Change in the resistance of partially hepatectomized mice to transplanted tumors in the period of liver regeneration completion]

There were two inhibition periods of the growth of ascitic hepatoma 22a when its cells were transplanted intraperitoneally to partially hepatectomized A/he mice 1 to 12 days after the operation. The first inhibition took place when the transplantation was performed one day, and the second--3 to 10 days, after partial hepatectomy. The animals which were most resistant to this tumour (5 to 8 days after the operation) proved to be resistant, although to a lesser extent, to the intraperitoneal transplantation of sarcoma 37 and Ehrlich's adenocarcinoma.     

Kinetics of hematopoietic stem cells in the bone marrow of hepatectomized mice

Two-thirds of the liver was removed from (CBA X C57BL/6j) F1 female mice. A significant increase of the number of endogenous colonies count in the spleen of partially hepatectomized mice was observed on the 5-th day after the operation. This increase was not associated with the changes in the number of stem cells in the bone marrow as partial hepatectomy at different times after the operation exerted no effect on the number of colony-forming units (CF1) in the bone marrow.     

Metabolism of radiolabelled chylomicron lipids in intact and hepatectomized rats

Intact rats removed more radiolabelled triacylglycerol, cholesterol, and cholesterol ester but not phosphatidylcholine (PC) in the first 6 min than hepatectomized rats. There was no difference between intact and hepatectomized rats in the transfer of radiolabelled chylomicron lipids to other lipoproteins. Specific radioactivity measurements demonstrated a net transfer of PC (intact and hepatectomized rats) and unesterified cholesterol (intact rats only) onto both the low density lipoprotein/high density lipoprotein-1 (LDL/HDL1) and HDL2 fractions. [3H]Fatty acids were rapidly incorporated into blood cell phospholipids and into HDL and LDL cholesterol esters of both intact and hepatectomized rats. Substantial rearrangements of [3H]palmitate occurred during lipid uptake by liver.     

Partial hepatectomy aggravates cyclosporin A-induced neurotoxicity by lowering the function of the blood-brain barrier in mice

AimsCyclosporin A, a calcineurin inhibitor, produces neurotoxicity with relatively high frequency in organ-transplanted patients. The aim of the present study was to clarify whether acute liver failure (ALF) simulated to the transient liver dysfunction at an early phase after liver transplantation increases the susceptibility to cyclosporin A-induced neurotoxicity through the blood–brain barrier (BBB) dysfunction.Main methodsThe right internal, left lateral and left internal lobes in male ddy mice were surgically excised under sodium pentobarbital anesthesia. Effect of cyclosporin A on harmine-induced tremors was examined and BBB permeability to ³[H]cyclosporin A was assessed in partially (70%) hepatectomized mice at postoperative days 1, 3 and 7.Key findingsPatrial hepatectomy aggravated harmine-induced tremors. Cyclosporin A (50 mg/kg, i.p.) markedly augmented harmine-induced tremors in partially hepatectomized mice at postoperative day 1. Consistent with these behavioral findings, the brain uptake of ³[H]cyclosporin A in mice injected with ³[H]cyclosporin A into the jugular vein at postoperative day 1 was significantly increased by partial hepatectomy compared with sham operation.SignificanceOur results indicate that ALF increases BBB permeability to cyclosporin A by lowering the function of P-glycoprotein and tight junctions, consequently leading to augmentation of cyclosporin A-induced neurotoxicity. The possibility that cyclosporin A increases the risk of neurotoxicity including tremors at an early phase of liver transplantation must be considered.     

Effect of a deficiency in the mononuclear phagocyte system and the administration of yeast polysaccharide on the development of a heterotopic source of hematopoiesis

Mononuclear phagocyte system (MPS) deficiency was induced by repeated peritoneal lavage in (C57Bl x CBA) F1 mice. The animals were then used as donors or recipients in heterotopic bone marrow transplantation. Yeast polysaccharide (YP) produced by Cryptococcus luteolus strain 228 was injected weekly (25 mg/kg) during 30 days after bone marrow transplantation under the kidney capsule. Bone marrow transplantation from MPC-deficient mice to intact mice 30 days later resulted in no variations from the control in cellularity and ossicle weight. YP produced an increase in cellularity, but not in ossicle weight. In the opposite experimental scheme (transplantation from intact mice to MPS-deficient mice) an increase in both cellularity and weight was not noticed. YP injections in this case resulted in the reduction of heterotopic organ size to the control level. Possible mechanisms of this phenomenon are discussed.     

