Intragraft gene expression profiles by cDNA microarray in small-for-size liver grafts

Graft inflow modulation in recipients with portal hypertension

The extended application of living donor liver transplantation (LDLT) has revealed the problem of graft size mismatching, potentially leading to the "small-for-size syndrome" (SFSS). SFSS is a rare dysfunction that may affect a partial liver graft, characterized by coagulopathy, cholestasis, ascites, and encephalopathy. A key role in the physiopathology of SFSS is played by portal hypertension (PHT) to which a small allograft is submitted after reperfusion, resulting in sinusoidal congestion and hemorrhage. Portal overflow injures the liver directly through nutrient excess, endothelial activation, and sinusoidal shear stress, and indirectly through arterial vasoconstriction. Thus, SFSS prevention relies not only on increasing graft volume (implementing the use of larger grafts or auxiliary/dual liver transplantation), but also on the control of the increased portal vein pressure (PVP) and portal vein flow (PVF). To this aim, surgical graft inflow modulation techniques (GIM) such as splenic artery ligation (SAL), splenectomy and hemiportocaval shunts, can be considered when an imbalance between the PVP and the hepatic arterial flow (HAF) is acknowledged. However, such strategies have their pros and cons, and a deep knowledge of the indications and complications is needed. Furthermore, pharmacological modulation has also been proposed. This review is aimed to update available literature on the current knowledge and strategies for modulating portal vein flow in LDLT.

Liver transplantation for hepatocellular carcinoma: Historical evolution of transplantation criteria

Liver transplantation (LT) for hepatocellular carcinoma is still a hot topic, and the main factor that is associated with the success of treatment is to determine the patients who will benefit from LT. Milan criteria have been defined 25 years ago and still is being used for patient selection for LT. However, in living donor LT, the Milan criteria is being extended. Current criteria for patient selection do not only consider morphologic characteristics such as tumor size and number of tumor nodules but also biologic markers that show tumor aggressiveness is also being considered. In the present review article, we have summarized all the criteria and scoring systems regarding LT for hepatocellular carcinoma. All criteria have 5-year overall survival rates that were comparable to the Milan Criteria and ranged between 60%-85%. On the other hand, it was seen that the recurrence rates had increased as the Milan criteria were exceeded; the 5-year recurrence rates ranged between 4.9% to 39.9%. Treatment of hepatocellular carcinoma needs a multidisciplinary approach. Ideal selection criteria are yet to be discovered. The same is true for treatment modalities. The goal will be achieved by a harmonic interplay between basic science researchers and clinicians.

Small-For-Size Syndrome and Graft Inflow Modulation Techniques in Liver Transplantation

BACKGROUND

Partial liver transplantation has recently been proposed to alleviate organ shortages. However, transplantation of a small-for-size graft is associated with an increased risk of posttransplant hepatic dysfunction, commonly referred to as small-for-size syndrome (SFSS). This review describes the etiology, pathological features, clinical manifestations, and diagnostic criteria of SFSS. Moreover, we summarize strategies to improve graft function, focusing on graft inflow modulation techniques. Finally, unmet needs and future perspectives are discussed.

SUMMARY

In fact, posttransplant SFSS can be attributed to various factors such as preoperative status of the recipients, surgical techniques, donor age, and graft quality, except for graft size. With targeted improvement measures, satisfactory clinical outcomes can be achieved in recipients at increased risk of SFSS. Given the critical role of relative portal hyperperfusion in the pathogenesis of SFSS, various pharmacological and surgical treatments have been established to reduce or partially divert excessive portal inflow, and recipients will benefit from individualized therapeutic regimens after careful evaluation of benefits against potential risks. However, there remain unmet needs for further research into different aspects of SFSS to better understand the correlation between portal hemodynamics and patient outcomes.

KEY MESSAGES

Contemporary transplant surgeons should consider various donor and recipient factors and develop case-specific prevention and treatment strategies to improve graft and recipient survival rates.

Cytomegalovirus Latency Exacerbated small-for-size Liver Graft Injury through Activation of CCL19/CCR7 in Hepatic Stellate Cells

BACKGROUND

The interplay between cytomegalovirus (CMV) latency and graft malfunction after living donor liver transplantation (LDLT) remains poorly defined due to the complexity of clinical confounding factors. Here, we aimed to investigate the effects of CMV latency on small-for-size graft injury and to get further insight on the pathogenic role of hepatic stellate cells (HSCs) in this process.

METHODS

Rat orthotopic liver transplantation with small-for-size grafts was performed in a CMV latent model developed in immunocompetent Sprague Dawley (SD) rats using Priscott strain. Post-transplant graft injury including hepatocyte damage, stellate cell activation and fibrogenesis were evaluated. Differential gene expression of HSCs in response to CMV latency was screened by cDNA microarray. Clinical validation was further conducted in human biopsies.

RESULTS

CMV latency aggravated hepatocyte apoptosis/necrosis in the early phase, enhanced HSC expansion and graft fibrosis during the middle-late phase in small-for-size liver grafts of the rat model. cDNA microarray mining revealed CCL19/CCR7 as one of the most noteworthy pathways bridging HSC activation and liver graft injury in the presence of CMV latency. Together with CCL19 upregulation, coherent overexpression of CCR7 in accumulated HSCs was confirmed in both rat and human CMV latent recipients. Moreover, addition of CCL19 in vitro promoted HSC migration by increasing the level of matrix metalloproteinase-2 (MMP2).

CONCLUSION

Our data demonstrated that CMV latency aggravated early/late phase liver graft damage and fibrogenesis via CCL19/CCR7/HSCs axis. Blockade of CMV latency-related stellate cell activation may shed light on the strategy of graft protection clinically.

Small-for-size syndrome in liver transplantation: Definition, pathophysiology and management

BACKGROUND

Since the first success in an adult patient, living donor liver transplantation (LDLT) has become an universally used procedure. Small-for-size syndrome (SFSS) is a well-known complication after partial LT, especially in cases of adult-to-adult LDLT. The definition of SFSS slightly varies among transplant physicians. The use of a partial liver graft has risks of SFSS development. Persistent portal vein (PV) hypertension and PV hyper-perfusion after LT were identified as the main factors. Hence, various approaches were explored to modulate PV flow and decrease PV pressure in order to alleviate this syndrome. Herein, the definition, clinical symptoms, pathophysiology, basic research, as well as preventive and treatment strategies for SFSS are reviewed based on an extensive review of the literature and on our own experiences.

DATA SOURCES

The articles were collected through PubMed using search terms "liver transplantation", "living donor liver transplantation", "living liver donation", "partial graft", "small-for-size graft", "small-for-size syndrome", "graft volume", "remnant liver", "standard liver volume", "graft to recipient body weight ratio", "sarcopenia", "porcine", "swine", and "rat". English publications published before March 31, 2020 were included in this review.

RESULTS

Many transplant surgeons performed PV flow modulation, including portocaval shunt, splenic artery ligation and splenectomy. With these techniques, patient outcome has been improved even when using a "small" graft. Other factors, such as preoperative recipients' nutritional and skeletal muscle status, graft congestion, and donor factors, were also identified as risk factors which all have been addressed using various strategies.

