Microchimeric cells from the peripheral blood associated with cardiac grafts are bone marrow derived, long-lived and maintain acquired tolerance to minor histocompatibility antigen H-Y

BACKGROUND

Although it has been well established that the microchimerism occurs in the peripheral blood of the recipients after various settings in both clinical and experimental organ transplantation, nevertheless, their roles in inducing and maintaining acquired transplantation tolerance are controversial. Furthermore, regarding the cell lineages, kinetics, and functions of the cells that constitute the microchimerism after organ transplantation, solid information is not available.

METHODS

Using rat heterotopic heart isografts from bone marrow chimeras between cross-sex and applying polymerase chain reaction with specific primers to rat sex determining region of Y chromosome, a relationship between a state of microchimerism and induction as well as maintenance of acquired tolerance to H-Y antigen were examined.

RESULTS

Microchimeric cells of the peripheral blood (MCPB) after cardiac grafting contain bone marrow-derived and radiation-sensitive cells. Furthermore, removal of the primary cardiac grafts revealed that microchimeric cells in the peripheral blood are long-lived cells, i.e., more than 6 months. When the female rats that had contained long-lasting MCPB, were innoculated with syngeneic male dendritic cells, failure to sensitize female toward male specific antigen H-Y was found to occur.

CONCLUSIONS

Thus it was suggested that radiation-sensitive, bone marrow derived, long-lived MCPB play a significant role in maintaining acquired transplantation tolerance to minor histocompatibility antigen H-Y.

In vitro prevention of cell-mediated xeno-graft rejection via the Fas/FasL-pathway in CrmA-transducted porcine kidney cells

Cell-mediated cytotoxicity may be involved in delayed and/or chronic xenograft rejection in which apoptosis is induced in the grafted cells via the Fas/Fas-ligand (FasL) and perforin/granzyme pathways. One barrier to the potential use of xeonogenic grafts for humans may be Fas/FasL-mediated apoptosis, which would be blocked by the gene expression of cytokine response modifier A (CrmA), a cowpox virus gene product. The purpose of this study is to explore whether crmA is an effective candidate gene for inhibiting apoptosis in an in vitro model of xenograft rejection, using Fas-expressing non-primate cells cultured with a soluble recombinant human FasL (sFasL). A recombinant adenovirus vector expressing CrmA (AxCALNLCrmA) was successfully generated with a Cre-mediated switching system. PK15 cells, derived from a porcine kidney and infected with AxCALNLCrmA and/or AxCANCre at a multiplicity of infection (MOI) ranging from 0.1 to 100, were cultured with human sFasL derived from KFL74.18, a human FasL-overexpressed cell line. The gene-expression level of the PK15 cells was confirmed by CrmA-immune staining. Approximately 70% of the control PK15 cells showed induced apoptosis when cultured with sFasL. In contrast, the apoptosis was dramatically reduced in crmA-gene-transduced PK15 cells. The inhibitory effect of apoptosis increased with an increase in the infection dose of AxCANCre. In addition, the activity of caspases 3 and 8 was significantly inhibited in the crmA-transduced cells. These results indicate that CrmA is an effective gene product for inhibiting Fas/FasL-mediated apoptosis, which suggests the potential therapeutic use of its gene transduction to protect against graft damage due to delayed and/or chronic xenograft rejection.

Long-term graft acceptance in rat heart transplantation by CTLA4Ig gene transfection combined with FTY720 treatment

CTLA4Ig strongly adheres to B7 molecules on antigen-presenting cells to block intracellular signal transduction via CD28 on helper T cells, which eventually inhibits immune responses. We have demonstrated that the administration to recipient animals of adenoviral vectors containing CTLA4Ig gene (adCTLA4Ig) prolonged graft survival, although the gene expression diminished in a time-dependent manner and the grafts were finally rejected. In addition, recipient animals treated with FTY720, a new immunosuppressant, exhibited a decrease in the number of peripheral lymphocytes due to apoptosis. In this study, we performed adCTLA4Ig transfection combined with FTY720 treatment in heart-grafted rats to determine if the combination could induce a mutual effect on graft survival. The recipient animals were given injections of 1 x 10(9) plaque-forming units of adCTLA4Ig via the tail vein immediately after grafting. On the day before transplantation we administered FTY720 orally to some of these animals at a dosage of 5 mg/kg and again on the day of transplantation. The median graft survival period in the adCTLA4Ig-only group was 27 days, whereas that in the combination group was markedly prolonged to 56 days. Of 15 grafts, 5 survived indefinitely. In these groups we observed detectable levels of CTLA4Ig in the sera 49 days after grafting; the levels were always higher in the combination group than in the adCTLA4Ig-only group. As a result, this study revealed that FTY720 and adCTLA4Ig have a potent mutual effect on graft survival during rat heart transplantation. Furthermore, it is highly possible that FTY720 enhances gene expression of adCTLA4Ig, which may be related to the long-term acceptance of grafts.

