Defibrotide for the treatment of veno-occlusive disease after liver transplantation

Early-onset hepatic veno-occlusive disease after liver transplantation: an institutional experience and analysis of a literature-based cohort

PURPOSE

Hepatic veno-occlusive disease (HVOD) after liver transplantation (LT) is almost always a fatal complication. We assessed the outcomes of HVOD in a single institute and analyzed a literature-based cohort.

METHODS

We reviewed the medical records of recipients of LT performed between 1995 and 2020 at our institute and the literature on HVOD after LT. We then analyzed the clinical features based on a "pooled" cohort of cases identified in our institute and reported in the literature.

RESULTS

HVOD was diagnosed in 3 of 331 LT recipients, all of whom died in hospital, on days 164, 12, and 13, respectively. Our comprehensive review of the literature, as well as our cases, identified eight cases of HVOD that developed within 14 days after LT (early-onset type). Early-onset HVOD had a significantly worse prognosis than HVOD that developed beyond 2 weeks after LT (non-early-onset type), which was identified in 22 cases (25.0% vs. 86.1% of the 3-month graft survival rate). The most common causes of early-onset and non-early-onset types were acute cellular rejection (50%) and drug-induced disease (50%), respectively.

CONCLUSION

Early-onset HVOD developing within 14 days after LT has a poor prognosis.

Tacrolimus-Induced Hepatic Vein Occlusive Disease After Deceased Donor Liver Transplantation: A Case Report

Advancements in surgical techniques and the optimization of immunosuppression have boosted organ transplant survival rates; however, liver transplant recipients still risk complications such as hepatic vein occlusive disease (HVOD), also called sinusoidal obstruction syndrome. Rare but potentially fatal HVOD damages endothelial cells due to factors like chemotherapy, stem cell transplantation, and certain medications such as azathioprine and tacrolimus. Typically, HVOD presents with distinct clinical symptoms, including ascites, jaundice, and significant weight gain. Herein, we present the case of a 66-year-old male with decompensated liver cirrhosis due to hepatitis C virus infection. The patient underwent a deceased donor liver transplantation at our center. Unfortunately, 4 months after the transplant, he experienced progressive dyspnea and developed right pleural effusion. Abdominal computed tomography and a liver biopsy confirmed the diagnosis of HVOD, likely induced by tacrolimus. After stopping tacrolimus, we observed a significant decrease in ascites and remission of the patient's clinical symptoms of abdominal distention and dyspnea; subsequently, we introduced cyclosporine. In this report, we describe this specific patient's case and discuss HVOD, including its diagnosis and management.

Prevalence and outcomes of patients with sinusoidal obstruction syndrome after liver transplantation: A ten year's experience of a third-level Centre in Japan

BACKGROUND

Sinusoidal obstruction syndrome (SOS) after liver transplantation (LT) is a rare and potentially lethal complication. We retrospectively reviewed the outcomes of patients with post-transplant SOS.

METHODS

Between May 2001 and December 2019, of 332 patients who underwent LT, 5 (1.5%) developed SOS. The median age at LT was 1.7 years (range 0.1-66.5). SOS was histopathologically diagnosed and classified as early-onset (<1 month) or late-onset.

RESULTS

The median time to diagnosis of SOS was one month after LT. All patients developed acute cellular rejection before SOS, and the cause of SOS was acute cellular rejection in four patients and unknown in one. The treatment of SOS included conversion to tacrolimus from cyclosporine, intrahepatic hepatic vein stent placement, strengthening of immunosuppression, and plasma exchange. The 5-year graft survival rates in patients with and without SOS were 53.0% and 92.5%, respectively (p < 0.001). Of three patients with early-onset SOS, two patients improved and are doing well, and one patient died of graft failure four months after LT.

CONCLUSIONS

The cause and treatment of post-transplant SOS are not yet defined. The poor outcomes in patients with early-onset SOS may be improved by strengthening of immunosuppression. Patients with late-onset SOS are ultimately treated by repeat LT.

Successful defibrotide treatment of a patient with veno-occlusive disease after living-donor liver transplantation: A case report

RATIONALE

Veno-occlusive disease (VOD) is characterized by painful hepatomegaly, ascites, weight gain, and jaundice with nonthrombotic, fibrous obliteration of the centrilobular hepatic veins. VOD after liver transplantation is a rare complication, with an incidence of approximately 2%; however, it can be life-threatening in severe cases. The precise etiology and mechanism of VOD after liver transplantation remains unclear. Acute cellular rejection, antibody-mediated rejection, and treatment with tacrolimus or azathioprine may be associated with the development of VOD after liver transplantation. Additionally, the optimal treatment of VOD after liver transplantation has not yet been established and focuses on supportive care. Defibrotide is an anti-ischemic and antithrombotic drug with no systemic anticoagulant effects. Moreover, only a few reports have investigated the use of defibrotide for VOD after liver transplantation, which has shown promising results.

