vWF-positive Cells Research Articles

Improved bladder contractility after transplantation of human mesenchymal stem cells overexpressing hepatocyte growth factor into underactive bladder from bladder outlet obstruction models of rats.

IntroductionAn underactive bladder can lead to difficulty in voiding that causes incomplete emptying of the bladder, suggesting the need for a new strategy to increase bladder contractility in such patients. This study was performed to investigate whether human mesenchymal stem cells (hMSCs) were capable of restoring bladder contractility in rats with underactive bladder due to bladder outlet obstruction (BOO) and enhancing their effects by overexpressing hepatocyte growth factor (HGF) in hMSCs.Materials and methodsThe hMSCs were transplanted into the bladder wall of rats. Fifty female Sprague-Dawley rats at six weeks of age were divided into five groups: group 1: control; group 2: sham intervention; group 3: eight-week BOO; group 4: BOO rats transplanted with hMSCs; and group 5: BOO rats transplanted with hMSCs overexpressing HGF. Two weeks after the onset of BOO in groups 4 and 5, hMSCs were injected into the bladder wall. Cystometry evaluation was followed by Masson’s trichrome staining of bladder tissues. Realtime PCR and immunohistochemical staining were performed to determine for hypoxia, apoptosis, and angiogenesis.ResultsCollagen deposition of bladder increased in BOO but decreased after transplantation of hMSCs. The increased inter-contraction interval and residual urine volume after BOO was reversed after hMSCs transplantation. The decreased maximal voiding pressure after BOO was restored by hMSCs treatment. The mRNA expression of bladder collagen1 and TGF-β1 increased in BOO but decreased after hMSCs transplantation. The decrease in vWF-positive cells in the bladder following BOO was increased after hMSCs transplantation. Caspase 3 and TUNEL-positive apoptosis of bladder cells increased in BOO but decreased after transplantation of hMSCs. These effects were enhanced by overexpressing HGF in hMSCs.ConclusionTransplantation of hMSCs into bladder wall increased the number of micro-vessels, decreased collagen deposition and apoptosis of detrusor muscle, and improved bladder underactivity. The effects were enhanced by overexpressing HGF in hMSCs. Our findings suggest that the restoration of underactive bladder using hMSCs may be used to rectify micturition disorders in patients following resolution of BOO. Further studies are needed before hMSCs can be used in clinical applications.

Tumor Necrosis Factor Induces Obliterative Pulmonary Vascular Disease in a Novel Model of Connective Tissue Disease-Associated Pulmonary Arterial Hypertension.

Connective tissue disease (CTD)-associated pulmonary arterial hypertension (PAH) is the second most common etiology of PAH and carries a poor prognosis. Recently, it has been shown that female human tumor necrosis factor (TNF)-transgenic (Tg) mice die of cardiopulmonary disease by 6 months of age. This study was undertaken to characterize this pathophysiology and assess its potential as a novel model of CTD-PAH. Histologic analysis was performed on TNF-Tg and wild-type (WT) mice to characterize pulmonary vascular and right ventricular (RV) pathology (n = 40 [4-5 mice per group per time point]). Mice underwent right-sided heart catheterization (n = 29) and micro-computed tomographic angiography (n = 8) to assess vascular disease. Bone marrow chimeric mice (n = 12), and anti-TNF-treated mice versus placebo-treated mice (n = 12), were assessed. RNA sequencing was performed on mouse lung tissue (n = 6). TNF-Tg mice displayed a pulmonary vasculopathy marked by collagen deposition (P < 0.001) and vascular occlusion (P < 0.001) with associated RV hypertrophy (P < 0.001) and severely increased RV systolic pressure (mean ± SD 75.1 ± 19.3 mm Hg versus 26.7 ± 1.7 mm Hg in WT animals; P < 0.0001). TNF-Tg mice had increased α-smooth muscle actin (α-SMA) staining, which corresponded to proliferation and loss of von Willebrand factor (vWF)-positive endothelial cells (P < 0.01). There was an increase in α-SMA-positive, vWF-positive cells (P < 0.01), implicating endothelial-mesenchymal transition. Bone marrow chimera experiments revealed that mesenchymal but not bone marrow-derived cells are necessary to drive this process. Treatment with anti-TNF therapy halted the progression of disease. This pathology closely mimics human CTD-PAH, in which patient lungs demonstrate increased TNF signaling and significant similarities in genomic pathway dysregulation. The TNF-Tg mouse represents a novel model of CTD-PAH, recapitulates key disease features, and can serve as a valuable tool for discovery and assessment of therapeutics.