Fulminant hepatitis by Fas-ligand expression in MRL-lpr/lpr mice grafted with Fas-positive livers and wild-type mice with Fas-mutant livers

BACKGROUND

Fulminant hepatitis in mice could be induced by gene-transfection of Fas ligand (FasL). However, the mechanisms of this event still remain controversial as to whether it is mediated by direct Fas/FasL interaction and/or neutrophil migration. To investigate the role of exogenous FasL-expression, we established a simple but clear mouse model on which we performed liver transplantation between Fas-mutant mice (MRL-lpr/lpr) and wild-type mice (MRL+/+).

METHODS

The controls were nontransplanted wild-type (group 1) and MRL-lpr/lpr (group 2) mice. We obtained recipients with a Fas defect only in the liver (group 3; MRL-lpr/lpr liver graft in wild-type mice) and Fas-defected recipients with Fas-positive livers (group 4; wild-type graft in MRL-lpr/lpr). We successfully expressed FasL in the liver by cotransfection of two types of adenoviral vectors, AxCALNFasL and AxCANCre, with a Cre-loxP switching system.

RESULTS

FasL-expression in the livers in groups 3 and 4 resulted in animal death due to fulminant hepatitis within 48 hr after administration of the vectors. We obtained similar findings in group 1, whereas the mice in group 2 survived without any evidence of hepatitis. Immune staining revealed a marked infiltration of CD11b-positive cells in group 1 and group 3. Despite the number of apoptotic cells, a few infiltration of CD11b-positive cells were seen in group 4. We observed no remarkable findings in the FasL-expressed livers in group 2.

CONCLUSION

The results indicated that exogenous FasL-expression induces hepatocyte apoptosis both by direct interaction with Fas and by recruiting Fas-positive inflammatory cells. These findings are important for generating a new strategy to prevent hepatitis as well as for understanding the role of the Fas/FasL interaction in the pathophysiology of hepatitis.

Induction of lymphocyte apoptosis in rat liver allograft with ongoing rejection by FTY720

The action mechanism of FTY720, a novel immunosuppressant, is completely different from conventional immunosuppressants. The drug, which triggers apoptosis in murine and human lymphocytes, has a potent immunosuppressive activity to prevent allograft rejection without any severe side-effect. The present study was designed to determine whether FTY720 induces apoptotic cell death in activated lymphocytes infiltrated into liver grafts with ongoing rejection. FTY720 was orally administered at 5 mg/kg to the recipients on day 3 and day 4 after grafting, when the graft rejection was histologically confirmed. The intragraft patterns of IL-2, interferon-gamma (IFN-gamma), perforin, and granzyme B gene expression were detected by reverse transcriptase-polymerase chain reaction. The treatment reversed ongoing rejection and significantly prolonged recipient survival time compared with the control group. Light microscopic observation of the graft sections stained with the DNA nick-end labelling method showed that the apoptosis in the control allografts was mainly induced in hepatocytes, while that in the FTY720-treated allografts was in infiltrated lymphocytes. The rejection therapy with FTY720 did not alter the expression of IL-2, IFN-gamma, and perforin mRNAs, but slightly decreased granzyme B expression. Our results suggest that FTY720 does not alter the intrinsic lymphocyte function to produce the rejection-related cytokines, but strongly induces apoptotic cell death in the activated lymphocytes. Thus, FTY720 affords new insight into the mechanisms underlying improvements in immunosuppressive treatments.

