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Nuclear-enriched RNA-binding proteins (RBPs) are mainly involved in transcriptional regulation, which is a critical checkpoint to tune gene diversity and expression levels. We analyzed nuclear RBPs in human HCC tissues and matched normal control tissues. Based on the gene expression levels, PTBP3 was identified as top-ranked in the nuclei of HCC cells. HCC cell lines then were transfected with siRNAs or lentiviral vectors. PTBP3 promoted HCC cell proliferation and metastasis both in vitro and in vivo. RNA immunoprecipitation (RIP), fluorescence in situ hybridization (FISH) and qRT-PCR assays verified that PTBP3 protein recruited abundant lnc-NEAT1 splicing variants (NEAT1_1 and NEAT1_2) and pre-miR-612 (precursor of miR-612) in the nucleus. NEAT1_1, NEAT1_2 and miR-612 expression levels were determined by PTBP3. Correlational analyses revealed that PTBP3 was positively correlated with NEAT1, but it was inversely correlated with miR-612 in HCC. The P53/CCND1 and AKT2/EMT pathways were determined by NEAT1 and miR-612 respectively in HCC. The PTBP3high and NEAT1high/miR-612low patients had a shorter overall survival. Therefore, nuclear-enriched RBP, PTBP3, promotes HCC cell malignant growth and metastasis by regulating the balance of splicing variants (NEAT1_1, NEAT1_2 and miR-612) in HCC.

Dendritic cell (DC) vaccination targeting cancer stem cells is an effective way to suppress tumor progression and reduce the metastasis and recurrence. In the present study, we explored the suitability of side population (SP) cells as source of antigens for DC vaccination against hepatocellular carcinoma (HCC) in a mouse model. In this study, we identified the "stem-like" characteristics of SP cells in the MHCC97 and Hepa 1-6 HCC cell lines. We found that SP cells express high levels of tumor-associated antigens and MHC class I molecules. Although loading with cell lysates did not change the characteristics of DCs, SP cell lysate-pulsed DCs induced antigen-specific T cell responses, including T cell proliferation and increased IFN-γ production by stimulated CD8(+) T cells. We investigated the cytotoxicity of T cells stimulated by SP cell lysate-pulsed DCs in nude mice co-injected with MHCC97 cells. To mimic the in vivo environment, we also confirmed the result in mouse HCC cell line Hepa 1-6 induced tumor-bearing C57/BL6 immune competent mice, and we demonstrated that vaccination with DCs loaded with Hepa 1-6 SP cell lysates could induce a T cell response in vivo and suppress the tumor growth. Our results may have applications for anti-HCC immunotherapy by targeting the cancer stem cells and may provide new insight for cancer vaccines.

MicroRNA-150 (miR-150) is frequently dysregulated in cancer and is involved in carcinogenesis and cancer progression. In this study, we found that miR-150 was significantly downregulated in hepatocellular carcinoma (HCC) tissues compared to adjacent noncancerous tissues. Low levels of miR-150 were significantly associated with worse clinicopathological characteristics and a poor prognosis for patients with HCC. miR-150 overexpression inhibited cell proliferation, migration and invasion in vitro and tumor growth and metastasis in vivo. Further experiments indicated that Grb2-associated binding protein 1 (GAB1) was a direct target of miR-150 in HCC cells. In addition, GAB1 expression was increased in HCC tissues and inversely correlated with miR-150 levels. Knockdown of GAB1 mimicked the tumor-suppressive effects of miR-150 overexpression on HCC cells, whereas restoration of GAB1 expression partially abolished the inhibitory effects. Moreover, miR-150 overexpression decreased GAB1 expression, subsequently downregulated phospho-ERK1/2 and suppressed epithelial-mesenchymal-transition (EMT). These effects caused by miR-150 overexpression were alleviated by exogenous GAB1 expression. Taken together, this study demonstrates that miR-150 may be useful as a prognostic marker and that the identified miR-150-GAB1-ERK axis is a potential therapeutic target for HCC.