Adult Human Vein Grafts Retain Plasticity of Vessel Identity

The spiral saphenous vein graft is an excellent choice for venous reconstruction after periphery vein injury, but only few cases have been reported. We implanted a segment of a single saphenous vein into both the popliteal vein as a venous vein graft and into the popliteal artery as an arterial vein graft at the same time in a trauma patient; we then had an extraordinary opportunity to harvest and examine both patent venous and arterial vein grafts at 2 weeks after implantation. A spiral saphenous vein graft was made as previously described and implanted into the popliteal vein and artery as interposition grafts; because of the patient's serious injuries, an amputation was performed at day 18 after vascular reconstruction. The grafts were harvested, fixed, and examined using histology and immunohistochemistry. Both grafts were patent, and there was a larger neointimal area in the venous graft compared to the arterial graft. There were CD31- and vWF-positive cells on both neointimal endothelia, with subendothelial deposition of α-actin-, CD3-, CD45-, and CD68-positive cells. There were fewer cells in the venous graft neointima compared to the arterial graft neointima; however, there were more inflammatory cells in the neointima of the venous graft. Some of the neointimal cells were PCNA-positive, whereas very few cells were cleaved caspase-3 positive. The venous graft neointimal endothelial cells were Eph-B4 and COUP-TFII positive, while the arterial graft neointimal endothelial cells were dll-4 and Ephrin-B2 positive. The spiral saphenous vein graft remains a reasonable choice for vessel reconstruction, especially in the presence of diameter mismatch. Both the venous and arterial grafts showed similar re-endothelialization and cellular deposition; the venous graft had more neointimal hyperplasia and inflammation. At an early time, endothelial cells showed venous identity in the venous graft, whereas endothelial cells showed arterial identity in the arterial graft. Veins can be used as venous or arterial vein grafts but venous grafts have more neointimal hyperplasia and inflammation; vein grafts acquire different vessel identity depending on the environment into which they are implanted.

Xiaoyukang Jiaonang Promotes the Degradation of Hypoxia-Inducible Factor 1α and Antiangiogenesis and Anti-Inflammation in Chronic Subdural Hematoma Rat Model.

Xiaoyukang Jiaonang (XYK) is a Chinese patent medicine approved by the National Medical Product Administration which is used to treat intracranial hematoma in China. In this study, we observed the molecular mechanism of XYK in hypoxia-inducible factor 1α (HIF-1α), inflammation and angiogenesis of chronic subdural hematoma (CSDH). The CSDH model was made by using internal iliac vein blood of Wister rats, and rats were divided into sham group, CSDH group and XYK group. The rats in the XYK group were gavaged with Xiaoyukang Jiaonang (185 mg/kg) for 7 days, and rats in the CSDH group and sham group were gavaged with the same amount of physiological saline for 7 days. In the CSHD rat model, active inflammation and angiogenesis were observed around the hematoma. XYK promoted the ubiquitination and degradation of HIF-1α, and reduced the concentration of VEGF and the ratio of angiopoietin-1/angiopoietin-2. XYK reduced proinflammatory cytokines and increased anti-inflammatory cytokine. In tissue section, XYK reduced the size of the hematoma and membrane, and reduced vWF positive cells in membrane. Furthermore, the endothelial progenitor cells in blood decreased as well. Overall, XYK shows anti-inflammatory and antiangiogenesis effects which may relate to the degradation of HIF-1α.

Autologous endothelialized small-caliber vascular grafts engineered from blood-derived induced pluripotent stem cells

An ideal cell source for human therapeutic and disease modeling applications should be easily accessible and possess unlimited differentiation and expansion potential. Human induced pluripotent stem cells (hiPSCs) derived from peripheral blood mononuclear cells (PBMCs) represent a promising source given their ease of harvest and their pluripotent nature. Previous studies have demonstrated the feasibility of using PBMC-derived hiPSCs for vascular tissue engineering. However, so far, no endothelialization of hiPSC-derived tissue engineered vascular grafts (TEVGs) based on fully biodegradable polymers without xenogenic matrix components has been shown.In this study, we have generated hiPSCs from PBMCs and differentiated them into αSMA- and calponin-positive smooth muscle cells (SMCs) as well as endothelial cells (ECs) positive for CD31, vWF and eNOS. Both cell types were co-seeded on PGA-P4HB starter matrices and cultured under static or dynamic conditions to induce tissue formation in vitro. The resulting small diameter vascular grafts showed abundant amounts of extracellular matrix, containing a thin luminal layer of vWF-positive cells and a subendothelial αSMA-positive layer approximating the architecture of native vessels. Our results demonstrate the successful generation of TEVGs based on SMCs and ECs differentiated from PBMC-derived hiPSC combined with a biodegradable polymer. These results pave the way for developing autologous PBMC-derived hiPSC-based vascular constructs for therapeutic applications or disease modeling. Statement of SignificanceWe report for the first time the possibility to employ human peripheral blood mononuclear cell (PBMC)-derived iPSCs to generate biodegradable polymer-based tissue engineered vascular grafts (TEVG), which mimic the native layered architecture of blood vessels.hiPSCs from PBMCs were differentiated into smooth muscle cells as well as endothelial cells. These cells were co-seeded on a biodegradable PGA/P4HB scaffold and cultured in a bioreactor to induce tissue formation in vitro. The resulting small diameter TEVG showed abundant amounts of extracellular matrix, containing a αSMA-positive layer in the interstitium and a thin luminal layer of vWF-positive endothelial cells approximating the architecture of native vessels.Our findings improving the generation of autologous vascular replacements using blood as an easily accessible cell source.