Engraftment of genetically engineered amniotic epithelial cells corrects lysosomal storage in multiple areas of the brain in mucopolysaccharidosis type VII mice

Cell-mediated gene therapy for visceral lesions of lysosomal storage diseases is promising; however, the treatment of central nervous system (CNS) lesions remains a challenge. In this study, we generated rat amniotic epithelial cells (AEC) that overexpress and secrete human beta-glucuronidase (GUSB) following transduction with an adenoviral vector encoding human GUSB. The AEC were used as donor cells for cell-mediated gene therapy of CNS lesions in mice with mucopolysaccharidosis type VII (MPSVII), a lysosomal storage disorder caused by an inherited deficiency of GUSB activity. After confirmation that the secreted GUSB was taken up mainly via mannose 6-phosphate receptors in primary cultured neurons, the AEC were transplanted into the brains of adult MPSVII mice. Histochemical analysis showed extensive GUSB activity throughout the ipsilateral hemisphere of the recipient brains, and pathological improvement of the lysosomal storage was observed even in regions far from the site of injection. These results suggest that intracerebral transplantation of genetically engineered AEC has therapeutic potential for the treatment of CNS lesions in lysosomal storage disorders.

Huanglian, A chinese herbal extract, inhibits cell growth by suppressing the expression of cyclin B1 and inhibiting CDC2 kinase activity in human cancer cells

Huanglian is an herb that is widely used in China for the treatment of gastroenteritis. We elected to determine whether huanglian could inhibit tumor cell growth by modulating molecular events directly associated with the cell cycle. Huanglian inhibited tumor growth and colony formation of gastric, colon, and breast cancer cell lines in a time- and dose-dependent manner. Cell growth was completely inhibited after 3 days of continuous drug exposure to 10 microg/ml of herb. This degree of growth inhibition was significantly greater than that observed with berberine, the major constituent of the herb. The inhibition of cell growth by huanglian was associated with up to 8-fold suppression of cyclin B1 protein. This resulted in complete inhibition of cdc2 kinase activity and accumulation of cells in G(2). The mRNA expression of cyclin B1 was not changed after huanglian treatment. There was no change in the protein expression of cyclins A or E. Therefore, the effect of huanglian on inhibiting tumor growth seems to be mediated by the selective suppression of cyclin B1, which results in the inhibition of cdc2 kinase activity. Inhibition of cyclin dependent kinase (cdk) activity is emerging as an attractive target for cancer chemotherapy. Huanglian represents a class of agents that can inhibit tumor cell growth by directly suppressing the expression of a cyclin subunit that is critical for cell cycle progression. These results indicate that traditional Chinese herbs may represent a new source of agents designed for selective inhibition of cyclin dependent kinases in cancer therapy.

Direct computation of multiple 3D flow convergence isovelocity surfaces from digital 3D reconstruction of colour Doppler data of the flow convergence region: an in vitro study with differently shaped orifices

AIMS

Evaluation of the accuracy of direct computation of multiple three-dimensional (3D) flow convergence (FC) isovelocities by using digital reconstruction of colour Doppler data of the flow convergence region.

METHODS AND RESULTS

We used a conventional ultrasound system (ATL HDI 3000) connected to a computer workstation via Ethernet link. The digital 3D datasets were directly transferred to a Silicon Graphic Imaging Octane workstation for later measurement. We generated nine pulsatile flows (20-60 ml/beat), with peak flow rates (67-180 ml/s), through three orifices (circular, rectangular and triangular, S=0.24 cm(2)). The 3D reconstructions of FC surface areas from multi-threshold velocities, including aliasing velocities were analysed to quantify the peak flow rate. For all orifices, linear regression demonstrated excellent correlation between the 3D calculated and electromagnetic flow meter recorded data. While there was a high correlation for 3D computation of flow rate from the single best Nyquist of 24 cm/s (r=0.97-0.98, SEE=7 .75-12.58 ml/s), the ability to average three threshold velocities (15, 18 and 24 cm/s) yielded an improved correlation (r=0.98-0.99, SEE=5.70-7.73 ml/s).

CONCLUSIONS

Direct computation of multiple 3D FC isovelocities from digital reconstruction of colour Doppler data of the FC region provides the potential to accurately quantify the complex asymmetric spatial flow events at any selected velocity.

