Erratum: Thioredoxin 1 supports colorectal cancer cell survival and promotes migration and invasion under glucose deprivation through interaction with G6PD: Erratum.

[This corrects the article DOI: 10.7150/ijbs.71809.].

Thioredoxin 1 supports colorectal cancer cell survival and promotes migration and invasion under glucose deprivation through interaction with G6PD.

Overcoming energy stress is a critical step for cells in solid tumors. Under this stress microenvironment, cancer cells significantly alter their energy metabolism to maintain cell survival and even metastasis. Our previous studies have shown that thioredoxin-1 (Trx-1) expression is increased in colorectal cancer (CRC) and promotes cell proliferation. However, the exact role and mechanism of how Trx-1 is involved in energy stress are still unknown. Here, we observed that glucose deprivation of CRC cells led to cell death and promoted the migration and invasion, accompanied by upregulation of Trx-1. Increased Trx-1 supported CRC cell survival under glucose deprivation. Whereas knockdown of Trx-1 sensitized CRC cells to glucose deprivation-induced cell death and reversed glucose deprivation-induced migration, invasion, and epithelial-mesenchymal transition (EMT). Furthermore, we identified glucose-6-phosphate dehydrogenase (G6PD) interacting with Trx-1 by HuPortTM human protein chip, co-IP and co-localization. Trx-1 promoted G6PD protein expression and activity under glucose deprivation, thereby increasing nicotinamide adenine dinucleotide phosphate (NADPH) generation. Moreover, G6PD knockdown sensitized CRC cells to glucose deprivation-induced cell death and suppressed glucose deprivation-induced migration, invasion, and EMT. Inhibition of Trx-1 and G6PD, together with inhibition of glycolysis using 2-deoxy-D-glucose (2DG), resulted in significant anti-tumor effects in CRC xenografts in vivo. These findings demonstrate a novel mechanism and may represent a new effective therapeutic regimen for CRC.

Synthesis of red/black phosphorus-based composite nanosheets with a Z-scheme heterostructure for high-performance cancer phototherapy.

Two dimensional black phosphorus nanosheets (BP NSs) have attracted plenty of attention in the research field of cancer photonic therapy. However, the poor stability and relatively low efficiency of reactive oxygen species (ROS) generation of BP NSs limit their practical application. To address these drawbacks, herein we report a red/black phosphorus (RP/BP) composite nanosheet, M-RP/BP@ZnFe2O4, which was synthesized by (1) partially converting red phosphorus (RP) to black phosphorus (BP) followed by liquid-phase ultrasonic exfoliation to form RP/BP NSs, (2) in situ synthesis of ZnFe2O4 nanoparticles on the surface of RP/BP NSs, (3) and wrapping with the MCF-7 cell membrane. Due to the presence of RP, BP, ZnFe2O4 and the cell membrane, the M-RP/BP@ZnFe2O4 NSs exhibited high performance in cancer phototherapy with the following features: (i) a Z-scheme heterojunction structure was formed between RP/BP NSs thus enabling high separation efficiency of the photogenerated electrons and holes; (ii) the photoexcitation holes in the valence band of RP can break the tumor microenvironment by oxidizing glutathione; (iii) the NSs could decompose water to produce H2O2 and O2, which can be further converted to toxic ˙OH through the ZnFe2O4 catalyzed Fenton reaction and 1O2 through energy transfer, respectively; and (iv) the cell membrane wrapping improved the targeting of the composite NSs at the tumor site and photonic therapy can be finally triggered by a 660 nm laser to convert O2 to ˙O2- and 1O2. The in vitro cytotoxicity experiments showed that more than 90% cells were killed after photodynamic therapy (PDT) at 0.3 mg mL-1 M-RP/BP@ZnFe2O4 NSs, and the animal experiments with xenograft tumor model mice indicated that tumor growth was completely inhibited and the highest survival rate of 83.3% at 60 days post PDT was obtained.

Thermal-triggered packing of lipophilic NIR dye IR780 in hepatitis B core at critical ionic strength and cargo-host ratio for improved stability and enhanced cancer phototherapy.

