Erythropoietin Treatment Improves Liver Regeneration and Survival in Rat Models of Extended Liver Resection and Living Donor Liver Transplantation

Experimental isolation and preservation of solid organs before transplantation: effects of pretreatment using four different molecules

OBJECTIVES

In transplantation surgery, the ischaemic organ and reperfusion impairment after cold storage remains a considerable risk factor for impaired function and potential failure of the grafted organ. Substantial logistical efforts have been undertaken to reduce the cold ischaemic time because the demand for available transplant organs and the periods of cold ischaemia are increasing.

METHODS

Four molecules were investigated (erythropoietin, sildenafil, lazaroid [U74389G], octreotide) in individual intravenous infusions 1 hour before the organ was harvested. This study was performed in 30 healthy landrace/large-white pigs (male; >10 weeks old; average weight, 22 ± 2 kg) in groups of six. The organs were studied at harvest, and at 8 and 24 hours post-harvest.

RESULTS

The lazaroid molecule increased malondialdehyde (MDA) levels in the liver and pancreas at 8 hours. Hepatic lazaroid molecules improved liver histology at 8 and 24 hours. For kidneys, erythropoietin had a positive effect at 24 hours post-harvest. For the pancreas, octreotide showed better performance. In the lungs, there was less interstitial oedema with erythropoietin and lazaroid compared with the control group at 8 hours post-harvest.

CONCLUSION

All molecules had a positive effect and decreased ischaemia/reperfusion graft injury. Thus, pretreatment before organ harvest has a beneficial role.

Co-administration of erythropoietin and iron complex improves late-phase liver regeneration

Erythropoietin and iron have individually shown beneficial effects on early-phase liver regeneration following partial hepatectomy (PHx); however, there are limited data on the combined effect on late-phase liver regeneration after PHx. Here we examined combined effects of recombinant human erythropoietin (rhEPO, 3,000 IU/kg) and iron isomaltoside (IIM, 40 mg/kg) on late-phase liver regeneration following PHx and investigated the possible underlying mechanism. Rats administrated with rhEPO showed significantly higher liver mass restoration, interleukin-6 (IL-6, a hepatocyte mitogen) levels, and Ki-67-positive hepatocytes on day 7 after PHx than saline-treated controls. These beneficial effects were further enhanced on days 7 and 14 by co-treatment with IIM. This combination also significantly improved liver function indices, such as increased albumin production and decreased bilirubin levels, but did not alter serum levels of toxic parameters, such as aspartate transaminase and alanine transaminase. This study demonstrates that the combination of rhEPO and IIM synergistically improves late-phase liver regeneration and function after PHx, probably by promoting IL-6-mediated hepatocyte proliferation without adverse effects. Thus, this combination treatment can be a potential therapeutic strategy for patients undergoing resection for hepatic malignancies.

[Preconditioning of the liver]

Posthepatectomy liver failure (PHLF) still represents a severe complication after major liver resection associated with a high mortality. In addition to an insufficient residual liver volume various factors play an important role in the pathophysiology of PHLF. These include the quality of the parenchyma, liver function, perfusion, i.e. maintenance of adequate inflow and outflow, as well as the condition of the patient and comorbidities. While the liver volume is relatively easy to evaluate using modern imaging techniques, the evaluation of liver function and liver quality require a differentiated approach. Both factors can be influenced by the constitutional status of the patient, medical history and previous treatment and must be given sufficient consideration in the risk evaluation. An adequate perfusion, e.g. portal and arterial circulation and adequate outflow by at least one hepatic vein as well an adequate biliary drainage should be always guaranteed in order to allow regeneration of the residual liver tissue. Only the understanding of all these aspects will support the surgeon in a correct and safe evaluation of the resectability. Additionally, the liver surgeon should be aware of all available perioperative and postoperative options to treat and to prevent PHLF. In this review article the most important questions regarding the risk factors related to PHLF are presented and the potential therapeutic and prophylactic management is described. The main goal is to ensure functional operability of the patient if oncological resectability is possible. In other words: in the case of correct oncological indication, the liver surgeon should be able to resect what is resectable or, alternatively, make resectable what primarily was not resectable.

