Evidence for and characterization of a liver cell proliferation factor from blood plasma of partially hepatectomized rats

Liver growth factor as a tissue regenerating factor in neurodegenerative diseases

Liver growth factor (LGF) is a hepatic mitogen purified by our group in 1986. In the following years we demonstrated its activity both in "in vivo" and "in vitro" systems, stimulating hepatocytes mitogenesis as well as liver regeneration in several models of liver injury. Furthermore, we established its chemical composition (albumin-bilirubin complex) and its mitogenic actions in liver. From 2000 onwards we used LGF as a tissue regenerating factor in several models of extrahepatic diseases. The use of Liver growth factor as a neural tissue regenerator has been recently protected (Patent No US 2014/8,642,551 B2). LGF administration stimulates neurogenesis and neuron survival, promotes migration of newly generated neurons, and induces the outgrowth of striatal dopaminergic terminals in 6-hidroxydopamine-lesioned rats. Furthermore, LGF treatment raises striatal dopamine levels and protects dopaminergic neurons in hemiparkinsonian animals. LGF also stimulates survival of grafted foetal neural stem cells in the damaged striatum, reduces rotational behaviour and improves motor coordination. Interestingly, LGF also exerts a neuroprotective role both in an experimental model of cerebellar ataxia and in a model of Friedrich´s ataxia. Microglia seem to be the cellular target of LGF in the CNS. Moreover, the activity of the factor could be mediated by the stimulation of MAPK´s signalling pathway and by regulating critical proteins for cell survival, such as Bcl-2 and phospho-CREB. Since the factor shows neuroprotective and neurorestorative effects we propose LGF as a patented novel therapeutic tool that may be useful for the treatment of Parkinson´s disease and cerebellar ataxias. Currently, our studies have been extended to other neurological disorders such as Alzheimer's disease (Patent No: US 2014/0113859 A1).

Biogenesis of hepatic acute-phase response to trauma

The bioorganic pathway(s) of hepatic acute-phase response in rat to single and compounded traumata triggered either by chemical or physical injury has been re-evaluated for the purpose of advancing a better understanding of mechanisms of hepatic regeneration. These insights would be useful in cases of liver cirrhosis and end-stage liver diseases and may allow avenues of surgical management other than liver transplantation. Mechanisms of acute-phase response in rat to a single inflammatory stimulus, e.g. intoxication with phalloidin, alpha-amanitin, subcutaneous administration of carageenan, subcutaneous implantation of Yoshida sarcoma or i.p. administration of Zajdela ascites are discussed and compared with (a) acute-phase response to intoxication by various factors leading to the development of liver cirrhosis, and (b) acute-phase response of nascent hepatocytes where hepatic regenerative activities were induced by chemical intoxication or surgical partial hepatectomy. Interestingly, hepatic acute-phase response was not limited only to these injuries outlined above but also to psychological conditions.

Artificial liver support: the pipe dream of today should be the reality of the near future

The title of this article is taken from an interesting Letter to the Editor entitled 'Artificial liver support-Pipe dream or reality' by Cattral and Levy of the Toronto Hospital, Canada, published in the New England Journal of Medicine 1994, in which the authors persuasively propose possibilities of artificial liver support and suggest its advantages. We find that their suggestions agree with the core of our thoughts on this subject. The present article deals with the concept of implanting livers taken from humans, primates or non-primates (e.g. hog) into patients in parallel with their own metabolically fatigued or cirrhotic livers, with minimal surgical manipulation, as a prelude to total artificial liver support via a liver dialysis device. While the possibility exists that the host liver may recover function, a donor liver, whether implanted into the patient's abdomen or connected in vitro to the patient's circulatory system extracorporeally, may provide the host liver respite and a period for recovery and proliferation, if possible. Once recovery is under way, the donor liver may be removed and the patient will not experience the usual risks of rejection and the necessary side-effects of immunosuppression associated with conventional full hepatectomy and donor transplantation. The viability of a liver implantation model in rats is correlated in this article with hepatic acute phase response.