PATIENT CONCERNS

A 39-year-old woman with primary biliary cholangitis underwent living-donor liver transplantation at our center. She experienced right upper quadrant pain with increased ascites, pleural effusion, and weight gain on postoperative day 14.

DIAGNOSES

Imaging and pathological tests showed no evidence of rejection or vessel complications. VOD was diagnosed clinically based on the findings of weight gain, ascites, jaundice, and pathological biopsy.

INTERVENTIONS

Defibrotid, 25 mg/kg/day, was administered intravenously for 21 days.

OUTCOMES

She showed complete clinical resolution of the VOD.

LESSONS

Herein, we report a case of successful defibrotide treatment of VOD after living-donor liver transplantation.

Somatostatin Therapy in Patients with Massive Ascites After Liver Transplantation

Background

Patients with massive ascites (MA) after liver transplantation (LT, defined here as daily ascitic drainage more than 1000 ml per day for more than 7 days after liver transplantation) are at increased risks of infection, hypoalbuminemia, graft loss, and even mortality. The aim of this retrospective cohort study was to investigate the effects of somatostatin on patients with MA after LT.

Material/Methods

Twenty-eight patients with liver cirrhosis or hepatocellular carcinoma who underwent LT complicated by MA postoperatively were included. Ten participants were receiving somatostatin therapy. The postoperative course and adverse drug effects were investigated. Daily postoperative ascitic drainage and urine output were also recorded and compared to those in the non-somatostatin group.

Results

The somatostatin group had significantly less ascites drainage after LT compared to the non-somatostatin group (p=0.002). Urine output was significantly increased after somatostatin administration (p<0.001). No serious adverse effects influencing graft function or fatal complications occurred after somatostatin therapy.

Conclusions

Somatostatin treatment is beneficial for the management of MA after liver transplantation.

Long-Term Outcome of Veno-Occlusive Disease After Liver Transplant: A Retrospective Single-Center Experience

OBJECTIVES

Veno-occlusive disease after liver transplant has been sporadically reported, and significant uncertainty exists concerning the best treatment and the long-term outcomes. Here, we reviewed our experience to evaluate clinical presentation, treatment, and the long-term outcomes of these patients.

MATERIALS AND METHODS

Between 2000 and 2015, 2165 patients underwent liver transplant at our center. The incidence of veno-occlusive disease was 0.3% (7/2165).

RESULTS

Timing of veno-occlusive disease onset (median 4.7 mo; interquartile range, 2.5-11.1 mo) varied widely as did clinical presentation, which was characterized by a variable association of liver failure and portal hypertension and different disease pro-gression rates. In all cases, diagnosis of veno-occlusive disease was confirmed by liver biopsy. Six patients (85.7%) presented with veno-occlusive disease after a previous episode of acute cellular rejection. Three patients died due to veno-occlusive disease (n = 2) or due to hepatocellular carcinoma recurrence (n = 1). Two patients were treated by increasing immunosuppression and with interventional procedures (pleurodesis and transjugular intrahepatic portosystemic shunt, respectively), and 2 had successful retransplants. 5-year patient and graft survival rates were 57.1% and 28.6%, respectively.

CONCLUSIONS

A tailored approach based on clinical features and including retransplant can achieve acceptable long-term survival in patients with veno-occlusive disease after liver transplant.

Devastating outflow obstruction after pediatric split liver transplantation

HVOO is a rare complication after pediatric LT, which may lead to graft failure. There are various causes of HVOO, such as mechanical anastomotic obstruction and SOS. A 10-month-old female underwent split LT from a deceased donor for ALF. Her postoperative course was uneventful. However, her liver function suddenly deteriorated a month later. A liver biopsy revealed centrilobular injury, and D-US suggested outflow obstruction. Venography was performed to reveal hepatic venous narrowing inside the graft. She received another graft from a living donor because of progressive graft failure in spite of successful venoplasty with stent insertion. The macroscopic findings of the explanted graft did not show an anastomotic stricture of the hepatic vein, although the pathological findings revealed necrosis of the first graft due to SOS. SOS might cause severe consequences with concomitant mechanical outflow obstruction after pediatric LT.