Hepatocellular carcinoma (HCC) is one of the most prevalent and lethal cancer worldwide. However, the mechanism underlying the HCC development remains unclear. Ras-related associated with diabetes (RRAD) is a small Ras-related GTPase which has been implicated in metabolic disease and several types of cancer, yet its functions in HCC remain unknown. A tissue microarray constructed by 90 paired HCC tissues and adjacent non-cancerous liver tissues was used to examine the protein levels of RRAD, and the messenger RNA (mRNA) expression of RRAD was also detected in a subset of this cohort. The prognostic significance of RRAD was estimated by the Kaplan-Meier analysis and Cox regression. The glucose utilization assay and lactate production assay were performed to measure the role of RRAD in HCC glycolysis. The effect of RRAD in HCC invasion and metastasis was analyzed by transwell assays. Our results suggested that the expression of RRAD was downregulated in HCC tissues compared to the adjacent non-tumorous liver tissues both in mRNA and protein levels and lower RRAD expression served as an independent prognostic indicator for the survival of HCC patients. Moreover, RRAD inhibited hepatoma cell aerobic glycolysis by negatively regulating the expression of glucose transporter 1 (GLUT1) and hexokinase II (HK-II). In addition, RRAD inhibition dramatically increased hepatoma cell invasion and metastasis. In conclusion, our study revealed that RRAD expression was decreased in HCC tumor tissues and predicted poor clinical outcome for HCC patients and played an important role in regulating aerobic glycolysis and cell invasion and metastasis and may represent potential targets for improving the treatment of HCC.

Mounting evidence has shown that induction of epithelial-mesenchymal transition (EMT) contributes to the the expression of CSC (cancer stem cell) markers. However, whether and how CSC markers could be involved in regulating EMT has rarely been reported. CD44, being one of the most commonly used CSC markers in hepatocellular carcinoma (HCC), has been demonstrated to act as a multidomain, transmembrane platform that serves to integrate a wide variety of extracellular signals. Therefore, we determined to seek whether CD44 is necessary for the EMT process in HCC. First, we noticed that CD44 expression was associated with the mesenchymal phenotype in HCC cell lines, and knocking down CD44 with lentivirus-mediated shRNA in HCC cell lines resulted in the mesenchymal-epithelial-transition (MET) and the subsequent impaired migration and invasion in vitro. Moreover, in a metastatic mice model established by tail vein injection of luciferase labelled MHCC97-H cells, we confirmed that CD44 knockdown resulted in the decreased metastasis of HCC cells. Furthermore, we found that the induction of MET by CD44 inhibition might be achieved, at least in part, by repressing the ERK/Snail pathway.

Nuclear-enriched RNA-binding proteins (RBPs) are mainly involved in transcriptional regulation, which is a critical checkpoint to tune gene diversity and expression levels. We analyzed nuclear RBPs in human HCC tissues and matched normal control tissues. Based on the gene expression levels, PTBP3 was identified as top-ranked in the nuclei of HCC cells. HCC cell lines then were transfected with siRNAs or lentiviral vectors. PTBP3 promoted HCC cell proliferation and metastasis both in vitro and in vivo. RNA immunoprecipitation (RIP), fluorescence in situ hybridization (FISH) and qRT-PCR assays verified that PTBP3 protein recruited abundant lnc-NEAT1 splicing variants (NEAT1_1 and NEAT1_2) and pre-miR-612 (precursor of miR-612) in the nucleus. NEAT1_1, NEAT1_2 and miR-612 expression levels were determined by PTBP3. Correlational analyses revealed that PTBP3 was positively correlated with NEAT1, but it was inversely correlated with miR-612 in HCC. The P53/CCND1 and AKT2/EMT pathways were determined by NEAT1 and miR-612 respectively in HCC. The PTBP3

Multidrug resistance (MDR) is usually correlated with the poor prognosis of gastric cancer. In this study, we revealed a total of 11 microRNAs (miRNA) that regulated MDR of gastric cancer via high-throughput functional screening, and miR-508-5p reversed MDR most efficiently among these candidate miRNAs. The overexpression of miR-508-5p was sufficient to reverse cancer cell resistance to multiple chemotherapeutics in vitro and sensitize tumours to chemotherapy in vivo. Further studies showed that miR-508-5p could directly target the 3'-untranslated regions of ABCB1 and Zinc ribbon domain-containing 1 (ZNRD1), and suppress their expression at the mRNA and protein levels. Meanwhile, the suppression of ZNRD1 led to a decrease in ABCB1. These findings suggest that a miR-508-5p/ZNRD1/ABCB1 regulatory loop has a critical role in MDR in gastric cancer. In addition, miR-508-5p could be used as a prognostic factor for overall survival in gastric cancer. These data reveal an important role for miR-508-5p in the regulation of MDR in gastric cancer, and suggest the potential application of miR-508-5p in drug resistance prediction and treatment.

