Nitrosyl hemoglobin detected by near-infrared spectroscopy in rat liver allografts

Near-infrared spectroscopy (NIRS) is a noninvasive biomeasurement system with rays in the near-infrared region that possess high permeability to biological tissues. NIRS was applied to liver allografts undergoing rejection in rats treated with deoxyspergualin (DSG) or tacrolimus (FK506). The nitrosyl hemoglobin (Hb) levels detected in the liver grafts increased 3 days and 5 days after grafting in both allogeneic and syngeneic transplantation. The levels on day 8 remained high in the allogeneic graft, but markedly decreased in the syngeneic graft. Although the serum levels of nitrite and nitrate were extremely low 8 days after grafting in allografted recipients treated with DSG or FK506, the nitrosyl-Hb level in DSG-treated graft was much higher than that in FK506-treated graft. There was no significant difference in survival time between DSG-treated and FK506-treated recipients. In conclusion, DSG and FK506 have a different effect on NO production in allografted liver with ongoing rejection, and circulating nitrite and /nitrate levels do not reflect the local levels of NO in the graft.

Prolonged cardiac allograft survival in rats systemically injected adenoviral vectors containing CTLA4Ig-gene

BACKGROUND

CTLA4Ig, a soluble recombinant fusion protein that contains the extracellular domain of the CTLA4 and Fc portion of IgG1, strongly adheres to the B7 molecule to block CD28-mediated costimulatory signals and inhibits in vitro and in vivo immune responses. In vivo gene transfer using adenovirus vector achieves a high transfection rate into organ cells that usually contain adenoviral receptors. In this study, we investigated expression levels of the transfected gene and the survival times of the allografts in cardiac recipients systemically administered adenoviral vectors containing CTLA4Ig.

METHODS

Hearts from DA rats (RT-1a) were transplanted into a cervical location in LEW recipients (RT1(1)). The adenoviral vectors containing CTLA4Ig was injected via a recipient vein immediately after grafting.

RESULTS

The serum level of CTLA4Ig reached to maximum at 51-93 microg/ml 3 to 7 days after gene-transfection and declined after 14 days, although detectable levels were observed up to 49 days. The median survival time of the allografts in the gene-transfected group were significantly prolonged (27 days) in compared to the control group (6 days). In addition, down-regulation of IL-2 and IFN-gamma mRNAs and persistence of IL-4 and IL-10 transcripts were observed in the graft infiltrating cells.

CONCLUSION

The adenovirous-mediated CTLA4Ig gene transfer into a recipient liver by systemic administration resulted in remarkable prolongation of cardiac allograft survival. Its action mechanisms may be mediated by inhibition of CD28-associated signal transduction, reduction of Th1-type cytokine production, and continuous expression of Th2-type cytokines in the activating lymphocytes.

[Effect of basic fibroblast growth factor on repairing transected sciatic nerve in rats]

OBJECTIVE

To investigate the effects of basic fibroblast growth factor(bFGF) on repairing transected sciatic nerves in rats.

METHODS

The animal models of the transected sciatic nerve of 40 SD rats were established, which divided into 4 groups: normal saline (NS) group, nerve growth factor (NGF) group, bFGF group and normal control group. The epineurium of the transected sciatic nerve was sutured under microscope, then bFGF or NGF was dropped into local sites and injected intramuscularly once a day for 30 days after operation. Functional repair for the transected sciatic nerves was studied by nerve conductive velocity (NCV) and sciatic nerve function index (SFI).

RESULTS

As a criterion, the level of the normal control group was regarded as zero, SFI of NS group, NGF group and bFGF group were -114.30 +/- 10.34, -70.50 +/- 11.01, -50.45 +/- 7.82 respectively at 1 month after operation, and they were -54.96 +/- 16.46, -35.21 +/- 10.80, -27.53 +/- 11.23 respectively in 3 months after operation. NCV of bFGF group was significantly faster than NS group and NGF group.

CONCLUSION

bFGF can significantly promote the functional repair of injured peripheral nerve, and its effects are better than NGF.

