Platelet transfusion can be related to liver regeneration after living donor liver transplantation

Thrombocytopenia Predicts Poor Prognosis of Liver Transplantation

BACKGROUND/AIM

Platelets not only participate in physiological hemostasis but also play a major role in liver ischemia-reperfusion injury, liver damage, tissue repair, and liver regeneration. A decrease in platelet count can lead to spontaneous bleeding, infection, and other complications that can seriously impact patient prognosis. Thrombocytopenia has been associated with increased complications after partial hepatectomy, although the effects of thrombocytopenia on patient outcomes remain unclear. Therefore, this study aimed to examine the impact of thrombocytopenia on short- and long-term prognosis following liver transplantation (LT).

METHODS

This was a retrospective analysis comprising 234 adult liver transplant recipients and conducted from January 2019 to June 2022. Preoperative and postoperative daily platelet counts were recorded up to the 30th postoperative day (POD). We defined people with platelet counts <70 × 109/L as the low platelet group, and people with platelet counts >70 × 109/L as the high platelet group. Multivariate analysis was carried out to determine whether low perioperative platelet count was a risk factor for postoperative complications, graft failure, and patient survival.

RESULTS

Of the 234 patients analyzed in this study, approximately half (n = 112, 47.9%) developed persistent thrombocytopenia after LT. The most substantial decrease in platelet levels occurred on POD7. The cumulative survival rates at 1, 2, and 3 years in the high platelet group were higher than those in the low platelet group, 94%, 87%, and 85%, respectively, while those of the low platelet group were 84%, 78%, and 70% (P = .0014). In addition, the high platelet group had a lower incidence of biliary complications compared with the low platelet group (8% vs 19%, P = .020). At the same time, the high platelet group had a lower incidence of posttransplant lung infection (55% vs 75%, P = .040).

CONCLUSIONS

Thrombocytopenia is a common complication of LT. It indicates the severity of the postoperative course and is closely associated with patient survival. In particular, patients who undergo orthotopic liver transplantation (OLT) and have a platelet count <70 × 109/L on the POD7 have significant negative prognostic implications and should be further investigated.

The Role of Immune Cells in Liver Regeneration

The liver is the only organ that can regenerate and regain its original tissue-to-body weight ratio within a short period of time after tissue loss. Insufficient liver regeneration in patients after partial hepatectomy or liver transplantation with partial liver grafts often leads to post-hepatectomy liver failure or small-for-size syndrome, respectively. Enhancing liver regeneration after liver injury might improve outcomes and increase patient survival. Liver regeneration comprises hepatocyte proliferation, and hepatic progenitor cell expansion and differentiation into hepatocytes. The immune system is intensively involved in liver regeneration. The current review provides a comprehensive overview of the diverse roles played by immune cells in liver regeneration. Macrophages, neutrophils, eosinophils, basophils, mast cells, platelets, dendritic cells, type 1 innate lymphoid cells, B cells, and T cells are implicated in promoting liver regeneration, while natural killer cells and overactivated natural killer T cells are supposed to inhibit hepatocyte proliferation. We also highlight the predominant underlying mechanisms mediated by immune cells, which may contribute to the development of novel strategies for promoting liver regeneration in patients with liver diseases.

Low viscoelastic clot strength, platelet transfusions, and graft dysfunction are associated with persistent postoperative ascites following liver transplantation

INTRODUCTION

High output, persistent ascites (PA) is a common complication following liver transplant (LT). Recent work has identified that platelets help maintain endothelial integrity and can decrease leakage in pathological states. We sought to assess the association of PA following LT with platelet count and platelet function.

METHODS

Clot strength (MA) is a measure of platelet function and was quantified using thrombelastography (TEG). Total drain output following surgery was recorded in 24-h intervals during the same time frame as TEG. PA was considered >1 L on POD7, as that much output prohibits drain removal.

RESULTS

105 LT recipients with moderate or high volume preoperative ascites were prospectively enrolled. PA occurred in 28%. Platelet transfusions before and after surgery were associated with PA, in addition to POD5 TEG MA and POD5 MELD score. Patients with PA had a longer hospital length of stay and an increased rate of intraabdominal infections.

CONCLUSION

Persistent ascites following liver transplant is relatively common and associated with platelet transfusions, low clot strength, and graft dysfunction.

Dualistic role of platelets in living donor liver transplantation: Are they harmful?

Platelets are anucleate fragments mainly involved in hemostasis and thrombosis, and there is emerging evidence that platelets have other nonhemostatic potentials in inflammation, angiogenesis, regeneration and ischemia/reperfusion injury (I/R injury), which are involved in the physiological and pathological processes during living donor liver transplantation (LDLT). LDLT is sometimes associated with impaired regeneration and severe I/R injury, leading to postoperative complications and decreased patient survival. Recent studies have suggested that perioperative thrombocytopenia is associated with poor graft regeneration and postoperative morbidity in the short and long term after LDLT. Although it is not fully understood whether thrombocytopenia is the cause or result, increasing platelet counts are frequently suggested to improve posttransplant outcomes in clinical studies. Based on rodent experiments, previous studies have identified that platelets stimulate liver regeneration after partial hepatectomy. However, the role of platelets in LDLT is controversial, as platelets are supposed to aggravate I/R injury in the liver. Recently, a rat model of partial liver transplantation (LT) was used to demonstrate that thrombopoietin-induced thrombocytosis prior to surgery accelerated graft regeneration and improved the survival rate after transplantation. It was clarified that platelet-derived liver regeneration outweighed the associated risk of I/R injury after partial LT. Clinical strategies to increase perioperative platelet counts, such as thrombopoietin, thrombopoietin receptor agonist and platelet transfusion, may improve graft regeneration and survival after LDLT.

Risk Factors for Development of Biliary Stricture After Liver Transplant in Adult Patients: A Single-Center Retrospective Study

Identification of risk factors for biliary stricture after liver transplant and its potential prevention is crucial to improve the outcomes and reduce the complications. We retrospectively analyzed donor and recipient characteristics with intraoperative and postoperative parameters to identify the risk factors for development of post-transplant anastomotic and nonanastomotic biliary strictures with additional analysis of the time onset of those strictures. A total of 412 patients were included in this study. Mean (SD) follow-up time was 79 (35) months (range, 1-152 months). Biliary stricture was diagnosed in 84 patients (20.4%). Multivariate analysis indicated that postoperative biliary leakage (odd ratio [OR], 3.94; P = .001), acute cellular rejection (OR, 3.05; P < .001), donor age older than 47.5 years (OR, 2.05; P = .032), preoperative recipient platelet value < 77.5 × 10³/mL (OR, 1.91; P = .023), University of Wisconsin solution (OR, 1.73; P = .041)), recipient male sex (OR, 1.78; P = .072), portal/arterial flow ratio > 4 (OR, 1.76; P = .083), and intraoperative bleeding > 2850 mL (OR, 1.70; P = .053) were independent risk factors for biliary stricture regardless of the time of their appearance. Multiple risk factors for biliary stricture were determined in this study. Some of these risk factors are preventable, and implementation of strategies to eliminate some of those factors should reduce the development of post-transplant biliary stricture.

