Response of fibronectin to liver regeneration after hepatectomy

Decellularized liver extracellular matrix and thrombin loaded biodegradable TOCN/Chitosan nanocomposite for hemostasis and wound healing in rat liver hemorrhage model

During deep noncompressible wound management, surgery, transplantation or post-surgical hemorrhage, rapid blood absorption and hemostasis are the key factors to be taken into consideration to reduce unexpected deaths from severe trauma. In this study, a novel hemostatic biodegradable nanocomposite was fabricated where decellularized liver extracellular matrix (L-ECM) was loaded with two natural polymers (oxidized cellulose and chitosan) in association with thrombin. Plant-derived oxidized cellulose nanofiber (TOCN) and Chitosan (CS) from deacylated chitin were self-assembled with each other by electrostatic interactions. ECM was prepared by the whole tissue decellularization process and incorporated into the composite as a source of collagen and other integrated growth factors to promote wound healing. Thrombin was also anchored with the polymers by freeze drying for enhanced hemostatic efficiency of the composite. This study is the first of its kind to report non-solubilized L-ECM and thrombin loaded TOCN and CS composite, CN/CS/EM-Th for faster hemostasis effect in a rat tail amputation (~71 s) and liver avulsion model (~41 s). Furthermore, excellent liver wound regeneration efficacy was observed in-vivo in comparison to the commercially available oxidized regenerated cellulose product SURGICEL gauge.

Infusion of Human Mesenchymal Stem Cells Improves Regenerative Niche in Thioacetamide-Injured Mouse Liver

BACKGROUND

This study investigated whether xenotransplantation of human Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) reduces thioacetamide (TAA)-induced mouse liver fibrosis and the underlying molecular mechanism.

METHODS

Recipient NOD/SCID mice were injected intraperitoneally with TAA twice weekly for 6 weeks before initial administration of WJ-MSCs. Expression of regenerative and pro-fibrogenic markers in mouse fibrotic livers were monitored post cytotherapy. A hepatic stallate cell line HSC-T6 and isolated WJ-MSCs were used for in vitro adhesion, migration and mechanistic studies.

RESULTS

WJ-MSCs were isolated from human umbilical cords by an explant method and characterized by flow cytometry. A single infusion of WJ-MSCs to TAA-treated mice significantly reduced collagen deposition and ameliorated liver fibrosis after 2-week therapy. In addition to enhanced expression of hepatic regenerative factor, hepatocyte growth factor, and PCNA proliferative marker, WJ-MSC therapy significantly blunted pro-fibrogenic signals, including Smad2, RhoA, ERK. Intriguingly, reduction of plasma fibronectin (pFN) in fibrotic livers was noted in MSC-treated mice. In vitro studies further demonstrated that suspending MSCs triggered pFN degradation, soluble pFN conversely retarded adhesion of suspending MSCs onto type I collagen-coated surface, whereas pFN coating enhanced WJ-MSC migration across mimicked wound bed. Moreover, pretreatment with soluble pFN and conditioned medium from MSCs with pFN strikingly attenuated the response of HSC-T6 cells to TGF-β1-stimulation in Smad2 phosphorylation and RhoA upregulation.

CONCLUSION

These findings suggest that cytotherapy using WJ-MSCs may modulate hepatic pFN deposition for a better regenerative niche in the fibrotic livers and may constitute a useful anti-fibrogenic intervention in chronic liver diseases.

