Fetal pancreas transplants are dependent on prolactin for their development and prevent type 1 diabetes in syngeneic but not allogeneic mice.

Transplantation of adult pancreatic islets has been proposed to cure type 1 diabetes (T1D). However, it is rarely considered in the clinic because of its transient effect on disease, the paucity of donors, and the requirement for strong immunosuppressive treatment to prevent allogeneic graft rejection. Transplantation of fetal pancreases (FPs) may constitute an attractive alternative because of potential abundant donor sources, possible long-term effects due to the presence of stem cells maintaining tissue integrity, and their supposed low immunogenicity. In this work, we studied the capacity of early FPs from mouse embryos to develop into functional pancreatic islets producing insulin after transplantation in syngeneic and allogeneic recipients. We found that as few as two FPs were sufficient to control T1D in syngeneic mice. Surprisingly, their development into insulin-producing cells was significantly delayed in male compared with female recipients, which may be explained by lower levels of prolactin in males. Finally, allogeneic FPs were rapidly rejected, even in the context of minor histocompatibility disparities, with massive graft infiltration with T and myeloid cells. This work suggests that FP transplantation as a therapeutic option of T1D needs to be further assessed and would require immunosuppressive treatment.

Effect of the purinergic inhibitor oxidized ATP in a model of islet allograft rejection.

The lymphocytic ionotropic purinergic P2X receptors (P2X1R-P2X7R, or P2XRs) sense ATP released during cell damage-activation, thus regulating T-cell activation. We aim to define the role of P2XRs during islet allograft rejection and to establish a novel anti-P2XRs strategy to achieve long-term islet allograft function. Our data demonstrate that P2X1R and P2X7R are induced in islet allograft-infiltrating cells, that only P2X7R is increasingly expressed during alloimmune response, and that P2X1R is augmented in both allogeneic and syngeneic transplantation. In vivo short-term P2X7R targeting (using periodate-oxidized ATP [oATP]) delays islet allograft rejection, reduces the frequency of Th1/Th17 cells, and induces hyporesponsiveness toward donor antigens. oATP-treated mice displayed preserved islet grafts with reduced Th1 transcripts. P2X7R targeting and rapamycin synergized in inducing long-term islet function in 80% of transplanted mice and resulted in reshaping of the recipient immune system. In vitro P2X7R targeting using oATP reduced T-cell activation and diminished Th1/Th17 cytokine production. Peripheral blood mononuclear cells obtained from long-term islet-transplanted patients showed an increased percentage of P2X7R⁺CD4⁺ T cells compared with controls. The beneficial effects of oATP treatment revealed a role for the purinergic system in islet allograft rejection, and the targeting of P2X7R is a novel strategy to induce long-term islet allograft function.

Comparison of 2 heterotopic heart transplant techniques in rats: cervical and abdominal heart.

OBJECTIVES: Heterotopic heart transplant in rats has been accepted as the most commonly used animal model to investigate the mechanisms of transplant immunology. Many ingenious approaches to this model have been reported. We sought to improve this model and compare survival rates and histologic features of acute rejection in cervical and abdominal heart transplants. MATERIALS AND METHODS: Rats were divided into cervical and abdominal groups. Microsurgical techniques were introduced for vascular anastomoses. In the abdominal heart transplant group, the donor's thoracic aorta was anastomosed end-to-side to the recipient's infrarenal abdominal aorta, and the donor's pulmonary artery was anastomosed to the recipient's inferior vena cava. In the cervical heart transplant group, the donor's thoracic aorta was anastomosed to the recipient's common carotid artery, and the donor's pulmonary artery was anastomosed to the recipient's external jugular vein. Survival time of the 2 models was followed and pathology was examined. Histologic features of allogeneic rejection also were compared in the cervical and abdominal heart transplant groups. RESULTS: The mean time to recover the donor's hearts was 7.4 ± 2.2 minutes in the cervical group and 7.2 ± 1.8 minutes in the abdominal group. In the cervical and abdominal heart transplant models, the mean recipient's operative time was 23.2 ± 2.6 minutes and 21.6 ± 2.8 minutes. Graft survival was 98% and 100% in the cervical and abdominal heart transplant groups. There was no significant difference in graft survival between the 2 methods. Heart allografts rejected at 5.7 and 6.2 days in the cervical and abdominal transplant groups. There was no difference in the histologic features of acute allogenic rejection in cervical and abdominal heart transplant. CONCLUSIONS: Both cervical and abdominal heart transplants can achieve a high rate of success. The histologic features of acute allogeneic rejection in the models are comparable.