Epalrestat, an Aldose Reductase Inhibitor, Restores Erectile Function in Streptozocin-induced Diabetic Rats

Epalrestat, an aldose reductase inhibitor (ARI), was adopted to improve the function of peripheral nerves in diabetic patients. The aim of this study was to investigate whether epalrestat could restore the erectile function of diabetic erectile dysfunction using a rat model. From June 2016, 24 rats were given streptozocin (STZ) to induce the diabetic rat model, and epalrestat was administered to ten diabetic erectile dysfunction (DED) rats. Intracavernous pressure (ICP) and mean systemic arterial pressure (MAP), levels of aldose reductase (AR), nerve growth factor (NGF), neuronal nitric oxide synthase (nNOS), α-smooth muscle antigen (α-SMA), and von Willebrand factor (vWF) in the corpus cavernosum were analyzed. We discovered that epalrestat acted on cavernous tissue and partly restored erectile function. NGF and nNOS levels in the corpora were increased after treatment with epalrestat. We also found that the content of α-SMA-positive smooth muscle cells and vWF-positive endothelial cells in the corpora cavernosum were declined. Accordingly, epalrestat might improve erectile function by increasing the upregulation of NGF and nNOS to restore the function of the dorsal nerve of the penis.

Vascular Endothelial Growth Factor Improves Physico-Mechanical Properties and Enhances Endothelialization of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/Poly(ε-caprolactone) Small-Diameter Vascular Grafts In vivo

The combination of a natural polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and a synthetic hydrophobic polymer poly(ε-caprolactone) (PCL) is promising for the preparation of biodegradable and biocompatible small-diameter vascular grafts for bypass surgery. However, physico-mechanical properties and endothelialization rate of PHBV/PCL grafts are poor. We suggested that incorporation of vascular endothelial growth factor (VEGF) into PHBV/PCL grafts may improve their physico-mechanical properties and enhance endothelialization. Here we compared morphology, physico-mechanical properties, and in vivo performance of electrospun small-diameter vascular grafts prepared from PHBV/PCL with and without VEGF. Structure of the graft surface and physico-mechanical properties were examined by scanning electron microscopy and universal testing machine, respectively. Grafts were implanted into rat abdominal aorta for 1, 3, and 6 months with the further histological, immunohistochemical, and immunofluorescence examination. PHBV/PCL grafts with and without VEGF were highly porous and consisted mostly of nanoscale and microscale fibers, respectively. Mean pore diameter and mean pore area were significantly lower in PHBV/PCL/VEGF compared to PHBV/PCL grafts (1.47 μm and 10.05 μm2; 2.63 μm and 47.13 μm2, respectively). Durability, elasticity, and stiffness of PHBV/PCL grafts with VEGF were more similar to internal mammary artery compared to those without, particularly 6 months postimplantation. Both qualitative examination and quantitative image analysis showed that three-fourths of PHBV/PCL grafts with VEGF were patent and had many CD31-, CD34-, and vWF-positive cells at their inner surface. However, all PHBV/PCL grafts without VEGF were occluded and had no or a few CD31-positive cells at the inner surface. Therefore, VEGF enhanced endothelialization and improved graft patency at all the time points in a rat abdominal aorta replacement model. In conclusion, PHBV/PCL grafts with VEGF have better biocompatibility and physico-mechanical properties compared to those without. Incorporation of VEGF improves graft patency and accelerates formation of endothelial cell monolayer.

Polymer-Based Reconstruction of the Inferior Vena Cava in Rat: Stem Cells or RGD Peptide?