[Gene therapy for acute hepatitis using CrmA gene transduction]

Fas-Fas ligand interactions between adenovirus-infected hepatocytes and cytotoxic T lymphocytes (CTLs) play a major role in killing of vector-transduced hepatocytes. Cytokine response modifier A (CrmA) is known to protect lymphoid cells from Fas-mediated apoptosis by inhibiting caspase 8. In this study, we generated an E1-deleted adenovirus expressing CrmA, and investigated the effect of exogenous CrmA expression on the inhibition of Fas-mediated apoptosis in murine hepatocytes in vitro and on the prolongation of the transgene expression in adenovirus-transduced hepatocytes in vivo. Agonistic anti-Fas antibody induced massive apoptosis into hepatocytes, however, most of the cells expressing CrmA were escaped from apoptosis and survived. This result showed that anti-apoptic function was obtained in murine hepatocytes by expressing CrmA. The prolongation of the transgene expression was studied using mice with congenital deficiency of lysosomal beta-glucuronidase (GUSB). The serum GUSB activity from the mice injected only an adenovirus expressing human beta-glucuronidase disappeared within 70 days, however, significant GUSB activity was observed for more than 130 days in the mice co-transduced with adenoviruses expressing both GUSB and CrmA. Moreover, histochemical analysis showed GUSB expressions in the liver even at 130 days after the viral administration. These observations demonstrate that the prolongation of the transgene expression can be achieved in rodent liver by CrmA co-expression using adenoviral gene transfer.

Prolonged survival of rat liver allografts transfected with Fas ligand-expressing plasmid

BACKGROUND

Transplantation of Fas ligand (FasL) gene-transfected tissues can have opposite effects. For example, cotransplantation of pancreas islets with myoblasts transfected with FasL-expressing plasmid vector (pFasL) prevented graft rejection, whereas the expression of FasL directly within islets using adenovirus vector led to graft destruction. It was also reported that FasL expression on pancreas islets led to neutrophilic infiltration and rapid destruction of the islets. From these results, overexpression of FasL in transfected tissues may lead directly to self destruction through an autocrine Fas-FasL pathway or graft destruction through neutrophil recruitment. To date there have been no reports of successful transplantation of FasL gene-transfected solid organs.

METHODS

Rat pFasL was transfected at a dose of 90, 180, 270, or 360 microg into rat liver with an inactivated hemagglutinating virus of Japan conjugated to liposome vesicles (HVJ-liposome), and the gene-transfected livers were transplanted to allogeneic rats.

RESULTS

In 18 rats transfected with 180 microg of pFasL, 14 (78%) did not develop fulminant hepatitis. FasL-mRNA was detected in these livers at 3, 5, 7, and 14 days after transfection. The expression of FasL protein was also observed in the transfected liver, and the transfection rate by this method was 11.1+/-1.9%. The livers were then transplanted to allogeneic recipients, resulting in significant (P<0.01) prolonged recipient survival times. Histological observation showed that the pFasL-transfected liver allografts caused apoptotic cell death in infiltrating activated T cells. In contrast, transfection of pFasL higher than 180 microg resulted in lethal hepatitis in all rats, and its low dose (90 microg) did not induce the hepatitis or prolong recipient survival.

CONCLUSION

Our results indicate that rat liver allografts can be protected to host immune responses by an adequate level (approximately 10%) of FasL expression in the livers using HVJ-liposome incorporating pFasL.

Fas-mediated apoptosis is involved in the elimination of gene-transduced hepatocytes with E1/E3-deleted adenoviral vectors

Gene-transduced hepatocytes with E1/E3-deleted adenoviral vectors are eliminated immediately and the expression of transduced genes disappears rapidly following the vector administration. In this report, we analysed the involvement of apoptotic cell death in the elimination of hepatocytes infected with adenoviral vectors. An E1/E3-deleted adenoviral vector expressing Escherichia coli beta-galactosidase (LacZ) was injected via the portal vein into congenitally Fas-deficient mice (lpr), Fas ligand-deficient mice (gld) and their control mice, MRL and C3H. 5-Bromo-4-chloro-3-indolyl-beta-D-galactoside (X-gal) staining of the liver specimens showed that 80-100% of hepatocytes were LacZ positive at 7 days after virus administration, suggesting that most of the hepatocytes received the injected adenoviral vectors. In normal mice, the number of LacZ-positive cells decreased dramatically at 14 and 21 days after transduction and few positive cells were observed at day 28. Beta-galactosidase activity, quantified by the O-nitrophenyl-beta-D-galactopyranoside assay, gave comparable results to X-gal staining. At days 14 or 21, many apoptotic hepatocytes and apoptotic infiltrating cells were detected with the terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling (TUNEL) in situ apoptosis detection method. This observation suggested that the apoptotic process was associated with the elimination of adenovirus-infected hepatocytes. To test the involvement of the Fas-Fas ligand interaction in this apoptotic process, the period of transgene expression was measured in lpr and gld mice, which had received the same amount of AxCALacZ. X-Gal histochemical analysis detected many LacZ-positive cells in lpr or gld mice liver even at 21 or 28 days after AxCALacZ injection. There were significant differences in the reduction rates of beta-galactosidase activity of liver homogenates between lpr and MRL, or gld and C3H mice. Based on these observations, we conclude that the Fas-mediated apoptotic process is involved in the elimination of hepatocytes infected with E1/E3-deleted adenoviral vectors.