Demonstration of the lymphokine mechanism of the reinforcement of lymphoid proliferation during liver regeneration in mice

Changes in the ability of mouse splenocytes to proliferate early after partial hepatectomy have been studied. Proliferative activity of mouse splenocytes in mixed lymphocyte culture and in spontaneous proliferation in vitro test increased within 4, 17 and 24 hours after operation as compared with pseudo-operated control. After 4 hours of cultivation splenocytes of partially hepatectomized mice excreted into culture medium factor(s) that enhanced proliferative activity of intact mouse lymphocytes both in vitro and in vivo. The factor is thermolabile, operates nonspecifically, and is produced by T-lymphocytes.     

Polyribosome distribution in regenerating livers of irradiated adrenalectomized rats.

The effect of gamma-radiation (1800 rad) on polyribosome distribution in the regenerating livers of intact and adrenalectomized rats was studied both before and after partial hepatectomy. The animals were divided into four sub-groups: (1) control; (2) irradiated only; (3) partially hepatectomized; and (4) irradiated partially hepatectomized. The relative distribution of lighter oligosomes to heavier polyribosomes was analysed by sucrose density gradient centrifugation (10-40 per cent). Partial hepatectomy by itself increased the proportion of heavier polyribosomes in both intact and adrenalectomized rats. However, when gamma-rays were delivered 2 hours before or 2 hours after partial-hepatectomy, the formation of heavy polyribosomes was decreased for at least 24 hours after hepatectomy in the adrenal intact rats. This depression was not maintained until later times (48 and 72 hours after hepatectomy) when an increase in the proportion of heavy polyribosomes relative to light oligosomes was observed. In addition, irradiation did not measurably affect the distribution of polyribosomes in regenerating hepatocytes of adrenalectomized rats at any time after partial hepatectomy.     

Ocular tissue interactions during the development of human fetal neuroretina grafted into nude mice

To determine the roles of different ocular tissues in the development of the human fetal neuroretina, a study ethically and technically impossible in human subjects, human embryonic and fetal retinas were heterotopically implanted into nude mice. Ninety-five eyeballs were obtained from legally aborted 6- to 7-week-old embryos or 8- to 10-week-old fetuses. Ten isolated neuroretinas with vitreous but without pigment epithelium, 20 half-eyeballs and 70 intact eyeballs, of which 12 had a thick layer of periocular tissue, were microsurgically grafted. Five intact eyeballs were used for reference. Over a period of 1-245 days, all of the grafts were removed for light and electron microscopy observations. All of the isolated neuroretinas had disappeared by the second day after transplantation. Grafts of the posterior section of the eyeball contained only some clusters of pigment epithelium, occasionally covered with undifferentiated neuroretinal cells. Grafts of the retrolental section of the eyeball contained small areas of dysplasic neuroretina with folds and rosettes. Grafts of the 70 intact eyeballs were successful, but only 26 showed normal histological organization of the choriocapillaris, the retinal pigment epithelium and the neuroretina in the posterior part of the posterior chamber. Photoreceptor differentiation was evident in these retinas after approximately 80 days of transplantation and was complete after 166 days. Their anterior part was always dysplasic, with occasional ciliary differentiation. Twenty-three grafted eyeballs had a dysplasic neuroretina with folds, rosettes and necrotized areas. Twenty-one were atrophic, 12 of which were the eyeballs grafted with periocular tissue. These results demonstrate the role of the fetal mesenchyme and pigment epithelium in the rapid revascularization, and subsequent survival and tissue organization, of the neuroretina. The stratified development of the neuroretina required a thin mesenchymal environment for revascularization of the graft by human vasculogenesis or neoangiogenesis and a normal retinal pigment epithelium for normal neuroretinal differentiation. When these conditions were not satisfied, the neuroretina disappeared or was dysplasic, partly necrotized or atrophic. This model might prove useful for a number of therapeutic or clinical studies.     