Transjugular intrahepatic portosystemic shunt for the treatment of sinusoidal obstruction syndrome in a liver transplant recipient and review of the literature

Sinusoidal obstruction syndrome (SOS) is a rare, life-threatening clinical syndrome resulting from sinusoidal congestion, and it is characterized by hepatomegaly, ascites, weight gain, and jaundice. The frequency of this condition after liver transplantation (LT) is low, but when SOS is severe and refractory to medical therapy, the ultimate solution is retransplantation. We describe a patient with SOS after LT who was successfully treated by the placement of a transjugular intrahepatic portosystemic shunt (TIPS). Although information on this approach is scarce because of the low incidence of SOS in LT patients, we review the available literature on treating this condition with a TIPS. On the basis of the reported information and our patient's outcome, we suggest that prompt TIPS placement can be considered for SOS when medical treatment fails. Nonetheless, a formal assessment and prospective studies are needed to confidently indicate TIPS placement in this situation.

Significance of isolated hepatic veno-occlusive disease/sinusoidal obstruction syndrome after liver transplantation

After liver transplantation (LT), hepatic veno-occlusive disease (VOD), which is also known as sinusoidal obstruction syndrome (SOS), has been reported initially in relation to azathioprine use and subsequently in relation to acute rejection (AR). Isolated veno-occlusive disease (iVOD)/SOS raises some questions about its significance and especially its treatment. From the post-LT biopsy samples of 1364 patients (2000-2008), 31 patients with index biopsy samples showing VOD/SOS (2.3%) were identified. After a review of the index biopsy samples and previous biopsy samples, those patients not exposed to azathioprine therapy were subdivided into 2 groups according to the absence or presence of AR. Fifteen of the 31 patients had no previous evidence of AR, whereas 16 experienced episodes of AR (before or concurrently with VOD). The 2 groups were similar in terms of demographic and clinical data and the range of histological centrilobular changes. AR episodes were characterized by an endothelial predilection. iVOD/SOS occurred later than acute rejection-related veno-occlusive disease (AR-VOD)/SOS (mean times of 65 and 4.4 months, respectively, P = 0.0098). There was a tendency for iVOD/SOS to progress less frequently to chronic rejection in comparison with AR-VOD/SOS (3/15 versus 9/15, P = 0.06). The histological resolution of iVOD/SOS was significantly more frequent in patients who benefited from increased immunosuppression in comparison with those who did not (5/7 versus 2/8, P = 0.05). When the groups were considered together, the same result was obtained (14/18 versus 4/12, P = 0.024). In conclusion, despite a constant overall prevalence of VOD/SOS, the proportion of iVOD/SOS has increased. The histological resolution of iVOD/SOS after increase in immunosuppression suggests an immune-mediated origin. Better optimization of immunosuppression may be a curative treatment.

Intractable ascites without mechanical vascular obstruction after orthotopic liver transplantation: etiology and clinical outcome of sinusoidal obstruction syndrome

Intractable ascites after orthotopic liver transplantation (OLT) is a relatively rare complication. However, it often takes a life threatening course, which requires re-transplantation. In previous studies, several reports gave hepatic sinusoidal obstruction syndrome (SOS) as one of the causes of refractory ascites. However, the detailed etiology of SOS after OLT and its association with clinical consequences remain unclear because there have been few studies to date. We report two recent cases with rapidly progressive refractory ascites associated with SOS, following completely different clinical courses. In case 1, the first episode of acute allograft rejection triggered SOS and subsequent intractable ascites, while the second acute rejection worsened his clinical status. A transjugular intrahepatic portosystemic stent-shunt (TIPS) was placed and this procedure resulted in complete disappearance of ascites and of renal dysfunction. In contrast, refractory ascites in case 2, who had neither rejection nor mechanical outlet obstruction, worsened despite TIPS stent placement, and re-transplantation was necessary. We speculate that the pre-existing diseased liver of the cadaver donor caused this serious complication, necessitating a second graft.

Veno-occlusive disease of the liver after lung transplantation

Veno-occlusive disease (VOD) of the liver is mainly described after chemo-irradiation conditioning regimens during haematopoietic stem cell transplantation (SCT) and has been sporadically reported after kidney and liver transplantation. In the latter cases, it is commonly attributed to azathioprine and/or tacrolimus. One case of tacrolimus-induced hepatic VOD developing after lung transplantation (LT) has been recently reported. Here we describe another case of VOD occurring after LT, but in which the causative role was played by azathioprine.