Cancer-associated fibroblasts (CAFs) play a pivotal role in regulating tumour progression. Therefore, understanding how CAFs communicate with hepatocellular carcinoma (HCC) is crucial for HCC therapy. Recently, exosomes have been considered an important “messenger” between cells. In this study, we performed microRNA (miRNA) sequencing of exosomes derived from CAFs and corresponding para-cancer fibroblasts (PAFs) of HCC patients. We found a significant reduction in the miR-320a level in CAF-derived exosomes. Using exogenous miRNAs, we demonstrated that stromal cells could transfer miRNA to HCC cells. In vitro and in vivo studies further revealed that miR-320a could function as an antitumour miRNA by binding to its direct downstream target PBX3 to suppress HCC cell proliferation, migration and metastasis. The miR-320a-PBX3 pathway inhibited tumour progression by suppressing the activation of the MAPK pathway, which could induce the epithelial–mesenchymal transition and upregulate cyclin-dependent kinase 2 (CDK2) and MMP2 expression to promote cell proliferation and metastasis. In xenograft experiments involving CAFs mixed with MHCC97-H cells, miR-320a overexpression in CAFs could inhibit tumourigenesis. Therefore, these data suggest that CAF-mediated HCC tumour progression is partially related to the loss of antitumour miR-320a in the exosomes of CAFs and that promoting the transfer of stromal cell-derived miR-320a might be a potential treatment option to overcome HCC progression.

Allograft tolerance is the ultimate goal in the field of transplantation immunology. Immature dendritic cells (imDCs) play an important role in establishing tolerance but have limitations, including potential for maturation, short lifespan in vivo and short storage times in vitro. However, exosomes (generally 30–100 nm) from imDCs (imDex) retain many source cell properties and may overcome these limitations. In previous reports, imDex prolonged the survival time of heart or intestine allografts. However, tolerance or long-term survival was not achieved unless immune suppressants were used. Regulatory T cells (Tregs) can protect allografts from immune rejection, and our previous study showed that the effects of imDex were significantly associated with Tregs. Therefore, we incorporated Tregs into the treatment protocol to further reduce or avoid suppressant use. We defined the optimal exosome dose as approximately 20 μg (per treatment before, during and after transplantation) in rat liver transplantation and the antigen-specific role of Tregs in protecting liver allografts. In the co-treatment group, recipients achieved long-term survival, and tolerance was induced. Moreover, imDex amplified Tregs, which required recipient DCs and were enhanced by IL-2. Fortunately, the expanded Tregs retained their regulatory ability and donor-specificity. Thus, imDex and donor-specific Tregs can collaboratively induce graft tolerance.

Autophagy is a life phenomenon in which autophagosomes remove damaged or aging organelles and long‐lived circulating proteins to maintain the cell's stability. However, disorders of excessive autophagy are a response of cancer cells to a variety of anticancer treatments which lead to cancer cell death. The Akt/mammalian target of rapamycin (mTOR) and the extracellular signal‐regulated kinase 1/2 (ERK1/2) pathways are both involved in nutrient‐induced autophagic phenomenon and exhibit vital relevance to oncogenesis in various cancer cell types, including hepatocellular carcinoma (HCC). However, the influence of autophagy for cancer cell death remains controversial and few scientists have investigated the variation of these two signaling pathways in cancer cell autophagic phenomenon induced by anticancer treatment simultaneously. Here, we explored the anticancer efficacy and mechanisms of glycyrrhizin (GL), a bioactive compound of licorice with little toxicity in normal cells. It is interesting that inhibition of Akt/mTOR signaling in concurrence with enhanced ERK1/2 activity exists in GL‐induced autophagy and cytotoxicity in HepG2 and MHCC97‐H hepatocellular carcinoma cells. These results imply that the GL‐related anticancer ability might correlate with the induction of autophagy. The influence of induced autophagic phenomenon on cell viability might depend on the severity of autophagy and be pathway specific. In the subsequent subcutaneous xenograft experiment in vivo with MHCC97‐H cells, GL obviously exhibited its inhibitory efficacy in tumor growth via inducing excess autophagy in MHCC97‐H cells (P