Long-term culture of glutamine synthetase-transfected HepG2 cells in circulatory flow bioreactor for development of a bioartificial liver

Glutamine synthetase (GS) is involved in an accessory pathway of ammonia removal in mammals. To develop a bioartificial liver with a human cell line, GS gene was transfected into HepG2 cells, which had no ammonia removal activity. After culturing in the presence of methionine sulfoximine (MSX), a GS inhibitor, we obtained a MSX-resistant HepG2 subline (GS-HepG2), which had amplified GS gene; ammonia removal activity was estimated to be 1/7 of that of rat primary culture hepatocytes. The cells were cultured in a circulatory flow bioreactor for 109 days, while they multiplied from 5 x 10(7) to 4 x 10(9) cells. Three days after inoculation, the ammonia level of the culture medium was lowered to a level maintained thereafter, suggesting that using recombinant cell lines for bioartificial livers enables long-term repeated treatment for hepatic failure patient. Judging from the rate of decrease in the amount of the added ammonia, the ammonia removal capability of 4 x 10(9) GS-HepG2 cells was almost equivalent to 5 x 10(8) porcine hepatocytes inoculated into the circulatory flow bioreactor. Apart from their ammonia removal activity, GS-HepG2 cells eliminated human tumor necrosis factor-alpha (TNF-alpha). Cytokine removal therefore promises to be another useful property of bioreactor cells.

Phenotype correction in murine mucopolysaccharidosis type VII by transplantation of human amniotic epithelial cells after adenovirus-mediated gene transfer

Cell therapy with human amniotic epithelial (HAE) cells was developed as an alternative method for enzyme replacement therapy in congenital lysosomal storage disorders, but only limited therapeutic efficacy has been reported. A major drawback is insufficient production and secretion of lysosomal enzymes from HAE cells. In this study, we infected HAE cells with an E1-deleted adenoviral vector expressing human beta-glucuronidase (GUSB), and generated cells overexpressing GUSB by a hundred times as much as endogenous GUSB in untreated HAE cells. GUSB secreted from the gene-transferred HAE cells were efficiently transported to murine fibroblasts with endocytosis mediated by mannose-6-phosphate receptors. The cells were administered into the spleen of the mice with the lysosomal storage disease mucopolysaccharidosis type VII (B6/MPSVII). Approximately 10-15% of the normal GUSB activity was detected in both liver and spleen 7 days after the cell administration. Histopathological examination showed that lysosomal enlargement in tissue macrophages in the liver and the spleen had disappeared by day 14. These results suggest that transplantation of the HAE cells transduced with adenoviral vectors can be employed for the treatment of congenital lysosomal storage disorders.

Strong, long-term transgene expression in rat liver using chicken beta-actin promoter associated with cytomegalovirus immediate-early enhancer (CAG promoter)

For successful gene therapy in hepatic enzyme deficiencies, it is essential to use promoters that can maintain strong transcriptional activity for the long term in the liver. Using Gunn rats, a model animal for Crigler-Najjar syndrome type I, the long-term transcriptional function of the CAG promoter (a combination of chicken beta-actin promoter and cytomegalovirus immediate-early enhancer) was evaluated in the rat liver. We constructed a plasmid pCAGGHUGT, containing expression cassettes of human bilirubin UDP-glucuronosyltransferase (BUGT) and hygromycin phosphotransferase, under the control of the CAG promoter and murine phosphoglycerate kinase promoter, respectively. Conditionally immortalized Gunn rat hepatocytes (IGRH), which had been established using mutant SV40 large T antigen ((TS)T), were transfected with pCAG-GHUGT. A stably transfected clone IGRHUGT, expressing a high level of BUGT, was obtained after selection with hygromycin. At 33 degrees C, the cells doubled in number in approximately 72 h; however, at 37 degrees C, cell proliferation stopped, indicating that the characteristic of temperature-dependent proliferation was retained in this clone. Ten million cells were injected into the spleen of syngeneic Gunn rats five times at 10-day intervals. Serum bilirubin levels were reduced by 45-50% at 70 days after the first transplantation and remained so throughout the duration of the study (120 days). These results suggested that the CAG promoter was able to maintain strong transcriptional activity in rat liver for at least 120 days.

