irradiated arteries before and after clamp injury. Loss of endothelial cells and necrosis of the media in the irradiated arteries continued for more than 1 week after the injury; however, in the rats treated with etanercept, the endothelial cells recovered in the intima, and alpha-smooth muscle actin-positive smooth muscle cells recovered in the injured and irradiated arteries. After clamp injury of common carotid arteries that had previously been irradiated, the blood flow in these arteries was visualized by magnetic resonance (MR) angiography. The time-of-flight signal was weakened in the injured and irradiated arteries. This time-of-flight signal was recovered by the etanercept treatment. These findings suggest that etanercept improves the radiation-impaired healing of arteries in rats.

Periostin localizes to cells in normal skin, but is associated with the extracellular matrix during wound repair

Epidermal tissue repair represents a complex series of temporal and dynamic events resulting in wound closure. Matricellular proteins, not normally expressed in quiescent adult tissues, play a pivotal role in wound repair and associated extracellular matrix remodeling by modulating the adhesion, migration, intracellular signaling, and gene expression of inflammatory cells, pericytes, fibroblasts and keratinocytes. Several matricellular proteins show temporal expression during dermal wound repair, but the expression pattern of the recently identified matricellular protein, periostin, has not yet been characterized. The primary aim of this study was to assess whether periostin protein is present in healthy human skin or in pathological remodeling (Nevus). The second aim was to determine if periostin is expressed during dermal wound repair. Using immunohistochemistry, periostin reactivity was detected in the keratinocytes, basal lamina, and dermal fibroblasts in healthy human skin. In pathological nevus samples, periostin was present in the extracellular matrix. In excisional wounds in mice, periostin protein was first detected in the granulation tissue at day 3, with levels peaking at day 7. Periostin protein co-localized with α-smooth muscle actin-positive cells and keratinocytes, but not CD68 positive inflammatory cells. We conclude that periostin is normally expressed at the cellular level in human and murine skin, but additionally becomes extracellular during tissue remodeling. Periostin may represent a new therapeutic target for modulating the wound repair process.

Mature, Adipocyte Derived, Dedifferentiated Fat Cells Can Differentiate Into Smooth Muscle-Like Cells and Contribute to Bladder Tissue Regeneration

We recently reported that mature, adipocyte derived, dedifferentiated fat cells show high proliferative activity and multilineage differentiation potential. In the current study we investigated whether such cells could differentiate into a smooth muscle cell lineage and contribute to bladder tissue regeneration in a mouse bladder injury model. Human adipocyte derived dedifferentiated fat cells were cultured for 1 week under conditions favorable for smooth muscle cell differentiation and immunostained for alpha-smooth muscle actin. The expression of smooth muscle cell marker genes for differentiating dedifferentiated fat cells was measured by real-time reverse transcription-polymerase chain reaction. Green fluorescence protein labeled dedifferentiated fat cells were injected into cryo-injured bladder walls in mice. The ability of the fat cells to regenerate smooth muscle tissue was examined immunohistochemically 14 and 30 days after transplantation. Immunohistochemical analysis revealed that more than 50% of the fat cells were successfully differentiated into alpha-smooth muscle actin positive cells under the optimum culture condition of a medium containing 5% fetal bovine serum and 5 ng/ml transforming growth factor-beta1. Real-time reverse transcription-polymerase chain reaction revealed increased expression of SM22alpha, alpha-smooth muscle actin and smooth muscle-myosin heavy chain in dedifferentiated fat cells during week 1 of differentiation culture. Cells expressing alpha-smooth muscle actin plus green fluorescence protein were observed at the bladder wall injection sites in mice 14 and 30 days after transplantation. Alpha-smooth muscle actin positive areas in injured bladder tissue in mice with fat cell injection were significantly larger than those in saline injected control mice. These findings suggest that dedifferentiated fat cells can differentiate into smooth muscle cell lineages and contribute to the regeneration of bladder smooth muscle tissue.

Erythropoietin and its non‐erythropoietic derivative: Do they ameliorate renal tubulointerstitial injury in ureteral obstruction?

