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ABSTRACT: No small-diameter synthetic graft has yet shown comparable performance to autologous vessels. Synthetic conduits fail due to their inherent surface thrombogenicity and the development of intimal hyperplasia. In addressing these shortcomings, electrospinning offers an interesting alternative to other nanostructured, cardiovascular substitutes because of the close match of electrospun materials to the biomechanical and structural properties of native vessels. In this study, we investigated the in vivo behavior of electrospun, small-diameter conduits in a rat model. Vascular grafts composed of polyurethane were fabricated by electrospinning. Prostheses were implanted into the abdominal aorta in 40 rats for either 7 days, 4 weeks, 3 months, or 6 months. Retrieved specimens were evaluated by histology, immunohistochemical staining, confocal laser scanning microscopy, and scanning electron microscopy. At all time points, we found no evidence of foreign body reaction or graft degradation. The overall patency rate of the intravascular implants was 95%. Within 7 days, grafts revealed ingrowth of host cells. CD34+ cells increased significantly from 7 days up to 6 months of implantation (P < 0.05). Myofibroblasts and myocytes showed increasing cell numbers up to 3 months (P < 0.05). Ki67 staining indicated unaltered cell proliferation during the whole follow-up period. Besides biomechanical benefits, electrospun polyurethane grafts exhibit excellent biocompatibility in vivo. Cell immigration and differentiation seems to be promoted by the nanostructured artificial matrix.
Artificial Organs 08/2011; 36(1):54-61. · 2.00 Impact Factor
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Hevidar Taha,
Klaudia Skrzypek,
Ibeth Guevara,
Anneliese Nigisch,
Stefan Mustafa,
Anna Grochot-Przeczek,
Pawel Ferdek,
Halina Was,
Jerzy Kotlinowski,
Magdalena Kozakowska,
Aneta Balcerczyk,
Lucie Muchova,
Libor Vitek, Guenter Weigel,
Jozef Dulak,
Alicja Jozkowicz
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ABSTRACT: Heme oxygenase-1 (HO-1) is an antioxidative, antiinflammatory, and cytoprotective enzyme that is induced in response to cellular stress. The HO-1 promoter contains a (GT)n microsatellite DNA, and the number of GT repeats can influence the occurrence of cardiovascular diseases. We elucidated the effect of this polymorphism on endothelial cells isolated from newborns of different genotypes.
On the basis of HO-1 expression, we classified the HO-1 promoter alleles into 3 groups: short (S) (most active, GT < or = 23), medium (moderately active, GT=24 to 28), and long (least active, GT > or = 29). The presence of the S allele led to higher basal HO-1 expression and stronger induction in response to cobalt protoporphyrin, prostaglandin-J(2), hydrogen peroxide, and lipopolysaccharide. Cells carrying the S allele survived better under oxidative stress, a fact associated with the lower concentration of oxidized glutathione and more favorable oxidative status, as determined by measurement of the ratio of glutathione to oxidized glutathione. Moreover, they proliferated more efficiently in response to vascular endothelial growth factor A, although the vascular endothelial growth factor-induced migration and sprouting of capillaries were not influenced. Finally, the presence of the S allele was associated with lower production of some proinflammatory mediators, such as interleukin-1beta, interleukin-6, and soluble intercellular adhesion molecule-1.
The (GT)n promoter polymorphism significantly modulates a cytoprotective, proangiogenic, and antiinflammatory function of HO-1 in human endothelium.
Arteriosclerosis Thrombosis and Vascular Biology 08/2010; 30(8):1634-41. · 6.37 Impact Factor
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ABSTRACT: Engineered small diameter vascular grafts must closely match mechanical characteristics of native vessels and exhibit stimulus-responsive bioactivity. In this study, mechanical homogeneity of electrospun small diameter polyurethane grafts as well as spontaneous attachment, proliferation, and adhesion molecule expression of endothelial cells (EC) in their presence was studied in vitro. Axial and circumferential tensile strengths were measured and found to be twofold higher in the circumferential direction. EC attachment was easily achieved without precoating the fiber matrix. Stimulation of EC with interleukin-1beta (IL-1beta) led to a statistically significant upregulation of the adhesion molecules E-Selectin, ICAM-1, and VCAM-1. Quantification of adhesion molecule expression by means of energy-dispersive X-ray microanalysis revealed no differences in the stimulatory responses of EC cultured on electrospun polyurethane when compared with cells grown on tissue culture-treated cover slips. Summarizing, highly uniform small diameter polyurethane grafts were fabricated and shown to allow spontaneous EC attachment. The synthetic graft surface neither impaired the endothelial response toward IL-1beta stimulation nor did it adversely affect the regulation of expression of endothelial adhesion molecules.