Platelets Stimulate Liver Regeneration in a Rat Model of Partial Liver Transplantation

Living donor liver transplantation (LDLT) is sometimes associated with impaired regeneration and severe ischemia/reperfusion injury (IRI) in the graft, resulting in small-for-size syndrome (SFSS). Platelets were previously reported to stimulate liver regeneration in models of hepatectomy, but the evidence in partial liver transplantation (LT) is lacking. In this study, a rat model of partial LT was used, and the impact of thrombopoietin (TPO)-induced perioperative thrombocytosis on graft regeneration, IRI, and survival was investigated. In experiment 1, a 30% partial LT was performed. Under thrombocytosis, SFSS was attenuated, as shown by decreased levels of serum aminotransferases, bilirubin, and ascites. Serum hepatocyte regeneration-related cytokines, including insulin-like growth factor-1, hepatocyte growth factor, interleukin 6 (IL6), and tumor necrosis factor α (TNF-α), were elevated. In addition, the proliferative signaling pathways, Ki-67-labeling index, proliferating cell nuclear antigen (PCNA)-labeling index, mitotic index, and liver/body weight ratio were increased under thrombocytosis. The platelet-induced regeneration was independent of TPO because increases in the Ki-67-labeling and PCNA-labeling indexes were eliminated after reducing platelet counts by antiplatelet serum in rats administered with TPO. For IRI, thrombocytosis did not aggravate oxidative stress or downstream signaling pathways, necrosis, or apoptosis in the graft. After Kupffer cell (KC) depletion, the platelet-induced attenuation of serum aminotransferases, increased serum levels of IL6 and TNF-α, and proliferation-related signaling pathways were eliminated. Moreover, platelet accumulation in the graft decreased substantially. In experiment 2, a 20% partial LT was performed, and thrombocytosis improved postoperative survival. In conclusion, our results suggested that thrombocytosis stimulated graft regeneration and prolonged survival without aggregating IRI after partial LT, and KCs vitally contributed to platelet-derived regeneration. Platelet therapies to increase perioperative platelet counts may improve the outcomes after LDLT.

Disease Mechanisms of Perioperative Organ Injury

Despite substantial advances in anesthesia safety within the past decades, perioperative mortality remains a prevalent problem and can be considered among the top causes of death worldwide. Acute organ failure is a major risk factor of morbidity and mortality in surgical patients and develops primarily as a consequence of a dysregulated inflammatory response and insufficient tissue perfusion. Neurological dysfunction, myocardial ischemia, acute kidney injury, respiratory failure, intestinal dysfunction, and hepatic impairment are among the most serious complications impacting patient outcome and recovery. Pre-, intra-, and postoperative arrangements, such as enhanced recovery after surgery programs, can contribute to lowering the occurrence of organ dysfunction, and mortality rates have improved with the advent of specialized intensive care units and advances in procedures relating to extracorporeal organ support. However, no specific pharmacological therapies have proven effective in the prevention or reversal of perioperative organ injury. Therefore, understanding the underlying mechanisms of organ dysfunction is essential to identify novel treatment strategies to improve perioperative care and outcomes for surgical patients. This review focuses on recent knowledge of pathophysiological and molecular pathways leading to perioperative organ injury. Additionally, we highlight potential therapeutic targets relevant to the network of events that occur in clinical settings with organ failure.

Platelet and liver regeneration after liver surgery

The success of liver surgery, including resection and transplantation, is largely dependent on the ability of the liver to regenerate. Despite substantial improvement in surgical techniques and perioperative care, one of the main concerns is post-hepatectomy liver failure and early allograft dysfunction, both of which are associated with impaired liver regeneration. Recent studies have demonstrated the positive role of platelets in promoting liver regeneration and protecting hepatocytes; however, the underlying mechanisms responsible for these effects are not fully understood. In this review, we updated the accumulated evidence of the role of platelets in promoting liver regeneration, with a focus on liver resection and liver transplantation. The goal of these studies was to support the clinical implementation of platelet agents, such as thrombopoietin receptor agonists, to augment liver regeneration after liver surgery. This "platelet therapy" may become a treatment choice for post-hepatectomy liver failure and early allograft dysfunction.

Clinical Implications of Thrombocytopenia for the Cirrhotic Patient

Thrombocytopenia is a frequent complication in patients with cirrhosis. As many as 84% of patients with cirrhosis have thrombocytopenia, and it is an independent variable indicative of advanced disease and poor prognosis. Although there is great concern that it may aggravate bleeding during surgical procedures, there is limited evidence to inform decisions regarding the treatment of cirrhotic patients with thrombocytopenia undergoing invasive procedures. Finally, there is evidence that platelets play a significant role in liver regeneration. In this report, the clinical implications of thrombocytopenia in cirrhotic patients are reviewed. The utility of platelet counts in the prognosis of cirrhosis and relationship to complications of advanced liver disease, including portal hypertension, esophageal varices, and hepatocellular carcinoma. The impact of low platelet counts on bleeding complications during invasive procedures is outlined. Finally, the role of platelets and potential adverse impact in liver regeneration is reviewed.

Factors associated with low graft regeneration in the early phase after living donor liver transplantation

Appropriate graft regeneration after living donor liver transplantation (LDLT) is crucial to avoid small-for-size syndrome. We enrolled 44 recipients who underwent ABO-identical/compatible LDLT from December 2007 to August 2016 and determined possible factors associated with low graft regeneration after LDLT. Liver regeneration was calculated by the ratio of the graft size on postoperative day (POD) 7 ± 1 day (calculated by CT volumetry) to the size of the donated liver at implant. Postoperative outcomes were compared between the low and high regeneration groups. Median regeneration rate was 1.65-fold. Regeneration rate was negatively correlated with graft-to-recipient weight ratio. Postoperative morbidity rates on POD 14-90 were significantly higher in the low group compared with the high group (63% vs 18%, P = .03). Graft and patient survival in the low group were significantly worse than the high group (1-year graft survival 73% vs 100%, P = .002; patient survival 82% vs 100%, P = .01). Cold ischemia time (CIT; per 10 minute; odds ratio [OR] =1.37) and platelet count <60 000/μL on POD 5 (OR = 14.32) were independently associated with low regeneration. In conclusion, longer CIT and postoperative thrombocytopenia were associated with low graft regeneration in the early phase after LDLT, which could consequently lead to poor graft and patient survival.