Efficient Fas-ligand gene expression in rodent liver after intravenous injection of a recombinant adenovirus by the use of a Cre-mediated switching system

An adenovirus vector AxCALNFasL was constructed in order to transduce a gene for rat Fas-ligand, requiring co-expression of Cre recombinase for its expression. In the cosmid cassette, pAxCALNFasL, a stuffer DNA fragment flanked with two loxP sequences was placed between the promoter and Fas-ligand cDNA to prevent its expression in transfected 293 cells. COS-7 cells infected with AxCALNFasL alone did not induce apoptosis in cocultivated Jurkat cells, but the cells treated with AxCALNFasL and AxCANCre (an adenovirus expressing Cre recombinase with the CAG promoter) did. BALB/c mice injected with 10(9) plaque-forming units of AxCALNFasL and with different doses of AxCANCre, developed lethal acute liver failure. The number of the apoptotic hepatocytes increased dramatically with increased doses of injected AxCANCre, indicating that the level of transgene expression in the rodent liver appeared to be adjustable. Based on these observations, we conclude that vectors expressing a gene to produce cytotoxic substances can be constructed by the use of a Cre-mediated switching system. Our system also demonstrated that efficient expression of the toxic gene in the rodent liver was achievable by co-infection of adenovirus vectors carrying the target gene and Cre recombinase.

Higher efficiency of retrovirus transduction in the late stage of primary culture of hepatocytes from nontreated than from partially hepatectomized rat

The aim of this investigation was to optimize the conditions for gene transduction by a retroviral vector into primary cultured hepatocytes. Because a retrovirus infection is dependent upon the proliferative activity of the target cells, we examined the thymidine incorporation of the primary culture, using cells from nontreated and partially hepatectomized donor rats. Partial hepatectomy 1 day before cell isolation greatly enhanced the thymidine incorporation, and similarly, the transduction of LacZ, the gene for E. coli beta-galactosidase, although the percentage of transduced cells remained low. With cells from the normal rat, the thymidine incorporation increased gradually after the beginning of the culture and reached 16 times the initial activity on day 2, while hepatocytes from the partially hepatectomized donor showed no increase at that stage of the culture. Correspondingly, the number of gene-transduced hepatocytes was increased when the vector was added to the cells 1 or 2 days after isolation. Therefore, hepatocytes cultured for 1 or 2 days after isolation are suitable for retroviral transduction.

Apoptosis is involved in acute cardiac allograft rejection in rats

BACKGROUND

Allograft rejection remains a major obstacle to long-term survival in heart transplantation. Recent studies have demonstrated that apoptotic cell death may occur in acute allograft rejection. The purpose of this study was to determine whether apoptotic cell death is involved in rat cardiac allograft rejection through both the perforin/granzyme pathway and the Fas/Fas ligand (Fas-L) pathway.

METHODS

Groups of Lewis (RT1(1)) rats underwent heterotopic heart transplantation from disparate DA (RT1a) or syngeneic Lewis rats. The cardiac grafts were harvested 1, 3, or 5 days after transplantation and analyzed for apoptotic cell death using DNA nick-end labeling, immunocytochemistry, and electron microscopy. In addition, the expression of granzyme B, perforin, Fas, and Fas-L messenger RNA were analyzed by reverse transcriptase-polymerase chain reaction.

RESULTS

Apoptotic cell death of cardiac myocytes was prominent in allografts on day 5 after transplantation. Fas gene transcripts were constitutively expressed in both syngeneic and allogeneic grafts, whereas expression of Fas-L was only upregulated in allografts with ongoing rejection. Granzyme B and perforin gene expression were also upregulated in allografts with ongoing rejection.

CONCLUSIONS

These results suggest that myocyte apoptosis through both the perforin-granzyme pathway and the Fas-Fas-L pathway may be involved in cardiac allograft rejection in rats.