Suppression of epithelial cell proliferation in mice by splenocytes from unilaterally sialoadenectomized syngeneic donors]

Partially hepatectomized CBA mice immediately after the operation were intra-orbitally injected with splenocytes of intact (I), Sham-operated (SH-0) or unilaterally sialadenectomized (USAE) syngenic donors. It was shown that splenocytes from USAE donors in contrast to their types of splenocytes acutely suppress the mitotic activity of hepatocytes in the regenerating liver 48 and 72 h after their transfer. Splenocytes isolated 17, 144 and 168 h after removal of submandibular (together with sublingual) gland had the biggest inhibiting ability. Similar effect was obtained in respect of corneal epithelium due to administration of USAE mice splenocytes 17, 48 and 72 h after surgery. Operated recipients are more susceptible to the action of splenocytes from USAE donors, than the non-operated ones.     

Appearance of the signs of stress in mice as affected by lymphoid cells from syngeneic hypokinetic animals

Lymphoid cells of the spleen were transferred from F1(CBA X C57BL/6) mice exposed to hypokinesia for 17 hours to unoperated and partially hepatectomized syngeneic recipients. It caused (on days 2, 3 and 7) changes in the body weight, thymus, spleen, adrenals and in proliferative activity of hepatocytes in the intact and regenerating liver, with these changes being similar to those induced by stress alone.     

Effect of pregnenolone-16alpha-carbonitrile, a microsomal enzyme inducer, on the regenerating rat liver.

PCN, a microsomal enzyme inducer, given orally (10 mg in 1 ml water twice daily for 5 days), increased liver weight and mitotic activity in intact as well as in partially hepatectomized rats. Electron microscopy revealed SER proliferation in the hepatocytes of animals treated with PCN alone. Accumulation of SER membranes was also evident in the liver cell cytoplasm of untreated, partially hepatectomized rats; it was however, more pronounced in the hepatocytes of partially hepatectomized animals given PCN. These results indicate that the steriod has a marked effect on the regeneration rat liver.     

Urethane interaction with nucleic acids and proteins from non-malignant fast growing tissues

The interaction of urethane metabolite(s) with macromolecules in tissues of pregnant and partially hepatectomized mice was studied. Pregnant mice were treated with tritiated urethane on the 17th day of pregnancy. Partially hepatectomized mice were studied at 72 h and 198 h after the operation. Operated mice were injected with tritiated urethane, 6 h before killing. It was observed that the specific radioactivity of lung DNA was highest in pregnant mice whereas in partially hepatectomized mice the specific radioactivities of lung DNA and regenerating liver DNA were comparable. It was also observed that binding to macromolecules was greatest at 72 h when the highest mitotic activity in regenerating liver occurs.     

Mixed hematopoietic molecular chimerism results in permanent transgene expression from retrovirally transduced hepatocytes in mice

BACKGROUND: Cytotoxic immune elimination of transduced hepatocytes may limit gene therapy for inherited liver diseases. Using beta-galactosidase as a marker gene, we studied whether creation of mixed beta-galactosidase molecular hematopoietic chimerism could induce tolerance to beta-galactosidase-transduced hepatocytes. METHODS: Molecular hematopoietic chimerism was established in irradiated recipient mice by transplantation of either a mixture of wild-type and beta-galactosidase-transgenic bone marrow or autologous bone marrow stem cells that were transduced with beta-galactosidase lentiviral vectors. After transplantation, mice were hepatectomized and injected with beta-galactosidase recombinant retroviruses to transduce regenerating hepatocytes. We monitored the presence of beta-galactosidase-expressing hepatocytes as well as the appearance of anti-beta-galactosidase antibodies during the time. RESULTS: In control animals, anti-beta-galactosidase antibodies and cytotoxic T-lymphocyte (CTL) response developed as early as 3 weeks after gene transfer. Transduced hepatocytes disappeared concomitantly. In bone marrow transplanted mice, tolerance could be observed in a significant proportion of animals. Tolerance resulted in permanent liver transgene expression and was absent unless a chimerism above 1% was achieved, demonstrating a threshold effect. CONCLUSIONS: Creation of a molecular hematopoietic chimerism can result in transgene tolerance and evade immune rejection of retrovirally transduced hepatocytes. This strategy may be useful for hepatic inherited diseases in which the transgene product behaves as a non-self protein.     