Low platelet count: Predictor of death and graft loss after liver transplantation

BACKGROUND

The impact of platelets on liver transplantation (LT) is well recognized, but not completely understood. Platelets exert dichotomous effects on the graft and on the patient. On the one hand, they are essential for primary hemostasis and tissue repair and regeneration. On the other hand, they support ischemia/reperfusion injury and inflammatory processes. Recent evidence has shown a new role for platelet count (PC) in predicting outcomes after LT.

AIM

To evaluate if low PC is a predictor of short- and long-term outcomes after LT.

METHODS

Four hundred and eighty consecutive LT patients were retrospectively assessed. PC from the preoperative to the seventh postoperative day (POD) were considered. C-statistic analysis defined the ideal cutoff point for PC. Cox regression was performed to check whether low PC was a predictor of death, retransplantation or primary changes in graft function within one year after LT.

RESULTS

The highest median PC was 86 × 10⁹/L [interquartile range (IQR) = 65–100 × 10⁹/L] on seventh POD, and the lowest was 51 × 10⁹/L (IQR = 38–71 × 10⁹/L) on third POD. The C-statistic defined a PC < 70 × 10⁹/L on fifth POD as the ideal cutoff point for predicting death and retransplantation. In the multivariate analysis, platelets < 70 × 10⁹/L on 5POD was an independent risk factor for death at 12 mo after LT [hazard ratio (HR) = 2.01; 95% confidence interval (CI) 1.06-3.79; P = 0.031]. In the Cox regression, patients with PC < 70 × 10⁹/L on 5POD had worse graft survival rates up to one year after LT (HR = 2.76; 95%CI 1.52-4.99; P = 0.001).

CONCLUSION

PC < 70 × 10⁹/L on 5POD is an independent predictor of death in the first year after LT. These results are in agreement with other studies that indicate that low PC after LT is associated with negative outcomes.

Platelet-rich plasma as a potential therapeutic approach against lead nitrate- and/or gamma radiation-induced hepatotoxicity

Because of the potential regenerative and cytoprotective effects of its content of numerous bioactive growth factors and cytokines, platelet-rich plasma (PRP) became an attractive biomaterial for therapeutic purposes. Therefore, the current study was designed to investigate the potential therapeutic effect of PRP against lead nitrate- and/or γ-radiation-induced hepatotoxicity. To do so, hepatotoxicity was induced in rats by intraperitoneal administration of lead nitrate (7.5 mg/kg) thrice weekly for two consecutive weeks and/or a whole-body γ-irradiation at a single dose of 6 Gy. Activated PRP (0.5 ml/kg) was injected subcutaneously 24 h after the last dose of lead nitrate and/or γ-irradiation and continued twice weekly for three successive weeks. Lead nitrate intoxication and/or γ-irradiation resulted in a significant elevation of serum alanine transaminase and aspartate transaminase activities accompanied with a significant decrease in serum levels of total protein and albumin. Further, a significant increase in malondialdehyde level and nitric oxide content accompanied with a significant decrease in the reduced glutathione content and the enzyme activities of glutathione-S-transferase, superoxide dismutase, and catalase were observed. Additionally, hepatic extracellular signal-regulated kinase (ERK) and Akt signaling pathways were stimulated. PRP treatment notably ameliorated the induced cell injury, reduced the intracellular oxidative and interestingly increased the upregulation of phosphorylated ERK1/2 and Akt. Moreover, PRP treatment relieved lead nitrate and/or γ-radiation-induced hepatic histological damages. In conclusion, this study sheds the light on a probable therapeutic role of PRP against lead nitrate- and/or γ-radiation-induced hepatotoxicity which might attribute to its ability to activate ERK and Akt signaling pathways.

Therapeutic implication of platelets in liver regeneration -hopes and hues

Mounting evidence highlights platelet involvement in liver regeneration via interaction with liver cells, growth factors release, and signaling contributions. Existing research suggests a compelling biological rationale for utilizing platelet biology, with the goal of improving liver function and accelerating its regenerative potential. Despite its expanding application in several clinical areas, the contribution of the platelet and its therapeutic implementation in liver regeneration so far has not yet fulfilled the initial high expectations. Areas covered: This review scrutinizes the progress, current updates, and discusses how recent understanding - particularly in the clinical implications of platelet-based therapy - may enable strategies to introduce and harness the therapeutic potential of the platelet during liver regeneration. Expert commentary: Several clinical and translational studies have facilitated a platform for the development of platelet-based therapy to enhance liver regeneration. While some of these therapies are effective to augment liver regeneration, the others have had some detrimental outcomes. The existing evidence represents a challenge for future projects that are focused on directly incorporating platelet-based therapies to induce liver regeneration.

Association Between Changes in Splanchnic Hemodynamics and Risk Factors of Portal Venous System Thrombosis After Splenectomy with Periesophagogastric Devascularization

Background

The purpose of this study was to investigate splanchnic hemodynamic changes and determine an optimal cutoff value for risk factors of portal venous system thrombosis (PVST) after splenectomy with periesophagogastric devascularization (SPD) in cirrhotic patients with esophageal and gastric variceal bleeding (EGVB) and portal hypertension (PH).

Material/Methods

Data on patients who underwent SPD were collected retrospectively from January 2013 to December 2017. Color Doppler ultrasound was performed to detect hemodynamic changes of the hepatic artery, splenic artery, splenic vein, and portal vein in included patients (n=60) and healthy volunteers (n=30). Outcomes were compared between preoperative and postoperative biochemical indicators. The cutoff values for hemodynamics were identified using receiver operating characteristic (ROC) curve analysis, and univariate and multivariate analyses of risk factors of PVST were performed.

Results

In our series, hemodynamic indexes of splenic artery, spleen vein, and portal vein in the study group were significantly higher than that of the control group (P<0.05). Multivariate analysis revealed that the portal vein flow and the internal diameter of the portal vein were significantly correlated with PVST. The ROC analysis revealed that the cutoff points for portal vein flow and internal diameter of the splenic vein and portal vein were ≥1822.32 ml/min, ≥1.37 cm, and ≥1.56 cm, respectively.

Conclusions

SPD is an effective treatment in cirrhotic patients with concomitant EGVB and PH by increasing hepatic artery flow and decreasing portal vein flow. High portal vein flow and wider diameters of the portal vein and splenic vein are important markers of PVST.

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.

Platelets in liver regeneration

Background and Objectives

Loss of liver tissue leading to impairment of liver function represents a major cause of mortality. Understanding the mechanism of liver regeneration and developing therapies to sustain liver regeneration are of high therapeutic relevance. In this regard, platelets are considered as potential candidates for stimulating liver regeneration.

Methods

We aim to review the most recent evidence regarding the role of platelets in liver regeneration.