Long noncoding RNAs (lncRNAs) have been shown to play critical roles in the development and progression of diseases. lncRNA activated by transforming growth factor beta (TGF-β) (lncRNA-ATB) was discovered as a prognostic factor in hepatocellular carcinoma, gastric cancer, and colorectal cancer. However, little is known about the role of lncRNA-ATB in pancreatic cancer. This study aimed to assess lncRNA-ATB expression in pancreatic cancer and explore its role in pancreatic cancer pathogenesis. Quantitative real-time polymerase chain reaction was performed to detect lncRNA-ATB expression in 150 pancreatic cancer tissues and five pancreatic cancer cell lines compared to paired adjacent normal tissues and normal human pancreatic ductal epithelial cell line HPDE6c-7. The correlations between lncRNA-ATB expression and clinicopathological characteristics and prognosis were also analyzed. We found that lncRNA-ATB expression was decreased in pancreatic cancer tissues and pancreatic cancer cell lines. Low lncRNA-ATB expression levels were significantly correlated with lymph node metastases (yes vs. no, P = 0.009), neural invasion (positive vs. negative, P = 0.049), and clinical stage (early stage vs. advanced stage, P = 0.014). Moreover, patients with low lncRNA-ATB expression levels exhibited markedly worse overall survival prognoses (P

Background: The activation of tissue factor (TF) is one of the major reasons for coagulation dysregulation after pig-to-primate xenotransplantation. Tissue factor pathway inhibitor (TFPI) is the most important inhibitor of TF. Studies have demonstrated species incompatibility between pig TFPI and human TF. Methods: A pig-to-macaque heterotopic auxiliary liver transplantation model was established to determine the origin of activated TF. Chimeric proteins of human and pig TFPI were constructed to assess the role of Kunitz domains in species incompatibility. Immortalised pig bone marrow mesenchymal stem cells transfected with human TFPI were tested for their ability to inhibit clotting in vitro. Results: TF from recipient was activated early after liver xenotransplantation. Pig TFPI Kunitz domain 2 bound human FXa, but Kunitz domain 1 did not effectively inhibit human TF/FVIIa. Immortalised pig bone marrow mesenchymal cells (BMSCs) transfected with human TFPI showed a prolonged recalcification time in vitro and in a rodent model. Conclusion: Recipient TF is relevant to dysregulated coagulation after xenotransplantation. Kunitz domain 1 plays the most important role in species incompatibility between pig TFPI and human TF, and clotting can be inhibited by human TFPI-transfected pig BMSCs. Our study shows a possible way to resolve the incompatibility of pig TFPI.

Hepatocellular carcinoma (HCC) is one of the most common human malignancies and also the leading cause of cancer-related death in the world. The mechanisms underlying the progression and metastasis of HCC remain unclear. The E3 ubiquitin ligase F-box and WD repeat domain-containing 7 (Fbxw7) is broadly considered as a tumor suppressor gene. However, the role of Fbxw7 in HCC is not clear. To investigate the expression and biological functions of Fbxw7 in HCC, we examined Fbxw7 expression level using HCC tissue microarray and immunohistochemistry. Our data showed that Fbxw7 expression is significantly reduced in HCC compared with non-cancerous tissues (P

Background Pig-to-nonhuman primate orthotopic liver xenotransplantation is often accompanied by thrombocytopenia and coagulation disorders. Furthermore, the release of cytokines can trigger cascade reactions of coagulation and immune attacks within transplant recipients. To better elucidate the process of inflammation in liver xenograft recipients, we utilized a modified heterotopic auxiliary liver xenotransplantation model for xeno-immunological research. We studied the cytokine profiles and the relationship between cytokine levels and xenograft function after liver xenotransplantation. Methods Appropriate donor and recipient matches were screened using complement-dependent cytotoxicity assays. Donor liver grafts from α1,3-galactosyltransferase gene-knockout (GTKO) pigs or GTKO pigs additionally transgenic for human CD47 (GTKO/CD47) were transplanted into Tibetan macaques via two different heterotrophic auxiliary liver xenotransplantation procedures. The cytokine profiles, hepatic function, and coagulation parameters were monitored during the clinical course of xenotransplantation. Results Xenograft blood flow was stable in recipients after heterotopic auxiliary transplantation. A Doppler examination indicated that the blood flow speed was faster in the hepatic artery (HA) and hepatic vein (HV) of xenografts subjected to the modified Sur II (HA-abdominal aorta+HV-inferior vena cava) procedure than in those subjected to our previously reported Sur I (HA-splenic artery+HV-left renal vein) procedure. Tibetan macaques receiving liver xenografts did not exhibit severe coagulation disorders or immune rejection. Although the recipients did suffer from a rapid loss of platelets, this loss was mild. In blood samples dynamically collected after xenotransplantation (post-Tx), dramatic increases in the levels of monocyte chemoattractant protein 1, interleukin (IL)-8, granulocyte-macrophage colony-stimulating factor, IL-6, and interferon gamma-induced protein 10 were observed at 1 hour post-Tx, even under immunosuppression. We further confirmed that the elevation in individual cytokine levels was correlated with the onset of graft damage. Finally, the release of cytokines might contribute to leukocyte infiltration in the xenografts. Conclusion Here, we established a modified auxiliary liver xenotransplantation model resulting in near-normal hepatic function. Inflammatory cytokines might contribute to early damage in liver xenografts. Controlling the systemic inflammatory response of recipients might prevent early post-Tx graft dysfunction.