CONCLUSIONS

The surgical approach controlling PV flow and pressure could help to prevent SFSS especially in severely ill recipients. In the absence of efficacious medications to resolve SFSS, conservative treatments, including aggressive fluid balance correction for massive ascites, anti-microbiological therapy to prevent or control sepsis and intensive nutritional therapy, are all required if SFSS could not be prevented.

Repressor and activator protein accelerates hepatic ischemia reperfusion injury by promoting neutrophil inflammatory response

Repressor and activator protein (Rap1) directly regulates nuclear factor-κB (NF-κB) dependent signaling, which contributes to hepatic IRI. We here intended to investigate the effect of Rap1 in hepatic ischemia reperfusion injury (IRI) and to explore the underlying mechanisms. The association of Rap1 expression with hepatic inflammatory response were investigated in both human and rat liver transplantation. The effect of Rap1 in hepatic IRI was studied in Rap1 knockout mice IRI model in vivo and primary cells in vitro. Our results showed that over expression of Rap1 was associated with severe liver graft inflammatory response, especially in living donor liver transplantation. The results were also validated in rat liver transplantation model. In mice hepatic IRI model, the knockout of Rap1 reduced hepatic damage and hepatic inflammatory response. In primary cells, the knockout of Rap1 suppressed neutrophils migration activity and adhesion in response to liver sinusoidal endothelial cells through down-regulating neutrophils F-Actin expression and CXCL2/CXCR2 pathway. In addition, the knockout of Rap1 also decreased production of pro-inflammatory cytokines/chemokines in primary neutrophils and neutrophils-induced hepatocyte damage. In conclusion, Rap1 may induce hepatic IRI through promoting neutrophils inflammatory response. Rap1 may be the potential therapeutic target of attenuating hepatic IRI.

Small for Size and Flow (SFSF) syndrome: An alternative description for posthepatectomy liver failure

Small for Size Syndrome (SFSS) syndrome is a recognizable clinical syndrome occurring in the presence of a reduced mass of liver, which is insufficient to maintain normal liver function. A definition has yet to be fully clarified, but it is a common clinical syndrome following partial liver transplantation and extended hepatectomy, which is characterized by postoperative liver dysfunction with prolonged cholestasis and coagulopathy, portal hypertension, and ascites. So far, this syndrome has been discussed with focus on the remnant size of the liver after partial liver transplantation or extended hepatectomy. However, the current viewpoints believe that the excessive flow of portal vein for the volume of the liver parenchyma leads to over-pressure, sinusoidal endothelial damages and haemorrhage. The new hypothesis declares that in both extended hepatectomy and partial liver transplantation, progression of Small for Size Syndrome is not determined only by the "size" of the liver graft or remnant, but by the hemodynamic parameters of the hepatic circulation, especially portal vein flow. Therefore, we suggest the term "Small for Size and Flow (SFSF)" for this syndrome. We believe that it is important for liver surgeons to know the pathogenesis and manifestation of this syndrome to react early enough preventing non-reversible tissue damages.

Small-for-size syndrome in living-donor liver transplantation using a left lobe graft

In living-donor liver transplantation with a left lobe graft, which can reduce the burden on the donor compared to right lobe graft, the main problem is small-for-size (SFS) syndrome. SFS syndrome is a multifactorial disease that includes aspects related to the graft size, graft quality, recipient factors and even technical issues. The main pathophysiology of SFS syndrome is the sinusoidal microcirculatory disturbance induced by shear stress, which is caused by excessive portal inflow into the smaller graft. The donor age, the presence of steatosis of the graft and a poor recipient status are all risk factors for SFS syndrome. To resolve SFS syndrome, portal inflow modulation, splenectomy, splenic artery modulation and outflow modulation have been developed. It is important to establish strict criteria for managing SFS syndrome. Using pharmacological interventions and/or therapeutic approaches that promote liver regeneration could increase the adequate outcomes in SFS liver transplantation. Left lobe liver transplantation could be adopted in Western countries to help resolve the organ shortage.

Scoring selection criteria including total tumour volume and pretransplant percentage of lymphocytes to predict recurrence of hepatocellular carcinoma after liver transplantation

AIM

The selection criteria for patients with hepatocellular carcinoma (HCC) to undergo liver transplantation should accurately predict posttransplant recurrence while not denying potential beneficiaries. In the present study, we attempted to identify risk factors associated with posttransplant recurrence and to expand the selection criteria.

PATIENTS AND METHODS

Adult patients with HCC who underwent liver transplantation between November 2004 and September 2012 at our centre were recruited into the current study (N = 241). Clinical and pathological data were retrospectively reviewed. Patients who died during the perioperative period or died of non-recurrence causes were excluded from this study (N = 25). All potential risk factors were analysed using uni- and multi-variate analyses.

RESULTS

Sixty-one recipients of 216 qualified patients suffered from recurrence. Similar recurrence-free and long-term survival rates were observed between living donor liver transplant recipients (N = 60) and deceased donor liver transplant recipients (N = 156). Total tumour volume (TTV) and preoperative percentage of lymphocytes (L%) were two independent risk factors in the multivariate analysis. We propose a prognostic score model based on these two risk factors. Patients within our criteria achieved a similar recurrence-free survival to patients within the Milan criteria. Seventy-one patients who were beyond the Milan criteria but within our criteria also had comparable survival to patients within the Milan criteria.

CONCLUSIONS

TTV and L% are two risk factors that contribute to posttransplant recurrence. Selection criteria based on these two factors, which are proposed by our study, expanded the Milan criteria without increasing the risk of posttransplant recurrence.

Living donor liver transplantation versus deceased donor liver transplantation for hepatocellular carcinoma: a meta-analysis

Because of the severe organ shortage, living donor liver transplantation (LDLT) offers a timely alternative to deceased donor liver transplantation (DDLT) for patients with hepatocellular carcinoma (HCC). However, the higher recurrence rate of HCC after LDLT and the indication criteria remain controversial. By conducting a quantitative meta-analysis, we sought to compare the survival outcomes and recurrence rates with LDLT and DDLT for patients with HCC. Comparative studies of LDLT and DDLT for HCC, which were identified by a comprehensive literature search, were included in this study. The evaluated outcomes included patient survival, recurrence-free survival (RFS), and recurrence rates at defined time points. Seven studies with a total of 1310 participants were included in this study. For LDLT and DDLT recipients, we found comparable patient survival rates [1 year, odds ratio (OR) = 1.03, 95% confidence interval (CI) = 0.62-1.73; 3 years, OR = 1.07, 95% CI = 0.77-1.48; and 5 years, OR = 0.64, 95% CI = 0.33-1.24] and RFS rates (1 year, OR = 0.86, 95% CI = 0.54-1.38; 3 years, OR = 1.04, 95% CI = 0.69-1.58; and 5 years, OR = 1.11, 95% CI = 0.70-1.77). Moreover, we found no significant differences in the 1-, 3-, or 5-year recurrence rates between LDLT and DDLT recipients (1 year, OR = 1.55, 95% CI = 0.36-6.58; 3 years, OR = 2.57, 95% CI = 0.53-12.41; and 5 years, OR = 1.21, 95% CI = 0.44-3.32). A subgroup analysis revealed similar outcomes for patients with HCC meeting the Milan criteria. These findings demonstrate that for HCC patients (especially those within the Milan criteria), LDLT represents an acceptable option that does not compromise patient survival or increase HCC recurrence in comparison with DDLT.