Assessment of Circulating Protein Signatures for Kidney Transplantation in Pediatric Recipients

Identification and use of non-invasive biomarkers for kidney transplantation monitoring is an unmet need. A total of 121 biobanked sera collected from 111 unique kidney transplant (KT) patients (children and adolescent) and 10 age-matched healthy normal controls were used to profile serum proteins using semi-quantitative proteomics. The proteomics data were analyzed to identify panels of serum proteins that were specific to various transplant injuries, which included acute rejection (AR), BK virus nephropathy (BKVN), and chronic allograft nephropathy (CAN). Gene expression data from matching peripheral blood mononuclear cells were interrogated to investigate the association between soluble serum proteins and altered gene expression of corresponding genes in different injury phenotypes. Analysis of the proteomics data identified from different patient phenotypes, with criteria of false discovery rate <0.05 and at least twofold changes in either direction, resulted in a list of 10 proteins that distinguished KT injury from no injury. Similar analyses to identify proteins specific to chronic injury, acute injury, and AR after kidney transplantation identified 22, 6, and 10 proteins, respectively. Elastic-Net logistic regression method was applied on the 137 serum proteins to classify different transplant injuries. This algorithm has identified panels of 10 serum proteins specific for AR, BKVN, and CAN with classification rates 93, 93, and 95%, respectively. The identified proteins could prove to be potential surrogate biomarkers for routine monitoring of the injury status of pediatric KT patients.

Effect of packed red blood cells transfusion on plasma fibronectin during liver resection

Our study aimed at evaluating the effect of blood transfusion - allogeneic or autologous - on plasma levels of fibronectin during liver resections. Thirty-five patients scheduled for liver resection were randomly allocated to receive autologous (group autologous blood transfusion (ABT), n= 19) or allogeneic (homologous) (homologous blood transfusion (HBT), n= 16) packed red blood cell to maintain serum haemoglobin concentration above 9 g. Serum levels of fibronectin were measured before induction of anaesthesia, at the end of operation and at first, third and sixth postoperative day. Perioperative morbidity and survival rate were also recorded. Serum fibronectin levels were significantly higher (P < 0.05) in the autologous group than in the allogeneic, at the first (134 +/- 49 microg mL(-1) vs. 89 +/- 31 microg mL(-1)) and third (178 +/- 51 microg mL(-1) vs. 96 +/- 41 microg mL(-1)) postoperative day. No differences in survival and complication rate between the two groups were observed. Concentrations of serum fibronectin seem to be adversely affected by allogeneic blood transfusion during liver resection surgery, although this does not seem to affect patients' morbidity and mortality.

Preoperative regional maximal removal rate of technetium-99m-galactosyl human serum albumin (GSA-Rmax) is useful for judging the safety of hepatic resection

BACKGROUND

For hepatic resection, the preoperative estimation of hepatic functional reserve in the predicted remnant liver may be more important than that of the entire liver. We evaluated the maximal removal rate of technetium-99m-galactosyl-human serum albumin (GSA-Rmax) in the remnant.

METHODS

One hundred and seventy-eight patients were admitted for elective hepatectomy. Conventional liver function, and 15-minute retention rate of indocyanine green (ICGR15) were carried out preoperatively. The GSA-Rmax was calculated according to a radiopharmacokinetic model; then we used the single photon emission computed tomography images to calculate the regional GSA-Rmax in the predicted residual liver (GSA-RL), depending on the operative procedures. The volume of the predicted residual liver (LV-RL) was calculated on the basis of computed tomography images.

RESULTS

The preoperative LV-RL correlated well with the GSA-RL in patients with normal liver; however, there was no such correlation in those with chronic hepatitis or cirrhosis. All of 7 postoperative hyperbilirubinemia occurred in the patients with GSA-RL < 0.15. Two patients died of postoperative liver failure 1 to 2 months after the operation. These 2 patients had GSA-RL values of 0.078 and 0.090, respectively, and severe discrepancies between the GSA-Rmax in the remnant liver and ICGR15.

CONCLUSIONS

We concluded that GSA-RL may be useful for determining the procedure of hepatectomy and that the value should be maintained at greater than 0.15 to avoid postoperative hyperbilirubinemia or hepatic failure.