Results

Platelets stimulate liver regeneration in animal models of liver resection. In humans, platelets are independent predictors of postoperative mortality, liver function and volume recovery. One proposed mechanism by which platelets stimulate liver regeneration relies on their direct effect on hepatocytes. Following partial hepatectomy, platelets accumulate in the residual liver and release their granule content. Platelet‐containing molecules, such as HGF, VEGF, IGF‐1 and serotonin, stimulate hepatocyte proliferation. A putative additional mechanism involves the transfer of platelet mRNA to hepatocytes following platelet internalization. Recent studies have suggested that the effect of platelets relies on their interactions with LSEC. Platelets induce the secretion of IL‐6 from LSEC, a strong initiator of hepatocyte proliferation. Additionally, platelets convey molecules that may impact LSEC function and, by extension, liver regeneration. Platelets potentially interact with Kupffer cells, but the effect of that interaction on liver regeneration remains to be determined.

Conclusion

Platelets stimulate liver regeneration. Several mechanisms seem to be involved, acting on the level of hepatocytes, LSEC and potentially Kupffer cells. Identification of the platelet‐molecule(s) involved may lead to targeted therapies for patients with impairment of liver function.

Prediction of biliary anastomotic stricture after deceased donor liver transplantation: the impact of platelet counts - a retrospective study

Biliary stricture is a common cause of morbidity after liver transplantation (LT). This study aimed to determine the risk factors for post-transplant biliary anastomotic strictures (BAS), focusing on perioperative platelet counts. We enrolled 771 consecutive recipients who underwent ABO-identical/compatible deceased donor LT with duct-to-duct biliary reconstruction from January 2000 to June 2012. BAS was identified in 142 cases. The median time for stricture development was 176 days. Preoperative and postoperative platelet counts within 5 days after LT were significantly lower in patients with BAS than those without BAS. Using cutoff values acquired by the receiver operating characteristic curve analysis, persistent postoperative thrombocytopenia was defined as platelet counts <41 × 1000/μl and <53 × 1000/μl on postoperative day (POD) 3 and POD 5, respectively. Multivariate analysis indicated persistent postoperative thrombocytopenia (OR = 2.38) was the only independent risk factor for BAS. No significant associations were observed in terms of donor and surgical factors. Multivariate analysis demonstrated estimated blood loss (OR = 1.01, per 100 ml) was an independent contributing factor for persistent postoperative thrombocytopenia. We demonstrated low platelet count was associated with progression of post-transplant BAS. Minimizing intraoperative blood loss potentially contributes to maintain post-transplant platelet count, which may reduce incidence of BAS.

Splenectomy before adult liver transplantation: a retrospective study

BACKGROUND

A considerable number of patients with portal hypertension (PHT) have to undergo splenectomy because they do not meet the requirements for liver transplantation (LT) or cannot find a suitable liver donor. However, it is not known whether pre-transplantation splenectomy may create occult difficulties for patients who require LT in future.

METHODS

We analyzed 1059 consecutive patients who underwent adult liver transplantation (ADLT). Patients with pre-transplantation splenectomy Sp(+) and without splenectomy Sp(-) were compared using a propensity score analysis to create the best match between groups.

RESULTS

There were no differences between patients in group Sp(+) and group Sp(-) with respect to the main post-operative infections (12.20% vs. 15.85%, P = 0.455), and the incidence of major complications (6.10% vs. 10.98%, P = 0.264). The post-operative platelet count was significantly higher in group Sp(+) (P = 0.041), while group Sp(-) had a higher rate of post-operative thrombocytopenia (91.46% vs. 74.39%, P = 0.006) and early allograft dysfunction (EAD) (23.20% vs. 10.98%, P = 0.038). The 5-year overall survival rates were similar in groups Sp(-) and Sp(+) (69.7% vs. 67.6%, P = 0.701).

CONCLUSIONS

Compared with Sp(-), the risk of infection and post-operative complications in group Sp(+) was not increased, while group Sp(-) had a higher rate of post-operative EAD. Moreover, pre-transplantation splenectomy is very effective for the prevention of thrombocytopenia after LT. Pre-transplantation splenectomy is recommended in cases with risky PHT patients without appropriate source of liver for LT.

Porcine model characterizing various parameters assessing the outcome after acetaminophen intoxication induced acute liver failure

AIM

To investigate the changes of hemodynamic and laboratory parameters during the course of acute liver failure following acetaminophen overdose.

METHODS

Eight pigs underwent a midline laparotomy following jejunal catheter placement for further acetaminophen intoxication and positioning of a portal vein Doppler flow-probe. Acute liver failure was realized by intrajejunal acetaminophen administration in six animals, two animals were sham operated. All animals were invasively monitored and received standardized intensive care support throughout the study. Portal blood flow, hemodynamic and ventilation parameters were continuously recorded. Laboratory parameters were analysed every eight hours. Liver biopsies were sampled every 24 h following intoxication and upon autopsy.

RESULTS

Acute liver failure (ALF) occurred after 28 ± 5 h resulted in multiple organ failure and death despite maximal support after further 21 ± 1 h (study end). Portal blood flow (baseline 1100 ± 156 mL/min) increased to a maximum flow of 1873 ± 175 mL/min at manifestation of ALF, which was significantly elevated (P < 0.01). Immediately after peaking, portal flow declined rapidly to 283 ± 135 mL/min at study end. Thrombocyte values (baseline 307 × 10³/µL ± 34 × 10³/µL) of intoxicated animals declined slowly to values of 145 × 10³/µL ± 46 × 10³/µL when liver failure occurred. Subsequent appearance of severe thrombocytopenia in liver failure resulted in values of 11 × 10³/µL ± 3 × 10³/µL preceding fatality within few hours which was significant (P > 0.01).

CONCLUSION

Declining portal blood flow and subsequent severe thrombocytopenia after acetaminophen intoxication precede fatality in a porcine acute liver failure model.

Prognostic impact of postoperative low platelet count after liver transplantation

BACKGROUND

The positive impact of platelets has been recently implicated in liver transplantation (LT). The aim of this study was to determine the risk factors for graft loss and mortality after LT, focusing on perioperative platelet counts.

METHODS

We reviewed all deceased donor LT from 2000 to 2012 and enrolled 975 consecutive recipients. The risk factors for graft loss and mortality were analyzed by multivariate analysis, using Cox's regression model.

RESULTS

Using cutoff values acquired by receiver operating characteristics curve analysis, multivariate analyses determined that viral hepatitis C (hazard ratio [HR]=1.32), donor age >40 (HR=1.33), higher peak serum alanine aminotransferase (HR=1.01), reoperation within 30 days (HR=1.51), and platelet count <72 500/μL on postoperative day (POD) 5 (HR=1.30) were independent risk factors for graft loss. Viral hepatitis C (HR=1.33), reoperation within 30 days (HR=1.35), and platelet count <72 500/μL on POD 5 (HR=1.38) were independent risk factors for mortality.

CONCLUSION

A low platelet count on POD 5 was associated with graft loss and mortality after LT. Platelet count <72 500/μL on POD 5 can be a predictor of poor graft and overall survival. Maintaining higher postoperative platelet counts could potentially improve graft and overall survival rates.