Veno occlusive disease: update on clinical management

Hepatic veno-occlusive disease is a clinical syndrome characterized by hepatomegaly, ascites, weight gain and jaundice, due to sinusoidal congestion which can be caused by alkaloid ingestion, but the most frequent cause is haematopoietic stem cell transplantation (STC) and is also seen after solid organ transplantation. The incidence of veno occlusive disease (VOD) after STC ranges from 0 to 70%, but is decreasing. Survival is good when VOD is a mild form, but when it is severe and associated with an increase of hepatic venous pressure gradient > 20 mmHg, and mortality is about 90%. Prevention remains the best therapeutic strategy, by using non-myeloablative conditioning regimens before STC. Prophylactic administration of ursodeoxycholic acid, being an antioxidant and antiapoptotic agent, can have some benefit in reducing overall mortality. Defibrotide, which has pro-fibrinolytic and antithrombotic properties, is the most effective therapy; decompression of the sinusoids by a transjugular intrahepatic portosystemic shunt (TIPS) can be tried, especially to treat VOD after liver transplantation and when multiorgan failure (MOF) is not present. Liver transplantation can be the last option, but can not be considered a standard rescue therapy, because usually the concomitant presence of multiorgan failure contraindicates this procedure.

The treatment of chronic hepatitis C with peginterferon alfa-2a (40 kDa) plus ribavirin in haemodialysed patients awaiting renal transplant

BACKGROUND/AIMS

We undertook a pilot study to investigate the efficacy and safety of peginterferon alfa-2a (40 kDa) plus ribavirin in haemodialysed chronic HCV patients awaiting renal transplant.

METHODS

Patients received peginterferon alfa-2a 135 microg/week plus ribavirin 200 mg/day for 24 or 48 weeks (genotype non-1 and 1, respectively). The dose of ribavirin was tailored according to plasma concentrations and to haemoglobin levels. Outcomes in treated patients were compared with those of a matched untreated control group.

RESULTS

Thirty-five patients received treatment, while 35 served as untreated controls. Thirty patients completed treatment; patients were withdrawn due to transplantation (n=2), severe anaemia (n=1), dermatitis (n=1) and non-response (n=1) resulting in a drop-out rate of 14%. Overall, 34/35 treated patients were HCV RNA negative at week 4 and had undetectable RNA at the end of treatment, compared with none of the untreated controls (ETR 97% vs 0%; p<0.001). Moreover, all achieved sustained virological response after 24 weeks of treatment-free follow-up versus no control patients (SVR 97% vs 0 %; p<0.001).

CONCLUSIONS

In this study, we have shown for the first time in a large cohort of patients that HCV-patients on haemodialysis can be treated successfully with peginterferon alfa-2a (40 kDa) plus ribavirin.

Pulmonary complications of haematopoietic cell transplantation in children

Paediatric haematopoietic cell transplantation has experienced significant advances in the last few decades. However, pulmonary complications are an important limitation to the efficacy of this intervention, contributing to post-transplantation morbidity and mortality. Such complications persist even in experienced centres and occur in adult and paediatric recipients. This review identifies the paediatric pulmonary complications that are commonly seen following haematopoietic cell transplantation and addresses both infectious and non-infectious aetiologies and their clinical manifestations, evaluation, and potential therapy. Ultimately, improvement in outcomes will require attention to immunosuppression as well as traditional diagnostic procedures and treatment. This article aims to review the current state of pulmonary complications post-transplantation, to examine the impact of our recent advances and changes in treatment, and to identify potential future therapies and hypothesise what role these might have on long-term survival.

The transjugular route: the key hole to the liver world

Portal hypertensive complications are major causes of morbidity and mortality in patients with liver cirrhosis. The advent of the transjugular route with its minimal access allows non-surgical management of portal hypertension, therapy of venous complications of liver transplantation, monitoring of therapy for portal hypertension, hepatic venous pressure gradient and is also the major route to treat hepatic venous obstruction syndromes. In addition, the transjugular route is a safe route to perform a liver biopsy (transjugular liver biopsy) and allows retrograde evaluation of the portal vein. All these procedures can be combined in the same session. These hepatic interventional radiological skills should be incorporated into the expertise of the liver team in specialised hepatological centres, particularly in liver transplant centres as they are especially useful in improving outcomes of cirrhotic patients on the liver transplantation waiting list. A limitation in achieving this goal, could be the number of experienced radiologists, but hepatologists can be trained, at least for the most simple procedures (transjugular liver biopsy and hepatic venous pressure gradient). This would allow wider applicability and use of these diagnostic and therapeutic techniques, all through a 2 mm hole in the neck--the key hole to the liver world.