Journal of Biomedical Materials Research Part A 08/2009; 93(2):716-23. · 2.63 Impact Factor
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ABSTRACT: The influence of an acellular porcine matrix on proinflammatory activation of endothelial cells (EC) during normoxia and hypoxia was investigated by a newly established semi-quantitative electron microscopic procedure. As a model, three adhesion molecules (E-selectin, ICAM-1, and VCAM-1) were localized by silver-enhanced immunogold staining and energy dispersive X-ray microanalysis after normoxic or hypoxic pretreatment of the cells and subsequent stimulation with IL-1beta. Morphology of EC grown on porcine matrix or coverslips was recorded simultaneously using secondary electron imaging. EC appeared tightly attached to the underlying surfaces with their typical cobblestone-like morphology. Statistically significant upregulations upon stimulation with IL-1beta were observed in both groups for all three adhesion molecules. Hypoxic pretreatment of the specimens with subsequent reoxygenation neither induced morphological changes nor caused an upregulation of adhesion molecule expression in cells grown on acellular porcine tissue. Unexpectedly, in cells seeded onto the acellular matrix, IL-1beta failed to upregulate ICAM-1 expression after a short period of hypoxia. The surface expression of VCAM-1 was also significantly lower even under normoxic conditions, which might indicate the development of functional impairment of cells in contact with acellular porcine tissue. The method presented in this study has proven valuable for the determination of antigen expression on scaffold materials in parallel with the characterization of surface morphology.
Tissue Engineering Part C Methods 01/2009; 15(2):257-63. · 4.64 Impact Factor
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ABSTRACT: In an attempt to monitor the pharmacodynamics of mycophenolate mofetil (MMF) we investigated the association of inosine monophosphate dehydrogenase (IMPDH) activity in peripheral blood mononuclear cells with the expression of lymphocyte activation markers in stable cardiac transplant recipients treated with MMF.
Twenty-four study patients were switched from azathioprine to MMF 7.2+/-4.1 years after heart transplantation.
While the MPA trough level remained unchanged, the mean activity of IMPDH declined from 890 to 462 pmol/10(6)PBMC/h three months after onset of MMF therapy, was almost completely inhibited at six months and partially restored to 160 pmol/10(6)PBMC/h 12 months after switch to MMF (p< .0001). We detected also significant changes in a number of activated lymphocyte subsets: CD4+/25+, CD8+/38+, CD19+/69+, CD3+/16+/56+, natural killer (NK) cells, and monocytes. Moreover, the IMPDH activity profile correlated positively with the number of CD8+/38+ T cells (correlation coefficient (CC) +0.53), and inversely with NK cells (CC -0.52) and CD19+/69+ cells (CC -0.61).
We revealed a close association of IMPDH baseline activity in mononuclear cells with the expression of lymphocyte activation markers in stable heart transplant patients after introduction of MMF therapy. This supports the assumption of a rather immunomodulatory than immunosuppressive effect of MMF.