A new organ preservation solution for static cold storage of the liver. Amniotic fluid

Purpose:

To evaluate the effect of amniotic fluid in liver preservation in organ transplantation, and compare it with standard preservation solutions.

Methods:

The groups consisted of Group 1: Ringer Lactate (RL) group, Group 2: HTK group, Group 3: UW group, Group 4: AF group. The livers of rats from Group 1, 2, 3, and 4 were perfused and placed into falcon tubes containing RL, HTK, UW, and AF solutions at +4‎°C, respectively. The tubes were stored for 12 hours in the refrigerator at +4°C. Tissue samples were taken at the 6^th and 12^th hours for histopathological examinations of the perfused livers, and storage solutions for biochemical analyzes at 6^th and 12^th hours.

Results:

AF was shown to maintain organ viability by reducing the number of cells undergoing apoptosis. Histopathological changes such as sinusoidal dilatation, hydropic degeneration, and focal necrosis were found to be similar to the groups in which the standard organ preservation solutions were used. Additionally, the results of INOS, IL-10, and TNF-α,which were evaluated immunohistochemically, have been shown to be similar to the UW and HTK groups.

Conclusions:

AF provided conservation similar to UW and HTK in the 12-hour liver SCS process. The fact that apoptosis values are comparable to standard preservation solutions supports the success of AF in the cold storage of the liver.

Preoperative erythropoietin treatment improves survival following major hepatic resection in a cirrhotic rat model

AIM

Major hepatic resection of a cirrhotic liver may result in a fatal clinical course. Preoperative erythropoietin (EPO) treatment has been shown to have protective properties and to stimulate liver regeneration. This study aims to investigate the effect of preoperative EPO on survival following major hepatic resection in a cirrhotic rat model.

METHODS

Cirrhotic liver was induced by intraperitoneal injection of thioacetamide (200mg/kg/mL) in 72 Lewis rats. Each 36 rats received EPO (1IU/g, every second day, 5 times preoperatively) or saline (control) and major hepatectomy (removal of the left and half of the median lobe) was performed. Biochemical and immunohistochemical parameters, cytokines and overall survival were compared following surgery.

RESULTS

Rats that received preoperative EPO had decreased hepatic aspartate aminotransferase, alanine aminotransferase and interleukin (IL)-1β expression, 48hours following surgery. They had increased hepatocyte growth factor and vascular endothelial growth factor expression at 1hour, increased IL-6 expression at 24, 48 and 120hours and increased Ki-67, 120hours following surgery. Overall, survival was significantly improved among EPO-treated rats (P=0.034).

CONCLUSION

Preoperative EPO treatment has a protective effect and stimulates liver regeneration, leading to improved overall survival following major hepatectomy in a cirrhotic rat model.

Re-Arterialized Rat Partial Liver Transplantation with an in vivo Vessel-Oriented 70% Hepatectomy

Split liver transplantation and living liver donor liver transplantation were developed in the clinic to utilize liver organs in a more efficient manner. To better understand the mechanism behind these surgical procedures, a rat partial liver transplantation (PLTx) model was established for relevant surgical studies. Because of the complexity of the rat PLTx model, a protocol with detailed descriptions is required. An article published previously reported a protocol in which ex vivo hepatectomy was used to achieve 50% rat PLTx. In contrast to this protocol, we introduced a re-arterialized PLTx with an in vivo 70% hepatectomy. An updated vessel-oriented hepatectomy was incorporated into the rat PLTx to refine the microsurgical procedure. The portal veins and hepatic arteries of the left lateral lobe and the median lobe were individually dissected and ligated before removal of the liver parenchyma, thereby decreasing the probability of bleeding in the remnant liver stump. Furthermore, an end-to-side vessel anastomosis between the common hepatic artery and the enlarged proper hepatic artery was introduced to re-arterialize the hepatic artery. By using this end-to-side vessel anastomosis technique, the diameter of the anastomosis was enlarged, thereby decreasing the difficulty of hand suture and maintaining a high rate of anastomotic patency. Moreover, the cuff anastomosis of the infrahepatic vena cava was slightly modified. A section of circumferential liver parenchyma around the vena cava of a recipient was preserved during cuff anastomosis to maintain the three-dimensional shape of the vascular lumen. This section of liver parenchyma was removed after completing the anastomosis. With this modification, the step involving placement of stay sutures was omitted, thereby further shortening the cuff anastomosis time. By using this protocol of rat PLTx, a low liver enzyme level, an intact liver lobular architecture and a high survival rate were achieved after microsurgery.