Comparison of thermally oxidized lipids and acetaminophen with concurrent consumption of ethanol as inducers of liver cirrhosis

The mechanism(s) of liver damage initiated by ingestion of toxic components of thermally oxidized lipids was compared in a rat model with the documented mechanisms of hepatic failure and necrosis initiated by acetaminophen. Acetaminophen (50 mg/kg body weight) or oxidized lipids (0.15 ml oxidized trilinolein or 1.05 ml oxidized butter oil per rat) were intubated at 12-h intervals to rats. Treated rats were allowed free access to food and water containing 3% ethanol. Changes in relative concentration of acute-phase plasma proteins, determined by two-dimensional (2D) immunoelectrophoresis, were taken as a marker of liver damage. In contrast to simple inflammation, acute-phase plasma proteins in this study disproportionately increased or decreased as histological damage of the liver due to intubation oxidized lipids or acetaminophen. Histological examination of liver of rats intoxicated with oxidized lipids revealed severe liver cirrhosis at the end of the trial, where the remaining viable hepatocytes were separated in a matrix of collagen. [3H1]Thymidine incorporation in hepatic DNA of acetaminophen or oxidized lipid intoxication increased in the early stages of intoxication, indicative of regenerative activity of the liver. Further progression of the cirrhosis inhibited continued liver regeneration and [3H1]thymidine incorporation into hepatic DNA. The cirrhotic liver at this stage failed to regenerate to the original mass upon 75% partial hepatectomy. Therefore, it may be concluded that hepatic necrosis produced by oxidized lipids or by acetaminophen may have similar mechanisms.

Beneficial effect of hepatic stimulatory substances on the survival of intrasplenically transplanted hepatocytes

Intrasplenic hepatocyte transplantation has been demonstrated to have a tentative role in treating experimental liver disease, but methods for promoting the rapid proliferation of intrasplenic hepatocytes are still quite limited. In this study, hepatic stimulatory substances (HSS) obtained from regenerating porcine livers were injected directly into the subcutaneously translocated spleens of recipient rats that had received intrasplenic hepatocyte transplantation. The clusters of intrasplenic hepatocytes contained more than 100 cells, and formed cord structures at 2 wk after transplantation, and the hepatocytes still survived at 6 wk in the HSS-treated rats. In contrast, the clusters contained less than 10 hepatocytes at 2 wk after transplantation, and no surviving hepatocytes was observed at 4 and 6 wk in control rats. Additionally, marked proliferation of bile ductular-like structures appeared around the clusters of surviving hepatocytes in the splenic red pulp of the HSS-treated rats, but were not found in control rats at 4 and 6 wk after transplantation.

Partially hepatectomized rats: a model for the study of the effect of toxins on the plasma protein profiles of nascent hepatocytes

A useful framework is proposed for unifying the synthesis of plasma proteins and their degradation by, or release from, liver cells of intact and partially hepatectomized rats, in which synthesis and release of acute-phase plasma proteins occur in synchrony with the internalization and catabolism of plasma and extracellular proteins. The catabolism of proteins and other hepato-intracellular glycoproteins during sepsis or trauma is essential to provide constituent amino acids and carbohydrates for the synthesis of acute-phase plasma proteins. Increases in the plasma levels of acute-phase response proteins in sham-operated rats reached a maximum between 1 and 2 d after mock surgery, and had returned virtually to control levels within 6 d. By contrast, acute-phase proteins in the plasma of partially hepatectomized rats were decreased by 10-20% of their initial values after 24 h. A maximum acute-phase response on d 7 after the operation was characterized by an increase of 181, 445, and 19% for alpha-1-acid glycoprotein, hepatoglobin, and hemopexin, whereas other acute-phase proteins remained below control levels, for example, by 11, 25, and 38% for albumin, transferrin, and prealbumin, respectively. This delayed response suggests that the nascent liver cells had inherited the capacity of the parent cells to respond to inflammatory signal and had synthesized acute-phase plasma proteins. Accordingly, a time frame for the application of toxin to nascent hepatocytes is suggested. An increased activity (300 +/- 50%) for both bound and free neuraminidase in remnant liver tissue 19 h post partial hepatectomy suggested that hepatic regenerating factor(s) were produced in liver tissue via the hepatic bound and/or free neuraminidase-mediated desialylation of humoral substrates. By contrast, circulating levels of lysosomal enzymes alpha-fucosidase and beta-N-acetyl-D-glucosaminidase were increased marginally after 24 h but had returned nearly to control levels after 7 d, suggesting that lysosomal acid hydrolases do not play a major role in regenerative DNA synthesis, mitosis, or in the synthesis of acute-phase plasma proteins.