Hepatocellular carcinoma is one of the most prevalent neoplasms and the leading cause of cancer-related mortality worldwide. Mitochondrial ribosomal protein S23 is encoded by a nuclear gene and participates in mitochondrial protein translation. Mitochondrial ribosomal protein S23 overexpression has been found in many types of cancer. In this study, we explored mitochondrial ribosomal protein S23 expression in primary hepatocellular carcinoma tissues compared with matched adjacent non-tumoral liver tissues using mitochondrial ribosomal protein S23 messenger RNA and protein levels collected from public databases and clinical samples. Immunohistochemistry was performed to analyze the relationship between mitochondrial ribosomal protein S23 and various clinicopathological features. The results indicated that mitochondrial ribosomal protein S23 was significantly overexpressed in hepatocellular carcinoma. High mitochondrial ribosomal protein S23 expression was correlated with the tumor size and tumor–metastasis–node stage. Moreover, patients with high mitochondrial ribosomal protein S23 expression levels presented poorer survival rates. Mitochondrial ribosomal protein S23 was an independent prognostic factor for survival, especially at the early stage of hepatocellular carcinoma. In addition, the downregulation of mitochondrial ribosomal protein S23 decreased the proliferation of hepatocellular carcinoma in vitro and in vivo. In conclusion, we verified for the first time that mitochondrial ribosomal protein S23 expression was upregulated in hepatocellular carcinoma. High mitochondrial ribosomal protein S23 levels can predict poor clinical outcomes in hepatocellular carcinoma, and this protein plays a key role in tumor proliferation. Therefore, mitochondrial ribosomal protein S23 may be a potential therapeutic target for hepatocellular carcinoma.

Background Pig organs are commonly used in xenotransplantation, and α-1,3-galactose has been shown to be the main cause of hyperacute rejection. The development of transgenic pigs that lack α-1,3-galactosyltransferase (GGTA1) has overcome this problem to a certain extent, but transgenic pigs are difficult to maintain, making their usefulness in basic research limited. For this reason, we propose to establish a cell model to study hyperacute rejection. Methods Immortalized primary porcine aortic endothelial cells were transfected with a short hairpin RNA targeted to GGTA1. Cell proliferation, apoptosis, complement C3 activation, and the binding of human immunoglobulins and components of the complement system, including IgM, IgG, C3, and C5b-9, were examined. Results After RNA interference, GGTA1 was found to be reduced at both the transcript and protein level as assessed by quantitative polymerase chain reaction and flow cytometry, respectively. When cultured in the presence of human serum, the proliferation rate of the transfected cells was higher than that of untransfected cells, and the apoptosis rate was lower. Additionally, activation of C3 and the binding of human immunoglobulins IgM and IgG and complement component C3 and C5b-9 to the transfected cells were lower than in the immortalized group but higher than in untransfected cells. Conclusions RNA interference of GGTA1 in cultured porcine endothelial cells reduces the reaction of immunoglobulin and complement system with the cells. Therefore, this in vitro cell model could be useful for further study of xenotransplantation.