Implanted adipose-derived stem cells attenuate small-for-size liver graft injury by secretion of VEGF in rats

Graft injury after small-for-size liver transplantation impairs graft function and threatens the survival of the recipients. The use of adipose-derived stem cells (ADSCs) for liver injury protection and repair is promising. Our aim was to investigate the role of vascular endothelial growth factor (VEGF) secreted by ADSCs in the treatment of small-for-size liver graft injury. Studies were performed using ADSCs with VEGF secretion blocked by RNA interference. In vitro, ADSCs prevented apoptosis of freshly isolated liver sinusoidal endothelial cells (LSECs) by secretion of VEGF. Syngeneic 35% orthotopic liver transplantation followed by implantation of syngeneic ADSCs through the portal vein system was performed using Wistar rats. We found VEGF secreted by implanted ADSCs improved graft microcirculatory disturbances, serum liver function parameters and survival. The improved microcirculatory status was also reflected by reduced hepatocellular damage, especially LSEC apoptosis and improved liver regeneration. These effects were accompanied by decreased expression of endothelin receptor type A, increased Bcl-2/Bax ratio, decreased expression of Bad and elevated proportion of phosphorylated Bad. In conclusion, implanted syngeneic ADSCs attenuated small-for-size liver graft injuries and subsequently enhanced liver regeneration in a rat 35% liver transplantation model. The VEGF secreted by implanted ADSCs played a crucial role in this process.

Antifibrotic effect of hepatocyte growth factor-expressing mesenchymal stem cells in small-for-size liver transplant rats

Ischemia-reperfusion and chronic injuries associated with small-for-size liver transplantation (SFSLT) impair the regeneration of liver graft and induce liver fibrosis. Mesenchymal stem cells (MSCs) can prevent the development of liver fibrosis, and hepatocyte growth factor (HGF) can also attenuate liver cirrhosis. Our previous studies have demonstrated that higher occurrence of liver fibrosis existed in rats post-SFSLT, and that implantation of HGF/MSCs, the human HGF (hHGF)-expressing MSCs, can improve liver regeneration, reduce mortality of rats, as well as have the potent antifibrotic effect in this SFSLT model. In the present study, we implanted HGF/MSCs into liver grafts via the portal vein and investigated their role in antifibrosis effect, using a 30% SFSLT rat model. Fibrosis indexes, including laminin (LN), hyaluronic acid (HA) levels in serum and hydroxyproline (Hyp) content in the liver grafts, the expression of transforming growth factor-beta1 (TGF-beta(1)), rat HGF (rHGF), alpha-smooth muscle actin (alpha-SMA) in hepatic stellate cells (HSCs), alanine aminotransferase (ALT), total bilirubin (BIL), and albumin (ALB) levels in serum, in rats in different treatment groups were assessed at different time points. We found that HGF/MSCs significantly inhibited the formation of liver fibrosis in rats undergoing SFSLT, while MSCs and HGF had synergistic effects in the process. The antifibrosis effect of HGF/MSCs may have contributed in modulating the activation and apoptosis of HSCs, elevating the rHGF expression level, and decreasing the TGF-beta(1) secretion of activated HSCs. These studies suggest that HGF/MSCs may be a novel therapeutic option for the treatment of liver fibrosis after SFSLT.

Comparative proteome profile during the early period of small-for-size liver transplantation in rats revealed the protective role of Prdx5

BACKGROUND & AIMS

In living-donor liver transplantation (LDLT), "small-for-size graft (SFSG) syndrome" is a complex process resulting primarily from ischemia-reperfusion injury (IRI) and portal hypertension associated with size mismatch between graft and recipient. In the early period of LDLT, molecular events related to subsequent apoptosis, necrosis, proliferation and regeneration appeared in specific protein expression patterns.

METHODS

We used 2D-PAGE and MALDI-TOF/TOF technology to construct a comparative proteome profile for small-for-size liver grafts (SFSGs) during the early period of LDLT in rats (ischemia 1h, and 2, 6, 24, 48 h post-reperfusion); sham-operated liver was the control. Western blotting was used to confirm the proteomics results and immunohistochemistry was carried out to explore the cellular localization of selected proteins. We further performed cluster and bioinformatics analyses of differential proteins. Lastly, we overexpressed Prdx5 in liver grafts using an adenoviral vector to evaluate its protective role.

RESULTS

We identified 314 differential protein spots corresponding to 259 different proteins. Cluster analyses revealed six expression patterns, and bioinformatics analyses revealed that each pattern was related to many specific cell processes. We also showed that Prdx5 overexpression could attenuate injury to SFSGs and increase survival in recipients.

CONCLUSIONS

Taken together, these results reveal an important proteome profile that is functional in SFSGs during early period of LDLT, and provide a strong basis for further research.

Protective effects of early CD4(+) T cell reduction in hepatic ischemia/reperfusion injury

AIM

CD4(+) T cells contribute to disturbances of liver microcirculation after warm ischemia/reperfusion (I/R). The aim of this study was to investigate a possible protective role of FTY720 (Sphingosine-1 phosphate receptor agonist) in this setting.

MATERIAL AND METHODS

In an in vivo model (42 Wistar rats), ischemia of the left liver lobe was induced for 90 min under anesthesia with xylazine/ketanest. Sham-operated untreated ischemic and treatment group with FTY720 (1 mg/kg body weight intravenous) were investigated. The effect of FTY on I/R injury was assessed by in vivo microscopy 30-90 min after reperfusion (perfusion rate, vessel diameter, leukocyte-endothelial cell interactions, T cell infiltration), by measurement of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), reverse transcription-polymerase chain reaction (RT-PCR) of interleukin (IL)-2, IL-6, IL-10, TNF-alpha, toll-like receptor 4 (TLR-4), and by histological investigation.

RESULTS

After 30 min of reperfusion, the number of T cells in sinusoids was increased four-fold. In the FTY group, the number of T cells was reduced to an half of the number of the ischemia group. Likewise, the number of adherent leukocytes in sinusoids (150.8 +/- 10.9% of s.o.) was reduced in the treatment group (117.3 +/- 12.2%; p < 0.05 vs ischemia), leading to an improvement in perfusion rate in this group (85.0 +/- 4.6% of sham group) compared to nontreated animals (57.5 +/- 10.8%; p < 0.05). According to improved microcirculation, AST/ALT values and histological tissue damage were reduced in the therapy group. RT-PCR revealed an increased expression of IL-2, IL-6, and TLR-4 in the nontreated ischemic group. This expression was clearly reduced in the treatment group.

CONCLUSION

In conclusion, FTY720 ameliorates the microcirculatory, biochemical, and histological manifestations of hepatic I/R injury by preventing T cell infiltration. These results indicate that T cells are pivotal mediators in hepatic I/R and may have important implications early after liver transplantation and in warm ischemia.