Pleiotropic effects of recombinant human erythropoietin (EPO) have recently been discovered in many non-renal animal models. The renoprotective effects of EPO and carbamylated-erythropoietin (CEPO), a novel EPO which has a small stimulatory effect on hemoglobin, have never been explored in unilateral ureteral obstruction (UUO), a chronic tubulointerstitial (TI) disease model which is independent of systemic factors. In order to examine the effects of EPO and CEPO treatments on renal TI injury, 36 male Sprague-Dawley rats, weighing 250-320 g, underwent: UUO without treatment (group 1, n = 12), UUO with EPO (groups 2, n = 12), and UUO with CEPO (group 3, n = 12). EPO and CEPO were injected subcutaneously at a dose of 5000 u/kg to each respective rat at 1 day pre-UUO and at day 3, 7 and 10 post-UUO. After days 3, 7, and 14 of UUO, TI injury, collagen, alpha-smooth muscle actin (alpha-SMA) positive cell, ED1-positive cell, terminal deoxynucleotidyl transferase (TdT) mediated nick-end labeling (TUNEL)-positive cell, and transforming growth factor-beta1 (TGF-beta1) messenger ribonucleic acid (mRNA) were determined. Bcl-2 expression was also assessed to verify the mechanism of apoptosis. At day 14 UUO caused severe TI injury with a significant increase in collagen, alpha-SMA, ED1-positive cell, TUNEL-positive cell, and TGF-beta1 mRNA expression. Administration of EPO and CEPO significantly attenuated TI injury, collagen, ED1-positive cells, and TUNEL-positive cells. Only CEPO-treated rats had decreased alpha-SMA positive cells and TGF-beta1 mRNA. The expression of Bcl-2 was demonstrated only in EPO-treated rats. The hematocrit levels in EPO-treated rats were higher than the control and CEPO-treated rats. EPO and CEPO can limit 14-day UUO-induced TI injury by reducing inflammation, interstitial fibrosis, and tubular apoptosis.

A fusion protein of hepatocyte growth factor enhances reconstruction of myocardium in a cardiac patch derived from porcine urinary bladder matrix

We sought to promote myocardial repair using urinary bladder matrix incorporated with a fusion protein that combined hepatocyte growth factor and fibronectin collagen-binding domain in a porcine model. Collagen-binding domain acted as an intermediary to promote hepatocyte growth factor binding and enhance hepatocyte growth factor stability within urinary bladder matrix. Urinary bladder matrix incorporated with collagen-binding domain and hepatocyte growth factor was implanted into the porcine right ventricular wall (F group) to repair a surgically created defect. Untreated urinary bladder matrix patches (U group) and Dacron patches (D group) served as controls (N = 5/group). Electromechanical mapping was performed 60 days after surgery. Linear local shortening was used to assess regional contractility, and electrical activity was recorded. Linear local shortening was significantly improved in the F group compared with controls (F: 0.51% +/- 1.57% [P < .05], U: -1.06% +/- 1.84%, D: -2.72% +/- 2.59%), whereas it was inferior to the normal myocardium (13.7% +/- 4.3%; P < .05). Mean electrical activity was 1.49 +/- 0.82 mV in the F group, which was statistically greater than in the control groups (U: 0.93 +/- 0.71 mV; D: 0.30 +/- 0.22 mV; P < .05) and less than the normal myocardium (8.24 +/- 2.49 mV; P < .05). Histologic examination showed predominant alpha-smooth muscle actin positive cells with the F group showing the thickest layer and the D group showing the thinnest layer, with an endocardial endothelial monolayer. Scattered isolated islands of alpha-actinin positive cells were observed only in the F group, but not in the controls, suggesting the presence of cardiomyocytes. The collagen-binding domain/hepatocyte growth factor/urinary bladder matrix patch demonstrated increased contractility and electrical activity compared with urinary bladder matrix alone or Dacron and facilitated a homogeneous repopulation of host cells. Urinary bladder matrix incorporated with collagen-binding domain and hepatocyte growth factor may contribute to constructive myocardial remodeling.

Characterization of Epithelial-to-Mesenchymal Transition of Mesothelial Cells in a Mouse Model of Chronic Peritoneal Exposure to High Glucose Dialysate

Animal models of peritoneal dialysis fluid (PDF) exposure are key tools in the study of mechanisms involved in alterations of the peritoneal membrane and in the design of therapies. We recently developed a mouse model of chronic peritoneal exposure to high glucose dialysate. Herein, we make a sequential analysis of the effects of glucose-based PDF on mouse peritoneal membrane and on mesothelium. We demonstrate that chronic exposure to PDF induces thickness and fibrosis of the peritoneal membrane in a time-dependent manner. We also show that mesothelial cells progressively detach and lose cytokeratin expression. In addition, we demonstrate that some mesothelial cells invade the submesothelial space, where they appear as cytokeratin- and alpha-smooth muscle actin-positive cells. These findings demonstrate that epithelial-to-mesenchymal transition (EMT) of mesothelial cells takes place in mouse peritoneum exposed to PDF, validating this model for the study of effects of drugs on the EMT process as a therapy for peritoneal deterioration.