FIBRONECTIN PREVENTS D-galactosamine/Lipopolysaccharide-induced lethal hepatic failure in mice

Plasma fibronectin (FN) has a broad range of biological functions involved in cellular adhesion, motility, differentiation, apoptosis, hemostasis, wound healing, reticuloendothelial system function, and ischemic injury. In this study, we examined the effects of FN on D-galactosamine (GalN)/lipopolysaccharide (LPS)-induced fulminant liver failure in mice. Female Balb/c mice received intraperitoneal injection of 50 mug/kg of LPS and 400 mg/kg of GalN simultaneously. Thirty minutes before GalN/LPS administration, human plasma FN (FN group) or the same dose of human serum albumin (control group) was given intravenously. GalN/LPS induced a marked decrease in plasma FN, which was reversed by FN pretreatment. The survival rate of the FN group was markedly improved in a dose-dependent manner compared with that of the control group (survival rate 0%). FN prevented increases in the concentrations of serum enzymes and total bilirubin related to liver injury. FN pretreatment significantly suppressed tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, and interleukin (IL)-6 levels, and enhanced IL-10 levels in serum and liver tissue compared with the control group. Moreover, TUNEL staining, caspase 3 and 8 activities, and necrosis in the remnant liver were significantly decreased in the FN-treated rats compared with the controls. Furthermore, FN pretreatment inhibited the activation of nuclear factor (NF)-kappaB and increased the expression of Bcl-xL protein in liver tissue. These results suggest that FN protected against GalN/LPS-induced liver failure by a mechanism involving inhibition of NF-kappaB activation, which caused down-regulation of TNF-alpha and involved up-regulation of IL-10, and elevation of Bcl-xL induced a blockage of apoptotic signals, by which apoptosis of hepatocytes caused by GalN/LPS was suppressed.

Relationship between expression of cyclin D1 and impaired liver regeneration observed in fibrotic or cirrhotic rats

BACKGROUND AND AIM

The mechanisms responsible for impaired regenerative ability after hepatic resection observed in chronic liver disease are not fully understood. We have examined the relationships between an altered expression of cell cycle-related proteins in regenerating liver after partial hepatectomy and the impaired regenerative process observed in fibrotic and cirrhotic rats.

METHODS

We performed 70% partial hepatectomy in both control and porcine serum-induced fibrotic rats, and 45% partial hepatectomy in thioacetamide-induced cirrhotic rats because of the high mortality associated with 70% partial hepatectomy. Liver regeneration was monitored by proliferating cell nuclear antigen labeling index and the expression of G1 regulatory cell cycle-related proteins was determined by immunoblot analysis.

RESULTS

Compared with controls, hepatocyte DNA synthesis, and induction of cyclin D1 and p21(CIP1) proteins were delayed but not suppressed in porcine serum-induced fibrotic rats and markedly inhibited in thioacetamide-induced cirrhotic rats. p27(KIP1) protein levels were unaffected by partial hepatectomy and did not differ among all three groups.

CONCLUSION

Two distinct rat models of liver fibrosis and cirrhosis showed markedly different proliferative responses after partial hepatectomy. The delay or failure of cyclin D1 induction, but not the increase of p21(CIP1) or p27(KIP1) might be responsible for their impaired liver regeneration.

Gene expression differences of regenerating rat liver in a short interval successive partial hepatectomy

AIM: To identify the genes expressed differentially in the regenerating rat liver in a short interval successive partial hepatectomy (SISPH), and to analyze their expression profiles.

METHODS: Five hundred and fifty-one elements selected from subtractive cDNA libraries were conformed to a cDNA microarray (cDNA chip). An extensive gene expression analysis following 0-36-72-96-144 h SISPH was performed by microarray.

RESULTS: Two hundred and sixteen elements were identified either up- or down-regulated more than 2-fold at one or more time points of SISPH. By cluster analysis and generalization analysis, 8 kinds of ramose gene expression clusters were generated in the SISPH. Of the 216 elements, 111 were up-regulated and 105 down-regulated. Except 99 unreported genes, 117 reported genes were categorized into 22 groups based on their biological functions. Comparison of the gene expression in SISPH with that after partial hepatectomy (PH) disclosed that 56 genes were specially altered in SISPH, and 160 genes were simultaneously up-regulated or down-regulated in SISPH and after PH, but in various amount and at different time points.