Darbepoetin-α Promotes Cell Proliferation in Established Extrahepatic Colorectal Tumors after Major Hepatectomy

BACKGROUND

The glycoprotein hormone erythropoietin and its analogue darbepoetin-α (DPO) have been shown to reduce the risk of acute liver failure after major hepatectomy. However, previous experimental studies have also shown that DPO significantly enhances neovascularization and tumor cell proliferation in established colorectal liver metastasis in hepatectomized and nonhepatectomized mice. The present study now analyzes whether DPO influences cell proliferation and migration as well as vascularization and growth of established colorectal metastasis at extrahepatic sites after major hepatectomy.

METHODS

GFP-transfected CT26.WT colorectal cancer cells were implanted into dorsal skinfold chambers of syngeneic BALB/c mice. Five days after tumor cell implantation, the animals received a single dose of DPO (10 µg/kg body weight) or phosphate-buffered saline solution (PBS) intravenously. Additional animals received a 70% hepatectomy and DPO or PBS treatment. Tumor vascularization and growth as well as tumor cell migration, proliferation and apoptosis were studied repetitively over 14 days using intravital fluorescence microscopy, histology and immunohistochemistry.

RESULTS

DPO did not influence tumor cell migration and apoptosis. In addition, DPO did not stimulate tumor cell infiltration or vascularization; however, significantly increased tumor cell proliferation was detected in hepatectomized animals.

CONCLUSION

DPO increases cell proliferation in established extrahepatic colorectal metastases after major hepatectomy. Thus, DPO may not be recommended to stimulate regeneration of the remnant liver after major hepatectomy for colorectal liver metastasis.

Can living donor liver transplantation offer similar outcomes to deceased donor liver transplantation using expanded selection criteria for hepatocellular carcinoma?

OBJECTIVE

To compare the outcomes of living donor liver transplantation (LDLT) versus deceased donor liver transplantation (DDLT) for patients with hepatocellular carcinoma (HCC) in different selection criteria.

METHODS

Data of patients with HCC who underwent liver transplantation between 2005 and 2013 at our center were reviewed. Clinical data of LDLT recipients and DDLT recipients were compared. The postoperative recurrence-free survival (RFS) rate and overall survival (OS) rate after LDLT versus DDLT were compared in the Milan recipients, the University of California, San Francisco (UCSF) recipients, the up-to-seven recipients, the Hangzhou recipients and the Chengdu recipients.

RESULTS

Data of 255 patients were retrospectively reviewed in this study. Seventeen DDLT recipient and 9 LDLT recipients died during the perioperative period. Among the remaining 229 recipients (NLDLT=66, NDDLT=163), 96 patients met the Milan criteria, 123 recipients met the UCSF criteria, 135 patients met the up-to-seven criteria, 216 patients met the Hangzhou criteria, and 229 recipients met the Chengdu criteria. The overall RFS and OS rates of the Milan recipients, the UCSF recipients, the up-to-seven recipients, the Hangzhou recipients and the Chengdu recipients after LDLT and DDLT were all similar.

CONCLUSION

Using well-studied selection criteria, LDLT offers similar outcomes to DDLT for patient with HCC, even using expanded selection criteria.

Expression profiles uncover the relationship between erythropoietin and cell proliferation in rat hepatocytes after a partial hepatectomy