Mesenchymal stem cells prolong composite tissue allotransplant survival in a swine model.

BACKGROUND: This study investigated whether mesenchymal stem cells (MSCs) combined with bone marrow transplantation (BMT), irradiation, or short-term immunosuppressant therapy could prolong composite tissue allotransplant survival in a swine hind-limb model. METHODS: Heterotopic hind-limb transplantation was performed in outbred miniature swine. Group I (n=5) was the untreated control. Group II (n=3) received MSCs alone (given on days -1, +3, +7, +14, +21). Group III (n=6) received cyclosporine A (CsA days 0 to +28). Group IV (n=4) received preconditioning irradiation (day -1), BMT (day +1), and CsA (days 0 to +28). Group V (n=5) received irradiation (day -1), BMT (day +1), CsA (days 0 to +28), and MSCs (days +1, +7,+14). The expression and localization of CD4/CD25 T cells and MSCs were assessed using flow cytometry and immunohistochemistry. RESULTS: The allografts survival with MSCs alone revealed a significant prolongation, when compared with the controls (P=0.02). Allografts with CsA treatment exhibited delayed rejection. Irradiation and BMT-CsA treatment revealed no significant allograft survival benefit when compared with the CsA treatment group, but graft-versus-host disease (GVHD) was evident. However, combination of MSCs-BMT-CsA treatment demonstrated significant prolongation of allograft survival (>200 days, P<0.001) and no signs of GVHD with the lowest degree of rejection in the allo-skin and interstitial muscle layers. The CD4/CD25 regulatory-like T-cell expression in the circulating blood and allo-skin significantly increased in the MSC-BMT-CsA group. Examination of bromodeoxyuridine-labeled MSCs revealed donor MSC engraftment into the recipient and donor skin and the recipient liver parenchymal tissue. CONCLUSION: These results suggested that the regulatory activity of MSCs on T cells and GVHD might contribute to significant prolongation of composite tissue allotransplant survival in the MSC-BMT-CsA treatment.

Prolongation of rat major histocompatibility complex-compatible cardiac allograft survival during pregnancy.

BACKGROUND: It has been suggested that pregnancy-related hormones play a critical role in mediating selective immune tolerance during pregnancy. An understanding of why a woman's body normally does not reject the fetus is highly relevant to the prevention of transplant rejection. METHODS: The hearts of female inbred F344 rats (RT-1(lvl)) were transplanted into naive Lewis (RT-1(l); nLewis) or pregnant (pLewis; Day 6, 12 and 18 of pregnancy) rats. The mean survival time (MST) of the cardiac allografts between the nLewis and pLewis rats was compared. We determined the rate of proliferation of the T cells isolated from nLewis and pLewis rats in response to concanavalin A (ConA), anti-CD3 and -CD28 antibody and alloantigen stimulation ex vivo. mRNA expression of several cytokines in these T cells was analyzed using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, the effect of estriol on the cardiac allograft was tested. RESULTS: The pLewis rats with transplant on Day 12 of pregnancy had the most significantly prolonged F344 cardiac graft survival (MST 13.3 days) as compared with nLewis recipients (MST 8 days). pLewis T-cell proliferation was stimulated by alloantigen and antibody but ConA was reduced, whereas Th1/Th2 cytokine mRNA profiles in the T cells were similar for nLewis and pLewis rats. Likewise, estriol also significantly prolonged survival of cardiac allografts. CONCLUSIONS: The results of this study demonstrate that pregnancy hormones not only appear to play a critical role in maternal acceptance of the fetus, but also have therapeutic potential for prolonging the survival of major histocompatibility complex (MHC)-compatible allografts during pregnancy.