Clinica Chimica Acta 09/2008; 394(1-2):67-71. · 2.54 Impact Factor
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ABSTRACT: 15-Deoxy-Delta(12,14)-prostaglandin-J(2) (15d-PGJ(2)) is a cyclopentenone prostaglandin regarded as antiinflammatory mediator, which can act through peroxisome proliferator-activated receptor-gamma (PPARgamma) or through G protein-coupled surface receptors. It has been demonstrated that 15d-PGJ(2) potently increases the generation of interleukin-8 (IL-8) in human microvascular endothelial cells (HMEC-1s); however, the mechanism of this induction is not known. The aim of the study was to find the pathway involved in 15d-PGJ(2)-mediated IL-8 stimulation. Our data confirmed that the effect of 15d-PGJ(2) is independent of PPARgamma. For the first time, we excluded the activation of G proteins and the contribution of G protein-coupled surface receptors in endothelial cells treated with 15d-PGJ(2). Instead, we demonstrated that stimulation of IL-8 involved induction of oxidative stress, activation of p38 kinases, and increase in stability of IL-8 mRNA. Upregulation of IL-8 promoter, although measurable, seemed to play a less-pronounced role. Additionally, our results indicate the involvement of cAMP elevation and may suggest a role for ATF2 transcription factor. Concomitant induction of heme oxygenase-1 in HMEC-1s did not influence the synthesis of IL-8. In summary, we showed that 15d-PGJ(2), acting through oxidative stress, may exert proinflammatory effects. The upregulation of IL-8 is mostly associated with p38-mediated stabilization of mRNA.
Antioxidants & Redox Signaling 08/2008; 10(12):2035-46. · 8.20 Impact Factor
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ABSTRACT: Decellularization treatment of heart valves has been thought to eliminate tissue immunogenicity. Early failure of tissue-engineered xenogeneic heart valves was seen in children and has been a major drawback in this promising field of research. This study was designed to characterize the effects of acellular porcine heart valve tissue on immune activation in vitro. Incubation of decellularized porcine tissue with human plasma led to adsorption of IgG, activation of the classical complement pathway and adhesion of activated polymorphonuclear leukocytes (PMN). This inflammatory response was strongly inhibited by proteins extracted from native porcine tissue which might indicate that inhibitors of PMN activation present in the extracellular matrix (ECM) are lost during the decellularization process.
Biomaterials 05/2008; 29(12):1824-32. · 7.40 Impact Factor
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ABSTRACT: Reports regarding the biocompatibility of xenogeneic, decellularized bioprosthetic implants differ between bioinertness and complete graft degradation. We investigated heparin-crosslinked and nonheparinized, xenogeneic vascular substitutes in a rat model. Porcine arteries (15 x 1.5 mm) were decellularized by multistep detergent and enzymatic techniques, which were followed by heparin-crosslinking in 50% of the implants. Prostheses were implanted into the abdominal aorta of 76 rats for 1 day and up to 6 months. Retrieved specimens were evaluated by histology, immunohistochemistry, laser scanning, and scanning electron microscopy. Graft patency did not differ between groups (97.3%). Heparinized grafts showed a statistically significant lower rate of aneurysm formation (p = 0.04 %). Implants revealed infiltration with granulocytes and macrophages up to 3 months. Recellularization with endothelial cells and myofibroblasts was detectable within 1 month. After 6 months elastin biosynthesis and complete graft remodeling toward an elastic vessel was evident. These results indicate that temporary inflammation does not interfere with long-term vascular remodeling.
Journal of Biomedical Materials Research Part B Applied Biomaterials 05/2008; 87(1):95-104. · 2.15 Impact Factor
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ABSTRACT: Strategies to recover myocardium in therapeutically unresponsive patients are again under scrutiny, including techniques developed in the pioneering days of cardiothoracic surgery such as retroperfusion via the coronary sinus--the Beck procedure. An underestimated aspect of retroperfusion is the formation of new vessels. This early observation of neoangiogenesis may be an important mechanism in observed benefits. We hypothesized that periodic pressure elevation in coronary veins induces an analogy to shear stress angiogenic pulses by activating venous endothelium. Pulsatile stretch on venous endothelium can be achieved easily by a pressure-controlled intermittent balloon blockade of the coronary sinus outflow.
Three hours of myocardial ischemia was induced in 12 pigs. Pressure-controlled intermittent coronary sinus occlusion was applied in 6 animals 15 minutes after occlusion of the left anterior descending coronary artery. Postmortem myocardial specimens were taken, and heme oxygenase-1, vascular endothelial growth factor gene expression, and hypoxia-induced factor activity were measured.