Severe venoocclusive disease after liver transplantation treated with transjugular intrahepatic portosystemic shunt

Venoocclusive disease (VOD) is due to hepatic sinusoidal lining injury leading to portal hypertension; its incidence after liver transplantation is about 2%. When severe, it does not respond to medical therapy and has a high mortality; retransplantation is the only therapeutic option. However, there are no detailed data regarding the use of transjugular intrahepatic portosystemic shunt for VOD after liver transplantation. We describe two patients who developed severe VOD after liver transplantation, failed defibrotide therapy, and were treated by transjugular intrahepatic portosystemic shunt (TIPS). The portal hypertension resolved completely and one had full histological recovery. We believe that TIPS should be attempted as it may resolve progressive portal hypertension and the hepatic congestion, while allowing the clinician time for listing for further liver transplantation if the patient fails to respond.

Refractory ascites after liver transplantation: an analysis of 1058 liver transplant patients at a single center

A retrospective study of 1058 liver transplant recipients was performed to determine: (i) the incidence, etiology, timing, clinical features and treatment of refractory ascites (RA), (ii) risk factors for RA development, (iii) predictors of RA disappearance, (iv) predictors of survival following RA and (v) the impact of RA on patient survival. Sixty-two patients (5.9%) developed RA and its disappearance occurred in 27/62 cases. Patients having hepatitis C virus (HCV) had a significantly higher hazard rate of developing RA (p < 0.00001). No other baseline characteristic was associated with RA. Cox stepwise regression analysis of the hazard rate of RA disappearance found two significant factors: HCV recurrence as the reason for developing RA implied a poorer outcome (p = 0.006), whereas an unknown reason implied a favorable outcome (p = 0.02). In addition, survival following RA was significantly poorer among patients having bacterial peritonitis or HCV recurrence. Finally, the mortality rate was significantly (nearly 8.6 times) higher in patients following RA development while it was ongoing (p < 0.00001); however, if the RA disappeared, then the additional risk of death also disappeared. This study illustrates the importance of developing an optimal treatment strategy to (i) effectively treat RA if it develops and (ii) prevent hepatitis C recurrence.

Counting the cost: markers of endothelial damage in hematopoietic stem cell transplantation

During hematopoietic stem cell transplantation (HSCT), endothelial damage is the pathological hallmark of veno-occlusive disease of the liver, thrombotic microangiopathy, capillary leak syndrome and graft-versus-host disease. Events prior to conditioning, the conditioning regimen itself as well as calcineurin inhibitors may all induce endothelial damage. Unfortunately, the relative importance of these factors and their interactions, the time frame of endothelial damage and individual susceptibility remain unknown. Moreover, it is conceivable that conditioning regimens differ markedly in their propensity to initiate endothelial damage. Monitoring endothelial damage and response to treatment is hampered by the current lack of suitable markers. In this regard, an ideal marker should be sensitive and specific and indicate the development of an endothelial disorder prior to the onset of symptoms and organ dysfunction. Soluble markers, such as thrombomodulin, are easily amenable with immunoassays; yet, the interpretation of their levels is hampered by the influence of comorbidity. Evaluation of circulating endothelial cells in HSCT demonstrated a marked and dose-dependent increase in cell numbers after conditioning. The challenge ahead is to establish and evaluate novel markers of endothelial damage to permit early detection of disease, monitor response to treatment and evaluate different conditioning regimens.

Fulminant liver failure due to severe veno-occlusive disease after haematopoietic cell transplantation: a depressing experience

BACKGROUND

Between 1988 and 2002, eight patients were referred to our unit from other institutions, for management of fulminant hepatic failure (FHF) complicating severe veno-occlusive disease (VOD).

AIM

To review our experience with these patients.

METHODS

Retrospective analysis of medical case notes.

RESULTS

In 7/8 cases, a histological diagnosis of VOD was confirmed by transjugular liver biopsy or post-mortem examination. All had undergone high-dose chemotherapy. Cyclophosphamide was included in the conditioning regimen of six patients. All developed encephalopathy and four progressed to grade 3 or 4 encephalopathy. All patients died, none surviving >75 days after haematopoietic cell transplantation. Three were listed for liver transplantation: one underwent transplantation, and two died before transplantation could be performed. Two suffered significant complications of transjugular liver biopsy. One underwent transjugular intrahepatic porto-systemic venous stent (TIPS) insertion.