Differentiation of xenografted human fetal lung parenchyma.

The goal of this study was to characterize xenografted human fetal lung tissue with respect to developmental stage-specific cytodifferentiation. Human fetal lung tissue (pseudoglandular stage) was grafted either beneath the renal capsule or the skin of athymic mice (NCr-nu). Tissues were analyzed from 3 to 42 days post-engraftment for morphological alterations by light and electron microscopy (EM), and for surfactant protein mRNA and protein by reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry (ICC), respectively. The changes observed resemble those seen in human lung development in utero in many respects, including the differentiation of epithelium to the saccular stage. Each stage occurred over approximately one week in the graft in contrast to the eight weeks of normal in utero development. At all time points examined, all four surfactant proteins (SP-A, SP-B, SP-C, and SP-D) were detected in the epithelium by ICC. Lamellar bodies were first identified by EM in 14 day xenografts. By day 21, a significant increase in lamellar body expression was observed. Cellular proliferation, as marked by PCNA ICC and elastic fiber deposition resembled those of canalicular and saccular in utero development. This model in which xenografted lung tissue in different stages of development is available may facilitate the study of human fetal lung development and the impact of various pharmacological agents on this process.

Orthotopic retransplantation in heterotopic transplant recipients: 3 case reports.

We report 3 patients who initially underwent heterotopic transplantation due to a size mismatch but then later underwent orthotopic retransplantation because of heart failure. In each case, the heterotopic graft was left in place, the native heart was removed, and the new allograft was placed orthotopically. This technique resulted in reduced postoperative morbidity and excellent long-term outcomes.

Host-derived circulating cells do not significantly contribute to cardiac regeneration in heterotopic rat heart transplants.

OBJECTIVES: The aim of this study was to investigate the contribution of host-derived circulating cells to cardiac repair after tissue damage using the model of heterotopic heart transplantation between transgenic recipient rats expressing green fluorescent protein (GFP) and wild-type donors. METHODS: Unlabeled donor rat hearts, some of which underwent prolonged cold ischemia pretreatment, were transplanted into the abdominal cavity of GFP+ transgenic recipient rats and were analyzed 15 and 90 days after surgery. An additional experimental group underwent heart transplantation following administration of granulocyte-colony stimulatory factor (G-CSF) to mobilize bone marrow cells. RESULTS: Most transplants contained GFP+ mature cardiomyocytes. However, systematic counting in the transplants showed that the proportion of GFP+ cardiomyocytes was only 0.0005% to 0.008% of all cardiomyocytes. These relative proportions did not change after G-CSF treatment, despite evidence for sustained marrow cell mobilization. Confocal image analysis showed that the majority of GFP+ cardiomyocytes contained a high number of nuclei, suggesting that these cells may derive from fusion events. Very rarely, small GFP+ undifferentiated cells, expressing GATA-4, were also identified. Occasionally, GFP+ endothelial cells, but not smooth muscle cells, were detected in blood vessels of some transplants. CONCLUSIONS: Our results demonstrate that cardiomyocytes expressing a host transgenic marker are detectable in heterotopic heart transplants; however, they do not significantly contribute to repopulation of the damaged myocardium.

Heterotopic transplantation of glycerin-preserved trachea: effect of respiratory epithelium desquamation on acute rejection.

An effective preservation method and decreased rejection are essential for tracheal transplantation in the reconstruction of large airway defects. Our objective in the present study was to evaluate the antigenic properties of glycerin-preserved tracheal segments. Sixty-one tracheal segments (2.4 to 3.1 cm) were divided into three groups: autograft (N = 21), fresh allograft (N = 18) and glycerin-preserved allograft (N = 22). Two segments from different groups were implanted into the greater omentum of dogs (N = 31). After 28 days, the segments were harvested and analyzed for mononuclear infiltration score and for the presence of respiratory epithelium. The fresh allograft group presented the highest score for mononuclear infiltration (1.78 +/- 0.43, P < or = 0.001) when compared to the autograft and glycerin-preserved allograft groups. In contrast to the regenerated epithelium observed in autograft segments, all fresh allografts and glycerin-preserved allografts had desquamation of the respiratory mucosa. The low antigenicity observed in glycerin segments was probably the result of denudation of the respiratory epithelium and perhaps due to the decrease of major histocompatibility complex class II antigens.