As compared with controls, treated animals released an angiogenic pulse by a 4-fold increase of heme oxygenase-1 gene expression in the infarct area (P < .001), together with a 2.5-fold enhanced transcription of vascular endothelial growth factor in the infarct (P < .006), border (P < .002), and remote (P < .02) areas, whereas hypoxia-induced factor activity was similar in both groups. A significant correlation (P < .01) of the achieved coronary sinus pressure elevation and gene expression was found.
Mechanotransduction of pulsatile stretch on coronary venous endothelium by pressure-controlled intermittent coronary sinus occlusion induces heme oxygenase-1 and vascular endothelial growth factor gene expression, leaving the ischemic pathway of the hypoxia-induced factor activity unchanged. This cascade of molecular events closes the argument gap to historical reports of the Beck procedure on revascularization and myocardial salvage.
The Journal of thoracic and cardiovascular surgery 06/2007; 133(6):1581-7. · 3.41 Impact Factor
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ABSTRACT: The objective of this study was to investigate purine nucleotide metabolism in peripheral blood mononuclear cells (PBMC) of cardiac transplant recipients switched from azathioprine to mycophenolate mofetil (MMF).
Concentrations of guanosine 5'triphosphate (GTP) and adenosine 5'triphosphate (ATP), the activities of inosine monophosphate dehydrogenase (IMPDH), guanine phosphoribosyltransferase (GPRT), and hypoxanthine phosphoribosyltransferase (HPRT) were determined in PBMC of 27 cardiac transplant recipients before switch to MMF and 3, 6, and 12 months thereafter.
There was no difference in the activities of IMPDH and salvage pathway enzymes GPRT and HRPT as well as in intracellular GTP and ATP concentrations between the patients before switch to MMF and healthy controls. The GTP and ATP concentrations in PBMC of cardiac recipients did not change during the entire observation period. Although the MPA trough level remained similar, IMPDH activity declined from 897 to 316 pmol/10(6)PBMC/h 3 months after MMF onset, was almost completely inhibited after 6 months, and partially restored to 143 pmol/10(6)PBMC/h 12 months after switch to MMF. In contrast, GPRT activity increased after 3, 6, and 12 months of MMF therapy and HPRT activity 3 and 6 months after switch to MMF.
We demonstrated for the first time an induction of salvage pathway enzyme activities in PBMC under MMF therapy. This probably accounts for the maintenance of intracellular purine nucleotide pools and prevents the GTP depletion.
Transplantation 08/2006; 82(1):113-8. · 4.00 Impact Factor
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ABSTRACT: 15-Deoxy-Delta(12,14)-prostaglandin-J(2) (15d-PGJ(2)) upregulates expression of vascular endothelial growth factor (VEGF), but may inhibit angiogenesis. We found that 15d-PGJ(2) (1-10muM) attenuated all VEGF-induced angiogenic activities in human umbilical vein endothelial cells (HUVEC). It blocked almost completely cell proliferation, potently reduced migration, assembly into tube-like network on matrigel, and growth of capillaries into collagen gel. 15d-PGJ(2) inhibited expression of VEGFR-1 and VEGFR-2 receptors both at mRNA and protein levels. This inhibition, however, was transient (observed after 6-12h, but not after 24h) and weak (20-30%), and could not fully explain inhibition of response to VEGF. Accordingly, proliferation was inhibited when 15d-PGJ(2) was added 24h after VEGF or in cells stimulated with basic fibroblast growth factor. Interestingly, 15d-PGJ(2) decreased activities of c-jun and c-myc in HUVEC and overexpression of c-myc attenuated its antiproliferative effects. This suggests that inhibition of this transcription factor by 15d-PGJ(2) contributes to decrease in angiogenic response.
Prostaglandins & other lipid mediators 06/2006; 79(3-4):230-44. · 2.70 Impact Factor
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ABSTRACT: In tissue engineering of heart valves using decellularized xenogenic valves, it has been suggested that cell elimination would result in a biologically inert matrix. The aim of this in-vitro investigation was to evaluate different decellularization methods in regard to the completeness of cell removal, inflammatory response, and thrombocyte activation.