Glucose homeostasis during the early stages of liver regeneration in fasted rats

Kinetic studies with [2-3H]glucose in vivo and gluconeogenic activity measurements in vivo and in vitro were performed in 70% hepatectomized rats submitted to fasting, which represents an extra burden for glucose synthesis but does not impair liver regeneration. Rates of glucose replacement, under steady-state conditions, 14 and 24 h postoperatively, did not differ in partially hepatectomized fasted rats and sham-operated controls. Phosphoenolpyruvate carboxykinase activities increased more rapidly during fasting in remnant livers than in intact livers from controls. Rates of incorporation of 14C from alanine into circulating glucose in hepatectomized rats were already maximal 14 h after surgery, whereas in controls they continued to augment. The maximal rates after partial hepatectomy could not be surpassed by performing the operation in diabetic animals. It is concluded that the relatively high blood sugar levels during fasting in hepatectomized rats do not depend on a reduced peripheral utilization of glucose, but only on a rapid increase in the gluconeogenic activity. The data suggest that hepatocytes in remnant liver can proliferate under conditions of maximal gluconeogenic and low glycolytic activities.     

Effect of diiodobenzotefa on the functionally different subpopulations of T-lymphocytes]

Diiodobenzo-tepa (DIB) was given orally to CBA mice in a dose of 25 mg/kg for 3 successive days. The number of nucleus-containing cells decreased 3.9 fold in the thymus and 1.4 fold in the bone marrow. In experiments on transplantation of lymphoid cells to intact or lethally irradiated (CBA X C57BL/6J)F1 mice treated with DIB this substance did not influence the helper activity of T lymphocytes but inhibited the activity or B and T lymphocytes, inducing "graft-versus-host" and T cell-suppressor functions.     

Genetic differences in lymphoid tissue reactivity during liver regeneration in mice of different lines]

The transfer of lymphocytes together with sheep erythrocytes from partially hepatectomized mice to syngenous lethally irradiated mice (CAB and C57BL) increased the number of antibody forming cells in the recipient's spleen. The lymphocytes of CBA mice acquired this ability much earlier after the operation (in 4 hours) than those of the C57BL mice (in 17 hours). After the transfer of lymphocytes in the semisyngenous system there was a decrease of antibody forming cells during subsequent recipient's immunization with sheep erythrocytes; this was the result of the graft versus host reaction. The latter reaction was less marked in the operated than in control mice. These changes also occurred earlier after the operation in the CBA than in C57BL mice.     

Male germ line stem cells have an altered potential to proliferate and differentiate during postnatal development in mice

Spermatogonial stem cells (SSCs) continuously support spermatogenesis after puberty. However, accumulating evidence suggests that SSCs differ functionally during postnatal development. For example, mutant mice exist in which SSCs support spermatogenesis in the first wave after birth but cease to do so thereafter, resulting in infertility in adults. Studies using a retroviral vector have shown that the vector transduces pup SSCs more efficiently than adult SSCs, which suggests that pup SSCs divide more frequently. Thus, it is hypothesized that the SSCs in pup and adult testes have different characteristics. As an approach to testing this hypothesis in the present study, we investigated the proliferation kinetics of pup SSCs (6-9 days old) and their self-renewal/differentiation patterns for the first 2 mo after transplantation, and compared them to those of adult SSCs. Using serial transplantation, we found that the number of pup SSCs declined over the first week after transplantation. Thereafter, it increased ~4-fold by 1 mo and ~9-fold by 2 mo after transplantation, which indicates that pup SSCs continuously proliferate from 1 wk to 2 mo after transplantation. Compared to the proliferation of SSCs derived from adult intact testes, that of pup SSCs was lower at 1 mo but similar at 2 mo, indicating the delayed proliferation of pup SSCs. However, the pup SSCs regenerated spermatogenic colonies at 1 mo that were similar in length to those of SSCs from adult intact testes. Therefore, these results suggest that some functional differences exist in SSCs during postnatal development, and that these differences may affect the abilities of SSCs to self-renew and differentiate.     