Heterotopic transplantation of glycerin-preserved trachea: effect of respiratory epithelium desquamation on acute rejection

An effective preservation method and decreased rejection are essential for tracheal transplantation in the reconstruction of large airway defects. Our objective in the present study was to evaluate the antigenic properties of glycerin-preserved tracheal segments. Sixty-one tracheal segments (2.4 to 3.1 cm) were divided into three groups: autograft (N = 21), fresh allograft (N = 18) and glycerin-preserved allograft (N = 22). Two segments from different groups were implanted into the greater omentum of dogs (N = 31). After 28 days, the segments were harvested and analyzed for mononuclear infiltration score and for the presence of respiratory epithelium. The fresh allograft group presented the highest score for mononuclear infiltration (1.78 ± 0.43, P <= 0.001) when compared to the autograft and glycerin-preserved allograft groups. In contrast to the regenerated epithelium observed in autograft segments, all fresh allografts and glycerin-preserved allografts had desquamation of the respiratory mucosa. The low antigenicity observed in glycerin segments was probably the result of denudation of the respiratory epithelium and perhaps due to the decrease of major histocompatibility complex class II antigens.

Testicular immune privilege promotes transplantation tolerance by altering the balance between memory and regulatory T cells.

Immune responses are suppressed in immunologically privileged sites, which may provide a unique opportunity to prolong allograft survival. However, it is unknown whether testicular immune privilege promotes transplantation tolerance. Mechanisms underlying immune privilege are also not well understood. Here we found that islet transplantation in the testis, an immunologically privileged site, generates much less memory CD8(+) T cells but induces more Ag-specific CD4(+)CD25(+) regulatory T cells than in a conventional site. These CD4(+)CD25(+) cells exhibited the suppression of alloimmune responses in vivo and in vitro. Despite the immune regulation, intratesticular islet allografts all were rejected within 42 days after transplantation although they survived longer than renal subcapsular islet allografts. However, blocking CD40/CD40L costimulation induced the tolerance of intratesticular, but not renal subcapsular, islet allografts. Tolerance to intratesticular islet allografts spread to skin allografts in the non-privileged sites. Either transfer of memory CD8(+) T cells or deletion of CD25(+) T cells in vivo broke islet allograft tolerance. Thus, transplantation tolerance requires both costimulatory blockade, which suppresses acute allograft rejection, and a favorable balance between memory and regulatory T cells that could favorably prevent late allograft failure. These findings reveal novel mechanisms of immune privilege and provide direct evidence that testicular immune privilege fosters the induction of transplantation tolerance to allografts in both immunologically privileged and non-privileged sites.

Induction of obliterative airway disease in murine tracheal allografts by CD8+ CTLs recognizing a single minor histocompatibility antigen.