Predictive factors of short term outcome after liver transplantation: A review

Liver transplantation represents a fundamental therapeutic solution to end-stage liver disease. The need for liver allografts has extended the set of criteria for organ acceptability, increasing the risk of adverse outcomes. Little is known about the early postoperative parameters that can be used as valid predictive indices for early graft function, retransplantation or surgical reintervention, secondary complications, long intensive care unit stay or death. In this review, we present state-of-the-art knowledge regarding the early post-transplantation tests and scores that can be applied during the first postoperative week to predict liver allograft function and patient outcome, thereby guiding the therapeutic and surgical decisions of the medical staff. Post-transplant clinical and biochemical assessment of patients through laboratory tests (platelet count, transaminase and bilirubin levels, INR, factor V, lactates, and Insulin Growth Factor 1) and scores (model for end-stage liver disease, acute physiology and chronic health evaluation, sequential organ failure assessment and model of early allograft function) have been reported to have good performance, but they only allow late evaluation of patient status and graft function, requiring days to be quantified. The indocyanine green plasma disappearance rate has long been used as a liver function assessment technique and has produced interesting, although not univocal, results when performed between the 1(th) and the 5(th) day after transplantation. The liver maximal function capacity test is a promising method of metabolic liver activity assessment, but its use is limited by economic cost and extrahepatic factors. To date, a consensual definition of early allograft dysfunction and the integration and validation of the above-mentioned techniques, through the development of numerically consistent multicentric prospective randomised trials, are necessary. The medical and surgical management of transplanted patients could be greatly improved by using clinically reliable tools to predict early graft function.

Effects of platelet-rich plasma on liver regeneration in CCl4-induced hepatotoxicity model

Numerous bioactive growth factors and cytokines in platelet-rich plasma (PRP) have recently made it an attractive biomaterial for therapeutic purposes. These growth factors have the potential to regenerate the injured tissues. The aim of this study was to investigate the therapeutic effects of PRP in hepatotoxic animal model. Hepatotoxicity was induced in rats by oral administration of 4 mL/kg/week of CCl₄ diluted 1:1 in corn oil for 10 weeks. To confirm the hepatotoxicity, 24 h after the last CCl₄ administration, blood samples were collected via cardiac puncture to assess the serum levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, albumin, total protein, and total bilirubin. Twenty-four hours after blood collection, the experimental animals received a single injection of PRP (1 mL) via the anterior mesenteric vein. One week later, all biochemical tests were performed again, and the rats were scarified and their livers were removed, prepared histologically, and stained. The stereological analyses were performed to evaluate the effects of PRP on histopathological features of CCl₄-treated livers. The results were compared statistically with the corresponding control and CCl₄+normal saline (NS)-treated animals. A significant decrease in the number and volume of hepatocytes (p = 0.01), and also a reduction in the volume of sinusoids (p = 0.001) and connective tissue (p = 0.04), were observed in the PRP-treated animals compared with the CCl₄+NS-treated ones. Our findings demonstrated that application of PRP had beneficial effects on CCl₄-induced fibrosis; however, it had detrimental effects on the total number of hepatocytes and the volume of hepatocytes and sinusoidal spaces.

Postoperative Decrease in Platelet Counts Is Associated with Delayed Liver Function Recovery and Complications after Partial Hepatectomy

Peripheral platelet counts decrease after partial hepatectomy; however, the implications of this phenomenon are unclear. We assessed if the observed decrease in platelet counts was associated with postoperative liver function and morbidity (complications grade ≤ II according to the Clavien-Dindo classification). We enrolled 216 consecutive patients who underwent partial hepatectomy for primary liver cancers, metastatic liver cancers, benign tumors, and donor hepatectomy. We classified patients as either low or high platelet percentage (postoperative platelet count/preoperative platelet count) using the optimal cutoff value calculated by a receiver operating characteristic (ROC) curve analysis, and analyzed risk factors for delayed liver functional recovery and morbidity after hepatectomy. Delayed liver function recovery and morbidity were significantly correlated with the lowest value of platelet percentage based on ROC analysis. Using a cutoff value of 60% acquired by ROC analysis, univariate and multivariate analysis determined that postoperative lowest platelet percentage ≤ 60% was identified as an independent risk factor of delayed liver function recovery (odds ratio (OR) 6.85; P < 0.01) and morbidity (OR, 4.90; P < 0.01). Furthermore, patients with the lowest platelet percentage ≤ 60% had decreased postoperative prothrombin time ratio and serum albumin level and increased serum bilirubin level when compared with patients with platelet percentage ≥ 61%. A greater than 40% decrease in platelet count after partial hepatectomy was an independent risk factor for delayed liver function recovery and postoperative morbidity. In conclusion, the decrease in platelet counts is an early marker to predict the liver function recovery and complications after hepatectomy.

A focus on the role of platelets in liver regeneration: Do platelet-endothelial cell interactions initiate the regenerative process?

Platelets are involved in the early phases of liver regeneration. Moreover, platelet transfusion and thrombocytosis were recently shown to enhance hepatocyte proliferation. However, the precise mechanisms remain elusive. This review discusses the latest updates regarding the mechanisms by which platelets stimulate liver regeneration, focusing on their interactions with liver sinusoidal endothelial cells and on their fate within the liver. Following liver injury, platelets are recruited to and trapped within the liver, where they adhere to the endothelium. Subsequent platelet activation results in the release of platelet granules, which stimulate hepatocyte proliferation through activation of the Akt and ERK1/2 signalling pathways. Platelets activate liver sinusoidal endothelial cells, leading to the secretion of growth factors, such as interleukin-6. Finally, liver sinusoidal cells and hepatocytes can also internalize platelets, but the effects of this alternate process on liver regeneration remain to be explored. A better understanding of the mechanisms by which platelets stimulate liver regeneration could lead to improvement in post-operative organ function and allow hepatectomies of a greater extent to be performed.

Immediate Postoperative Low Platelet Counts After Living Donor Liver Transplantation Predict Early Allograft Dysfunction

To investigate whether the platelets can improve liver function by mediating liver regeneration. Using a retrospective cohort with 234 consecutive adult-to-adult living donor liver transplantation recipients, we have discussed the relationship between immediate postoperative platelet count and outcome. Patients have been stratified into Low Platelet Group (106 patients) with platelet ≤68 × 10/L and High Platelet Group (128 patients) with platelet >68 × 10/L.Low Platelet Group has a higher rate of preoperative thrombocytopenia (90.6% vs. 32.8%, P<0.001), higher model for end-stage liver disease score (15 vs. 11, P<0.001), cirrhosis (86.8% vs. 76.6%, P=0.046), hepatorenal syndrome (18.2% vs. 4.0%, P=0.005) and fulminant hepatic failure (26.4% vs. 7.8%, P<0.001). The packed red blood cells transfusion (7.5 vs. 5, P = 0.023) and plasma transfusion (1275 mL vs. 800 mL, P=0.001) are more in patients with low platelet count. Low Platelet Group has a higher early allograft dysfunction (EAD) (22.6% vs. 7.0%, P=0.001) and severe complications (22.6% vs. 10.9%, P = 0.016). The 90-day mortality between the 2 groups is similar. The multivariate analysis has found that postoperative platelet ≤68 × 10/L is an independent risk factor for EAD.Platelet maybe influences the functional status of the liver by promoting graft regeneration after liver transplantation.