Erythropoietin (EPO) has a beneficial effect on hepatic cell proliferation during liver regeneration. However, the underlying mechanism has not yet been elucidated. To uncover the proliferation response of EPO in rat liver regeneration after partial hepatectomy (PH) at the cellular level, hepatocytes (HCs) were isolated using Percoll density gradient centrifugation. The genes of the EPO-mediated signaling pathway and the target genes of the transcription factor (TF) in the pathway were identified in a pathway and TF database search. Their expression profiles were then detected using Rat Genome 230 2.0 Microarray. The results indicated that the EPO-mediated signaling pathway is involved in 19 paths and that 124 genes participate, of which 32 showed significant changes and could be identified as liver regeneration-related genes. In addition, 443 targets regulated by the TFs of the pathway and 60 genes associated with cell proliferation were contained in the array. Subsequently, the synergetic effect of these genes in liver regeneration was analyzed using the E(t) mathematical model based on their expression profiles. The results demonstrated that the E(t) values of paths 3, 8, 12 and 14-17 were significantly strengthened in the progressing phase of liver regeneration through the RAS/MEK/ERK or PI3K/AκT pathways. The synergetic effect of the target genes, in parallel with target-related cell proliferation, was also enhanced 12-72 h after PH, suggesting a potential positive effect of EPO on HC proliferation during rat liver regeneration. These data imply that the EPO receptor may allow EPO to promote HC proliferation through paths 3, 8, 12 and 14-17, mediating the RAS/MEK/ERK and PI3K/AκT pathways in rat liver regeneration after PH.

Multiple low doses of erythropoietin delay the proliferation of hepatocytes but promote liver function in a rat model of subtotal hepatectomy

PURPOSE

The impact of various doses of erythropoietin (EPO) on liver regeneration after partial hepatectomy (PH) in different animal models is still under debate. We investigated the impact of low doses of EPO on liver regeneration in a rat model of subtotal hepatectomy.

METHODS

We established a 90 % PH rat model with perioperative injections of low-dose EPO (1,000 IU/kg). We analyzed survival and hepatocyte proliferation in animals treated with or without EPO and assessed liver function by blood ammonia measurement and the indocyanine green 15-min retention test.

RESULTS

Low doses of EPO treatment improved the survival of rats after 90 % PH. Unexpectedly, during the first 24 h after the operation, liver regeneration in the EPO-treated rats was inhibited. DNA synthesis, cell proliferation, and the expression of cyclins and p-STAT3 peaked 48 h after PH, which was delayed by about 24 h vs. the control rats. Furthermore, EPO treatment increased the serum level of IL-6 and protected the hepatocytes from apoptosis.

CONCLUSION

Low doses of EPO do not stimulate early hepatocyte proliferation in the regenerating liver, but contribute to liver protection by inducing IL-6 and inhibiting apoptosis.

Darbepoetin inhibits proliferation of hepatic cancer cells in the presence of TGF-β

Darbepoetin (DPO), an erythropoietin (EPO) derivative, was licensed in 2002 to treat patients with solid tumors suffering from chemotherapy-dependent anemia, although various tumors express EPO to improve vascularization, thus favoring tumor growth and spreading. Therefore, we wanted to investigate direct effects of DPO on the liver tumor cell lines HepG2, SkHep1, Huh-7, AKN1, HCC-T and HCC-M, as well as on primary human hepatocytes (hHeps). DPO (0-40 ng/ml) did not affect viability of hHeps, HepG2, SkHep1, AKN1, HCC-T and HCC-M cells, as determined by Resazurin conversion. However, Huh-7 cells' viability dose-dependently decreased from 5 ng/ml DPO on. Lack of LDH release into culture medium and negative DNA laddering excluded apoptosis or necrosis as the cause for the reduced Resazurin conversion. In Huh-7 cells, DPO increased the expression of p53. Interestingly, Huh-7 cells showed the highest basal TGF-β1 expression as compared to the other cell lines. Upon inhibition of TGF-β1 signaling, DPO no longer reduced viability in Huh-7 cells. On the contrary, co-incubation with TGF-β1 made the other cell lines responsive to DPO. Summarizing our data, we show that DPO reduces the growth of Huh-7 cells by up-regulation of the tumor-suppressor gene p53. This mechanism seems to be dependent on a strong TGF-β expression and corresponding signaling in these cells, as other cell lines became responsive to DPO with TGF-β1 supplementation. The knowledge of this mechanism offers great perspectives for the understanding and treatment of solid liver tumors.