The role of minor histocompatibility Ag (mHAg)-specific CD8+ CTLs in the pathogenesis of chronic lung allograft rejection (bronchiolitis obliterans syndrome) remains to be elucidated. Thus, the goal of this study was to define the role of a single mHAg mismatch at the polymorphic H13 allele in the development of obliterative airway disease (OAD) after murine heterotopic tracheal transplantation. The H13a and H13b alleles encode for the SSVVGVWYL (SVL9) and SSVIGVWYL (SIL9) mHAgs, respectively, presented in the context of the H2Db MHC class I molecule. Toward this, C56BL/10SnJ (H13a) tracheal allografts were transplanted into congenic B10.CE-H13b Aw(30NX)/Sn (H13b) recipients. The allografts were harvested at 30, 60, and 90 days after transplantation, and OAD lesions (epithelial damage, cellular infiltration, and luminal fibrosis) were confirmed histologically. Selected groups of mice were immunized (s.c.) or tolerized (i.v.) with the SVL9 peptide before transplantation. This single mHAg mismatch induced the development of OAD within 90 days. SVL9 immunization significantly accelerated the kinetics of the OAD lesions. In contrast, SVL9 tolerization completely abrogated the development of OAD. This was correlated with a complete abrogation of H13a-specific CD8+ CTL responses with a significant reduction in the frequency of IFN-gamma-producing CTLs and the activation of TGF-beta-producing CD8+ T cells. In conclusion, a single mHAg mismatch can induce the development of OAD. These data also suggest that mHAg-reactive CD8+ CTLs may play an important role in the pathogenesis of chronic lung allograft rejection in humans.

Impaired recall of CD8 memory T cells in immunologically privileged tissue.

Foreign Ags that enter immunologically privileged sites such as the eye, brain, and testis persist for an extended period of time, whereas the same Ags are rapidly eliminated at conventional sites. Immune privilege, therefore, provides unwanted refuge for pathogens and tumor cells but is beneficial for the survival of allogeneic grafts. In this study, we asked whether memory T cells can eliminate foreign Ags deposited at an immunologically privileged site by studying CD8 memory T cell-mediated rejection of pancreatic islet allografts placed either in the testis (a privileged organ) or under the kidney capsule (a nonprivileged site) of diabetic mice. We found that CD8 memory T cells reject intratesticular grafts at a significantly slower rate than the rejection of intrarenal grafts. Delayed graft rejection in the testis was not due to reduced homing or proliferation of memory T cells but due to their increased apoptosis at that site. Apoptosis was mediated by the combined actions of two TNFR family members that are up-regulated on activated memory T cells, Fas, and CD30. Therefore, memory T cells survey immunologically privileged tissues but are subject to the immunosuppressive mechanisms present at these sites.

Depletion of CXCR2 inhibits tumor growth and angiogenesis in a murine model of lung cancer.

The Glu-Leu-Arg(+) (ELR(+)) CXC chemokines are potent promoters of angiogenesis and have been demonstrated to induce a significant portion of nonsmall cell lung cancer-derived angiogenic activity and support tumorigenesis. ELR(+) CXC chemokines share a common chemokine receptor, CXCR2. We hypothesized that CXCR2 mediates the proangiogenic effects of ELR(+) CXC chemokines during tumorigenesis. To test this postulate, we used syngeneic murine Lewis lung cancer (LLC; 3LL, H-2(b)) heterotopic and orthotopic tumor model systems in C57BL/6 mice replete (CXCR2(+/+)) and deficient in CXCR2 (CXCR2(-/-)). We first demonstrated a correlation of the expression of endogenous ELR(+) CXC chemokines with tumor growth and metastatic potential of LLC tumors. Next, we found that LLC primary tumors were significantly reduced in growth in CXCR2(-/-) mice. Moreover, we found a marked reduction in the spontaneous metastases of heterotopic tumors to the lungs of CXCR2(-/-) mice. Morphometric analysis of the primary tumors in CXCR2(-/-) mice demonstrated increased necrosis and reduced vascular density. These findings were further confirmed in CXCR2(+/+) mice using specific neutralizing Abs to CXCR2. The results of these studies support the notion that CXCR2 mediates the angiogenic activity of ELR(+) CXC chemokines in a preclinical model of lung cancer.

Absence of allograft ICAM-1 attenuates alloantigen-specific T cell priming, but not primed T cell trafficking into the graft, to mediate acute rejection.