As part of a program targeted at developing a resorbable valved tube for replacement of the right ventricular outflow tract, we compared three biopolymers (polyurethane [PU], polyhydroxyalkanoate (the poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxyvalerate) [PHBVV]), and polydioxanone [PDO]) and two biofunctionalization techniques (using adipose-derived stem cells [ADSCs] or the arginine-glycine-aspartate [RGD] peptide) in a rat model of partial inferior vena cava (IVC) replacement. Fifty-three Wistar rats first underwent partial replacement of the IVC with an acellular electrospun PDO, PU, or PHBVV patch, and 31 nude rats subsequently underwent the same procedure using a PDO patch biofunctionalized either by ADSC or RGD. Results were assessed both in vitro (proliferation and survival of ADSC seeded onto the different materials) and in vivo by magnetic resonance imaging (MRI), histology, immunohistochemistry [against markers of vascular cells (von Willebrand factor [vWF], smooth muscle actin [SMA]), and macrophages ([ED1 and ED2] immunostaining)], and enzyme-linked immunosorbent assay (ELISA; for the expression of various cytokines and inducible NO synthase). PDO showed the best in vitro properties. Six weeks after implantation, MRI did not detect significant luminal changes in any group. All biopolymers were evenly lined by vWF-positive cells, but only PDO and PHBVV showed a continuous layer of SMA-positive cells at 3 months. PU patches resulted in a marked granulomatous inflammatory reaction. The ADSC and RGD biofunctionalization yielded similar outcomes. These data confirm the good biocompatibility of PDO and support the concept that appropriately peptide-functionalized polymers may be successfully substituted for cell-loaded materials.

Tissue-engineered mitral valve: morphology and biomechanics †.

The present study aimed at developing tissue-engineered mitral valves based on cell-free ovine mitral allografts. The ovine mitral valves (OMVs) (n = 46) were harvested in the local slaughter house. They were decellularized using detergent solutions and DNase. The effectiveness of decellularization was assessed by histological (haematoxylin-eosin, Movat's pentachrome) and immunofluorescent staining (for DNA and α-Gal), and DNA-quantification. To reveal the receptiveness of decellularized tissue to endothelial cells (ECs), the valve leaflets were reseeded with ovine ECs, derived from endothelial progenitor cells in vitro. For assessment of biomechanical properties, uniaxial tensile tests were carried out. Histology and immunofluorescent staining revealed absence of cell nuclei in decellularized leaflets, chordae and papillary muscles. According to the software for immunofluorescence analysis, reduction in DNA and α-Gal was 99.9 and 99.6%, respectively. DNA-quantification showed 71.2% reduction in DNA content without DNase and 96.4% reduction after DNase treatment. Decellularized leaflets were comparable with native in ultimate tensile strain (native, 0.34 ± 0.09 mm/mm, vs decellularized, 0.44 ± 0.1 mm/mm; P = 0.09), and elastin modulus (native, 0.39 ± 0.27, vs decellularized, 0.57 ± 0.55, P = 0.46), had increased ultimate tensile stress (native, 1.23 ± 0.35 MPa, vs decellularized 2.12 ± 0.43 MPa; P = 0.001) and collagen modulus (native, 5.5 ± 1.26, vs decellularized, 8.29 ± 2.9; P = 0.04). After EC seeding, immunofluorescent staining revealed a monolayer of CD31-, eNOS- and vWF-positive cells on the surface of the leaflet, as well as a typical cobble-stone morphology of those cells. Decellularization of ovine mitral valve results in a mitral valves scaffold with mechanical properties comparable with native tissue, and a graft surface, which can be repopulated by endothelial cells.

Gastric cancer-associated enhancement of von Willebrand factor is regulated by vascular endothelial growth factor and related to disease severity.

Backgroundvon Willebrand factor (vWF) is a potent regulator of angiogenesis, tumor growth, and metastasis. Yet, the expression pattern of vWF in human gastric cancer (GC) tissues and its relation to clinicopathological features of these cases remains unknown.MethodsTumor and 5-cm adjacent non-tumoral parenchyma specimens were collected from 99 patients with GC (early stages I/II and late stages III/IV), and normal specimens were collected from 32 healthy controls (reference group). Plasma vWF antigen (vWF:Ag) and vWF activity were assessed by ELISA. The role of vascular endothelial growth factor (VEGF) in differential vWF expression was investigated using cultured human umbilical vein endothelial cells (HUVECs). vWF and VEGF protein and mRNA expression levels were investigated by qRT-PCR, western blotting and immunohistochemistry (IHC) respectively. The correlation of IHC-detected vWF expression with patient clinicopathological characteristics was analyzed.ResultsCompared to the reference group, the patients with late GC showed significantly higher levels of vWF:Ag (72% (21-115) vs. 101% (40-136)) and vWF activity (62% (20-112) vs. 117% (33-169)) (both P < 0.001). The GC tumor tissues also showed higher vWF mRNA and protein levels than the adjacent non-tumoral parenchyma. Patients at late GC stage had significantly higher median number of vWF-positive cells than patients at early GC stage (P < 0.05). VEGF induced vWF mRNA and protein expression in HUVECs in dose- and time-dependent manners. Patients with late GC stage also had significantly higher serum VEGF than patients at early GC stage (23 ± 26 vs. 10 ± 12 pg/mL, P < 0.01). Most of the undifferentiated GC tumor tissues at late disease stage exhibited strong VEGF and VEGFR2 protein staining, which co-localized with the vWF protein staining pattern.ConclusionsGC-related plasma vWF:Ag and vWF activity levels become substantially elevated in the late stage of disease. The higher mRNA and protein expression of vWF in GC tumor stroma may be regulated by the VEGF-VEGFR2 signaling pathway in vitro and may contribute to GC progression in vivo.