Decellularized porcine Synergraft valves were compared with porcine pulmonary conduits decellularized with Triton X-100, sodium deoxycholate, Igepal CA-630 and ribonuclease. Completeness of decellularization was evaluated with staining for nuclei and alpha-Gal epitope. Decellularized heart valves with and without seeding with endothelial cells (ECs) were incubated with human platelet-rich plasma and stained for CD41 and PAC-1 to evaluate thrombocyte activation. Samples were processed for laser scanning microscopy (LSM) and scanning electron microscopy (SEM). Migration of human monocytic cells towards extracted valve proteins was tested.
In contrast to the Synergraft, complete cell removal and elimination of the alpha-gal epitope was achieved with the new decellularization method. Numerous adherent and activated platelets were found on the decellularized matrix. This was inhibited by seeding with ECs. Even in completely cell-free valve tissue extracellular matrix proteins attracted human monocytic cells as in early inflammation, depending on whether porcine or human tissue was used.
Important differences were found in the decellularization efficacy of treatment methods. However, even complete elimination of cells and their remnants did not result in a biologically inert matrix. The decellularized porcine heart valve matrix has the potential to attract inflammatory cells and to induce platelet activation. These findings suggest that it will be important to control the different inflammation-stimulating factors if porcine tissues are to be used successfully in tissue engineering.
The Journal of heart valve disease 04/2006; 15(2):278-86; discussion 286. · 0.81 Impact Factor
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ABSTRACT: The mechanism of action of mycophenolic acid (MPA) has been described as a blockade of inosine 5'-monophosphate dehydrogenase (IMPDH) and is thought to selectively influence T- and B-lymphocytes due to their strong dependency on guanine nucleotides synthesized via the de novo purine synthesis pathway. Recent evidence suggests MPA to affect antigen-presenting cells.
Using CD14+ derived human dendritic cells (DC) we have investigated the effects of MPA on differentiation, maturation and function and studied intracellular nucleotide content and IMPDH activity.
GTP content and IMPDH activities of DC were strongly and dose-dependently decreased when MPA was present during the entire culture period or was added after the fifth (immature DC) or the seventh (mature DC) day of culture. Concurrent to low GTP levels, a dose-dependent reduction in the expression of CD80, CD86, CD40, CD54 and CD83 was seen which was accompanied by a decreased capacity of DC to stimulate T-cells. Our data for the first time shows a direct effect of MPA on the maturation and function of human CD14+ derived DC, indicates a role of IMPDH and a dependency on the de novo purine synthesis pathway.
Clinica Chimica Acta 03/2006; 364(1-2):139-47. · 2.54 Impact Factor
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ABSTRACT: The aim of this investigation was to provide evidence that leukocyte depleted whole blood meets the requirements for transfusion of the European Council and thus may be an alternative to leukocyte and plasma depleted packed red blood cells in autologous blood predeposit for patients undergoing elective surgery programs.
Standard units of 450mL blood were collected from 25 healthy male volunteers. Leukocyte depletion was done via inline filtration 4h after collection. Storage lesion was assessed by measuring the release of K(+), LDH, free hemoglobin, and lactate into the storage medium, as well as by the increase of hemolysis, the decrease of pH and consumption of glucose over a storage period of 35 days. As surrogate marker for red cell quality the intracellular concentrations of adenine nucleotides [ATP, ADP, AMP] were determined.
The extent of storage lesion remained within the ranges of standard liquid storage conditions. Hemolysis was far below the threshold of 0.8% in all WB units at the end of their shelf life. Only minor changes of intracellular adenine nucleotide levels were measured indicating a preserved function of red blood cells in leukocyte depleted whole blood. At the end of shelf life 70%+/-18% of initial ATP levels were detected.
Based on our data we propose that leukocyte depleted whole blood, stored for 35 days can be an option in the autologous blood supply as it meets the requirements for transfusion of the European Council.
International journal of surgery (London, England) 02/2006; 4(3):179-83.