The expression and function of ICAM-1 are critical components in the initiation and elicitation of many T cell-mediated responses. Whether ICAM-1 expression is required on the T cells or on the APC during T cell priming remains unclear. To address this issue in alloantigen-specific T cell activation, the priming and function of T cells in response to heart allografts from MHC-mismatched wild-type vs ICAM-1(-/-) donors were tested. Wild-type C57BL/6 (H-2(b)) heart allografts were rejected by A/J (H-2(a)) recipients on days 7-9, whereas B6.ICAM-1(-/-) allografts survived until days 18-23 post-transplant. On day 7 post-transplant, infiltrating macrophages and CD4(+) and CD8(+) T cells in the ICAM-1(-/-) allografts were 20-30% those observed in the wild-type allografts. ELISPOT analyses indicated that the number of alloantigen-specific T cells producing IFN-gamma from recipients of ICAM-1-deficient grafts was 60% lower than that from recipients of wild-type allografts. On day 16 post-transplant, these numbers did not markedly increase in ICAM-1-deficient allograft recipients. Consistent with the reduced priming of alloreactive T cells, isolated dendritic cells from ICAM-1(-/-) mice stimulated allogeneic T cell proliferation poorly compared with wild-type dendritic cells. When A/J mice were primed with wild-type dendritic cells and then received wild-type or ICAM-1-deficient heart allografts 3 days later, the primed recipients rejected the wild-type and ICAM-1(-/-) allografts on days 5-6 post-transplant. These results indicate that optimal priming of alloreactive T cells requires allograft expression of ICAM-1, but, once primed, recipient T cell infiltration into the allograft is independent of graft ICAM-1 expression.

Evaluation of the hormonal function and histological features of heterotopic isogenic ovarian transplantation in rats.

The purpose of the study was to determine the feasibility of preserving ovarian function after heterotopic transplantation by means of microvascular anastomosis of the transplanted vascular pedicles to a set of preselected vessels. Six groups of 10 Sprague-Dawley inbred rats were used in this study. Group I underwent bilateral ovariectomy operation and served as the ovariectomy control. Group II underwent bilateral ovariectomy followed by heterotopic isogenic ovarian implantation. Group III underwent bilateral ovariectomy and isogenic heterotopic ovarian transplantation by means of microvascular anastomosis. Group IV served as the laparotomy sham-operated control. Group V served as the ovarian donor for group II. Group VI served as the donor of the ovarian-kidney vascular pedicle complex for group III. Postoperative ovarian estradiol levels were measured, and histological characteristics were elucidated in groups I, II, III, and IV. The results demonstrated that the estradiol level of the transplantation group was comparable to that of the sham operation group and was significantly higher than that of the implantation group. Histologically normal ovarian architecture was observed in the sham group (IV) and also in the transplantation group (III). Altered architecture was observed in the implantation group (II). These findings indicate that extraabdominal heterotopic ovarian transplantation with microvascular anastomosis led to normal ovarian hormonal function and was effective in preserving oocyte production capacity.

Different kinetics of obliterative airway disease development in heterotopic murine tracheal allografts induced by CD4+ and CD8+ T cells.

BACKGROUND: Both T and B cells have been shown to be implicated in the pathogenesis of bronchiolitis obliterans syndrome, which is considered to represent chronic lung allograft rejection. However, the relative contributions of T cells and alloantibodies in the pathogenesis of the disease are still unknown. In this study, we used an heterotopic murine tracheal transplantation model to determine the contribution of these components of the immune system in the pathogenesis of posttransplant obliterative airway disease (OAD). METHODS: Tracheal allografts from BALB/c and HLA-A2-transgenic (HLA-A2+) mice were heterotopically transplanted into C57BL/6, CD4-knockout (KO), CD8-KO, Ig-KO, and Rag1-KO mice. In additional experiments, recipient mice were pretreated with depleting antibodies against CD4+, CD8+, and NK1.1+ cells. Development of OAD was determined by histopathology at days 10, 30, 60, 90, and 180 after transplantation. RESULTS: HLA-A2+ allografts transplanted into C57BL/6, CD8-KO, and Ig-KO mice demonstrated OAD lesions by day 30. In contrast, allografts transplanted into CD4-KO mice showed no OAD lesions at day 30, partial OAD development by days 60 and 90, and complete OAD development by day 180. No OAD development was observed in allografts transplanted into Rag1-KO mice. Treatment with anti-NK1.1 antibody did not show any effect on posttransplant OAD development. In contrast, anti-CD4+ or anti-CD8+ antibody treatments partially reduced the OAD histopathology and combined anti-CD4/CD8 antibody treatment further abrogated the histopathology of the disease. CONCLUSION: These results show that both CD4+ and CD8+ T cells have a role in the pathogenesis of OAD and that natural killer cells and alloantibodies are not necessary for the development of this disease.