Virus-like particles (VLPs) holding internal cavity with diameter from tens up to one hundred nanometers are attractive platform for drug delivery. Nevertheless, the packing of drugs in the nanocage mainly relies on complicated disassembly-reassembly process. In this study, hepatitis B core protein (HBc) VLPs which can withstand temperature up to 90 °C was employed as carrier to load a lipophilic near infrared dye IR780. It was found that an attaching-dis-atching-diffusing process was involved for the entering of IR780 in the cavity of HBc. The first two steps were associated with the electrostatic interactions between oppositely charged HBc and IR780, which was critically manipulated by ionic strength and HBc/IR780 mass ratio at which they were mixed; while the diffusion of IR780 across the shell of HBc showed a temperature-dependent manner that can be triggered by thermal induced pore-opening of the HBc capsid. At optimized condition, about 1055 IR780 molecules were encapsulated in each HBc by simply mixing them for 10 min at 60 °C. Compared with free IR780, the HBc-IR780 particles showed significantly improved aqueous and photostability, as well as enhanced photothermal and photodynamic performance for cancer therapy. This study provides a novel drug loading strategy and nanomemedicine for cancer phototherapies.

Black phosphorus quantum dots encapsulated in anionic waterborne polyurethane nanoparticles for enhancing stability and reactive oxygen species generation for cancer PDT/PTT therapy.

Black phosphorus quantum dots (BPQDs) with excellent biocompatibility, outstanding photothermal and photodynamic efficacies have attracted significant attention in cancer therapy. However, the low environmental stability and poor dispersity of BPQDs limit their practical applications. In the present work, biocompatible anionic waterborne polyurethane (WPU) nanoparticles were synthesized from castor oil to encapsulate the BPQDs. The WPU-BPQDs with a BPQDs loading capacity of about 13.8% (w/w) exhibited significantly improved dispersion and environmental stability without affecting the photothermal efficiency of BPQDs. Intriguingly, it was found that WPU encapsulation led to significant enhancement in the reactive oxygen species (ROS) generation of BPQDs, which indicated the enhanced photodynamic efficacy of the encapsulated BPQDs as compared to the bare BPQDs. The effect of solution pH on the ROS generation efficiency of BPQDs and the pH variation caused by BPQDs degradation was then investigated to explore the possible mechanism. In acidic solution, ROS generation was suppressed, while BPQDs degradation led to the acidification of the solution. Fortunately, after being encapsulated inside the WPU nanoparticles, the degradation rate of BPQDs became slower, while the acidic environment around BPQDs was favorably regulated by WPU nanoparticles having a special electrochemical double layer consisting of interior COO- and exterior NH(Et3)+, thus endowing the WPU-BPQDs-boosted production of ROS as compared to the bare BPQDs. Considering the undesired acidic tumor environment, this unique pH regulation effect of WPU-BPQDs would be beneficial for in vivo photodynamic efficacy. Both in vitro and in vivo experiments showed that WPU-BPQDs could effectively improve photodynamic therapy (PDT) and maintain outstanding photothermal therapy (PTT) effects. Together with the excellent dispersity, biocompatibility, and easy biodegradability, WPU-BPQDs can be a promising agent for PDT/PTT cancer treatments.

Interaction of Mycoplasma synoviae with chicken synovial sheath cells contributes to macrophage recruitment and inflammation.

Mycoplasma synoviae (MS) is an important avian pathogen causing considerable economic hardship in the poultry industry. A major inflammation caused by MS is synovitis that occurs in the synovial tendon sheath and joint synovium. However, the overall appearance of pathological changes in the tendon sheath and surrounding tissues caused by MS infection at the level of pathological tissue sections was poor. Studies on the role of MS and synovial sheath cells (SSCs) interaction in the development of synovitis have not been carried out. Through histopathological observation, our study found that a major MS-induced pathological change of the tendon sheath synovium was extensive scattered and focal inflammatory cell infiltration of the tendon sheath synovial layer. In vitro research experiments revealed that the CFU numbers of MS adherent and invading SSC, the levels of expression of various pattern recognition receptors, inflammatory cytokines, and chemokines coding genes, such as IL-1ß, IL-6, IL-8, CCL-20, RANTES, MIP-1ß, TLR7, and TLR15 in SSCs, and chemotaxis of macrophages were significantly increased when the multiplicity of infection (MOI) of MS to SSC were increased tenfold. The expression level of IL-12p40 in SSC was significantly higher when the MOIs of MS to SSC were increased by a factor of 100. The interaction between MS and SSC can activate macrophages, which was manifested by a significant increase in the expression of IL-1ß, IL-6, IL-8, CCL-20, RANTES, MIP-1ß, and CXCL-13. This study systematically demonstrated that the interaction of MS with chicken SSC contributes to the inflammatory response caused by the robust expression of related cytokines and macrophage chemotaxis. These findings are helpful in elucidating the molecular mechanism of MS-induced synovitis in chickens.