DISCUSSION

FHF complicating severe VOD is associated with multi-organ failure, and has a very poor prognosis. Our experience and that described in published literature, questions the benefits of measures such as liver transplantation or prolonged intensive care.

The protective mechanisms of defibrotide on liver ischaemia-reperfusion injury

During some surgical interventions, temporary occlusion of the hepatic blood supply may cause ischaemia-reperfusion (I/R) injury and hepatic dysfunction. In this study the protective effect of defibrotide (DEF) was evaluated in a rat model of liver I/R injury. Four groups of rats were subjected to the following protocols: saline infusion without ischaemia, DEF infusion without ischaemia, DEF infusion with hepatic I/R, and saline infusion with hepatic I/R. After a midline laporatomy, liver ischaemia was induced by 45 min of portal occlusion. DEF 175 mg/kg(-1) was infused before ischaemia in 10 ml of saline. The same volume of saline was infused into the control animals. At the end of the 45-min reperfusion interval, the animals were sacrified. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) enzyme activities were determined in haemolysates, and malondialdehyde (MDA) level in the liver tissue was measured. Tissue MDA levels were significantly higher in the I/R plus saline group compared to the sham operation control groups (p < 0.01 and p < 0.05, respectively). Tissue MDA levels decreased in the DEF plus I/R group compared to the I/R plus saline group (p < 0.05), but DEF could not reduce tissue lipid peroxidation to the levels of the control sham operation groups. SOD and GSH-Px enzyme activities were significantly higher in DEF-treated animals than in the other groups (p < 0.05). These results suggest that DEF protects liver against I/R injury by increasing the antioxidant enzyme levels.

Scintigraphic patterns of veno-occlusive disease in liver transplantation

Venous vascular complications in liver transplant recipients are rare. Diagnosis is usually based on clinical criteria and typical findings on liver biopsy. The scintigraphic patterns of posttransplant liver veno-occlusive disease are described, and the value of follow-up studies is suggested. The authors present 2 patients who developed posttransplantation hepatic veno-occlusive disease. The first patient had a severe form of the disease and a fatal outcome. The second patient had a mild to moderate form of this disorder with complete resolution following treatment.

Defibrotide reduces procoagulant activity and increases fibrinolytic properties of endothelial cells

Defibrotide (DF), a polydeoxyribonucleotide with antithrombotic properties, has recently proven effective in patients with severe hepatic veno-occlusive disease (VOD), a life-threatening complication of high-dose chemo/radiotherapy regimens for stem cell transplantation. To understand the mechanism of its beneficial effect, we studied the impact of DF on the expression of tissue factor (TF) and fibrinolytic proteins (PAI-1 and t-PA) on endothelial cells. The in vitro response to DF of two types of human endothelial cells (ECs) of different origins, that is from macrovascular (HUVEC) and microvascular (HMEC-1 cell line) beds, was evaluated in the presence or absence of a proinflammatory stimulus (ie bacterial endotoxin, LPS). The results show that DF was able to significantly reduce the LPS-induced TF expression by HMEC-1, and less prominently by HUVEC. In addition, DF importantly influenced the fibrinolytic properties of both HMEC-1 and HUVEC. Specifically, it dose-dependently counteracted the LPS-induced increase in PAI-1 levels and decrease in t-PA activity expression. It also significantly incremented t-PA antigen in resting EC. Decreasing the procoagulant activity and increasing the fibrinolytic potential of EC favors an anticoagulant phenotype of the endothelium, which may protect from fibrin deposition and vascular occlusion.

Defibrotide modulates prostaglandin production in the rat mesenteric vascular bed

Defibrotide 1 microM, a polydeoxyribonucleotide extracted from mammalian organs, reduced the contractile responses to noradrenaline (NA) in the rat isolated and perfused mesenteric vascular bed, in intact as well as in de-endothelialized preparations. Defibrotide was without effect on the acetylcholine-induced relaxations of U-46619-precontracted mesenteric vascular beds. Moreover, defibrotide increased 6-keto prostaglandin (PG) F(2alpha) (stable metabolite of prostacyclin) release sixfold in the presence, but not in the absence of the endothelium, with no modification on the release of other prostanoids. Defibrotide also inhibited the NA-induced increase in PGF(2alpha) release, in both intact and de-endothelialized mesenteric vascular beds. In conclusion, the present results show that defibrotide modulates PG production in the mesenteric bed and that the observed inhibition of the contractile responses should be due to the impairment of the NA-induced increase in PGF(2alpha) release.