Fetuin-A Expression in Early Venous Stenosis Formation in a Porcine Model of Hemodialysis Graft Failure

Because fetuin-A is a cytokine with multifunctional effects on vascular smooth muscle cells and fibroblasts, the authors examined the course of its expression in early venous stenosis formation in a porcine model of chronic renal insufficiency with polytetrafluoroethylene (PTFE) arteriovenous (AV) hemodialysis grafts. Pigs had chronic renal insufficiency created by complete embolization of the left kidney and partial embolization of the right kidney. Twenty-eight days later, PTFE AV grafts were placed from the carotid artery to the ipsilateral jugular vein, and the animals were euthanized 3 days (n = 4), 7 days (n = 4), or 14 days (n = 4) later. Expression of fetuin-A was determined by Western blot analysis of the venous stenosis, control veins, and plasma. Immunohistochemical analysis of the venous stenosis and control vein was performed. Blood urea nitrogen (BUN) and creatinine were measured before embolization and at the time of graft placement. The mean BUN and creatinine levels at graft placement were significantly higher than before embolization (P < .05). Severe venous neointimal hyperplasia occurred by day 14 and was characterized by primarily alpha-smooth muscle actin-positive cells. By day 14, fetuin-A levels had increased significantly (P < .05) at the venous stenosis compared with control veins and in the serum compared with measurements before embolization. Significantly increased expression of fetuin-A was observed in early venous stenosis by day 14 and in serum compared with baseline measurements. Understanding the role of fetuin-A in venous neointimal hyperplasia could help in improving outcomes in patients undergoing hemodialysis.

Ellagic Acid Inhibits Pancreatic Fibrosis in Male Wistar Bonn/Kobori Rats

The key pathological features of chronic pancreatitis are chronic inflammation, acinar atrophy, and pancreatic fibrosis. We have previously shown that ellagic acid, a plant-derived polyphenol found in fruits and nuts, inhibited activation of pancreatic stellate cells, a major profibrogenic cell type in the pancreas, in vitro. Here we examined whether ellagic acid inhibited the development of pancreatic fibrosis in vivo. Ellagic acid was administered orally in the diet to ten-week-old male Wistar Bonn/Kobori rats, an experimental model of spontaneous chronic pancreatitis, for ten weeks. Ellagic acid (100 mg/kg body weight/day) attenuated pancreatic inflammation and fibrosis. The protective effects were confirmed by an increase in pancreatic weight and decreases in myeloperoxidase activity (an index of neutrophil infiltration), collagen content, transforming growth factor-beta1 expression, and the number of alpha-smooth muscle actin-positive cells (activated pancreatic stellate cells) and ED-1-positive cells (macrophages/monocytes). Ellagic acid inhibited the production of reactive oxygen species in pancreatic stellate cells in response to transforming growth factor-beta1 or platelet-derived growth factor. Our results suggest that ellagic acid might be a candidate for treatment of chronic pancreatitis.

Decellularized ureter for tissue-engineered small-caliber vascular graft

Previous attempts to create small-caliber vascular prostheses have been limited. The aim of this study was to generate tissue-engineered small-diameter vascular grafts using decellularized ureters (DUs). Canine ureters were decellularized using one of four different chemical agents [Triton-X 100 (Tx), deoxycholate (DCA), trypsin, or sodium dodecyl sulfate (SDS)] and the histology, residual DNA contents, and immunogenicity of the resulting DUs were compared. The mechanical properties of the DUs were evaluated in terms of water permeability, burst strength, tensile strength, and compliance. Cultured canine endothelial cells (ECs) and myofibroblasts were seeded onto DUs and evaluated histologically. Canine carotid arteries were replaced with the EC-seeded DUs (n = 4). As controls, nonseeded DUs (n = 5) and PTFE prostheses (n = 4) were also used to replace carotid arteries. The degree of decellularization and the maintenance of the matrix were best in the Tx-treated DUs. Tx-treated and DCA-treated DUs had lower remnant DNA contents and immunogenicity than the others. The burst strength of the DUs was more than 500 mmHg and the maximum tensile strength of the DUs was not different to that of native ureters. DU compliance was similar to that of native carotid artery. The cell seeding test resulted in monolayered ECs and multilayered alpha-smooth muscle actin-positive cells on the DUs. The animal implantation model showed that the EC-seeded DUs were patent for at least 6 months after the operation, whereas the nonseeded DUs and PTFE grafts become occluded within a week. These results suggest that tissue-engineered DUs may be a potential alternative conduit for bypass surgery.

