Defibrotide normalizes cardiovascular function hampered by established atherosclerosis in the rabbit

Monocyte-predominant engraftment, cytokine levels and early transplant-related complications in pediatric hematopoietic stem cell recipients

Myeloablative conditioning is a well‐established procedure that precedes hematopoietic stem cell transplantation (HSCT), particularly in pediatric patients. In the period directly following transplantation, several factors may contribute to complications that lead to the activation or damage of endothelial cells, involved in the pathogenesis of vascular endothelial syndromes (VES). However, to date, sufficiently specific and sensitive diagnostic markers for the various forms of VES have not been identified. This was a retrospective single‐center study of patients who underwent allogeneic HSCT. For this cohort of patients, parameters including type of engraftment, donor characteristics, and cytokine production were measured and correlated with a high prevalence of short‐term complications after HSCT. The aim of this study was to identify specific parameters useful for improving diagnostics and predicting adverse effects in VES. We confirmed that monocyte‐predominant engraftment was related to a higher risk for an early transplant‐related complication termed sinusoidal obstruction syndrome (SOS). The increased production of specific cytokines, in particular RANTES, represents a marker associated with prevalent engraftment. In addition, patients undergoing prophylaxis with defibrotide had “classical” engraftment, a common cytokine profile and a lower incidence of life‐threatening transplant‐related complications. The beneficial effect of defibrotide might be a starting point for developing selective prophylaxis for patients with monocyte engraftment to prevent severe early transplant‐related complications.

The onset of vascular endothelial syndromes after hematopoietic stem cell transplantation is significantly associated with monocyte‐predominant engraftment (P < 0.0001). The increased production of specific cytokines, in particular RANTES, represents a marker associated with monocyte‐predominant engraftment. There is close association between the prophylactic administration of defibrotide, a powerful endothelial protector, and the incidence of vascular endothelial syndromes (P < 0.0001). Given the high cost of defibrotide, selective prophylaxis may be considered for patients with extremely high values of RANTES or with monocyte engraftment.

Defibrotide: a review of its use in severe hepatic veno-occlusive disease following haematopoietic stem cell transplantation

Defibrotide (Defitelio(®)) was recently approved in the EU for the treatment of severe hepatic veno-occlusive disease (VOD), also known as sinusoidal obstructive syndrome, in haematopoietic stem cell transplantation (HSCT) therapy. It is indicated in adults, adolescents, children and infants over 1 month of age. Defibrotide is also available in the US via an expanded-access protocol. Defibrotide is thought to protect endothelial cells and restore the thrombo-fibrinolytic balance in VOD. In a multicentre, phase III trial, the complete response rate by day +100 (primary endpoint) was significantly higher, and mortality at day +100 was significantly lower, in patients with severe hepatic VOD and multiorgan failure following HSCT who received intravenous defibrotide 6.25 mg/kg every 6 h than in a group of historical controls. The efficacy of defibrotide in severe hepatic VOD following HSCT was also supported by findings from a phase II dose-finding study, compassionate-use data and information provided from an independent transplant registry. Intravenous defibrotide was generally well tolerated in patients with severe hepatic VOD following HSCT, and was not associated with an increased risk of haemorrhagic adverse events. In conclusion, defibrotide is the only agent approved (in the EU) for use in severe hepatic VOD following HSCT and represents a useful advance in the treatment of this condition.

Association between paraoxonases gene expression and oxidative stress in hepatotoxicity induced by CCl4

Objectives. The purpose of the study is to evaluate the hepatoprotective effect of rutin in carbon tetrachloride- (CCl₄-) induced liver injuries in rat model. Methods. Forty male Wistar albino rats were divided into four groups. Group I was the control group and received dimethyl sulphoxide (DMSO) and olive oil. Group II received rutin. Groups III was treated with CCl₄. Group IV was administered rutin after 48 h of CCl₄ treatment. Liver enzymes level, lipid profile, lipid peroxidation, and hydrogen peroxide were measured. The genes expression levels were monitored by real time RT-PCR and western blot techniques. Results. CCl₄ group showed significant increase in alanine aminotransferase (ALT), aspartate aminotransferase (AST), thiobarbituric acid reactive substances (TBAR), hydrogen peroxide (H₂O₂), and lipid profile and a significant decrease in glutathione peroxidase (GPx), glutathione S transferase (GST), catalase (CAT), paraoxonase-1 (PON-1), paraoxonase-3 (PON-3), peroxisome proliferator activated receptor delta (PPAR-δ), and ATP-binding cassette transporter 1 (ABAC1) genes expression levels. Interestingly, rutin supplementation completely reversed the biochemical and gene expression levels induced by CCl₄ to control values. Conclusion. CCl₄ administration causes aberration of genes expression levels in oxidative stress pathway resulting in DNA damage and hepatotoxicity. Rutin causes hepatoprotective effect through enhancing the antioxidant genes.

Defibrotide: properties and clinical use of an old/new drug

The drug named defibrotide (DFT) has been studied for many years. It has been shown to possess many activities: profibrinolytic, antithrombotic-thrombolytic, antiischemic (heart, liver, kidney, skin, brain), antishock, antiatherosclerotic, antirejection and anti-angiogenic. The previously displayed activities, as antithrombotic, profibrinolytic and anti-inflammatory, suggested its use in vascular disorders, as in the treatment of peripheral obliterative arterial disease and in thrombophlebitis. Some years after, the use of DFT in hepatic veno-occlusive disease has been also proposed. Even if DFT was considered for long time a multi-target drug, now it could be considered on the whole as a drug able to protect endothelium against activation. The present work reviews the more important experimental and clinical studies performed to detect DFT effects.

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.

Fludarabine induces apoptosis, activation, and allogenicity in human endothelial and epithelial cells: protective effect of defibrotide

Fludarabine is a nonmyeloablative immunosuppressant increasingly used as a component of alternative conditioning regimens before allogeneic bone marrow transplantation. It is expected to reduce conditioning-related toxicity and proinflammatory activation of the host tissues. However, in our in vitro study, we provide evidence that 2-fluoroadenine 9-beta-D-arabinofuranoside (F-Ara) as the active metabolized form of fludarabine damages human microvascular endothelial cells (HMECs) and dermal and alveolar epithelial cell lines after 48 hours of culture when it is used in pharmacologically relevant concentrations (range, 10 microg/mL-1 microg/mL). In addition, flow cytometric analyses revealed a significant up-regulation of intercellular adhesion molecule 1 and major histocompatibility complex (MHC) class I molecules by F-Ara, suggesting a proinflammatory activation of HMECs. Cytotoxicity assays demonstrated that target HMECs pretreated with F-Ara (10 microg/mL) showed increased lysis by allogeneic MHC class I-restricted cytotoxic T lymphocytes from healthy human donors. We conclude that, beside its immunosuppressive activities, F-Ara can be harmful for target tissues of transplantation-related complications and can even stimulate allogeneic immune responses. We identified the pharmaceutical compound defibrotide as protective against F-Ara- induced apoptosis and alloactivation, importantly, without affecting the antileukemic effect of F-Ara. This observation argues for a potential clinical usage of defibrotide in pretransplantation conditioning.