Induced Pluripotent Stem Cell Transplantation in the Treatment of Porcine Chronic Myocardial Ischemia

This study was designed to test the effects of induced pluripotent stem cell (iPSC) in the treatment of chronic myocardial ischemia. The reprogramming of passage 3 myocardial fibroblasts was performed by using the lentiviral vector containing 4 human factors: OCT4, SOX2, KLF4, and c-MYC. The iPSC colonies at P12-17 were allogeneically transplanted into ischemic myocardium of 10 swine by direct injection. Cohorts of 2 animals were sacrificed at 2,4, 6, 8, and 12 weeks after injection. No signs of graft versus host disease were evident at any time points. At 2 weeks, clusters of SSEA-4-positive iPSCs were detected in the injected area. At 4 to 8 weeks, these cells started to proliferate into small spheres surrounded by thin capsules. At 12 weeks the cell clusters still existed, but decreased in size and numbers. The cells inside these masses were homogeneous with no sign of differentiation into any specific lineage. Increased smooth muscle actin or vWF positive cells were found inside and around the iPSC clusters, compared with non-injected areas. By real-time polymerase chain reaction, the levels of VEGF, basic FGF, and ANRT expression were significantly higher in the iPSC-treated myocardium compared with untreated areas. These results suggest that iPSCs contributed to angiogenesis. Allogeneically transplanted pig iPSCs proliferated despite an ischemic environment in the first 2 months and survived for at least 3 months in immunocompetent hosts. Transplanted iPSCs were also proangiogenic and thus might have beneficial effects on the ischemic heart diseases.

Caspase-3 inhibition prevents the development of hepatopulmonary syndrome in common bile duct ligation rats by alleviating pulmonary injury.

Common bile duct ligation (CBDL) rats is an accepted experimental model of hepatopulmonary syndrome (HPS), defined as liver disease and intrapulmonary vascular dilatation and hypoxaemia. Pulmonary Akt and ERK activation followed by angiogenesis in the later stages of CBDL, contribute to the pathogenesis of HPS. However, the mechanisms behind Akt and ERK activation remain undefined. Pulmonary injury induced by increased bilirubin, endotoxin and inflammatory mediators occurs in the early stages of CBDL. We assessed the effects of relieving pulmonary injury on Akt and ERK activation and on the development of HPS following CBDL. Pulmonary injury, angiogenesis, arterial oxygenation, cell proliferation and, phospho-Akt and ERK1 were evaluated in CBDL animals with or without caspase-3 inhibition (Z-DEVD-FMK). Pulmonary injury was assessed by histology and quantifying apoptosis and aquaporin-1 (AQP1) levels. Lung angiogenesis was assessed by quantifying AQP1 level, vWF-positive cells and microvessel count. Pulmonary apoptosis and caspase-3 activation were markedly increased in the early stages of CBDL. Caspase-3 inhibition alleviated apoptosis, the reduction in AQP1, phospho-Akt and ERK1 levels and pulmonary injury 1 week after CBDL. Caspase-3 inhibition also reduced AQP1, phospho-Akt and ERK1 levels, vWF-positive cells, cell proliferation, microvessel count, and microvascular dilatation and improved arterial oxygenation 3 weeks following CBDL. Caspase-3 inhibition alleviates pulmonary injury, thereby preventing angiogenesis as well as the development of HPS in CBDL rats. These effects are related to the regulation of the Akt and ERK1 pathways.

Intima/medulla reconstruction and vascular contraction–relaxation recovery for acellular small diameter vessels prepared by hyperosmotic electrolyte solution treatment

This study aims at the evaluation of blood vessel reconstruction process of decellularized small diameter vessels prepared by a hyperosmotic electrolyte solution treatment not only histologically but also physiologically in rat transplantation model. Complete cell removal by a hyperosmotic electrolyte solution treatment was confirmed by hematoxylin/eosin staining and scanning electron microscopic observation. All acellular vessels transplanted into the rat abdominal aorta were patent up to 14months. One week post-transplantation, the vWF-positive cells were observed on the luminal surface but the layer formation did not complete. Five weeks following transplantation, the vWF-positive endothelial cells were located on the intima consistent with intact endothelial cells. Beneath the endothelial cells, α-SMA-positive smooth muscle cells were distributed. The harvested vessels displayed formation of tunica intima (endothelial cells) and tunica medulla (smooth muscle cell) layers. We also examined the physiological properties of the vessels 12months post-transplantation using a wire myograph system. The transplanted vessels contracted upon addition of norepinephrine and relaxed upon addition of sodium nitroprusside as well as the native vessels. In conclusion, the acellular vessels prepared with hyperosmotic electrolytic solution showed excellent and long-term patency, which may be related to the successful preservation of vascular ECM. In addition, the acellular vessels revealed the intima/medulla regeneration with the physiological contraction-relaxation functions in response to the each substance.

