Prolonged thrombocytopenia after living donor liver transplantation is a strong prognostic predictor irrespective of splenectomy: the significance of ADAMTS13 and graft function [corrected]

Thrombocytopenia after liver transplantation: Should we care?

Transient thrombocytopenia is a common phenomenon after liver transplantation. After liver transplantation (LT), platelet count decreases and reaches a nadir on postoperative days 3-5, with an average reduction in platelet counts of 60%; platelet count recovers to preoperative levels approximately two weeks after LT. The putative mechanisms include haemodilution, decreased platelet production, increased sequestration, medications, infections, thrombosis, or combination of these processes. However, the precise mechanisms remain unclear. The role of platelets in liver transplantation has been highlighted in recent years, and particular attention has been given to their effects beyond hemostasis and thrombosis. Previous studies have demonstrated that perioperative thrombocytopenia causes poor graft regeneration, increases the incidence of postoperative morbidity, and deteriorates the graft and decreases patient survival in both the short and long term after liver transplantation. Platelet therapies to increase perioperative platelet counts, such as thrombopoietin, thrombopoietin receptor agonist, platelet transfusion, splenectomy, and intravenous immunoglobulin treatment might have a potential for improving graft survival, however clinical trials are lacking. Further studies are warranted to detect direct evidence on whether thrombocytopenia is the cause or result of poor-graft function and postoperative complications, and to determine who needs platelet therapies in order to prevent postoperative complications and thus improve post-transplant outcomes.

Von Willebrand Factor Deposition and ADAMTS-13 Consumption in Allograft Tissue of Thrombotic Microangiopathy-like Disorder After Living Donor Liver Transplantation: A Case Report

BACKGROUND

Thrombotic microangiopathy (TMA) pathogenesis after living donor liver transplantation (LDLT) is thought to be caused by release of unusually large von Willebrand factor multimers (UL-vWFMs) resulting from sinusoidal endothelial cell damage and induction of platelet adhesion and aggregation. A decrease in a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs-13 (ADAMTS-13) that cleave UL-vWFMs might cause excessive UL-vWFMs activity and result in platelet thrombus formation. However, this phenomenon has not undergone a full pathologic assessment.

PROCEDURES

A 60-year-old man was diagnosed with hepatitis C-related end-stage cirrhosis. His son was the donor, and he underwent LDLT. On postoperative day 44, his laboratory findings met most TMA diagnostic criteria, and he was diagnosed with TMA-like disorder (TMALD). Localization of CD42b as a platelet marker, vWF, and ADAMTS-13 in allograft tissue of this patient were evaluated using immunohistochemistry.

RESULTS

CD42b expression was observed as platelet aggregates attached to hepatocytes or within the hepatocyte cytoplasm, a morphology called extravasated platelet aggregation (EPA). vWF expression was observed mainly as deposited compact clusters, and ADAMTS-13 expression resembled distinct dots throughout the liver tissue.

CONCLUSION

These findings suggest that EPA indicated sinusoidal endothelial cell damage followed by detachment, and vWF deposition resulted from UL-vWFM oversynthesis. ADAMTS-13 might be consumed in the allograft tissue to cleave UL-vWFMs, but ADAMTS-13 levels might be insufficient to cleave all the deposited UL-vWFMs. We present the case of an LDLT recipient diagnosed with TMALD using blood tests, which showed the presence of TMA pathogenesis in the allograft.

Postoperative changes in neutrophil-to-lymphocyte ratio and platelet count: A simple prognostic predictor for adult-to-adult living donor liver transplantation

BACKGROUND/OBJECTIVE

The neutrophil-to-lymphocyte ratio (NLR) is a simple index that represents systemic inflammatory change. The number of platelets is also known to reflect both post-transplant graft regeneration and dysfunction. Thus, we aimed to investigate the usefulness of NLR and platelet number in predicting the clinical course after adult-to-adult living donor liver transplantation (AA-LDLT) in the acute postoperative period in recipients.

METHODS

Between January 1999 and December 2013, 61 patients underwent their first AA-LDLT at our institute. We retrospectively analyzed their clinical data, including NLR and number of platelets, until postoperative day 14, and evaluated their ability to predict prognosis after AA-LDLT.

RESULTS

The optimal cutoff values of postoperative maximum NLR and maximum platelets to predict prognosis were 50 and 80 × 10³/μL, respectively. The 1- and 5-year survival rates were 87.5% and 79.1% in the normal maximum NLR group, respectively, and 46.2% for both in the high maximum NLR group (p = 0.0033). The 1- and 5-year survival rates, respectively, were 90.9% and 84.1% in the high maximum platelets group and 47.1% and 41.2% in the low maximum platelets group (p < 0.0001). In multivariate analysis, maximum NLR ≥ 50 and maximum platelets < 80 × 10³/μL were independently associated with 1-year mortality.

CONCLUSION

A high NLR and a low platelet count during acute postoperative period might correlate with poor prognosis after AA-LDLT.

Elevated Soluble Platelet Glycoprotein VI Levels in Patients After Living Donor Liver Transplantation

Plasma-soluble platelet glycoprotein VI (sGPVI) levels were examined in patients undergoing living donor liver transplantation (LDLT), and the relationship between platelet activation and thrombocytopenia was evaluated to understand the mechanism of thrombocytopenia in LDLT. Platelet counts were significantly higher in the donors compared to the recipient, and the plasma sGPVI levels increased in both groups after the operation. Regarding the relationship between the platelet counts and the sGPVI levels, the slope varied on different days, and it became negative on day 3, suggesting that the plasma sGPVI levels are related to platelet activation in LDLT. The frequency of complications was high in the nonsurvivors. The platelet counts were higher in the survivors than in the nonsurvivors on days 14 and 28. Although the plasma levels of sGPVI in the survivors increased after the operation, those in the nonsurvivors were high only on day 3. Although the ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 domain, member 13) levels were markedly reduced, von Willebrand factor (VWF) and VWF propeptide (VWFpp) were markedly elevated during LDLT. The antithrombin activity was significantly lower (day 14) and VWFpp (day 28) was significantly higher in the nonsurvivors than in the survivors. These findings suggest that platelet activation first occurs after LDLT, and it is high in the nonsurvivors on day 3. Thereafter, the hemostatic abnormality and vascular endothelial cell injuries may appear on days 14 and 28.

The efficacy of the administration of recombinant human soluble thrombomodulin in patients with DIC

Efficacy of recombinant human soluble thrombomodulin (rhTM), which is frequently used to treat patients with disseminated intravascular coagulation (DIC), was compared with that of gabexate mesilate (GM), which was previously used routinely in the treatment of DIC patients in Japan. Although there was no significant difference in the resolution rates of the patients who were treated with rhTM and GM, the results of our analysis revealed that the mortality rate was significantly higher among infectious disease patients treated with GM than in those treated with rhTM. Levels of fibrinogen and fibrin degradation products (FDP), antithrombin (AT) activity, and thrombin AT complex (TAT) were significantly lower in the DIC patients with infectious diseases, while fibrinogen levels were high. FDP level, D-dimer, platelet count, PT ratio, and DIC score all showed significant improvement following rhTM treatment. There were no significant difference between survivors and non-survivors in terms of DIC score, FDP level, platelet count, AT activity, or in TAT, SF and PPIC levels before rhTM treatment. However, fibrinogen levels were significantly lower in non-survivors than in survivors. These results indicate that rhTM may be superior to GM for the treatment of DIC.