Low immediate postoperative platelet count is associated with hepatic insufficiency after hepatectomy

AIM: To investigate the relationship between low immediate postoperative platelet count and perioperative outcome after liver resection in patients with hepatocellular carcinoma (HCC).

METHODS: In a cohort of 565 consecutive hepatitis B-related HCC patients who underwent major liver resection, the characteristics and clinical outcomes after liver resection were compared between patients with immediate postoperative platelet count < 100 × 10⁹/L and patients with platelet count ≥ 100 × 10⁹/L. Risk factors for postoperative hepatic insufficiency were evaluated by multivariate analysis.

RESULTS: Patients with a low immediate postoperative platelet count (< 100 × 10⁹/L) had more grade III-V complications (20.5% vs 12.4%, P = 0.016), and higher rates of postoperative liver failure (6.8% vs 2.6%, P = 0.02), hepatic insufficiency (31.5% vs 21.2%, P < 0.001) and mortality (6.8% vs 0.5%, P < 0.001), compared to patients with a platelet count ≥ 100 × 10⁹/L. The alanine aminotransferase levels on postoperative days 3 and 5, and bilirubin on postoperative days 1, 3 and 5 were higher in patients with immediate postoperative low platelet count. Multivariate analysis revealed that immediate postoperative low platelet count, rather than preoperative low platelet count, was a significant independent risk factor for hepatic insufficiency.

CONCLUSION: A low immediate postoperative platelet count is an independent risk factor for hepatic insufficiency. Platelets can mediate liver regeneration in the cirrhotic liver.

Low platelet counts after liver transplantation predict early posttransplant survival: the 60-5 criterion

Platelets play a critical role in liver injury and regeneration. Thrombocytopenia is associated with increases in postoperative complications after partial hepatectomy, but it is unknown whether platelet counts could also predict outcomes after transplantation, a procedure that is often performed in thrombocytopenic patients. Therefore, the aim of this study was to evaluate whether platelet counts could be indicators of short- and long-term outcomes after liver transplantation (LT). Two hundred fifty-seven consecutive LT recipients (January 2003-December 2011) from our prospective database were analyzed. Preoperative and daily postoperative platelet counts were recorded until postoperative day 7 (POD7). Univariate and multivariate analyses were performed to assess whether low perioperative platelet counts were a risk factor for postoperative complications and graft and patient survival. The median pretransplant platelet count was 88 × 10(9) /L [interquartile range (IQR) = 58-127 × 10(9) /L]. The lowest platelet counts occurred on POD3: the median was 56 × 10(9) /L (IQR = 41-86 × 10(9) /L). Patients with low platelet counts on POD5 had higher rates of severe (grade IIIb/IV) complications [39% versus 29%, odds ratio (OR) = 1.09 (95% CI = 1.1-3.3), P = 0.02] and 90-day mortality [16% versus 8%, OR = 2.25 (95% CI = 1.0-5.0), P = 0.05]. In the multivariate analysis, POD5 platelet counts < 60 × 10(9) /L were identified as an independent risk factor for grade IIIb/IV complications [OR = 1.96 (95% CI = 1.07-3.56), P = 0.03)], graft survival [hazard ratio (HR) = 2.0 (95% CI = 1.1-3.6), P = 0.03)], and patient survival [HR = 2.2 (95% CI = 1.1-4.6), P = 0.03)]. The predictive value of platelet counts for graft and patient survival was lost in patients who survived 90 days. In conclusion, after LT, platelet counts < 60 × 10(9) /L on POD5 (the 60-5 criterion) are an independent factor associated with severe complications and early graft and patient survival. These findings may help us to develop protective strategies or specific interventions for high-risk patients.

Therapeutic rather than prophylactic platelet transfusion policy for severe thrombocytopenia during liver transplantation

Platelet transfusion (PTx) has been identified as an important risk factor for morbidity and mortality after liver transplantation (LTx). Our aim was to evaluate the safety of therapeutic rather than prophylactic PTx policy in severe thrombocytopenic patients undergoing LTx. Recipients of LTx were divided into two groups: group I (GI) (n = 76) platelet count (PC) ≥ 50 × 10(9)/l and group II (GII) PC < 50 × 109/l (n = 76). Platelets were transfused following a thromboelastometry protocol and clinical signs of diffuse bleeding. Both groups were compared regarding hemoglobin (Hb), international normalized ratio (INR), fibrinogen level, blood loss (BL), blood products required, percentage of bloodless surgery, duration of mechanical ventilation, ICU stay, and vascular complications. Each group was further subdivided according to PTx into (GI NPTx and GII NPTx) with no platelet transfusion (NPTx) and (GI PTx and GII PTx) received PTx. These subgroups were further compared for some variables. Base line Hb was significantly higher while INR was significantly lower in GI.75% avoided PTx in GII. Comparisons of BL, packed red blood cells (PRBCs), and cryoprecipitate transfusion were insignificant. Fresh frozen plasma (FFP) transfusion was higher and the percentage of bloodless surgery was lower in GII. In GII, PC increased after start of surgery. Two cases of hepatic artery thrombosis in GI and one in GII were recorded. Recovery of platelets was quicker, and duration of mechanical ventilation and ICU stay was shorter in NPTx patients regardless the base line PC. Cut-off values of PC 30 × 10(9)/l (with sensitivity 73.7% and specificity 78.8%, p < 0.01), BL of 3750 ml in GI (sensitivity of 75% and specificity of 69%, p < 0.01) and of 3250 ml in GII (sensitivity of 84.2% and specificity of 87.7% (p < 0.01)) could indicate the need of PTx. With therapeutic approach, 75% of patients in GII could avoid unnecessary PTx with its hazards without excessive bleeding. PC in GII increased intraoperatively, PTx may lead to delayed recovery of platelets, increased duration of mechanical ventilation and ICU stay. The given cut-off values may help to guide PTx.

Novel therapy for liver regeneration by increasing the number of platelets

Platelets are the smallest blood constitutes which contain three types of granules; alpha granules, dense granules, and lysosomal granules. Each granule contains various biophysiological substances such as growth factors, cytokines, etc. Platelets have been conventionally viewed as a trigger of inflammatory responses and injury in the liver. Some studies revealed that platelets have strong effects on promoting liver regeneration. This review presents experimental evidence of platelets in accelerating liver regeneration and describes three different mechanisms involved; (1) the direct effect on hepatocytes, where platelets translocate to the space of Disse and release growth factors through direct contact with hepatocytes, (2) the cooperative effect with liver sinusoidal endothelial cells, where the dense concentration of sphingosine-1-phosphate in platelets induces excretion of interleukin-6 from liver sinusoidal endothelial cells, and (3) the collaborative effect with Kupffer cells, where the functions of Kupffer cells are enhanced by platelets.