Characterization of the erythropoietin/erythropoietin receptor axis in a rat model of liver damage and cholangiocarcinoma development

It has been recently shown that the biological effects of erythropoietin (EPO) are not limited to the hematopoietic compartment but, as pleiotropic glycoprotein, this hormone can exert pro-angiogenic and tissue-protective functions also in a wide range of non-hematopoietic organs. The role of EPO and the effective functionality of its receptor in solid tumors are still a controversial point of debate. In the present work we analyzed the gene expression of EPO and its cognate receptor (EpoR) in a rat model of thioacetamide-induced damage and tumor. An analysis of the EPO/EpoR axis was also performed on human cholangiocarcinoma (CC) cell lines. A progressive increase of EPO and EpoR mRNA can already be observed during the fibrotic–cirrhotic development with a peak of expression rising at tumor formation (24.7 ± 9.9-fold increase and 15.5 ± 1.1-fold increase, respectively, for the two genes). Co-localization studies by immunofluorescence revealed hepatocytes in the regenerative cirrhotic nodules (Hep Par-1⁺) and in the dysplastic bile duct cells (CK19⁺) as the major EPO producers in this specific condition. The same cell populations, together with endothelial cells, exhibited an increased expression of EpoR, although all the non-parenchymal cell populations in the liver exhibited modest basal mRNA levels. Challenging human CC cells, Mz-Cha-2, with a combination of EPO and SCF resulted in a synergistic effect on the gene expression of EPO, CyclinD1 and PCNA. This study suggests that the autocrine and paracrine release of endogenous EPO in the microenvironment may contribute to the development and maintenance of the CC possibly in cooperation with other signaling pathways.

Both darbepoetin alfa and carbamylated erythropoietin prevent kidney graft dysfunction due to ischemia/reperfusion in rats

BACKGROUND

Ischemia/reperfusion (I/R) injury is an important cause of renal graft dysfunction. Increases in cold and warm ischemia times lead to a higher risk of early posttransplant complications including delayed graft function and acute rejection. Moreover, prolonged cold ischemia is a predictor of long-term graft loss in kidney transplant patients.

METHODS

Darbepoetin alfa (DA) and carbamylated nonerythropoietic derivative of erythropoietin (CEPO) protective effects were evaluated in a model of I/R injury after kidney transplantation in both syngeneic and allogeneic combinations. The effects of wortmannin (phosphorylated Akt [p-Akt] inhibitor) administration were also investigated. Serum creatinine was evaluated at 16, 24, 48 hr and at 4 and 7 days posttransplant. Animals were killed 24 hr or 7 days after transplant and kidneys were processed for histological analysis, immunohistochemistry assessment of erythropoietin receptor (EPOR) and β-common chain receptor expression, granulocyte infiltration, nitrotyrosine staining, p-Akt expression, peritubular capillary (PTC) density, apoptosis, antioxidant, and antiapoptotic gene expression.

RESULTS

DA and CEPO significantly reduced serum creatinine, tubular injury, tubular nitrotyrosine staining, and prevented I/R-induced tubular apoptosis, but only when given both to the donor and to the recipient. DA and CEPO cytoprotection was associated with prevention of I/R-induced drop of p-Akt expression in tubuli, and almost complete preservation of capillary density in the tubulointerstitium of the graft. CEPO was more effective than DA in reducing tubular oxidative stress and preserving PTCs.

CONCLUSION

DA and CEPO when given both to the donor and to the recipient, prevented renal graft dysfunction, tubular oxidative stress, and apoptosis after I/R injury in kidney transplantation. Their cytoprotection was mediated by tubular p-Akt activation and PTC density preservation.

Proteomic analysis to display the effect of low doses of erythropoietin on rat liver regeneration

AIMS

Several groups found different impact of erythropoietin (EPO) on liver regeneration. Both pro-proliferative as well as anti-proliferative and non-proliferative activities have been reported using high dosage of EPO. Systemic administration of high doses of this cytokine is a clinical concern due to risk of thrombosis. Herein, we applied EPO in low dosages and investigated whether it can stimulate liver regeneration after liver resection.

MAIN METHODS

Parameters of liver regeneration were assessed 3 days after 70% hepatectomy by means of immunochemistry and proteomics. EPO was given twice in low dosages (200 and 600 IU/kg BW).

