Prophylactic Effect of Recombinant Human Soluble Thrombomodulin for Hepatic Sinusoidal Obstruction Syndrome Model Mice

Assaying ADAMTS13 Activity as a Potential Prognostic Biomarker for Sinusoidal Obstruction Syndrome in Mice

Sinusoidal obstruction syndrome (SOS) is a serious liver disorder that occurs after liver transplantation, hematopoietic stem cell transplantation, and the administration of anticancer drugs. Since SOS is a life-threatening condition that can progress to liver failure, early detection and prompt treatment are required for the survival of patients with this condition. In this study, female CD1 mice were divided into treatment and control groups after the induction of an SOS model using monocrotaline (MCT, 270 mg/kg body weight intraperitoneally). The mice were analyzed at 0, 12, 24, and 48 h after MCT administration, and blood and liver samples were collected for assays and histopathology tests. SOS was observed in the livers 12 h after MCT injection. In addition, immunohistochemical findings demonstrated CD42b-positive platelet aggregations, positive signals for von Willebrand factor (VWF), and a disintegrin-like metalloproteinase with thrombospondin type 1 motifs 13 (ADAMTS13) in the MCT-exposed liver sinusoid. Although ADAMTS13's plasma concentrations peaked at 12 h, its enzyme activity continuously decreased by 75% at 48 h and, inversely and proportionally, concentrations in the VWF-A2 domain, in which the cleavage site of ADAMTS13 is located, increased after MCT injection. These findings suggest that the plasma concentration and activity of ADAMTS13 could be useful biomarkers for early detection and therapeutic intervention in patients with SOS.

Efficacy and Safety of Recombinant Thrombomodulin for the Prophylaxis of Veno-Occlusive Complication in Allogeneiccit Hematopoietic Stem Cell Transplantation: A Systematic Review and Meta-Analysis

BACKGROUND

Hepatic veno-occlusive disease (VOD), also termed as sinusoidal obstruction syndrome (SOS), is a lethal complication after hematopoietic stem cell transplantation (HSCT). Various factors put patients undergoing allogeneic HSCT at an increased risk for VOD. Thrombomodulin (TM) is an important factor which has a wide range of effects, including anticoagulant, anti-inflammatory, angiogenic, and protective effect, on endothelial cells. It plays a role in preventing excessive coagulation and thrombosis by binding with thrombin and inhibiting the coagulation cascade. There are a limited number of options for the prevention of this fatal complication. Recombinant thrombomodulin (rTM), an endothelial anticoagulant co-factor, as prophylactic therapy might be able to prevent veno-occlusive complications after stem cell transplantation.

METHODS

A literature search was performed on PubMed, Embase, and Web of Science. We used the following Mesh terms and Emtree terms, "Hepatic Veno-Occlusive Diseases" OR "Sinusoidal Obstruction" OR "Stem Cell Transplantations " AND "Thrombomodulin" from the inception of data up to April 1, 2021. The PICO (Patient/Population, Intervention, Comparison and Outcomes) framework was used for the literature search.

RESULTS

For the VOD incidence after HSCTstem cell transplantation, the result was in favor of rTM with a risk ratio (RR) of 0.53 (I2 = 0%, 95% confidence interval [CI] = 0.32-0.89). The incidence of transplant-associated thrombotic microangiopathy (TA-TMA) after HSCT was reduced in rTM group. The RR for incidence of TA-TMA was 0.48 (I2 = 62%, 95% CI = 0.20-1.17) favoring rTM. The RR for incidence of graft-versus-host disease (GvHD) was also lower in rTM group, 0.48 (I2 = 64%, 95% CI = 0.32-0.72).

CONCLUSION

In our meta-analysis, we evaluate the efficacy and safety of rTM in the prevention of SOS after HSCT. According to our results, rTM use led to a significant reduction in SOS episodes, TA-TMA, and GvHD after HSCT.

Thrombopoietin accumulation in hepatocytes induces a decrease in its serum levels in a sinusoidal obstruction syndrome model