Influence of neural stem cell transplantation on angiogenesis in rats with spinal cord injury.

We examined the influence of neural stem cell transplantation on angiogenesis in rats with spinal cord injury. Sixty rats with spinal cord injury were divided into an experimental group and a control group and given neural stem cells or an equivalent amount of phosphate-buffered saline by intravenous transplantation, respectively. Basso, Beattie, and Bresnahan (BBB) motor function assessment was performed in rats at different times after transplantation, and von Willebrand factor (vWF) immunofluorescence and Western blot analysis of vascular endothelial growth factor (VEGF) protein were also performed. The BBB scores of rats in the 2 groups were both zero before transplantation. The BBB score gradually increased over time. The BBB score of the experimental group showed no significant difference compared with that of the control group (P > 0.05) 7 days after transplantation. The BBB score of the experimental group was significantly improved compared with that of the control group 14 days after transplantation (P < 0.05). vWF-positive cells and VEGF protein expression in the experimental group were significantly increased compared with those in the control group 7 and 14 days after transplantation, respectively (P < 0.05). Neural stem cell transplantation may promote angiogenesis by inducing VEGF expression as well as improve functional recovery of limb movements.

Transplantation of human umbilical cord-derived endothelial progenitor cells promotes re-endothelialization of the injured carotid artery after balloon injury in New Zealand white rabbits

Background Cell transplantation has great potential for promoting endothelial repair and reducing the complications of percutaneous coronary intervention (PCI). The aim of this study was to investigate the effect of transplantation of human umbilical cord blood endothelial progenitor cells (EPCs) on injured arteries. Methods Umbilical cord blood mononuclear cells were obtained from post-partum lying-in women, and EPCs were isolated, cultured, expanded and identified by immunofluorescence. The carotid arterial endothelium of New Zealand white rabbits was injured by dilatation with a 3F balloon, and the EPCs were injected into the lumen of the injured artery in the transplanted group (n=16), while an equal volume of phosphated buffered saline (PBS) was injected into the control group after balloon injury (n=16). The animals were sacrificed after either 2 or 4 weeks, and the grafted cells were identified by double immunofluorescence staining with human nuclear antigen (HNA) and CD31 antibodies. Arterial cross sections were analyzed by pathology, immunohistochemisty and morphometry to evaluate the reparative effects of EPCs. Proliferating cell nuclear antigen (PCNA) and transforming growth factor (TGF)-β1 mRNA expression were detected by reverse transcription-polymerase chain reaction (RT-PCR). Results Fluorescence-labeled EPCs were found in the neointima. The neointimal area and the neointimal/medial area ratio were significantly lower in the transplanted group than in the control group (P &lt;0.05). von Willebrand factor (vWF) immunohistostaining showed more VWF-positive cells in the transplanted animals than in the controls (8.75±2.92 vs. 4.50±1.77, P &lt;0.05). Compared with the control group, the transplanted group had lower expression of PCNA mRNA (0.67±0.11 vs. 1.25±0.40, P &lt;0.01) and higher expression of TGF-β1 mRNA (1.10±0.21 vs. 0.82±0.07, P &lt;0.05). Conclusions EPCs derived from human umbilical cord blood were successfully transplanted into injured vessels. The transplanted EPCs inhibited neointimal hyperplasia and promoted vascular re-endothelialization.

Allogeneic Transplantation of Induced Pluripotent Stem Cells in a Porcine Model of Chronic Myocardial Ischemia Failed to Stimulate Myocyte Differentiation