Human platelets inhibit liver fibrosis in severe combined immunodeficiency mice

AIM

To investigate the role of human platelets in liver fibrosis.

METHODS

Severe combined immunodeficiency (SCID) mice were administered CCl4 and either phosphate-buffered saline (PBS group) or human platelet transfusions (hPLT group). Concentrations of hepatocyte growth factor (HGF), matrix metallopeptidases (MMP)-9, and transforming growth factor-β (TGF-β) in the liver tissue were compared between the PBS and the hPLT groups by enzyme-linked immunosorbent assay (ELISA) and Western blotting. The effects of a human platelet transfusion on liver fibrosis included the fibrotic area, hydroxyproline content, and α-smooth muscle actin (α-SMA) expression, which were evaluated by picrosirius red staining, ELISA, and immunohistochemical staining using an anti-mouse α-SMA antibody, respectively. Phosphorylations of mesenchymal-epithelial transition factor (Met) and SMAD3, downstream signals of HGF and TGF-β, were compared between the two groups by Western blotting and were quantified using densitometry. Hepatocyte apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling. Furthermore, the accumulation of human platelets in the liver 2 h after platelet transfusion was compared between normal and fibrotic livers by immunohistochemical staining using an anti-human CD41 antibody.

RESULTS

The fibrotic area and hydroxyproline content in the liver were both significantly lower in the hPLT group when compared to the PBS group (fibrotic area, 1.7% ± 0.6% vs 2.5% ± 0.6%, P = 0.03; hydroxyproline content, 121 ± 26 ng/g liver vs 156 ± 47 ng/g liver, P = 0.04). There was less α-smooth muscle actin staining in the hPLT group than in the PBS group (0.5% ± 0.1% vs 0.8% ± 0.3%, P = 0.02). Hepatic expression levels of mouse HGF and MMP-9 were significantly higher in the hPLT group than in the PBS group (HGF, 109 ± 13 ng/g liver vs 88 ± 22 ng/g liver, P = 0.03; MMP-9, 113% ± 7%/GAPDH vs 92% ± 11%/GAPDH, P = 0.04). In contrast, the concentration of mouse TGF-β in the liver tissue was significantly lower in the hPLT group than in the PBS group (22 ± 5 ng/g liver vs 39 ± 6 ng/g liver, P = 0.02). Phosphorylation of Met was more prevalent in the hPLT group than in the PBS group (37% ± 4%/GAPDH vs 20% ± 8%/GAPDH, P = 0.03). Phosphorylation of SMAD3 was weaker in the hPLT group than in the PBS group (60% ± 12%/GAPDH vs 84% ± 12%/GAPDH, P = 0.1), although this difference was not significant. Furthermore, a lower rate of hepatocyte apoptosis was observed in the hPLT group than in the PBS group (5.9% ± 1.7% vs 2.9% ± 2.1%, P = 0.02). Significant human platelet accumulation was observed in the fibrotic liver tissues, whereas few platelets accumulated in the normal liver.

CONCLUSION

Human platelets inhibit liver fibrosis in SCID mice. Increased concentration of HGF in the liver suppresses hepatic stellate cell activation, induces MMPs, and inhibits hepatocyte apoptosis.

Human platelets promote liver regeneration with Kupffer cells in SCID mice

BACKGROUND

Platelets contain several growth factors, including vascular endothelial growth factor (VEGF) and insulin-like growth factor. We examined the role of human platelets in liver regeneration with a focus on Kupffer cells (KCs).

MATERIALS AND METHODS

Severe combined immunodeficiency mice were subjected to 70% hepatectomy and phosphate-buffered saline administration (PBS); 70% hepatectomy and human platelet transfusion (hPLT); 70% hepatectomy, KC depletion, and PBS administration (KD + PBS); 70% hepatectomy, KC depletion, and human platelet transfusion (KD + hPLT); or a sham operation and human platelet transfusion (sham). The groups were evaluated for liver regeneration, accumulation and activation of human platelets in the liver, and/or co-localization of platelets and KCs.

RESULTS

The liver-to-body weight ratio was significantly higher 48 h post-transfusion in the hPLT group compared with the PBS, KD + PBS, and KD + hPLT groups. Human VEGF concentrations were higher in liver tissues from the hPLT group, whereas VEGF was not detected in the other groups. Hepatic levels of KC-derived cytokines were elevated in the hPLT group compared with the PBS group. Molecules in signaling cascades downstream of these cytokines were phosphorylated earlier and more robustly in the hPLT group than in the PBS group. Activated human platelets accumulated in livers in the hPLT group, whereas fewer platelets accumulated and many were not activated in the sham and KD + hPLT groups. In the hPLT group, most human platelets were attached to KCs.

CONCLUSIONS

Human platelet transfusion promoted liver regeneration in severe combined immunodeficiency mice. Together, human platelets and KCs resulted in growth factor release and enhanced liver regeneration.

Splenectomy affects the balance between hepatic growth factor and transforming growth factor-β and its effect on liver regeneration is dependent on the amount of liver resection in rats

Purpose

Small-for-size syndrome (SFSS) is a major problem in liver surgery, and splenectomy has been used to prevent SFSS. However, it is unknown whether splenectomy has the same effect on liver regeneration in both standard and marginal hepatectomy. The aim of this study is to see a difference in effect of splenectomy on liver regeneration according to the amount of liver resection.

Methods

Thirty male Sprague-Dawley rats (220 to 260 g) were divided into the following five groups: control (n = 6), 70% hepatectomy (n = 6), 70% hepatectomy with splenectomy (n = 6), 90% hepatectomy (n = 6), and 90% hepatectomy with splenectomy (n = 6). The animals were euthanized 24 hours after surgery and liver specimens were obtained. To assess liver regeneration, we performed immunohistochemistry of liver tissue using 5-bromo-2-deoxyuridine (BrdU) labeling and Western blot analysis of hepatic growth factor (HGF) and transforming growth factor-β (TGF-β) in the liver tissue.

Results

The splenectomized subgroup had a higher BrdU-positive cell count in the 90% hepatectomy group, but not in the 70% hepatectomy group (P < 0.001). Splenectomy significantly decreased TGF-β expression (P = 0.005) and increased the HGF to TGF-β ratio (P = 0.002) in the 90% hepatectomy group, but not in the 70% hepatectomy group.

Conclusion

The positive effect of splenectomy on liver regeneration was greater in the group with the larger liver resection. This phenomenon may be related to the relative balance between HGF and TGF-β in the liver.