Sinusoidal obstruction syndrome (SOS) is a type of fatal hepatic injury, which predominantly occurs following exposure to drugs, such as oxaliplatin, or bone marrow transplantation. Extravasated platelet aggregation (EPA) plays an important role in the development of SOS in rat and mouse models. Furthermore, platelets invading the space of Disse adhere to hepatocytes and are phagocytized in patients with SOS. Aging platelets and platelets in patients with sepsis are phagocytized by hepatocytes through Ashwell‑Morell receptors, and thrombopoietin (TPO) is produced by the JAK2‑STAT3 signaling pathway. The purpose of the present study was to examine the significance of TPO as a biomarker of SOS. SOS was induced in Crl:CD1(ICR) female mice by intraperitoneal administration of monocrotaline (MCT). TPO levels were measured in the serum and liver tissue. Pathological and immunohistochemical studies of the liver were performed to analyze the expression levels of TPO. TPO mRNA expression levels were measured using reverse transcription‑quantitative PCR. In the SOS model, the platelet counts in peripheral blood samples were significantly decreased at 24 and 48 h after MCT treatment as compared with that at 0 h. In addition, a pathological change in hepatic zone 3 was observed in the SOS model group. Furthermore, the protein levels of TPO in liver tissue were significantly increased in the SOS model group compared with those in the control group, which was confirmed by immunohistochemistry. By contrast, serum TPO protein levels were significantly decreased in the SOS model group compared with those in the control group. These results indicated that EPA may induce sinusoidal endothelial fenestration in a mouse model of SOS, preventing TPO from translocating into the blood. In conclusion, serum TPO levels may be reduced in a mouse model of SOS owing to the accumulation in hepatocytes, suggesting that TPO could be a useful biomarker of SOS.

Early vascular endothelial complications after hematopoietic cell transplantation: Role of the endotheliopathy in biomarkers and target therapies development

This work aims to review the role of endothelial dysfunction underlying the main complications appearing early after autologous and allogeneic hematopoietic cell transplantation (HCT). The endothelial damage as the pathophysiological substrate of sinusoidal obstruction syndrome (SOS) is well established. However, there is growing evidence of the involvement of endothelial dysfunction in other complications, such as acute graft-versus-host disease (aGVHD) and transplant-associated thrombotic microangiopathy (TA-TMAs). Moreover, HCT-related endotheliopathy is not only limited to the HCT setting, as there is increasing evidence of its implication in complications derived from other cellular therapies. We also review the incidence and the risk factors of the main HCT complications and the biological evidence of the endothelial involvement and other linked pathways in their development. In addition, we cover the state of the art regarding the potential use of the biomarkers of endotheliopathy in the prediction, the early diagnosis, and the follow-up of the HCT complications and summarize current knowledge points to the endothelium and the other linked pathways described as potential targets for the prevention and treatment of HCT-complications. Lastly, the endothelium-focused therapeutic strategies that are emerging and might have a potential impact on the survival and quality of life of post-HCT-patients are additionally reviewed.

The role of liver sinusoidal endothelial cells in cancer liver metastasis

Liver sinusoidal endothelial cells (LSECs) are the gatekeeper cells in the liver, contributing critical roles in liver physiological and pathological changes. Factors such as dietary macronutrients, toxins, and aging impact LSEC fenestration. Defenestration of LSECs changes their phenotype and function. Under liver injury, capillarized LSECs promote hepatic stellate cells (HSCs) activation and fibrogenesis, while decapillarized LSECs protect the activation of HSCs and liver injury. The expression of chemokines, such as CXCL9 and CXCL16, changes and impacts the infiltration of immune cells in the liver during disease progression, including hepatocellular carcinoma (HCC). As the largest solid organ, liver is one of the most favorable organs into where tumor cells metastasize. The increased interaction and adhesion of circulating tumor cells (CTCs) with LSECs in the local microenvironment and LSEC-induced tolerance of immunity promote cancer liver metastasis. Several strategies can be applied to target LSEC to modulate their function to prevent cancer liver metastasis, including gut microbiota modulation, microRNA therapy, and medical treatment. Delivery of different treatment agents with nanoparticles may promote precise target treatment. Overall, targeting LSECs is a potential strategy for treatment of early liver diseases and prevention of cancer liver metastasis.

Platelets prevent the development of monocrotaline-induced liver injury in mice

Destruction of liver sinusoidal endothelial cells (LSECs) is an initial event in sinusoidal obstruction syndrome (SOS) that leads to accumulation of platelets in the liver. Herein, we explored the role of platelets during progression of experimental SOS induced by monocrotaline (MCT) in mice. Depletion of platelets using an anti-CD41 antibody or anti-thrombocyte serum exacerbated MCT-induced liver injury in C57BL/6 mice, as indicated by an increase in the alanine transaminase (ALT) level, which was associated with hemorrhagic necrosis. Thrombocytosis induced by thrombopoietin (TPO) or the TPO receptor agonist romiplostim (ROM) attenuated MCT-induced liver injury, as evidenced by lower levels of ALT and mRNA encoding matrix metalloproteinase (MMP) 9, and higher levels of mRNA encoding vascular endothelial growth factor receptor (VEGFR) 2 and VEGFR3. The level of activated hepatic platelets was higher in TPO- and ROM-treated mice than in saline-treated mice. Co-culture with a high number of platelets increased the viability of LSECs and their mRNA levels of CD31, VEGFR2, and VEGFR3, and decreased their mRNA level of MMP9. The level of VEGF-A was increased in the culture medium of LSECs co-cultured with platelets. These results indicate that platelets attenuate MCT-induced liver injury by minimizing damage to LSECs.