Increased Thioredoxin-1 Expression Promotes Cancer Progression and Predicts Poor Prognosis in Patients with Gastric Cancer.

BACKGROUND: Thioredoxin-1 (Trx-1) is a small redox protein, which plays an important role in many biological processes. Although increased expression of Trx-1 in various solid tumors has been reported, the prognostic significance and function of Trx-1 in human gastric cancer (GC) are still unclear. Here, we investigated the clinical and prognostic significance of Trx-1 expression and the function and mechanism of Trx-1 in human GC. METHODS: We analyzed Trx-1 mRNA expression from the GEO database and Trx-1 protein expression in 144 GC tissues using immunohistochemistry. Effects of Trx-1 on GC cell were assessed in vitro and in vivo through Trx-1 knockdown or overexpression. The antitumor effects of the Trx-1 inhibitor, PX-12, on GC cells were investigated. PTEN and p-AKT expressions were evaluated by Western blotting. RESULTS: Increased Trx-1 expression was found in GC tissues and associated with poor prognosis and aggressive clinicopathological characteristics in patients with GC. High Trx-1 expression predicted poor prognosis, and its expression was an independent prognostic factor for overall survival of GC patients. Knockdown of Trx-1 expression inhibited GC cell growth, migration, and invasion in vitro and tumor growth and lung metastasis in vivo. Conversely, overexpression of Trx-1 promoted GC cell growth, migration, and invasion. We also found that PX-12 inhibited GC cell growth, migration, and invasion. Overexpression of Trx-1 caused a decrease in PTEN and increase in p-AKT levels whereas silencing Trx-1 caused an increase in PTEN and decrease in p-AKT levels in GC cells. Inhibition of AKT signaling pathway by MK2206 also inhibited GC cell growth, migration, and invasion. CONCLUSION: Our results indicate that Trx-1 may be a promising prognostic indicator and therapeutic target for GC patients.

HOXB8 enhances the proliferation and metastasis of colorectal cancer cells by promoting EMT via STAT3 activation.

BACKGROUND: Previous studies have demonstrated that the expression of homeobox8 (HOXB8) is higher in colorectal cancer (CRC) tissues than in normal tissues; however, the precise role of HOXB8 in human CRC cells remains to be elucidated. METHODS: We generated lentiviral constructs to overexpress and silence HOXB8 in CRC cell lines, and examined their biological functions through MTT, wound healing, colony and transwell, expression of signal transducer and activator of transcription 3 (STAT3) and epithelial-mesenchymal transition (EMT) related factors through western-blot. RESULTS: HOXB8 knockdown inhibited cellular proliferation and invasion in vitro as well as carcinogenesis and metastasis in vivo. HOXB8 also induced EMT, which is characterized by the down-regulation of E-cadherin and the up-regulation of Vimentin, N-cadherin, Twist, Zeb1 and Zeb2. Moreover, HOXB8 activated STAT3, which is known to play an oncogenic role in diverse human malignancies. CONCLUSIONS: Our results indicate that HOXB8 may be an independent prognostic factor in CRC. Therefore, deserved a deeper research.

Anti-Cancer Effect of α-Solanine by Down-Regulating S100P Expression in Colorectal Cancer Cells.

BACKGROUND: α-Solanine, the most important and active component of Solanum nigrum, was found to have anti-cancer activity on multiple cancer cells. However, its effects on colorectal cancer (CRC) and associated molecular mechanisms remain to be further elucidated. OBJECTIVE: In this study, we investigated the anti-cancer effects of α-solanine against CRC cells in vitro and in vivo. MATERIALS & METHODS: Cell viability was measured using Cell Counting Kit-8 (CCK-8) assay; cell cycle was analyzed with a Cycletest Plus DNA Reagent Kit; cell apoptosis was detected by flow cytometer; cell migration and invasive ability was determined by Transwell assays; S100P protein expression was also analyzed by western blotting; lentiviral vectors expressing shRNA targeting the S100P gene. RESULTS: We demonstrated that α-solanine inhibited CRC cell (SW480, SW620 and HT-29) growth as well as migration and invasion, induced cell cycle arrest and apoptosis in vitro, and suppressed tumor growth in vivo. Moreover, we observed that S100P expression was downregulated by α-solanine. Overexpression of S100P partially reversed the α-solanine-induced growth inhibition of CRC cells. Conversely, knockdown of S100P by lentiviral-mediated RNAi resulted in significantly promoting the α-solanine-induced growth inhibition. CONCLUSION: These findings suggest that α-solanine is a potential agent for the treatment of CRC, and the anti-tumor effect of α-solanine in the CRC cells may be mediated at least partly by the downregulation of S100P.