Risk factors and outcomes of massive red blood cell transfusion following living donor liver transplantation

OBJECTIVES

To identify the factors influencing blood loss and secondary blood transfusion and to investigate the outcomes of patients who underwent a massive blood transfusion (MBT) following living donor liver transplantation (LDLT).

METHODS

Patients who underwent primary adult-to-adult right hepatic lobe LDLT were included in the study, and were divided into the MBT group [≥6 red blood cell (RBC) units in 24 h] and the non-massive blood transfusion (NMBT) group (<6 RBC units in 24 h). All potential risk factors, length of intensive care unit (ICU) stay and long-term survival rate of the patients in the two groups were analyzed.

RESULTS

The data of 181 eligible patients were retrospectively analyzed. A decreased long-term survival rate, a higher incidence of postoperative infection and prolonged ICU stay were observed in the MBT group. No significant difference was observed in survival rate between patients having platelet transfusion>2 units and ≤2 units. Hemoglobin<100 g/L, platelet counts<70×10(9)/L, fibrinogen level<1.5 g/L and history of upper abdominal surgery were found to be independent risk factors.

CONCLUSIONS

Blood transfusion during LDLT can be predicted using preoperative variables. Massive RBC transfusion may lead to poor long-term survival, higher postoperative infection rate and prolonged ICU stay. Platelet transfusion may not be a risk factor for long-term survival.

Influence of platelet lysate on the recovery and metabolic performance of cryopreserved human hepatocytes upon thawing

BACKGROUND

Storage of human hepatocytes is essential for their use in research and liver cell transplantation. However, cryopreservation and thawing (C/T) procedures have detrimental effects on the viability and functionality compared with fresh cells. The aim of this study was to upgrade the standard C/T methodology to obtain better quality hepatocytes for cell transplantation to improve the overall clinical outcome.

METHODS

Human hepatocytes isolated from donor livers were cryopreserved in University of Wisconsin solution with 10% dimethyl sulfoxide (standard medium), which was supplemented with 10% or 20% of platelet lysate. Thawing media supplemented with up to 30 mM glucose was also investigated. The effects on cell viability, adhesion proteins (e-cadherin, β-catenin, and β1-integrin) expression, attachment efficiency, apoptotic indicators, Akt signaling, ATP levels, and cytochrome P450 activities have been evaluated.

RESULTS

The results indicate that the hepatocytes cryopreserved in a medium supplemented with platelet lysate show better recovery than those preserved in the standard medium: higher expression of adhesion molecules, higher attachment efficiency and cell survival; decreased number of apoptotic nuclei and caspase-3 activation; maintenance of ATP levels; and drug biotransformation capability close to those in fresh hepatocytes. Supplementation of thawing media with glucose led to a significant decrease in caspase-3 activation and to increased adhesion molecules preservation and Akt signal transduction after C/T. Minor nonsignificant changes in cell viability and attachment efficiency were observed.

CONCLUSIONS

These promising results could lead to a new cryopreservation procedure to improve human hepatocyte cryopreservation outcome.

Intensive care management of liver transplanted patients

Advances in pre-transplant treatment of cirrhosis-related organ dysfunction, intraoperative patient management, and improvements in the treatment of rejection and infections have made human liver transplantation an effective and valuable option for patients with end stage liver disease. However, many important factors, related both to an increasing "marginality" of the implanted graft and unexpected perioperative complications still make immediate post-operative care challenging and the early outcome unpredictable. In recent years sicker patients with multiple comorbidities and organ dysfunction have been undergoing Liver transplantation; appropriate critical care management is required to support prompt graft recovery and prevent systemic complications. Early post-operative management is highly demanding as significant changes may occur in both the allograft and the "distant" organs. A functioning transplanted liver is almost always associated with organ system recovery, resulting in a new life for the patient. However, in the unfortunate event of graft dysfunction, the unavoidable development of multi-organ failure will require an enhanced level of critical care support and a prolonged ICU stay. Strict monitoring and sustainment of cardiorespiratory function, frequent assessment of graft performance, timely recognition of unexpected complications and the institution of prophylactic measures to prevent extrahepatic organ system dysfunction are mandatory in the immediate post-operative period. A reduced rate of complications and satisfactory outcomes have been obtained from multidisciplinary, collaborative efforts, skillful vigilance, and a thorough knowledge of pathophysiologic characteristics of the transplanted liver.

Progressive postinjury thrombocytosis is associated with thromboembolic complications

BACKGROUND

Our previous investigation demonstrated that despite routine chemoprophylaxis, thrombelastography, which is a comprehensive test measuring the viscoelastic properties of blood, identified a hypercoagulable state in a cohort of critically ill surgical patients that was associated with thromboemobolic events. Furthermore, because thrombelastography allows for the comprehensive assessment of coagulation status, this work suggested that platelet hyperactivity is a component of the hypercoagulable state. We hypothesized that progressive postinjury thrombocytosis contributes to a hypercoagulable state that is associated with thrombelastography.

METHODS

One thousand four hundred and forty severely injured patients surviving >48 h were entered into a database prospectively over 12 years. The variables that were evaluated in associated with thrombocytosis (platelet count >450,000) included age, Injury Severity Score, packed red blood cell transfusions in 12 h, and thromboemobolic complications (TE) (deep venous thrombosis, pulmonary embolus, mesenteric thrombosis, stroke, and arterial thrombosis). The time frame for the development of thrombocytosis was assessed at greater or less than 7 days postinjury. Logistic regression was used to identify the independent variables predictive of thrombocytosis and to adjust the association of thrombocytosis with TE for other risk factors. C-statistic was used to assess the discriminative power of thrombocytosis for prediction of TE.

RESULTS

The mean age was 37.4 ± 0.4 years. The Injury Severity Score was 29.3 ± 0.3, and mean red blood cell transfusions in 12 h was 4.4 ± 0.2 units. Injury via blunt force occurred in 76% of patients, and 72% of patients were male. Thrombocytosis was identified in 447 (31%) patients and was noted almost exclusively >7 days postinjury (98%). TE developed in 35 (8%) of the 447 patients with thrombocytosis, compared with 45 (4.5%) of the remaining 993 patients who did not develop thrombocytosis. Persistent thrombocytosis >7 days was associated with TE (P > .0001). Logistic regression analysis indicated that when adjusted for intensive care unit duration of stay, transfusions, age, and Injury Severity Score, patients with sustained thrombocytosis more than 3 days were noted to have a 1.4 × increased risk of TE (odds ratio, 1.12; 95% confidence interval, 1.04-1.2; P = .002; C-statistic = 0.82).

CONCLUSION

Persistent thrombocytosis in critically injured patients receiving routine chemoprophylaxis is associated with thrombotic complications. Subsequent investigation is warranted to differentiate enzymatic from platelet hypercoagulability to ascertain the role of antiplatelet therapy for prevention of TE.