Role of Rac1 in a bleomycin‐induced scleroderma model using fibroblast‐specific Rac1‐knockout mice

Activated adhesive signaling is a hallmark of fibroblasts isolated from the scars of scleroderma (systemic sclerosis [SSc]) lesions. Rac1 plays a key role in adhesive signaling. The aim of the present study was to examine the role of Rac1 in bleomycin-induced scleroderma, using mice with a fibroblast-specific deletion of Rac1. Cutaneous sclerosis was induced by subcutaneous injection of bleomycin. Control groups were treated with phosphate buffered saline. Mice with a fibroblast-specific deletion of Rac1 and control mice were investigated. Dermal thickness, inflammation, collagen production, and the number of alpha-smooth muscle actin-positive cells were determined. The quantity of the collagen-specific amino acid hydroxyproline was also measured. Bleomycin treatment induced marked cutaneous thickening, inflammation, and fibrosis in control mice. Conversely, deletion of Rac1 resulted in resistance to bleomycin-induced fibrosis and inflammation. Rac1 expression by fibroblasts is required for fibrogenesis. Inhibition of Rac1 may be a viable method to alleviate the development of cutaneous sclerosis.

Concurrent Differentiation of Marrow Stromal Cells to Osteogenic and Vasculogenic Lineages

When rat bone marrow stromal (BMS) cells were seeded on aligned type I collagen scaffolds and cultured in osteogenic media, they underwent simultaneous maturation and differentiation into osteogenic and vascular cell lineages. In addition, these cells produced mineralized matricellular deposits. BMS cells were seeded in Petri dish or the collagen scaffold, cultured in osteogenic media for 3, 6, and 9 d and subsequently processed for immunohistochemical and cytochemical analysis. Immunolocalization of lineage-specific proteins were visualized using confocal microscopy and mRNA transcript analysis was performed by real-time quantitative polymerase chain reaction (RT-qPCR). The alkaline phosphatase activity and calcium content significantly increased over the observed period of time in an osteogenic medium. Sheets of abundant Pecam (CD31), Flk-1 (VEGFR-2), tomato lectin (TL/LEL), and alpha-smooth muscle actin (alpha-SMA) positive cells were observed in the collagen scaffolds. Nascent capillary-like vessels were also seen amidst the osteoblasts in osteogenic culture, augmenting the maturation and differentiation of BMS cells into osteoblasts. In our in vitro study, concurrent differentiation of BMS cells, a heterogeneous cell population with multilineage differentiation potential, to osteogenic and vascular lineages demonstrated that the substrates (three-dimensional (3-D), collagen type I, aligned fibrils) had a profound effect on guiding the differentiation pathway of BMS cells.

Mice Lacking 12/15-Lipoxygenase Have Attenuated Airway Allergic Inflammation and Remodeling

Arachidonate 15-lipoxygenase (LO)-1 has been implicated in allergic inflammation and asthma. The overall effect of 15-LO in allergic inflammation in vivo is, however, unclear. This study investigates systemic allergen sensitization and local allergic airway inflammation and remodeling in mice lacking the murine 12/15-LO, the ortholog to human 15-LO-1. Upon systemic sensitization with intraperitoneal ovalbumin, 12/15-LO-/- mice produced elevated levels of allergen-specific immunoglobulin E compared with wild-type (Wt) controls. However, when challenged with repeated aerosolized allergen, sensitized 12/15-LO-/- mice had an impaired development of airway allergic inflammation compared with Wt controls, as indicated by reduced bronchoalveolar lavage fluid leukocytes (eosinophils, lymphocytes, macrophages) and Th2 cytokines (IL-4, IL-5, IL-13), as well as tissue eosinophils. Allergen-induced airway epithelial proliferation was also significantly attenuated in 12/15-LO-/- mice, whereas goblet cell hyperplasia was unaffected. However, 12/15-LO-/- mice had significantly reduced luminal mucus secretions compared with Wt controls. The repeated allergen challenges resulted in a dramatic increase of alpha-smooth muscle actin-positive alveolar cells in the peripheral airways, a phenomenon that was significantly less developed in 12/15-LO-/- mice. In conclusion, our data suggest that 12/15-LO-/- mice, although having a fully developed systemic sensitization, did not establish a fully developed allergic airway inflammation and associated manifestations of central and peripheral airway remodeling. These data suggest that 12/15-LO-derived metabolites play an important pathophysiologic role in allergen-induced inflammation and remodeling. Hence, pharmacologic targeting of the human 15-LO-1 may represent an attractive therapeutic strategy to control inflammation and remodeling in asthma.