Inhibition of Fas-mediated fulminant hepatitis in CrmA gene-transfected mice

Hyperimmune response via Fas/Fas-ligand and perforin/granzyme pathways may be essential in pathogenesis of virus-induced fulminant hepatitis. CrmA inhibits activation of caspases and granzyme B, suggesting it may block these pathways. We investigated whether CrmA expression would inhibit Fas-associated lethal hepatitis in mice. We successfully generated AxCALNLCrmA, a recombinant adenovirus expressing CrmA gene with a Cre-mediated switching cassette. We increased CrmA expression level in the liver transfected with AxCALNLCrmA (10(9) pfu) by increasing administration dose (10(7)-10(9) pfu) of AxCANCre, a recombinant, adenovirus-expressing Cre gene. Injection of anti-Fas antibody into the control mice rapidly led to animal death due to massive liver apoptosis, while the apoptosis was dramatically reduced in the CrmA-expressed mice. The animal survival increased with an increase of CrmA expression. The formation of active caspase-3 was markedly inhibited in the crmA-transfected hepatocytes in vitro. These results suggest that crmA is an effective gene that can inhibit immune-related liver apoptosis.

Adenovirus-mediated gene therapy for mucopolysaccharidosis VII: involvement of cross-correction in wide-spread distribution of the gene products and long-term effects of CTLA-4Ig coexpression

Recombinant adenoviruses expressing human beta-glucuronidase (AxCAhGUS) and CTLA-4Ig (AxCACTLA-4Ig) were generated and therapeutic efficacy was investigated using a murine model of mucopolysaccharidosis type VII (MPSVII). Seven days after the intravenous administration of AxCAhGUS, high levels of beta-glucuronidase (GUSB) activity were observed in the liver, spleen, heart, lung, kidney, and serum, while viral DNA was predominantly detected in the liver. To investigate the contribution of in vivo cross-correction of GUSB between the liver and other organs, we injected the serum obtained from the transduced mice into untreated MPSVII mice. Similar distributions of GUSB activity were observed in the serum-injected mice, suggesting that GUSB activities detected in the extrahepatic organs were due to the cross-correction rather than the direct gene transduction. This result also suggested that maintaining high levels of GUSB in the systemic circulation was essential for the effective treatment of MPSVII. To achieve this, we injected AxCAhGUS and AxCACTLA-4Ig into MPSVII mice. Serum GUSB activity was sustained at high levels for more than 200 days and morphological normalization of the liver and spleen was observed for a year. This suggests that long-term therapeutic efficacy in visceral organs of MPSVII is achievable by coexpression of CTLA-4Ig through an in vivo cross-correction pathway.

An improved method for the purification of stellate cells from rat liver with dichloromethylene diphosphate (CL2MDP)

Hepatic perisinusoidal cell population consists of hepatic stellate cells, Kupffer cells, endothelial cells, and Pit cells. These cells are isolated by enzymic digestion and purified by density gradient centrifugation. With isolation of stellate cells, conventional method is unable to eliminate the contamination of Kupffer cells because the densities of these two cells are similar. We report here an improved method for isolation of highly purified hepatic stellate cells, using dichloromethylene diphosphate (CL2MDP), which has selective cytotoxicity of Kupffer cells. Three days after the single intravenous administration of liposome-encapsulated CL2MDP, the Kupffer cells disappeared almost completely from the liver. Following Percoll density gradient centrifugation, the purity of the hepatic stellate cells exceeded 98% without any contamination of the Kupffer cells. Kupffer cells are reported to affect the physiological functions of stellate cells. The availability of highly purified stellate cells will facilitate the investigation of their functions in primary culture.