Background: Recently, pig induced pluripotent stem cells (iPSCs) have been produced by by ectopic expression of four human transcriptional factors, OCT4, SOX2, KLF4, and cMYC in pig fetal fibroblasts through a lentiviral vector. The pig iPSCs showed pluripotency via in vitro differentiation assays and teratoma testing. However, these cells have failed to differentiate into beating myocytes in vitro. To determine whether in vivo conditions would drive iPSC differentiation into myocytes, we performed allogeneic transplantation of the pig iPSCs into areas of chronically ischemic myocardium. Methods: Pig iPSCs were expanded by standard ES cell culture method, and allogeneically transplanted into chronically ischemic myocardium of eight Yorkshire pigs by direct intramyocardial injection (four 10-cm culture dishes, total of 10-16 million cells, suspended in 2.5 ml of saline, with 25 injection sites). Cohorts of two animals were sacrificed at 2, 4, 8 wks and 3 months after injection to study the differentiation of the injected cells. Results: After transplantation, there were no signs of adverse side effects or graft versus host disease at any time point. Two weeks after injection, clusters of SSEA-4 positive cells were detected in the frozen sections of the injected area using immunofluorescent staining. Four to 8 weeks later, these clusters of cells started to proliferate, within the injected area, into spherical shaped small tumors surrounded by thin capsules. The cells inside these tumors showed homogeneous phenotype with no signs of differentiation into any lineage. Three months after the injection, no such small tumors were found; instead, similar SSEA-4 positive cell clusters were found in the injected area but in smaller numbers. By immunofluorescent staining, few smooth muscle actin or vWF positive cells were found inside the cell clusters, but no positive desmin cells were found, and by RT-PCR, the expression of VEGF, FGF, ANRT were significantly higher in the injected myocardium compared with none injected, suggesting that injected iPSCs were not differentiated into myocytes and might contribute to the formation of some new vessels. Conclusions: Allogeneic transplantation of iPSCs can be safely used to test the lineage differentiation of stem cells for the future iPSC-based therapy. Despite an ischemic environment, pig iPSCs continue to proliferate in vivo for three months after injection. However the proliferation ability of the iPSCs was limited within the immunoconpetent hosts. For future cell-based therapy, iPSCs with pro-myocyte differentiation will be needed to study their potential for myocardial regeneration.

Endothelial Progenitor Cells (EPCs) as Gene Carrier System for Rat Model of Human Glioma

BackgroundDue to their unique property to migrate to pathological lesions, stem cells are used as a delivery vehicle for therapeutic genes to tumors, especially for glioma. It is critically important to track the movement, localization, engraftment efficiency and functional capability or expression of transgenes of selected cell populations following transplantation. The purposes of this study were to investigate whether 1) intravenously administered, genetically transformed cord blood derived EPCs can carry human sodium iodide symporter (hNIS) to the sites of tumors in rat orthotopic model of human glioma and express transgene products, and 2) whether accumulation of these administered EPCs can be tracked by different in vivo imaging modalities.Methods and ResultsCollected EPCs were cultured and transduced to carry hNIS. Cellular viability, differential capacity and Tc-99m uptake were determined. Five to ten million EPCs were intravenously administered and Tc-99-SPECT images were acquired on day 8, to determine the accumulation of EPCs and expression of transgenes (increase activity of Tc-99m) in the tumors. Immunohistochemistry was performed to determine endothelial cell markers and hNIS positive cells in the tumors. Transduced EPCs were also magnetically labeled and accumulation of cells was confirmed by MRI and histochemistry. SPECT analysis showed increased activity of Tc-99m in the tumors that received transduced EPCs, indicative of the expression of transgene (hNIS). Activity of Tc-99m in the tumors was also dependent on the number of administered transduced EPCs. MRI showed the accumulation of magnetically labeled EPCs. Immunohistochemical analysis showed iron and hNIS positive and, human CD31 and vWF positive cells in the tumors.ConclusionEPC was able to carry and express hNIS in glioma following IV administration. SPECT detected migration of EPCs and expression of the hNIS gene. EPCs can be used as gene carrier/delivery system for glioma therapy as well as imaging probes.

Evaluation of a biodegradable scaffold‐ and stem cell‐based tissue‐engineered vascular graft in rat and pig models

Bi‐layered, synthetic, biodegradable, elastomeric tubular scaffolds comprised of a highly porous medial layer and an external, reinforcing fibrous layer were bulk‐seeded with allogeneic (rat studies) or autologous (pig studies), LacZ+ muscle‐derived stem cells (MDSCs) using a previously described rotational vacuum seeding device, then placed in spinner flask culture for 24 hours. Cellular integration was assessed via nuclear and cytoskeletal staining. Constructs were implanted as interposition grafts in the abdominal aorta of rats for 8 weeks or carotid arteries of pigs for 30 days. Angiogram, histology, immunostaining and SEM were performed at time of explant. In the rat studies, cell‐seeded constructs showed a higher patency rate than the unseeded controls (63% vs. 0%). A smooth muscle‐like layer of cells was observed near the luminal surface of the constructs. LacZ+ cells were shown to be engrafted in the remodeled construct. A confluent layer of vWF‐positive cells was observed in the lumen of seeded constructs, whereas controls showed thrombosis. In the pig studies to date, all TEVGs were patent, though intimal hyperplasia was observed. We have demonstrated the successful integration of allogeneic stem cell‐based TEVGs in a rat model and the feasibility of a completely autologous approach in a pig model. Support from NIH BRP #R01 HL069368.