The cytoprotective effects of addition of activated protein C into preservation solution on small-for-size grafts in rats

Small-for-size liver grafts are a serious obstacle for partial orthotopic liver transplantation. Activated protein C (APC), a potent anticoagulant serine protease, is known to have cell-protective properties due to its anti-inflammatory and antiapoptotic activities. This study was designed to examine the cytoprotective effects of a preservation solution containing APC on small-for-size liver grafts, with special attention paid to ischemia-reperfusion injury and shear stress in rats. APC exerted cytoprotective effects, as evidenced by (1) increased 7-day graft survival; (2) decreased initial portal pressure and improved hepatic microcirculation; (3) decreased levels of aminotransferase and improved histological features of hepatic ischemia-reperfusion injury; (4) suppressed infiltration of neutrophils and monocytes/macrophages; (5) reduced hepatic expression of tumor necrosis factor alpha and interleukin 6; (6) decreased serum levels of hyaluronic acid, which indicated attenuation of sinusoidal endothelial cell injury; (7) increased hepatic levels of nitric oxide via up-regulated hepatic endothelial nitric oxide synthesis expression together with down-regulated hepatic inducible nitric oxide synthase expression; (8) decreased hepatic levels of endothelin 1; and (9) reduced hepatocellular apoptosis by down-regulated caspase-8 and caspase-3 activities. These results suggest that a preservation solution containing APC is a potential novel and safe product for small-for-size liver transplantation, alleviating graft injury via anti-inflammatory and antiapoptotic effects and vasorelaxing conditions.

Adenosine restores the hepatic artery buffer response and improves survival in a porcine model of small-for-size syndrome

The aim of the study is to define the role of the HABR in the pathophysiology of the SFS liver graft and to demonstrate that restoration of hepatic artery flow (HAF) has a significant impact on outcome and improves survival. Nine pigs received partial liver allografts of 60% liver volume, Group 1; 8 animals received 20% LV grafts, Group 2; 9 animals received 20% LV grafts with adenosine infusion, Group 3. HAF and portal vein flow (PVF) were recorded at 10 min, 60 min and 90 min post reperfusion, on POD 3 and POD 7 in Group 1, and daily in Group 2 and 3 up to POD 14. Baseline HAF and PVF (ml/100 g/min) were 29 +/- 12 (mean +/- SD) and 74 +/- 8 respectively, with 28% of total liver blood flow (TLBF) from the HA and 72% from the PV. PVF peaked at 10 mins in all groups, increasing by a factor of 3.8 in the 20% group compared to an increase of 1.9 in the 60% group. By POD 7-14 PVF rates approached baseline values in all groups. The HABR was intact immediately following reperfusion in all groups with a reciprocal decrease in HAF corresponding to the peak PVF at 10 min. However in the 20% group HAF decreased to 12 +/- 8 ml/100 g/min at 90 min and remained low out to POD 7-14 despite restoration of normal PVF rates. Histopathology confirmed evidence of HA vasospasm and its consequences, cholestasis, centrilobular necrosis and biliary ischemia in Group 2. HA infusion of adenosine significantly improved HAF (p < .0001), reversed pathological changes and significantly improved survival (p = .05). An impaired HABR is important in the pathophysiology of the SFSS. Reversal of the vasospasm significantly improves outcome.

Unique early gene expression patterns in human adult-to-adult living donor liver grafts compared to deceased donor grafts

Because of inherent differences between deceased donor (DD) and living donor (LD) liver grafts, we hypothesize that the molecular signatures will be unique, correlating with specific biologic pathways and clinical patterns. Microarray profiles of 63 biopsies in 13 DD and 8 LD liver grafts done at serial time points (procurement, backbench and postreperfusion)were compared between groups using class comparisons, network and biological function analyses. Specific genes were validated by quantitative PCR and immunopathology. Clinical findings were also compared. Following reperfusion, 579 genes in DD grafts and 1324 genes in LDs were differentially expressed (p < 0.005). Many upregulated LD genes were related to regeneration, biosynthesis and cell cycle, and a large number of downregulated genes were linked to hepatic metabolism and energy pathways correlating with posttransplant clinical laboratory findings. There was significant upregulation of inflammatory/immune genes in both DD and LD, each with a distinct pattern. Gene expression patterns of select genes associated with inflammation and regeneration in LD and DD grafts correlated with protein expression. Unique patterns of early gene expression are seen in LD and DD liver grafts, correlating with protein expression and clinical results, demonstrating distinct inflammatory profiles and significant downregulation of metabolic pathways in LD grafts.

The Pringle manoeuvre should be avoided in hepatectomy for cancer patients due to its side effects on tumor recurrence and worse prognosis

Curative hepatectomy is still the best therapeutic strategy for liver cancer treatment up to now. The Pringle manoeuvre has been commonly used to avoid massive blood loss during operation since its advent, which greatly accelerates the advance of liver surgery and oncological surgery. In the past century, more attentions have been paid to different effects of ischemia-reperfusion injury elicited by Pringle manoeuvre. Theses include its impacts on complex metabolic, immunological, and microvascular changes, which altogether might contribute to hepatocellular damage and dysfunction, and contribute to haemodynamic instability. Despite these adverse impacts, the short-term outcome of affected patients under hepatectomy was greatly improved with the advances of surgical techniques and perioperative management in recent years. While the long-term prognosis remains unsatisfactory due to a high incidence of intra/extrahepatic recurrence. The reason for it was not totally elucidated. Furthermore, the effect of the Pringle manoeuvre on the prognosis of oncologic patients and behavior of the tumor cell was not deliberately mentioned. This point was put forward to the front-desk by the specific phenomenon from recent animal studies. It is showed that ischemia-reperfusion injury of the liver remnant may be a significant factor to promote the tumor recurrence and metastasis. If it is a truth in human, there must be a big challenge to the Pringle manoeuvre. So we hypothesized that the long-term prognosis of cancer patients could be worsened by the ischemia-reperfusion injury elicited by Pringle manoeuvre during the hepatectomy and it should be revised, or even, avoided in future hepatectomy for oncologic patients. The less surgical stress including ischemia-reperfusion injury in the hepatic resection without Pringle manoeuvre might contribute to a better prognosis. To get a deeper understanding, prospective randomized clinical trials need to be done. It is surely supposed to provide more important information about the long-term effects of the Pringle manoeuvre, and to our hypothesis.

Effects of prophylactic splenic artery modulation on portal overperfusion and liver regeneration in small-for-size graft

BACKGROUND

The small-for-size (SFS) syndrome is caused by excessive portal inflow into a small-sized liver graft. Various approaches for portal decompression have been used, but details of their impact on liver regeneration in SFS graft remain unclear. We examined the effect of prophylactic splenic artery modulation (SAM).

METHODS

We conducted a retrospective cohort study. The study group was 39 consecutive adult-to-adult living liver transplantation recipients, with a graft-to-recipient body weight ratio of less than 0.8. Patients were assigned into the non-SAM group (n=18, without any portal inflow attenuation) or SAM group (n=21, preoperative embolization in 15 patients and intraoperative ligation in 6 patients). Hepatic hemodynamics, graft function, liver regeneration, and outcome were evaluated.