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ABSTRACT: An approach in tissue engineering of heart valves is the use of decellularized xenogeneic matrices to avoid immune response after implantation. The decellularization process must preserve the structural components of the extracellular matrix to provide a biomechanically stable scaffold. However, it is known that in vascular lesions platelet adhesion to extracellular matrix components occurs and platelet activation is induced. In the present study we examined the effects of a decellularized porcine heart valve matrix on thrombocyte activation and the influence of re-endothelialisation in vitro. Porcine pulmonary conduits were decellularized using Triton X-100, Na-deoxycholate and Igepal CA-630 followed by a ribonuclease digestion. Cryostat sections of decellularized heart valves with and without seeding with human umbilical vein endothelial cells (HUVEC) were incubated with platelet rich plasma. Samples were either stained with fluorescent antibodies for CD41 and PAC-I (recognizing the activated fibrinogen receptor) or fixed with glutaraldehyde. Thereafter, the samples were processed for laser scanning microscopy (LSM) or scanning electron microscopy (SEM). Examination by LSM showed numerous platelets with co-localized staining for CD41 and PAC-1 on the nonseeded decellularized heart valve matrix whereas after seeding with endothelial cells no platelet activation was detected. SEM revealed platelet adhesion and aggregate formation only on the surface of the non-seeded or partially denuded matrix specimens. We show in this study that the decellularized porcine matrix acts as a platelet-activating surface. Seeding with endothelial cells effectively abolishes the platelet adhesion and activation and therefore is necessary to eliminate thrombogenicity in tissue engineered heart valves.
Thrombosis and Haemostasis 10/2005; 94(3):562-7. · 5.04 Impact Factor
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ABSTRACT: Tissue-engineered or decellularized heart valves have already been implanted in humans or are currently approaching the clinical setting. The aim of this study was to examine the migratory response of human monocytic cells toward decellularized porcine and human heart valves, a pivotal step in the early immunologic reaction.
Porcine and human pulmonary valve conduits were decellularized, and migration of U-937 monocytic cells toward extracted heart valve proteins was examined in a transmigration chamber in vitro. Homogenized tissue specimens were size fractionated by SDS-PAGE. The decellularization procedure effectively reduced the migration of human monocytes toward all heart valve tissue. However, only the antigen reduction of human pulmonary valves abolished the monocytic response (wall, 0.88+/-0.19% versus 30.20+/-3.93% migrated cells [mean+/-SEM]; cusps, 0.10+/-0.06% versus 10.24+/-1.83%) and was significantly lower (P<0.05) than that of the decellularized porcine equivalent (wall, 5.03+/-0.14% versus 24.31+/-2.38%; cusps, 3.18+/-0.38% versus 10.24+/-1.83%). SDS-PAGE of the pulmonary heart valve tissue revealed that considerable amounts of proteins with different molecular weights that were not detected in the human equivalent remain in the decellularized porcine heart valve.
We describe for the first time that the remaining potential of decellularized pulmonary heart valves to attract monocytic cells depends strongly on whether porcine or human scaffolds were used. These findings will have an important impact on further investigations in the field of heart valve tissue engineering.
Circulation 05/2005; 111(21):2792-7. · 14.74 Impact Factor
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ABSTRACT: 15-Deoxy-delta12,14-Prostaglandin-J2 (15d-PGJ2), an endogenous ligand of PPARgamma transcription factor, modifies expression of many genes involved in inflammation and angiogenesis. Enzyme which contributes to regulation of both these processes is endothelial nitric oxide synthase (eNOS). Our aim was to investigated the effect of 15d-PGJ2 on eNOS in human umbilical vein endothelial cells (HUVEC). We demonstrated that 24 h incubation of HUVEC with 15d-PGJ2 (1-10 microM) does not influence eNOS. On the contrary, the longer exposure (48-72 h) resulted in concentration-dependent inhibition of eNOS mRNA and protein expressions and led to reduction in eNOS enzymatic activity by approximately 50%. This effect was mediated by regulation of the transcription rate from eNOS promoter, what may be associated with inhibition of AP-1 binding capacity. The stability of mRNA was unchanged. Since none of the observed effects could be mimicked by troglitazone, a more potent PPARgamma ligand, we suppose that 15d-PGJ2 diminishes expression of eNOS via PPARgamma-independent mechanisms.