KEY FINDINGS

We showed that EPO facilitated hepatic regeneration in rats. Enhanced hepatocyte proliferation (Ki67, BrdU-positive cells) was observed in all EPO-treated groups. By performing Differential Proteomic analysis, we identified two proteins which resulted sensitive to EPO treatment after hepatectomy: Peroxiredoxin-1 and glutathione S-transferase Mu 1.

SIGNIFICANCE

Based on our results, low doses of rhEPO increase the hepatic regenerative capacity after partial hepatectomy in rats by enhancing hepatocyte proliferation and acting on antioxidant enzymes. Both proteins identified by proteomic analysis have not previously been associated with liver regeneration and will aid in the understanding of EPO's regenerative response having clinical implications to treat liver failure.

The combined effect of erythropoietin and granulocyte macrophage colony stimulating factor on liver regeneration after major hepatectomy in rats

Background

The liver presents a remarkable capacity for regeneration after hepatectomy but the exact mechanisms and mediators involved are not yet fully clarified. Erythropoietin (EPO) and Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) have been shown to promote liver regeneration after major hepatectomy.

Aim of this experimental study is to compare the impact of exogenous administration of EPO, GM-CSF, as well as their combination on the promotion of liver regeneration after major hepatectomy.

Methods

Wistar rats were submitted to 70% major hepatectomy. The animals were assigned to 4 experimental groups: a control group (n = 21) that received normal saline, an EPO group (n = 21), that received EPO 500 IU/kg, a GM-CSF group (n = 21) that received 20 mcg/kg of GM-CSF and a EPO+GMCSF group (n = 21) which received a combination of the above. Seven animals of each group were killed on the 1st, 3rd and 7th postoperative day and their remnant liver was removed to evaluate liver regeneration by immunochemistry for PCNA and Ki 67.

Results

Our data suggest that EPO and GM-CSF increases liver regeneration following major hepatectomy when administered perioperatively. EPO has a more significant effect than GM-CSF (p < 0.01). When administering both, the effect of EPO seems to fade as EPO and GM-CSF treated rats have decreased regeneration compared to EPO administration alone (p < 0.01).

Conclusion

EPO, GM-CSF and their combination enhance liver regeneration after hepatectomy in rats when administered perioperatively. However their combination has a weaker effect on liver regeneration compared to EPO alone. Further investigation is needed to assess the exact mechanisms that mediate this finding.

Dual effect of erythropoietin on liver protection and regeneration after subtotal hepatectomy in rats

The only currently offered curative option for many patients with primary or secondary liver tumors is the resection of hepatic tumors. The aim of this study was to evaluate the role of recombinant human erythropoietin (rhEPO) in liver protection and regeneration after subtotal hepatectomy in rats. Rats undergoing 70% hepatectomy received an intraperitoneal injection of saline (control) or rhEPO (4 U/g) 30 minutes prior to resection. Liver function was assessed by the measurement of the international normalized ratio (INR) levels, and hepatic injury was assessed by serum alanine aminotransferase and aspartate aminotransferase levels. Hepatic apoptosis was assessed by intrahepatic caspase-3 activity and morphological criteria. The regeneration capacity of remnant livers was assessed over 7 days with the regenerated liver/body weight ratio, immunohistochemistry markers of cell proliferation (Ki-67) and angiogenesis (von Willebrand factor), and phosphorylated extracellular signal-regulated kinase signaling. Two and 4 days after subtotal hepatectomy, the regenerated liver/body weight ratio was significantly higher in animals treated with rhEPO versus the control group (P < 0.005). Serum liver enzymes and INR levels on days 2 and 4 post-hepatectomy were significantly lower in animals pretreated with rhEPO in comparison with the control group (P < 0.005). No statistically significant difference was noted in intrahepatic hepatic caspase-3 activity, immunohistochemistry for caspase-3, or a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay between the hepatectomized groups. In the rhEPO-pretreated group, the mitotic index, Ki-67 and von Willebrand factor expression, and extracellular signal-regulated kinase activity were significantly higher on day 2 post-hepatectomy (P < 0.05) in comparison with the control group. In conclusion, rhEPO treatment may offer a unique beneficial dual-function strategy for hepatic protection and regeneration immediately after subtotal hepatectomy in rats.