RESULTS

In the SAM group, the excessive portal flow was significantly reduced (P<0.01) and the effect of embolization on portal decompression was equivalent to that of ligation. In the acute postoperative phase, serum transaminases, interleukin-6, and tumor necrosis factor-alpha, were lower in the SAM group than in non-SAM group. In both groups, a negative correlation was observed between graft-to-recipient body weight ratio and liver regeneration rate at 2 weeks after living donor liver transplantation. Splenic artery modulation was advantageous for liver regeneration, and significantly improved clinical features, hyperbilirubinemia, and prolonged ascites. Small-for-size syndrome occurred in five patients of the non-SAM group, and only one of SAM group (P=0.038).

CONCLUSION

In SFS graft with severe portal hypertension, prophylactic splenic embolization/ligation seems to relieve portal overperfusion injury and contributes in improvement of posttransplantation prognosis through liver regeneration.

Immunosuppressive drug-free operational immune tolerance in human kidney transplant recipients: Part I. Blood gene expression statistical analysis

Survival of solid organ grafts depends on life-long immunosuppression, which results in increased rates of infection and malignancy. Induction of tolerance to allografts would represent the optimal solution for controlling both chronic rejection (CR) and side effects of immunosuppression. Although spontaneous "operational tolerance" can occur in human kidney transplantation, the lack of noninvasive peripheral blood biological markers of this rare phenomenon precludes the identification of potentially tolerant patients in whom immunosuppression could be tapered as well as the development of new tolerance inducing strategies. Here, the potential of high throughput microarray technology to decipher complex pathologies allowed us to study the peripheral blood specific gene expression profile and corresponding EASE molecular pathways associated to operational tolerance in a cohort of human kidney graft recipients. In comparison with patients with CR, tolerant patients displayed a set of 343 differentially expressed genes, mainly immune and defense genes, in their peripheral blood mononuclear cells (PBMC), of which 223 were also different from healthy volunteers. Using the expression pattern of these 343 genes, we were able to classify correctly >80% of the patients in a cross-validation experiment and classified correctly all of the samples over time. Collectively, this study identifies a unique PBMC gene signature associated with human operational tolerance in kidney transplantation by a classical statistical microarray analysis and, in the second part, by a nonstatistical analysis.

Ischemia-reperfusion of small liver remnant promotes liver tumor growth and metastases--activation of cell invasion and migration pathways

Elucidating the mechanism of liver tumor growth and metastasis after hepatic ischemia-reperfusion (I/R) injury of a small liver remnant will lay the foundation for the development of therapeutic strategies to target small liver remnant injury, and will reduce the likelihood of tumor recurrence after major hepatectomy or liver transplantation for liver cancer patients. In the current study, we aimed to investigate the effect of hepatic I/R injury of a small liver remnant on liver tumor development and metastases, and to explore the precise molecular mechanisms. A rat liver tumor model that underwent partial hepatic I/R injury with or without major hepatectomy was investigated. Liver tumor growth and metastases were compared among the groups with different surgical stress. An orthotopic liver tumor nude mice model was used to further confirm the invasiveness of the tumor cells from the above rat liver tumor model. Significant tumor growth and intrahepatic metastasis (5 of 6 vs. 0 of 6, P=0.015), and lung metastasis (5 of 6 vs. 0 of 6, P=0.015) were found in rats undergoing I/R and major hepatectomy compared with the control group, and was accompanied by upregulation of mRNA levels for Cdc42, ROCK (Rho kinase), and vascular endothelial growth factor, as well as activation of hepatic stellate cells. Most of the nude mice implanted with liver tumor from rats under I/R injury and major hepatectomy developed intrahepatic and lung metastases. In conclusion, hepatic I/R injury of a small liver remnant exacerbated liver tumor growth and metastasis by marked activation of cell adhesion, invasion, and angiogenesis pathways.

Role of reactive metabolites of oxygen and nitrogen in partial liver transplantation: lessons learned from reduced-size liver ischaemia and reperfusion injury

1. Hepatic resection with concomitant periods of ischaemia and reperfusion (I/R) is required to perform reduced-size liver (RSL) transplantation procedures, such as living donor or split liver transplantation. Although a great deal of progress has been made using these types of surgical procedures, a significant number of patients develop tissue injury from these procedures, ultimately resulting in graft failure. 2. Because of this, there is a real need to understand the different mechanisms responsible for the tissue injury induced by I/R of RSL transplantation (RSL + I/R), with the ultimate goal to develop new and improved therapeutic agents that may limit the tissue damage incurred during RSL transplantation. 3. The present paper reviews the recent studies that have been performed examining the role of reactive metabolites of oxygen and nitrogen in a mouse model of RSL + I/R. In addition, we present data demonstrating how the pathophysiological mechanisms identified in this model compare with those observed in a model of RSL transplantation in rats.

FTY720 for treatment of ischemia-reperfusion injury following complete renal ischemia; impact on long-term survival and T-lymphocyte tissue infiltration

BACKGROUND

Organ dysfunction due to ischemia-reperfusion (I/R) injury is a common problem in transplant, liver, trauma, and heart surgery. I/R injury is mediated by upregulated expression of endothelial cell surface adhesion molecules and subsequent adhesion and activation of circulating leukocytes. The purpose of this study was to evaluate the effect of an intraoperative administration of FTY720 in an animal model with controlled bilateral warm kidney ischemia compared to steroids or placebo application.

METHODS

Male C57BL6/J mice (n = 72, weight 25 to 30 g) were exposed to 30 minutes of bilateral kidney ischemia and followed by a 48 hour observation period. FTY720 (1 mg/kg body weight [BW]), steroids (5 mg/kg BW), or saline solution were administered. In addition, a sham-operated control group was included. At the termination of the experiments, all surviving animals were humanely killed. The impact of the various drugs on overall animal survival, timing of death, peripheral T-cell count, and T-lymphocyte infiltration in the kidneys was determined.

RESULTS

Following bilateral kidney I/R injury, FTY720 was associated with a significant improved animal survival (85.7%) compared with steroids (50%) or controls (42.4%). FACS analysis showed significant T-lymphocyte depletion in peripheral blood in the FTY720 but not in the other groups. T-lymphocyte tissue concentration in liver and kidney tissue did not show statistically significant differences following FTY720, steroid, or saline treatment.

CONCLUSION

FTY720, when administered intraoperatively, improved survival significantly in mice submitted to bilateral kidney ischemia but did not have any significant impact on the parenchymal T-lymphocyte infiltration in the ischemic organ.

Mesenchymal stem cells over-expressing hepatocyte growth factor improve small-for-size liver grafts regeneration

Ischemia-reperfusion (I/R) associated with small-for-size liver transplantation (SFSLT) impairs liver graft regeneration. Mesenchymal stem cells (MSCs) have the capability, under specific conditions, of differentiating into hepatocytes. Hepatocyte growth factor (HGF) has potent anti-apoptotic and mitogenic effects on hepatocytes during liver injury, and has been utilized in many experimental and clinical applications. In this study, we implanted HGF-expressing MSCs into liver grafts via the portal vein, using a 30% small-for-size rat liver transplantation model. HGF, c-met expression, hepatic injury and liver regeneration were assessed after liver transplantation. Our study demonstrated that MSCs over-expressing HGF prevented liver failure and reduced mortality in rats after SFSLT. These animals also exhibited improved liver function and liver weight recovery during the early post-transplantation period. Using green fluorescent protein (GFP) gene as a marker, we demonstrated that the engrafted cells and their progeny incorporated into remnant livers and produced albumin. These findings suggest that MSCs genetically modified to over-express HGF and implanted in the liver graft, may offer a novel approach to promoting liver regeneration after small-for-size transplantations.