Prostaglandins & other lipid mediators 11/2004; 74(1-4):11-28. · 2.70 Impact Factor
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ABSTRACT: We compared effects of vascular endothelial growth factor-121 (VEGF121) and vascular endothelial growth factor-165 (VEGF165) on generation of NO in HUVEC and the involvement of NO in VEGF121- and VEGF165-induced angiogenesis. VEGF stimulated synthesis of NO within seconds, reaching peak concentrations of 450 +/- 25 and 180 +/- 15 nmol/l for VEGF121, and VEGF165, respectively. The VEGF121 increased NO production for about 40 s while VEGF165-stimulated NO release lasted only for about 20 s. Accordingly, cGMP elevation was stronger in VEGF121- than in VEGF165-treated cells. The VEGF121 was a very weak mitogen but strong chemoattractant for HUVEC, whereas VEGF165 potently induced both cell proliferation and migration. NO appeared to be involved in the endothelial migration and morphogenesis but not in the proliferation. NO was also a permissive molecule for VEGF121- but not for VEGF165-induced capillary sprouting in spheroid culture. In conclusion, VEGF121 is a stronger stimulator of endothelial nitric oxide synthase (eNOS) activity, and angiogenic potential of VEGF121 is more reliant on NO contribution.
Growth Factors 04/2004; 22(1):19-28. · 1.65 Impact Factor
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ABSTRACT: We compared 3 different decellularization protocols in porcine heart valves for efficiency of complete cell removal and potential for recellularization.
Porcine aortic and pulmonary roots were treated with trypsin, sodium-dodecyl-sulphate, or a new method using 0.25% tert-octylphenyl-polyoxyethylen in combination with sodium-deoxycholate. After a subsequent ribonuclease digestion, specimens were seeded with in vitro expanded human saphenous vein endothelial cells and myofibroblasts.
After treatment with trypsin and subsequent ribonuclease digestion, endothelial attachment took place; however, xenogenic cells were still visible within the matrix. Unexpectedly, when human cells were seeded onto specimens that had been decellularized with sodium-dodecyl-sulphate, the matrices were surrounded by nonviable endothelial cell fragments, indicating a toxic influence of the ionic detergent; 0.25% tert-octylphenyl-polyoxyethylen together with sodium-deoxycholate completely removed porcine cells and enabled host recellularization.
Compared with trypsin and sodium-dodecyl-sulphate involving decellularization procedures, reported to be effective in cell removal and susceptible to recellularization with human cells, only the porcine matrix treated with a new detergent-based decellularization method using 0.25% tert-octylphenyl-polyoxyethylen/sodium-deoxycholate followed by nuclease digestion presented an excellent scaffold for recellularization with human cells.
Journal of Thoracic and Cardiovascular Surgery 03/2004; 127(2):399-405. · 3.41 Impact Factor
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ABSTRACT: The vascular endothelial growth factor (VEGF) is produced in response to hypoxia or inflammatory cytokines. In normoxia VEGF synthesis is upregulated by 15-deoxy-Delta(12,14)-prostaglandin-J(2) (15d-PGJ(2)) via induction of heme oxygenase-1 (HO-1). Here we compared the influence of 15d-PGJ(2) on VEGF expression in human microvascular endothelial cells in normoxia (approximately 20% O(2)) and hypoxia ( approximately 2% O(2)). Regardless of the oxygen concentration, 15d-PGJ(2) inhibited activity of hypoxia inducible factor-1 (HIF-1), the major hypoxic regulator of VEGF. However, in normoxic conditions 15d-PGJ(2) (1-10microM) activated the VEGF promoter and increased synthesis of the VEGF protein. Concomitantly, it strongly induced expression of HO-1. In contrast, in hypoxia, 15d-PGJ(2) decreased VEGF promoter activity and reduced VEGF release by 50%. Inhibition of HO-1 activity additionally attenuated VEGF synthesis in hypoxia. We conclude that induction of HO-1 by 15d-PGJ(2) results in augmentation of VEGF synthesis in normoxia. In hypoxia, however, the stimulatory effect of HO-1 is outweighed by 15d-PGJ(2)-mediated inhibition of the HIF-1 pathway.
Biochemical and Biophysical Research Communications 02/2004; 314(1):31-8. · 2.48 Impact Factor