A highly selective inhibitor of Rho-associated coiled-coil forming protein kinase, Y-27632, prolongs cardiac allograft survival of the BALB/c-to-C3H/He mouse model.

BACKGROUND: Current studies provide evidence that a small G protein, RhoAp21, and its target protein, Rho-associated coiled-coil forming protein kinase (ROCK), regulate not only cell shape but also cell migration. However, contribution of Rho/ROCK signaling to graft rejection is unknown. The purpose of this study was to evaluate the inhibitory effect of Y-27632, a highly selective ROCK inhibitor, on rejection of heterotopic cardiac transplantation in mice. METHODS: BALB/c (H-2(d)) hearts were transplanted into C3H/He (H-2(k)) as allografts that were full histoincompatibility combinations. The recipients received several doses of Y-27632, commencing 1 day before cardiac transplantation until rejection. We used immunohistochemical study to detect the expression of myocardial intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), and we immunoenzymatically measured serum interleukin (IL)-6. Furthermore, we evaluated cardiac allograft vasculopathy treated with either FK506 or Y-27632 at Day 100. RESULTS: The Y-27632-treated (2 mg/kg/day) allografts prolonged the mean survival time (49.6 +/- 10.1 days, n = 12) as compared with the untreated allografts (8.1 +/- 0.4 days, n = 7, p < 0.001). Histologic examinations of the Y-27632-treated allografts at Day 7 showed greatly reduced leukocyte infiltration compared with the untreated allografts. The Y-27632-treated allografts revealed faint expression of myocardial ICAM-1 and VCAM-1 at Day 7. The serum IL-6 levels also decreased in the Y-27632-treated mice. In the long-surviving Y-27632-treated allografts at Day 100, we saw neither active rejection nor apparent thickening of vascular intima. CONCLUSION: Our results suggest that ROCK plays a major role in cardiac rejection in the BALB/c-to-C3H/He mouse model. Inhibition of this Rho/ROCK signaling may be an alternative therapeutic option for managing acute and chronic rejection.

Systematic analysis of the effects of hepatocyte transplantation on rats with acute liver failure.

BACKGROUND/AIMS: Acute liver failure either after liver resection or as part of underlying liver disease is still associated with high mortality. Hepatocyte transplantation in various forms has attracted attention recently. However, none of those reports have investigated the thorough and systematic analysis of effect of hepatocyte transplantation on acute liver failure induced by 90% hepatectomy. Therefore, we investigated systematic analysis of effect of hepatocyte transplantation on rats with acute liver failure. METHODOLOGY: Male Sprague-Dawley rats were used. Group I rats (n = 26) received intrasplenic injection of 2 x 10(7) hepatocytes in 0.3 mL Dulbecco's modified Eagle's medium (DMEM) 24 hours prior to 90% hepatectomy. Group II rats (n = 24) received intrasplenic injection of DMEM only. Twenty-two rats from group I and 20 from group II were observed for the determination of survival time. The remaining 8 (4/each group) rats were used to assess the liver function and regeneration. RESULTS: The hepatocyte bearing spleen revealed active glucose-6-phosphatase activity. In group I rats, the survival was longer and that group had more long-term survivors than those of group II controls. In group I, there was significant increase in the ratio of weight of remnant liver lobes to body weight. At 24 hours after hepatectomy, group I rats had improved biochemical parameters compared to those of group II rats. CONCLUSIONS: In rats with acute liver failure, intrasplenic hepatocyte transplantation acts as a bridge to support experimental rats from acute liver failure to liver regeneration, prolong survival in rats with acute liver failure and improve biochemical parameters.