Splenic artery ligation improves remnant liver function in partially hepatectomized rats with ischemia/reperfusion injury

BACKGROUND

In liver resection, the temporary occlusion of the hepatoduodenal ligament (Pringle maneuver) is often used. However, the maneuver causes severe ischemia/reperfusion injury in the remnant liver. Our aim was to investigate the effects of splenic artery ligation on the liver function in partially hepatectomized rat with the Pringle maneuver.

METHODS

The Pringle maneuver was conducted for 30 min just before a two-thirds partial hepatectomy. Splenic artery ligation was performed before the Pringle maneuver. The efficacy of splenic artery ligation was assessed by survival, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), recovery of remnant liver weight, and portal pressure.

RESULTS

On day 3, animal survival was four rats of 12 in partially hepatectomized rats with the Pringle maneuver and 10 rats of 12 in the splenic artery ligation-treated partially hepatectomized rats with the Pringle maneuver. A two-thirds partial hepatectomy alone or splenic artery ligation itself did not show any effects on the survival. Compared with partially hepatectomized rats with the Pringle maneuver, splenic artery-ligated animals had lower serum AST and ALT levels, and higher recovery of remnant liver weight. Splenic artery ligation significantly reduced the portal pressure and also decreased the fatality in excessively hepatectomized rats.

CONCLUSIONS

Splenic artery ligation ameliorated the remnant liver function in partially hepatectomized rats with the Pringle maneuver and excessively hepatectomized rats. The amelioration may be mediated at least by decreasing portal pressure.

FTY720 Application Following Isolated Warm Liver Ischemia Improves Long-Term Survival and Organ Protection in a Mouse Model

BACKGROUND

Ischemia-reperfusion-Injury (I/RI) is a common complication in transplant-, liver-, and heart surgery. The I/RI is mediated and aggravated by different types of leukocytes such as lymphocytes, monocytes, and neutrophil granulocytes, with consecutive enlargement of the expression of adhesion molecules. This study shows an organ-protective effect of an intraoperative FTY720 administration following warm liver ischemia (Pringle's maneuver).

METHODS

Male c57BL6/J mice (n = 46, body weight [BW] 25 to 30 g) were used. Either FTY720 (1 mg/kg BW), steroids (5 mg/kg BW), or physiological saline solution was administered intraperitoneally. Liver-ischemia was applied for 30 minutes with subsequent follow-up for 48 hours. At termination, all surviving animals were sacrificed. The impact of the drugs administered on long-term survival, time of death, and development of blood T-lymphocyte concentration was determined. Follow-up of T-lymphocyte concentration in peripheral blood was examined throughout FACS-analysis.

RESULTS

Following 30 minutes of ischemia, FTY720, but not steroid or vehicle treatment, showed a significant protective effect on long-term survival. FACS-analysis showed significant T-lymphocyte depletion in peripheral blood following FTY720 but not steroids or vehicle treatment.

CONCLUSION

The improved long-term survival following FTY720 application shown in this study might be due to a protective effect of FTY720 in prevention of I/RI. This might be mediated by the T-lymphocyte depletion shown in the FACS-analysis.

Living donor versus deceased donor liver transplantation for early irresectable hepatocellular carcinoma

BACKGROUND

Hypothetical studies that favour living donor liver transplantation (LDLT) for early hepatocellular carcinoma (HCC) assumed a comparable outcome after LDLT and deceased donor liver transplantation (DDLT). The aim of this study was to compare the outcome after LDLT with that after DDLT, and to identify factors that might account for any differences.

METHODS

The study included 60 patients who met the radiological Milan or University of California at San Francisco (UCSF) criteria and underwent LDLT (43 patients) or DDLT (17).

RESULTS

The LDLT group had fewer incidental tumours and a lower rate of pretransplant transarterial chemoembolization but a higher rate of salvage transplantation. Waiting time was shorter and graft weight to standard liver weight (GW : SLW) ratio was lower in this group. The perioperative course, and histopathological tumour size, number, grade and stage were comparable. Median follow-up was 33 (range 4-120) months. The cumulative 5-year recurrence rate was 29 per cent in the LDLT group and 0 per cent in the DDLT group (P = 0.029). A GW : SLW ratio of 0.6 or less, salvage transplantation, three or more tumour nodules, microscopic vascular invasion, and pathological stage beyond the Milan or UCSF criteria were significant confounding risk factors. Multivariable analysis identified salvage transplantation (relative risk 5.16 (95 per cent confidence interval (c.i.) 1.48 to 18.02); P = 0.010) and pathological stage beyond the UCSF criteria (relative risk 4.10 (95 per cent c.i. 1.02 to 16.48); P = 0.047) as independent predictors of recurrence.

CONCLUSION

Despite standard radiological selection criteria based on number and size, patients who underwent LDLT for HCC had more recurrence because of selection bias for other clinical characteristics.

Microarrays: a monitoring tool for transplant patients?

Microarray technology holds a distinct advantage over traditional genomic methods, with the unique capability to rapidly generate multiple global gene expression profiles in parallel. This technology is quickly gaining widespread use in many areas of science and medicine because it can be easily adapted to study many experimental questions, particularly relating to disease heterogeneity. Microarray experiments have begun to advance our understanding of the underlying molecular processes in solid organ transplantation; however, several obstacles must be overcome before this technology is ready for application in the clinical setting. This article will review the current applications of microarray technology in the field of transplantation, and discuss the potential impact of this technology on monitoring of solid organ transplant recipients.

Pathophysiologic observations and histopathologic recognition of the portal hyperperfusion or small-for-size syndrome

In an attempt to more completely define the histopathologic features of the portal vein hyperperfusion or small-for-size syndrome (PHP/SFSS), we strictly identified 5 PHP/SFSS cases among 39 (5/39; 13%) adult living donor liver transplants (ALDLT) completed between 11/01 and 09/03. Living donor segments consisting of 3 right lobes, 1 left lobe, and 1 left lateral segment, with a mean allograft-to-recipient weight ratio (GRWR) of 1.0 +/- 0.3 (range 0.6 to 1.4), were transplanted without complications, initially, into 6 relatively healthy 25 to 63-year-old recipients. However, all recipients developed otherwise unexplained jaundice, coagulopathy, and ascites within 5 days after transplantation. Examination of sequential posttransplant biopsies and 3 failed allografts with clinicopathologic correlation was used in an attempt to reconstruct the sequence of events. Early findings included: (1) portal hyperperfusion resulting in portal vein and periportal sinusoidal endothelial denudation and focal hemorrhage into the portal tract connective tissue, which dissected into the periportal hepatic parenchyma when severe; and (2) poor hepatic arterial flow and vasospasm, which in severe cases, led to functional dearterialization, ischemic cholangitis, and parenchymal infarcts. Late sequelae in grafts surviving the initial events included small portal vein branch thrombosis with occasional luminal obliteration or recanalization, nodular regenerative hyperplasia, and biliary strictures. These findings suggest that portal hyperperfusion, venous pathology, and the arterial buffer response importantly contribute to early and late clinical and histopathologic manifestations of the small-for-size syndrome.