The in vivo effect of bryostatin-1 on paclitaxel-induced tumor growth, mitotic entry, and blood flow

Pretreatment of tumor cells with the protein kinase C (PKC) inhibitor bryostatin-1 enhances the cytotoxicity of most chemotherapeutic agents. However, in the case of paclitaxel, this effect has been shown in vitro to be best achieved when bryostatin-1 follows (rather than precedes) paclitaxel treatment. With combination trials of bryostatin-1 and paclitaxel planned for clinical trials and with only in vitro data available regarding drug sequence, we elected to undertake an in vivo study evaluating the effect of sequential bryostatin-1 and paclitaxel in a tumor-bearing mouse model and to correlate this effect to cell cycle events, tumor metabolism, and tumor blood flow. At the maximum tolerated i.p. dose, bryostatin-1 at 80 microg/kg resulted in a small but significant increase in tumor doubling time (4.2 +/- 0.3 days) compared with control tumors (3.0 +/- 0.3 days; P < 0.01). Mice treated with i.v. paclitaxel, administered at a dose of 12 mg/kg every 12 h for three doses, weekly for 3 weeks, had a tumor doubling time of 23.4 +/- 1.7 days. Mice pretreated with i.p. bryostatin-1 (80 microg/kg) followed 12 h later by i.v. paclitaxel (12 mg/kg every 12h for three doses) weekly for 3 weeks had a tumor doubling time of 9.7 +/- 1.1 days. This was significantly less (P < .001) than paclitaxel alone, which indicated an inhibitory effect by bryostatin-1 on paclitaxel therapy. In comparison, tumor-bearing mice that were treated with the same dose but with the sequence of paclitaxel followed by bryostatin-1 had a tumor doubling time of 29.6 +/- 0.6 days. This was significantly greater than the tumor doubling times for any condition tested (P < 0.01), demonstrating the sequence dependence of this combination. The efficacy of paclitaxel is dependent on mitotic entry, a step that requires activation of p34cdc2 kinase activity. Treatment with paclitaxel in vivo increased p34 cdc2 kinase activity in the mouse mammary tumors, whereas administration of bryostatin-1 before paclitaxel prevented the p34cdc2 kinase activation by paclitaxel. This was further evaluated in vitro by flow cytometry in MKN-74 human gastric cancer cells. As determined by MPM-2 labeling, which identifies cells in mitosis, pretreatment with bryostatin-1 prevented paclitaxel-treated cells from entering mitosis. Bryostatin-1 has been reported to induce changes in muscle metabolism and to decrease muscle blood flow. These events could impact on the interaction of bryostatin-1 with paclitaxel. Using proton-decoupled phosphorus nuclear magnetic resonance (31P-NMR) spectroscopy in vivo, bryostatin-1 at 80 micro1g/kg induced a decrease in both intratumoral pH and high-energy phosphates. In vivo perfusion studies, using dynamic enhanced NMR imaging with gadolinium diethylenetriamine pentaacetic acid, also demonstrated decreased tumor blood flow. These studies suggest that the inhibition of tumor response to paclitaxel by bryostatin-1 is multifactorial and includes such diverse factors as inhibition of cell entry into mitosis, a decrease in pH and energy metabolism, and a decrease in tumor blood flow. These results indicate that, as this combination enters Phase I clinical trials, the sequence of paclitaxel followed by bryostatin-1 will be critical in the clinical trial design.

Immunosuppressive therapy using FTY720 combined with tacrolimus in rat liver transplantation

BACKGROUND

FTY720 (FTY) exerts its effects through a reduction of peripheral lymphocytes. This unique mechanism allows for a possible combination effect with other immunosuppressants. We investigated therapy with FTY combined with tacrolimus (FK) in rat liver transplantation.

METHODS

Different doses of FK, FTY, or both were orally administered to the recipients for 15 days. Expression of cytokine mRNAs using RT-PCR and appearance of lymphocyte apoptosis by immunohistologic staining were studied in the allografts.

RESULTS

Recipients treated with a low dose of FK (0.3 mg/kg) or FTY (0.03 mg/kg) showed a slightly prolonged survival time, although combination therapy with these drugs prolonged survival time similar to the duration obtained by an optimal dose of each drug alone. A marked suppression of lymphocyte infiltration and decreased levels of mRNAs for IL-2, IFN-gamma, and granzyme B were seen in the grafts with combination therapy. Grafts with combination therapy showed an increased number of cells double-stained with TUNEL and CD2 in infiltrated lymphocytes.

CONCLUSIONS

Allografts that underwent combination therapy demonstrated markedly reduced lymphocyte infiltration; a number of cells had induced apoptosis and an inhibition of IL-2, IFN-gamma, and granzyme B mRNA transcription, but not IL-4 and IL-10 transcripts, accounting for powerful mutual effect of FTY and FK.