STIM1 (stromal interaction molecule 1), an endoplasmic reticulum Ca2+ sensor that triggers the store-operated Ca2+ entry activation, has recently been implicated in cancer progression. However, the role of STIM1 in the progression and metastasis of colorectal cancer (CRC) has not been addressed. In this study, we confirmed increased expression of STIM1 in highly invasive CRC cell lines. Enhanced expression of STIM1 promoted CRC cell metastasis in vitro and in vivo, whereas silencing of STIM1 with small interfering RNA resulted in reduced metastasis. Ectopic expression of STIM1 in CRC cells induced epithelial-to-mesenchymal transition (EMT), whereas silencing of STIM1 had the opposite effect. Furthermore, STIM1 expression was markedly higher in CRC tissues than in adjacent noncancerous tissues. STIM1 overexpression correlated with poor differentiation and higher tumor node metastasis stage. CRC patients with positive STIM1 expression had poorer prognoses than those with negative STIM1 expression. Moreover, STIM1 was found to be a direct target of miR-185, a microRNA (miRNA) that has not previously been reported to be involved in EMT, in both CRC tissues and cell lines. Taken together, these findings demonstrate for the first time that STIM1 promotes metastasis and is associated with cancer progression and poor prognosis in patients with CRC. In addition, we show that expression of STIM1 is regulated by a posttranscriptional regulatory mechanism mediated by a new EMT-related miRNA. This novel miR-185–STIM1 axis promotes CRC metastasis and may be a candidate biomarker for prognosis and a target for new therapies.

To investigate whether Tg737 is regulated by microRNA-548a-5p (miR-548a-5p), and correlates with hepatocellular carcinoma (HCC) cell proliferation and apoptosis.Assays of loss of function of Tg737 were performed by the colony formation assay, CCK assay and cell cycle assay in HCC cell lines. The interaction between miR-548a-5p and its downstream target, Tg737, was evaluated by a dual-luciferase reporter assay and quantitative real-time polymerase chain reaction. Tg737 was then up-regulated in HCC cells to evaluate its effect on miR-548a-5p regulation. HepG2 cells stably overexpressing miR-548a-5p or miR-control were also subcutaneously inoculated into nude mice to evaluate the effect of miR-548a-5p up-regulation on in vivo tumor growth. As the final step, the effect of miR-548a-5p on the apoptosis induced by cisplatin was evaluated by flow cytometry.Down-regulation of Tg737, which is a target gene of miR-548a-5p, accelerated HCC cell proliferation, and miR-548a-5p promoted HCC cell proliferation in vitro and in vivo. Like the down-regulation of Tg737, overexpression of miR-548a-5p in HCC cell lines promoted cell proliferation, increased colony forming ability and hampered cell apoptosis. In addition, miR-548a-5p overexpression increased HCC cell growth in vivo. MiR-548a-5p down-regulated Tg737 expression through direct contact with its 3' untranslated region (UTR), and miR-548a-5p expression was negatively correlated with Tg737 levels in HCC specimens. Restoring Tg737 (without the 3'UTR) significantly hampered miR-548a-5p induced cell proliferation, and rescued the miR-548a-5p induced cell proliferation inhibition and apoptosis induced by cisplatin.MiR-548a-5p negatively regulates the tumor inhibitor gene Tg737 and promotes tumorigenesis in vitro and in vivo, indicating its potential as a novel therapeutic target for HCC.

BACKGROUND: Dendritic cells (DCs) release bioactive exosomes that play an important role in immune regulation. Because they express low levels of class I major histocompatibility complex (MHC) and co-stimulatory molecules, exosomes derived from donor immature DCs (imDex) prolong allograft survival by inhibiting T-cell activation. However, this effect is limited and does not induce immunological tolerance when imDex are administered alone. Thus, we tested the effect of combined treatment with donor imDex and low-dose rapamycin on inducing tolerance in a mouse cardiac transplantation model. METHODS: ImDex were obtained from the culture supernatant of immature DCs derived from donor mouse (C57BL/6) bone marrow and were injected with suboptimal doses of rapamycin into recipient mouse (BALB/c) before and after transplantation. The capacity of this treatment to induce immune tolerance was analyzed in vitro and in vivo using the mouse cardiac transplantation model. RESULTS: Donor imDex expressed moderate levels of MHC class II and low levels of MHC class I and co-stimulatory molecules, but neither imDex nor subtherapeutic rapamycin dose alone induced cardiac allograft tolerance. Combined treatment with imDex and rapamycin, however, led to donor specific cardiac allograft tolerance. This effect was accompanied by decreased anti-donor antigen cellular response and an increased percentage of spleen CD4(+)CD25(+) T cells in recipients. Furthermore, this donor specific tolerance could be further transferred to naïve allograft recipients through injection of splenocytes, but not serum, from tolerant recipients. CONCLUSION: Combined with immunosuppressive treatment, donor imDex can prolong cardiac allograft survival and induce donor specific allograft tolerance.