Divergent roles of superoxide and nitric oxide in reduced-size liver ischemia and reperfusion injury: Implications for partial liver transplantation

Hepatic resection with concomitant periods of ischemia and reperfusion (I/R) are required to perform partial liver transplantation procedures such as split liver or living donor transplantation. Although great progress has been made using these types of surgeries, there remains substantial risk to both donors and recipients, with a significant number of patients developing liver injury and failure during the course these operations. Therefore, there is need to investigate the different mechanisms responsible for the tissue injury induced by ischemia and reperfusion of a reduced-size liver (RSL+I/R) with the ultimate objective of developing new therapeutic agents that may limit hepatocellular damage induced during partial liver transplantation. This review summarizes recent studies that have been performed in a mouse model of RSL+I/R. In addition, we present data demonstrating how the pathophysiological mechanisms identified in this model compare to those observed in a rat model of RSL transplantation.

Impact of preoperative steroids administration on ischemia-reperfusion injury and systemic responses in liver surgery: a prospective randomized study

Hepatic injury secondary to warm ischemia-reperfusion (I/R) injury and alterations in haemostatic parameters are often unavoidable events after major hepatic resection. The release of inflammatory mediator is believed to play a significant role in the genesis of these events. It has been suggested that preoperative steroid administration may reduce I/R injury and improve several aspects of the surgical stress response. The aim of this prospective randomized study was to investigate the clinical benefits on I/R injury and systemic responses of preoperatively administered corticosteroids. Seventy-six patients undergoing liver resection were randomized either to a steroid group or to a control group. Patients in the steroid group received preoperatively 500 mg of methylprednisolone. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, coagulation parameters, and inflammatory mediators, interleukin 6 and tumor necrosis factor alpha were compared between the 2 groups. Length of stay, and type and number of complications were recorded as well. Postoperative serum levels of ALT, AST, total bilirubin, and inflammatory cytokines were significantly lower in the steroid than in the control group at postoperative days 1 and 2. Changes in hemostatic parameters were also significantly attenuated in the steroid group. In conclusion, the incidence of postoperative complications in the steroid group tended to be significantly lower than the control group. It is of clinical interest that preoperative steroids administration before major surgery may reduce I/R injury, maintain coagulant/anticoagulant homeostasis, and reduce postoperative complications by modulating the inflammatory response.

Rapamycin attenuates liver graft injury in cirrhotic recipient--the significance of down-regulation of Rho-ROCK-VEGF pathway

To investigate whether rapamycin could attenuate hepatic I/R injury in a cirrhotic rat liver transplantation model, we applied a rat orthotopic liver transplantation model using 100% or 50% of liver grafts and cirrhotic recipients. Rapamycin was given (0.2 mg/kg, i.v.) at 30 min before graft harvesting in the donor and 24 h before operation, 30 min before total hepatectomy and immediately after reperfusion in the recipient. Rapamycin significantly improved small-for-size graft survival from 8.3% (1/12) to 66.7% (8/12) (p = 0.027). It also increased 7-day survival rates of whole grafts (58.3%[7/12] vs. 83.3%[10/12], p = 0.371). Activation of hepatic stellate cells was mainly found in small-for-size grafts during the first 7 days after liver transplantation. Rapamycin suppressed expression of smooth muscle actin, which is a marker of hepatic stellate cell activation, especially in small-for-size grafts. Intragraft protein expression and mRNA levels of vascular endothelial growth factor (VEGF) were down-regulated by rapamycin at 48 h both in whole and small-for-size grafts. Consistently, mRNA levels and protein expression of Rho and ROCK I were decreased by rapamycin during the 48 h after liver transplantation. In conclusion, rapamycin attenuated graft injury in a cirrhotic rat liver transplantation model by suppression of hepatic stellate cell activation, related to down-regulation of Rho-ROCK-VEGF pathway.

Attenuation of acute phase shear stress by somatostatin improves small-for-size liver graft survival

The major concern of living donor liver transplantation is small-for-size graft injury at the early phase after transplantation. Novel therapeutic strategies should be developed. To investigate the protective effect of somatostatin related to hemodynamic stress on small-for-size liver graft injury, we applied a treatment regimen of low-dose somatostatin in a rat orthotopic liver transplantation model using small-for-size grafts (median, 38.7%; range, 35-42%). Somatostatin was given at 5 minutes before total hepatectomy and immediately after reperfusion in the recipient (20 microg/kg). Graft survival, portal hemodynamics, intragraft gene expression and hepatic ultrastructural changes were compared between the rats with or without somatostatin treatment. Seven-day graft survival rates in the somatostatin treatment group were significantly improved compared to the control group (66.7% vs. 16.7%, P = 0.036). In the treatment group, portal pressure and hepatic surface blood flow were significantly decreased within the first 30 minutes after reperfusion, whereas in the control group, transient portal hypertension and excessive hepatic blood flow were observed. Intragraft expression (both messenger RNA and protein) of endothelin-1 was significantly downregulated accompanied with upregulation of heme oxygenase-1 and A20. Better preservation of liver function was found in the treatment group. Hepatic ultrastructure, especially the integrity of sinusoids, was well protected in the treatment group. In conclusion, low-dose somatostatin rescues small-for-size grafts from acute phase injury in liver transplantation by attenuation of acute-phase shear stress that resulted from transient portal hypertension.

Fat-derived hormone adiponectin combined with FTY720 significantly improves small-for-size fatty liver graft survival

Owing to the discrepancy between organ donation and the demand for liver transplantation, expanding the liver donor pool is of vital importance. However, marginal liver grafts, such as small-for-size and/or fatty grafts, were associated with primary graft nonfunction or poor function. Therefore, novel combination therapies to rescue small-for-size fatty liver grafts should be investigated. In this study, we applied a combination therapy using a fat-derived hormone adiponectin (anti-steatosis) plus immunomodulator FTY720 (anti-inflammatory) in a rat liver transplantation model using small-for-size fatty liver grafts, and investigated the underlying protective mechanism such as anti-steatosis, intra-graft energy metabolism, hepatic microcirculatory changes, cell signaling cascades for survival, apoptosis and inflammation. The current study demonstrated that even a single treatment of adiponectin or FTY720 improved the 7-day graft survival from 0% to 62.5% (p = 0.001). The combination therapy significantly increased the 7-day graft survival rate to 100% by remarkable attenuation of graft steatosis and acute phase inflammatory response, significant activation of cell survival Akt pathway and maintenance of intra-graft adenosine triphosphate metabolism and improvement of hepatic microcirculation. In conclusion, the fat-derived hormone adiponectin combined with FTY720 might be a novel combination drug therapy for prevention of small-for-size fatty liver graft injury.