Effects of nucleosides and a nucleotide on DNA and RNA syntheses by the salvage and de novo pathway in primary monolayer cultures of hepatocytes and hepatoma cells

Studies were made on the effects of inosine, guanosine 5'-monophosphate (GMP), cytidine, uridine, thymidine, and their mixture (4:4:4:3:1, OG-VI) on DNA and RNA syntheses in primary monolayer cultures of normal hepatocytes and cultures of hepatoma cells, AH130, to use these compounds for total parenteral nutrition. Addition of an appropriate amount of inosine, GMP, uridine, or thymidine to primary cultures of hepatocytes enhanced both DNA and RNA syntheses by the salvage and de novo pathways. Cytidine appeared to have lower optimal concentration for enhancing these pathways. The OG-VI mixture also enhanced the syntheses of DNA and RNA, but the composition of the mixture was not optimal. Additions of inosine, GMP, uridine, and thymidine to cultured hepatoma cells also enhanced their DNA and RNA syntheses, but the cells consumed more of the added nucleic acid compounds than hepatocytes did. Addition of cytidine had no effect on proliferation of the cells. The OG-VI mixture at relatively higher concentration inhibited the syntheses of DNA and RNA by hepatoma cells. Addition of high concentrations of nucleic acid compounds was found to suppress the proliferation of both hepatocytes and hepatoma cells. These results suggest that addition of optimal amounts of nucleic acid compounds such as nucleosides and nucleotides would enhance growth of hepatocytes, particularly during liver regeneration, but that they may also enhance proliferation of tumor cells in the liver.

Biological efficacy of partial hepatectomy and hepatopoietin in long-term selenium-deficient mice

After partial hepatectomy the normal low proliferation rate of hepatocytes increases dramatically. This is based on a feed-back system whose central link is a liver cell proliferation hormone, the so-called hepatopoietin. This glycoprotein is organ-specific but not species-specific, i.e. an extract from rats is also active in mice. In order to examine the influence of selenium on liver cell proliferation, male albino NMRI mice were fed a selenium-deficient diet containing less than 10 ppb Se for at least 2 months (Se-). In the plasma protein profile and in the basic DNA synthesis rate of Se(-)-animals, no significant changes were observed compared to controls. However, liver cell proliferation induced by hepatopoietin or by partial hepatectomy was increased about 3-fold in Se-deficient mice. We assume a compensated metabolic Se-deficiency state in mice under these nutritional conditions, which leads to expression of enhanced metabolic capacity when induced by stress.

Inhibition by the mushroom toxins alpha-amanitin and phalloidin of hepatopoietin-induced 3H-thymidine incorporation into rat liver DNA and of plasma protein production in hepatocyte cultures

In primary cultures of rat hepatocytes the induction of 3H-thymidine uptake into DNA of liver cells by the liver cell proliferation factor hepatopoietin demonstrates that this factor is active not only in vivo but also in vitro. Addition of the mushroom toxins alpha-amanitin or phalloidin to liver cell culture decreased the uptake of 3H-thymidine into hepatocytes (in the absence or presence of hepatopoietin) as well as the attachment of the hepatocyte cultures. Mushroom toxins also inhibited the production of plasma proteins in hepatocyte cultures. The inhibition, observed at toxin concentrations from 10(-5) to 10(-7) M, was dose-dependent. At low concentrations of phalloidin the inhibition appears to be selective for certain proteins.

DNA synthesis in exocrine and endocrine pancreas after partial hepatectomy in Syrian golden hamsters

3H-thymidine autoradiography showed an enhanced DNA synthesis in acinar and islet cells of pancreas after partial hepatectomy in syrian golden hamsters. A significant nuclear labeling index of acinar cells was observed between 48 and 84 h and reached control levels by 120 h. An increased labeling index of islet cells was also observed, however, this increase was not statistically significant. These results indicate growth factor(s) produced after partial hepatectomy is capable of inducing DNA synthesis in pancreas.

Purification of a liver DNA-synthesis promoter from plasma of partially hepatectomized rats

A protein was isolated from plasma of partially (70%) hepatectomized rats that, injected in mice, increases the uptake of [3H]thymidine by liver DNA by 200-300% over that by injected control saline. The purification procedure consists essentially of three chromatography steps, employing Sephadex G-75, DEAE-cellulose and hydroxyapatite. The hepatic promoter (HP) preparation shows a single band in SDS/polyacrylamide (15%)-gel electrophoresis (silver stained), with an Mr of 64 000; its activity is suppressed by trypsin or pepsin and is unaffected by deoxyribonuclease or ribonuclease. On injection into mice (150 ng/mouse), it increases the mitotic index of the liver. It shows organ-specificity, acting on liver but not on spleen, kidney, lung or brain. In primary liver cultures, it produces an increase in uptake of [3H]thymidine into DNA in the range 1-10 ng/ml. In this system in vitro, it increases the uptake of 22Na+ immediately after addition.