CONCLUSION: Genes expressed consistently are far less than that intermittently; the genes strikingly increased are much less than that increased only 2-5 fold; the expression trends of most genes in SISPH and in PH are similar, but the expression of 56 genes is specifically altered in SISPH. Microarray combined with suppressive subtractive hybridization can in a large scale effectively identify the genes related to liver regeneration.

Mixture of N-carbamoyl-L-glutamate plus L-arginine can protect rats with liver cirrhosis from acute ammonia intoxication

BACKGROUND/AIMS

We earlier reported that N-carbamoyl-L-glutamate (CG) plus L-arginine (Arg) protected normal and 70% hepatectomized rats from intoxication by a lethal or sub-lethal dose of ammonium acetate, respectively. In the present study, the protective effect of these compounds on cirrhotic rats was assessed.

METHODS

CG plus Arg were administered prior to the injection of a sub-lethal dose of ammonium acetate into dimethylnitrosamine-induced cirrhotic rats. Control rats were given phosphate-buffered saline (PBS) instead of the mixture. The behavior of the rats was monitored until the time of sacrifice. Blood ammonia level, blood urea nitrogen (BUN) and liver carbamoylphosphate synthetase I (CPS I) activity were determined.

RESULTS

Pretreatment of rats with the mixture of CG plus Arg could significantly lower the blood ammonia level (P<0.05), increase the activity of CPS I (P<0.05), improve abnormal behavior associated with ammonia intoxication (P<0.05), and increase BUN (P<0.05), as compared with the PBS-injected control group. There were significantly close correlations between (1) the increase of CPS I activity; (2) the improvement of abnormal behavior; (3) the increase of BUN; and (4) the decrease of the blood ammonia level.

CONCLUSIONS

A mixture of CG plus Arg could protect rats with liver cirrhosis from acute ammonia intoxication.

Different responses to surgical stress between extra domain A+ and plasma fibronectins

1. Fibronectins (FN) are believed to have a role in haemorheological perturbation associated with tissue damage. Fibronectins exist in two antigenically related forms, plasma (p) and cellular fibronectin, which has the extra domain sequences A (EDA) or B (EDB). The present study was designed to determine changes in plasma p-FN and EDA + FN under different types of surgical stress. 2. Sixty-two patients were divided into three groups: (i) group A, 33 patients undergoing hepato-pancreato-biliary surgery; (ii) group B, 19 patients undergoing laparoscopic cholecystectomy; and (iii) group C, 10 patients with postoperative complications. Plasma FN and EDA + FN levels were measured in these patients undergoing different types of surgical operation and either with or without liver cirrhosis using an enzyme-linked immunosorbent assay. 3. After surgery, a significant decrease in p-FN levels and a significant increase in EDA + FN levels was observed in all patient group compared with pre-operative levels. The duration of increased EDA + FN levels, but not p-FN levels, in group A patients was significantly longer than in group B patients. Although changes in p-FN levels between patients with and without liver cirrhosis were significantly different, there were no significant differences in the EDA + FN levels between these two patient groups. 4. In conclusions, EDA + FN and p-FN levels were found to exhibit opposite responses to surgical stress. Furthermore, with greater surgical stress, greater increases in EDA + FN levels were seen. The presence of liver cirrhosis had no significant effect on EDA + FN levels during the perioperative period; however, p-FN levels were significantly affected. 5. Thus, it is suggested that plasma EDA + FN levels reflect the magnitude of surgical stress more closely than do p-FN levels.

Stimulation of liver regeneration and function after partial hepatectomy in cirrhotic rats by continuous infusion of recombinant human hepatocyte growth factor

BACKGROUND/AIMS

Radical resection is accepted as one of the most curative treatments for hepatocellular carcinoma. However, most patients have coexisting cirrhosis and their liver function is usually impaired. It is therefore important to stimulate the regeneration and function of the remnant cirrhotic liver after hepatectomy. Hepatocyte growth factor is a potent mitogen that has been suggested to play a crucial role in liver regeneration.