Activation pattern of mitogen-activated protein kinases in early phase of different size liver isografts in rats

Mitogen-activated protein kinases (MAPK) play a pivotal role in ischemia reperfusion injuries of heart and liver, but the activation pattern of MAPKs in the early phase of different size liver isografts remains unclear. The experiment is designed to investigate the activation pattern and role of MAPKs in isografts of the rat with different size liver transplantation. The animal models of different size graft liver transplantation (whole graft, 50% size, or 30% size, respectively) were established and the sham operation group served as a control. The recipients were sacrificed at 0.5-, 2-, 6-, and 24-hour time points after transplantation to harvest the graft specimens and blood samples. The serum aspartate amino transferase (AST), alanine amino transferase (ALT) and tumor necrosis factor-alpha (TNF-alpha) levels, and histological findings were evaluated. The expressions of the total and phosphorylated p46/p54 JNKs, p38 MAPK, and p42/p44 ERKs were detected by Western blot. The serum ALT and AST levels increased significantly at the 0.5-hour time point and maintained high with the peak levels at the 6-hour time point after liver transplantation. The different sizes of liver isografts did not change the expressions of total p46/p54JNKs, p38MAPK, and p42/p44 ERKs. While the expressions of phosphorylated p46/p54JNKs, p38 MAPK, and p42/p44 ERKs were either negative or mildly up-regulated in the sham operation group, they were significantly activated in the transplanted liver at the 0.5-hour time point, especially in the 30% size liver transplantation group. In conclusion, the activation of three MAPKs in liver isografts correlates with graft size and the JNK and p38 MAPK are responsible for the graft injury while the ERK signal pathway maybe participate in the regulation of cell growth and differentiation after small-for-size liver transplantation.

Small-for-size syndrome after partial liver transplantation: definition, mechanisms of disease and clinical implications

Widespread application of cadaveric split or living donor liver transplantation bears considerable potential to increase the pool of available organs and thus alleviate the problem of organ shortage. Although splitting of a cadaveric liver into two grafts for adult recipients can be performed successfully, sufficient function of undersized grafts is a major concern. To minimize the risk for living donors, transplant surgeons aim at procuring the least necessary liver volume, also leading to potentially small grafts. When small partial grafts are unable to meet the functional demands, the recipients can develop a so-called small-for-size syndrome (SFSS). There is currently limited data on the pathogenesis of SFSS, with clinical studies mainly focusing on portal hyperperfusion. Additional aspects include graft-related factors such as functional and regenerative capacity, as well as recipient-related factors, such as overall health status and severity of cirrhosis. However, there is currently no consensus on the definition of SFSS. We propose a novel definition, based on simple clinical criteria, which divides the syndrome into either nonfunction or dysfunction of a small graft after the exclusion of other causes. This definition should ease comparability of future clinical trials, and thus improve understanding of the pathogenesis of SFSS.

FTY720 attenuates hepatic ischemia-reperfusion injury in normal and cirrhotic livers

Hepatic ischemia-reperfusion injury is an inevitable consequence during liver surgery. The outcome is particularly poor in cirrhotic livers, which are more prone to hepatic ischemia-reperfusion injury. We aim to study whether FTY720 could attenuate hepatic ischemia-reperfusion injury both in normal and in cirrhotic livers. We applied a 70% liver-ischemia (60 min) model in rats with normal or cirrhotic livers. FTY720 was given 20 min before ischemia and 10 min before reperfusion (1 mg/kg, i.v.). Liver tissues and blood were sampled at 20 min, 60 min, 90 min, 6 h and 24 h after reperfusion for detection of MAPK-Egr-1, Akt pathways and caspase cascade. Hepatic ultrastructure and apoptosis were also compared. FTY720 significantly improved liver function in the rats with normal and cirrhotic livers. Akt pathway was activated at 6 and 24 h after reperfusion. FTY720 significantly down-regulated Egr-1, ET-1, iNOS and MIP-2 accompanied with up-regulation of A20, IL-10, HO-1 and Hsp70. MAPK (Raf-MEK-Erk) pathway was down-regulated. Hepatic ultrastructure was well maintained and fewer apoptotic liver cells were found in the FTY720 groups. In conclusion, FTY720 attenuates ischemia-reperfusion injury in both normal and cirrhotic livers by activation of cell survival Akt signaling and down-regulation of Egr-1 via Raf-MEK-Erk pathway.

Attenuation of small-for-size liver graft injury by FTY720: significance of cell-survival Akt signaling pathway

To investigate the protective mechanism of FTY720 in small-for-size liver grafts, we applied a rat orthotopic liver transplantation model using 40% of liver grafts. FTY720 was administered (1 mg/kg, i.v.) at 20 min before graft harvesting in the donor, immediately before total hepatectomy and immediately after graft reperfusion in the recipient. The 7-day graft survival rates in the FTY720 group were significantly improved compared with the control group [100% (6/6) vs. 40% (4/10), p = 0.034]. FTY720 significantly reduced serum ALT and AST levels at 24 h after liver transplantation. The cell-survival Akt signaling pathway was activated in FTY720 groups by phosphorylation of Glycogen Synthase Kinase-3beta, Bad and Forkhead Transcription Factor at 6 and 24 h after liver transplantation. The cleaved-caspases 3, 7 and 9 were down-regulated, accompanied with less apoptotic nuclei after FTY720 treatment. Acute-phase inflammatory MAPK pathway was down-regulated by dephosphorylation of c-Raf, Mek and Erk in the treatment groups. A20 and endothelial nitric oxide synthase were up-regulated together with down-regulation of iNOS. Hepatic sinusoids were well preserved in the FTY720 group but disrupted in the control group. In conclusion, FTY720 attenuates small-for-size liver graft injury by activation of cell-survival Akt signaling and down-regulation of the MAPK pathway.

FK 409 ameliorates small-for-size liver graft injury by attenuation of portal hypertension and down-regulation of Egr-1 pathway

OBJECTIVE

To investigate whether low-dose nitric oxide donor FK 409 could attenuate small-for-size graft injury in liver transplantation using small-for-size grafts.

SUMMARY BACKGROUND DATA

The major concern of live donor liver transplantation is small-for-size graft injury at the early phase after transplantation. Novel therapeutic strategies should be investigated.

METHODS

We employed a rat orthotopic liver transplantation model using small-for-size (40%) graft. FK 409 was given at 30 minutes before graft harvesting (2 mg/kg) to the donor and immediately after reperfusion (1 mg/kg) to the recipient (FK group). Graft survival, intragraft genes expression, portal hemodynamics, and hepatic ultrastructural changes were compared between the 2 groups.

RESULTS

Seven-day graft survival rates in the FK group were significantly improved compared with those of rats not receiving FK 409 (control group; 80% versus 28.6%, P = 0.018). In the FK group, portal pressure was significantly decreased within the first 60 minutes after reperfusion whereas in the control group, transient portal hypertension was observed. Intragraft expression (both mRNA and protein) of early growth response-1, endothelin-1, endothelin-1 receptor A, tumor necrosis factor-alpha, macrophage-inflammatory protein-2, and inducible nitric oxide synthase was significantly down-regulated accompanied with up-regulation of heme oxygenase-1, A20, interferon-gamma-inducible protein-10, and interleukin-10 during the first 24 hours after reperfusion. Hepatic ultrastructure, especially the integrity of sinusoids was well protected in the FK group.

CONCLUSIONS

Low-dose FK 409 rescues small-for-size grafts in liver transplantation by attenuation of portal hypertension and amelioration of acute phase inflammatory response by down-regulation of Egr-1, together with prior induction of heat shock proteins.