Effect of the spleen cells from partially splenectomized and partially hepatectomized mice on the proliferation of hepatocytes in the regenerating liver of syngeneic recipients

Cells of mouse spleen obtained 48 h after foster splenectomy, foster hepatectomy, resection of 2/3 of spleen or 36 h after resection of 2/3 of liver were introduced intravenously into partially hepatectomized (resection of 2/3 or 1/4 of liver) syngeneic recipients. Cells of regenerating spleen sharply inhibited the mitotic activity of cells of the recipient liver following resection of 1/4 of liver 48 h after the operation and introduction of cells. Inhibition proved to be dose-dependent: it became apparent when 30 million cells were introduced, increased at a dose of 60 million cells and remained at the same level at higher doses. Division of hepatocytes after resection of 1/4 of liver was inhibited by spleen cells taken in the donors 36 h after partial hepatectomy. Spleen cells of intact and pseudo-operated donors had no such ability. Introduction of 60 million of cells of the regenerating spleen and of the spleen of partially hepatectomized animals into recipients with resection of 2/3 of liver did not inhibit reliably the division of hepatocytes, thus indicating the dependence of inhibition on the level of suppressors in the organism. Resection of a major part of liver was accompanied by a greater decrease in the activity of endogenous suppressors which could not be recovered by the introduced cells. Inhibition of cell division by suppressors was not organ specific. Suppressors inhibited proliferation in liver irrespective of the site of operation.     

Preliminary experience with subcutaneous human ovarian cortex transplantation in the NOD-SCID mouse.

Xenogeneic transplantation of ovarian cortex into an immunodeficient animal host may be an approach toward fertility preservation for young female patients undergoing cancer therapy. Our objective was to evaluate the development of follicles in human ovarian cortex placed s.c. in non-obese diabetic-severe combined immune deficiency (NOD-SCID) mice (n = 54). The following variables were compared: 1) male versus female mice as hosts, 2) intact versus pituitary down-regulated mice, and 3) warm versus cold tissue transport. After 2 wk, 37 of 50 (74%) of the human xenografts contained follicles. At 12 wk after transplantation, exogenous gonadotropin stimulation resulted in follicle growth in 19 of 37 (51%) of the grafts, including the development of antral follicles, which could be palpated and visualized through the mouse skin. Significantly more developing follicles were identified in male versus female mice (13 of 17 vs. 6 of 20, respectively; p = 0.013) after stimulation. No difference was found between intact and pituitary down-regulated mice as hosts. Follicular survival was significantly increased by warm versus cold tissue transport. Our results suggest that s.c. ovarian cortex xenografting into NOD-SCID mice is feasible. Primordial follicles in ovarian xenografts retain their developmental potential and form antral follicles following gonadotropin stimulation.     

THE f NUMBER OF PRIMARY TRANSPLANTED SPLENIC COLONY-FORMING CELLS

The proportion of murine haemopoietic stem cells that settled in the spleen, after transplanting spleen cells into lethally-irradiated recipient mice, was found by comparing the number of spleen colonies obtained by transplanting a whole spleen with an estimate of the total number of colony-forming units (CFU) present in the intact spleen. the latter number was estimated assuming that endogenous spleen colonies were produced from surviving spleen-derived CFU which exhibited the same survival parameters as transplanted CFU.
Account was taken of the post-irradiation loss of CFU from the spleen in the endogenous assay, which was found to be a reasonably constant factor for doses higher than about 100 rad X-rays.
The total measured number of CFU/spleen from transplantation was less than the number calculated in the intact spleen by a factor, the primary f number, of 0.03 ± 0.02.