METHODS

In this study, we performed 45% hepatectomy in rats with cirrhosis induced by thioacetamide, and administered recombinant human hepatocyte growth factor (rhHGF) with dextran sulfate by continuous infusion into the jugular vein with an infusion pump.

RESULTS

rhHGF stimulated an increase in the wet weight of the remnant liver compared with untreated control rats. The proliferating cell nuclear antigen labeling index showed that this increase resulted from the stimulation of DNA synthesis. Serum levels of liver enzymes increased after hepatectomy, but returned to the prehepatectomy level more rapidly in rhHGF-treated rats than in controls. rhHGF increased hepatic protein synthesis above prehepatectomy levels and also markedly increased the serum levels of hepatic lipid metabolites.

CONCLUSIONS

These results demonstrate that continuous intravenous infusion of rhHGF enhances the growth and function of the remnant liver in rats with cirrhosis after partial hepatectomy. Therefore, rhHGF may be useful after hepatic resection in patients with cirrhosis.

Liver regeneration: methods for monitoring and their applications

Liver regeneration is an essential component of the reparative process following liver injury and surgical resection. It can be assessed by different tissue-based tests such as liver weights, mitotic counts, DNA contents and synthesis rates, immunohistochemical staining of nuclear antigens, gene expressions and certain protein levels or various serum-based tests that largely consist of specific enzyme determinations or documentation of certain proliferation markers. Although the simplest tissue-based test of liver regeneration is measurement of liver weights, these determinations are influenced by the extent of deposition of various materials not directly related to regeneration, such as lipids, glycogen and blood volumes. Because mitosis constitutes a very short segment of the cell cycle, mitotic counts are infrequently observed by light microscopy. Thymidine and BrdU incorporation into DNA are the reference tools for studying DNA synthesis, but their use requires pre-injection with radioactive isotopes or nucleotides which render them impractical for human studies. Flow cytometry is an accurate and objective method of monitoring hepatic regenerative activity but requires sophisticated equipment that is not generally available in many laboratories. Immunohistochemical staining for nuclear antigens (Ki-67, proliferating cell nuclear antigen [PCNA], DNA polymerase alpha and nucleolar organizer region [NOR] proteins) are acceptable and commonly used methods of monitoring regenerative activity but are subject to inter- and intra-observer variability. Gene expression rates such as Histone-3 mRNA abundance are hampered by the relatively low rates of gene transcription and the need for recombinant DNA technology. Protein and enzyme levels in liver tissues, such as putrescine, ornithine decarboxylase and thymidine kinase, are not precise and are confounded by the nutritional status of the host. While PCNA protein levels measured by immunoblot hold promise as a simple, accurate and reproducible marker of liver regeneration, additional studies are required to determine if this is a valid marker of regenerative activity in various models of hepatic injury and in humans. Of the serum-based determinations: thymidine kinase, ornithine decarboxylase, fibronectin, alpha fetoprotein, and early pregnancy factor offer practical and non-invasive tools to monitor liver regeneration, but the sensitivity and specificity of these tests have yet to be determined. In conclusion, many tissue and serum-based methods have been employed in clinical and experimental studies to assess liver regeneration; however, a gold standard has yet to be identified. Because of the disadvantages inherent in each method, and until a new, more accurate marker is identified, clinicians and scientists should incorporate a minimum of two independent markers in studies of liver regeneration.

The accumulation and energy load of exogenous lipids in cirrhotic rat liver after partial hepatectomy

BACKGROUND

The suitability of three energy substrates, glucose, medium-chain triglycerides (MCT) and long-chain triglycerides (LCT), was studied in cirrhotic rats after a partial hepatectomy.