Purification and partial characterization of a liver cell proliferation factor called hepatopoietin

The purification and partial characterization of a liver cell proliferation factor called hepatopoietin are described. Hepatopoietin was isolated from remnant livers or blood plasma of partially hepatectomized rats and purified approximately 13,000-fold. The stokes radius was 2.65 +/- 0.2 nm and the apparent molecular weight was calculated to be 38,000 +/- 5,000 D. Hepatopoietin is a heat-stable glycoprotein and is organ specific but species nonspecific. In vivo it stimulates about three to four times the DNA synthesis as well as the mitotic rate of the liver of normal rats after i.p. injection. Hepatopoietin is inactivated upon incubation with galactosidase or trypsin-chymotrypsin.

Regulation of hepatocyte proliferation. The feed-back system of hepatopoietin

After partial hepatectomy the low proliferation rate of hepatocytes increases dramatically. This is based on a feed-back system whose central link is a liver cell proliferation hormon, the so-called hepatopoietin. The hormon originates from the Peyer's patches: after their resection, the liver cell proliferation after partial hepatectomy decreases by about 80%. Hepatopoietin effects organ specific but species nonspecific.

Factors effective in reducing rat mortality due to acute liver failure as induced by D-galactosamine poisoning

Mortality from D-galactosamine hydrochloride (D-GalN)-induced acute liver failure (ALF) in rats can be reduced by (1) transplanting intact hepatocytes; (2) injecting cytosol from fractionated hepatocytes dispersed from a liver subjected to 70% hepatectomy 24 hr earlier (CYT-H); (3) injecting a cell-free supernate derived from cultured hepatocytes (SUP); or (4) injecting neuraminidase-treated plasma where the plasma is drawn 24 hr after donor rats are subjected to 70% hepatectomy (PHP-neu). These treatments are effective when administered 20-24 hr after D-GalN poisoning, but experiments to determine the alterations in mortality rates as a function of time of treatment in relation to poisoning have not been performed. Two experiments are reported here. In the first the survival of lethally poisoned rats was compared after intravenously injecting either SUP prepared from cultured hepatocytes of syngeneic adult or fetal rat sources, or CYT-H from syngeneic adult rats 20 hr after poisoning. Untreated rats, rats treated with culture media alone, or rats treated with CYT from a nonregenerating source had an 88-100% mortality, with all deaths occurring within 72 hr following poisoning. Improved survival followed all other treatments: 55% of the rats receiving adult SUP, 70% of the rats receiving fetal SUP, and 80% of the rats receiving CYT-H survived. In the second experiment the survival of poisoned rats was compared after injecting them with PHP-neu, PHP not treated with neuraminidase (PHP without neu), and neuraminidase-treated plasma from sham-operated rats (SP-neu) or normal, nonoperated rats (NP-neu) 20 hr after poisoning.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of polypeptide growth factors in normal and abnormal growth

In the preceding sections we have shown evidence that growth-promoting factors are involved in three basic situations. In normal embryonic development and function of mature organisms, growth factors such as NGF and EGF are of prime importance in supporting the necessary embryonic cell proliferation and the development of specific cell types. Other factors operate on subsets of mature cells during specialized functions such as inflammation. Included in this set would be factors such as CSF/MGF and Interleukin-2. Another basic function of growth factors has been shown to be wound repair and organ regeneration. This includes the well characterized PDGF and FGF as well as the various renotropic factors and liver growth factors. As these factors must operate in mature organisms with many different cell types and similar cell types in many locations, more specificity is needed than in embryonic growth. This has resulted in the organ specific factors such as the renotropins and in the unique delivery system of the PDGF. The recent discovery and characterization of the transforming growth factors has provided a possible connection between embryonic and normal developmental growth and the rapid cellular proliferation characteristic of tumor cells. The TGF not only interacts with receptors for normal growth factors such as EGF but are also detectable in low levels in normal tissue and embryos. The exact relationships between these various factors will have to await the determinations of more amino acid sequences for comparisons. The other tumor-related product, tumor angiogenesis factor, is also found in normal tissue and inflammatory reaction sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in plasma protein profiles in serum and in liver DNA synthesis of rats following administration of alpha-amanitin, phalloidin and/or carbon tetrachloride

The aim of the present study is to investigate the capacity of damaged rat liver cells to respond to a second inflammation by a change in plasma protein profile, while the first inflammatory process is in progress. Quantitation of these effects would be useful, especially in situations where patients are suffering from complications due to emergence of a new pathological factor. We therefore studied the effect of phalloidin on rat livers already made necrotic by oral intubation of CCl4. Our data showed that a decrease in acute-phase response does not necessarily always imply healing, but may also be indicative of a second pathological complication.