Upregulation of EMMPRIN after permanent focal cerebral ischemia

Elevated activities of matrix metalloproteinases (MMPs) following ischemic stroke have been shown to mediate ischemic injury as well as neurovascular remodeling. The extracellular MMP inducer (EMMPRIN) is a 58-kDa cell surface glycoprotein, which has been known to play a key regulatory role for MMP activities. The roles of EMMPRIN in stroke injury are not clearly understood. In this study, we investigated changes of EMMPRIN in a mouse model of permanent focal cerebral ischemia, and examined potential association between EMMPRIN and MMP-9 expression. Adult male CD-1 mice were subjected to permanent focal ischemia by intraluminal occlusion of the left middle cerebral artery (MCAO) under anesthesia. EMMPRIN expression was markedly upregulated in the peri-infarct area at 2–7 days after ischemia compared to the contralateral non-ischemic hemisphere by Western blot analysis. Immunofluorescent double staining demonstrated that EMMPRIN signals co-localized with vwF-positive endothelial cells and GFAP-positive peri-vascular astrocytes. In contrast, EMMPRIN signal did not co-localize with NeuN-positive neurons, or MPO-positive neutrophils. Dual fluorescent staining revealed that EMMPRIN co-localized with MMP-9. Our data also demonstrated that increased EMMPRIN expression correlated with increased MMP-9 levels in a temporal manner. In summary, we report for the first time that EMMPRIN expression was significantly increased in a mouse model of permanent focal cerebral ischemia. The spatial and temporal association between increased EMMPRIN expression and elevated MMP-9 levels suggest that EMMPRIN may modulate MMP-9 activity, and participate in neurovascular remodeling after ischemic stroke.

Cilengitide Inhibits Proliferation and Differentiation of Human Endothelial Progenitor Cells In Vitro.

Neo-angiogenesis plays an important role in many diseases such as cancer or rheumatoid arthritis. The existence of CD133+ hemangioblasts with dual differentiation capacity into both hematopoietic and endothelial cells was shown by several groups. Growing evidence indicate contribution of these endothelial progenitor cells (EPCs) to tumor angiogenesis in different preclinical models. Cytokines such as VEGF mobilize EPCs from the bone marrow leading to integration into the growing tumor vasculature. Several local factors including extracellular matrix proteins and cell-cell-interactions via adhesion molecules are responsible for differentiation, homing and incorporation of EPCs into tumor vessels. Our group has developed a cell culture system which allows expansion and endothelial differentiation of human CD133+ precursor cells in vitro. In the present study we analyzed the effect of the integrin inhibitor cilengitide on proliferation and differentiation of EPCs. Cilengitide is a peptide-like molecule, targeting αvβ3- and αvβ5-integrins with high affinity. Inhibition of these integrins by Cilengitide blocked angiogenesis and tumor growth in preclinical models and showed efficiency in clinical investigations. CD133+ cells were isolated from leukapheresis products by an immunomagnetic approach and subsequently cultivated for 28 days using the cytokines VEGF, SCGF and FLT3L. Afterwards EPCs were differentiated into endothelial cells by withdrawal of SCGF and FLT3L for 14 days. Expression of the target molecule αvβ3-integrin on freshly isolated CD133+ cells, 28 days ex-vivo expanded and subsequently differentiated cells was analyzed by immunofluorescence (n=3). αvβ3-integrin was detected only on 2 +/−3% of freshly isolated CD133+ stem cells, but after 4 weeks of expansion culture αvβ3-integrin was expressed on 34+/−4% of cells. When culture conditions were switched to induce endothelial differentiation, almost all adherent cells (98+/−1%) were positive for αvβ3 integrin. Of the non-adherent EPC the percentage of αvβ3-integrin positive cells was 60+/−9%. The influence of Cilengitide on the proliferation of EPCs was analysed by counting triplicates obtained from three individual donors over a period of 9 days with 0.1, 0.5, 1 μM Cilengitide and the appropriate solvent control. We could show a significant dose dependent reduction of cell proliferation in the presence of Cilengitide (p<0.0002 for each timepoint). After withdrawal of FLT3 ligand and SCGF, cell proliferation ceased and cells became adherent and showed endothelial morphology. Immunofluorescence analysis of adherent cells showed coexpression of VE-Cadherin and vWF. To analyze the effect of Cilengitide on the differentiation of EPCs, expanded cells were incubated after withdrawl of FLT3L and SCGF with solvent or 0.1, 0.5, or 1 μM Cilengitide. Adherent cells were counted after 7 and 14 days of differentiation. A dose dependent decrease in the number of adherent cells was noted at both time points (n=3, p< 0.03 for each time point). We then investigated the expression of endothelial antigens on EPCs after withdrawal of SCGF and FLT3L in the presence or absence of Cilengitide. Cilengitide caused a significant decrease in the percentage of VE-Cadherin- and vWF-positive cells at days 7 and 14 in a dose-dependent manner. In summary, we could show that Cilengitide inhibited proliferation and differentiation of EPCs.