METHODS

Rats with thioacetamide-induced cirrhosis underwent a 70% hepatectomy, and were divided into three groups. Each group was then injected with 14C-labeled glucose, 14C-labeled MCT or 14C-labeled LCT, respectively. The subsequent tissue distribution of 14C and the cumulative amount of expired 14CO2 were determined. In a second experiment, the 70%-hepatectomized cirrhotic rats received total parenteral nutrition (TPN). The source of the nonprotein calories was 100% glucose (glucose group), 60% MCT + 40% glucose (MCT group), and 60% LCT + 40% glucose (LCT group). The adenylate energy charge and the glycogen content in the liver remnant were determined.

RESULTS

The tissue distribution of 14C revealed that the fat emulsions accumulated preferentially in the liver. One hour after the partial hepatectomy, the concentration of 14C-labeled MCT in the liver remnants was threefold higher than in sham-operated controls. Similarly, the concentration of 14C-labeled LCT was twofold higher. The adenylate energy charge in the glucose group with TPN recovered to preoperative levels within 1-hour after the partial hepatectomy, whereas the LCT group with TPN showed a 24-hour delay in their recovery. The MCT group with TPN exhibited an intermediate time course.

CONCLUSIONS

It is suggested that the specific accumulation of MCT and especially LCT emulsions in the cirrhotic liver remnant acts as an energy load rather than an energy substrate.

Effect of hepatocyte volume on energy status in the cirrhotic rat liver

To evaluate the effect of reduced hepatocyte volume on liver energy status, the relationship between the morphologically quantified hepatocyte volume and biochemical parameters, and the difference in nuclear density between the parenchyma and stroma were assessed in rat livers with thioacetamide-induced cirrhosis. The ratio of hepatocytes to whole liver tissue, defined as the 'hepatocyte area ratio', and the nuclear densities of the parenchyma and stroma were calculated microscopically with an image analysing system. Adenine nucleotide, protein and DNA contents, and the ornithine carbamoyltransferase activity in the liver were assayed. In the cirrhotic group, adenine nucleotide content, protein content and ornithine carbamoyltransferase activity were positively correlated with the hepatocyte area ratio, whereas DNA content was negatively correlated with this ratio. The adenylate energy charge of the cirrhotic liver was maintained at a constant level regardless of the ratio. Adenine nucleotide content, protein content and ornithine carbamoyltransferase activity per fractional 'hepatocyte area ratio' in cirrhotic livers were significantly lower than in control livers. The nuclear density of the stroma was significantly greater than that of the parenchyma. These results suggest that the lowered energy status in the cirrhotic liver is not caused by reduced hepatocyte volume but rather by impaired hepatocyte metabolism. In addition, the morphological measurement with an image analysing system was found to be useful for evaluating the effects of decreased hepatocyte volume on biochemical derangements in cirrhotic tissue.

Assessment of the fibrogenetic activity in chronic pancreatitis. The role of circulating levels of extracellular matrix components

Determination of circulating levels of extracellular matrix components has been proposed as a reliable method to assess the activity of fibrogenetic processes. Therefore, we aimed to analyze circulating levels of laminin, fibronectin, and procollagen III peptide (PIIIP) in patients with chronic pancreatitis (CP) and to correlate them with the morphological and functional stage, and duration of the disease. Thirty patients with CP and 18 healthy controls were studied. Serum PIIIP concentrations (RIA), but not fibronectin (RID) and laminin (RIA), were abnormally high in 8 patients with CP. No correlation was found between circulating levels of extracellular matrix components and both functional and morphological stage and duration of CP. Nevertheless, patients with elevated serum PIIIP levels tend to have a more advanced CP (morphological and functional changes) than those with normal levels after a similar duration of the disease. We hypothesize that whereas functional and morphological findings reflect the cumulative effect of chronic inflammation on the pancreas, serum PIIIP concentrations would reflect the activity of the fibrogenetic process within the gland at the time of sampling. The results shown in the present study may be considered a starting point for longitudinal studies that examine the relationship between serum PIIIP or other markers for fibrogenetic activity and evolution of CP.