Interplay between Trx-1 and S100P promotes colorectal cancer cell epithelial-mesenchymal transition by up-regulating S100A4 through AKT activation.

We previously reported a novel positive feedback loop between thioredoxin-1 (Trx-1) and S100P, which promotes the invasion and metastasis of colorectal cancer (CRC). However, the underlying molecular mechanisms remain poorly understood. In this study, we examined the roles of Trx-1 and S100P in CRC epithelial-to-mesenchymal transition (EMT) and their underlying mechanisms. We observed that knockdown of Trx-1 or S100P in SW620 cells inhibited EMT, whereas overexpression of Trx-1 or S100P in SW480 cells promoted EMT. Importantly, S100A4 and the phosphorylation of AKT were identified as potential downstream targets of Trx-1 and S100P in CRC cells. Silencing S100A4 or inhibition of AKT phosphorylation eliminated S100P- or Trx-1-mediated CRC cell EMT, migration and invasion. Moreover, inhibition of AKT activity reversed S100P- or Trx-1-induced S100A4 expression. The expression of S100A4 was higher in human CRC tissues compared with their normal counterpart tissues and was significantly correlated with lymph node metastasis and poor survival. The overexpression of S100A4 protein was also positively correlated with S100P or Trx-1 protein overexpression in our cohort of CRC tissues. In addition, overexpression of S100P reversed the Trx-1 knockdown-induced inhibition of S100A4 expression, EMT and migration and invasion in SW620 cells. The data suggest that interplay between Trx-1 and S100P promoted CRC EMT as well as migration and invasion by up-regulating S100A4 through AKT activation, thus providing further potential therapeutic targets for suppressing the EMT in metastatic CRC.

The siderophore-interacting protein is involved in iron acquisition and virulence of Riemerella anatipestifer strain CH3.

Riemerella anatipestifer causes epizootic infectious disease in poultry and serious economic losses especially to the duck industry. However, little is known regarding the molecular basis of its pathogenesis. The ability to acquire iron under low-iron conditions is related to the virulence of a variety of bacterial pathogens. In this study, a sip (Riean_1281) deletion mutant CH3Δsip was constructed and characterized for iron-limited growth, biofilm formation, and pathogenicity to ducklings. Results showed that siderophore-interacting protein (SIP) was involved in iron utilization and the sip deletion significantly reduced biofilm formation and adherence to and invasion of Vero cells. In addition, the sip gene was absent in 1 of 24 (4.17%) virulent strains and 2 of 3 (66.7%) avirulent strains of R. anatipestifer, and the sip gene from six R. anatipestifer strains, which belong to serotypes 1, 2, and 10, respectively, shared 100% amino acid identities to those of R. anatipestifer strains DSM15868 and RA-GD. These results suggested that siderophore-mediated iron acquisition may be an important iron-uptake pathway in R. anatipestifer. Animal experiments indicated that the median lethal dose of the CH3Δsip mutant in ducklings was about 35-fold higher than that of the wild-type CH3 strain. Thus, our results demonstrated that R. anatipestifer SIP was involved in iron acquisition and necessary for its optimal virulence.

The role of TonB-dependent receptor TbdR1 in Riemerella anatipestifer in iron acquisition and virulence.

Riemerella anatipestifer is an important duck pathogen and causes serious economic losses to the duck industry worldwide. To date, four full R. anatipestifer genomic sequences have been submitted to the GenBank database and 31 TonB-dependent outer membrane receptors, which may play critical roles in host-bacteria interactions, were predicted for R. anatipestifer strain GSM15868. In our previous study, we reported that the TonB-dependent receptor TbdR1 was a cross immunogenic antigen among R. anatipestifer serotypes 1, 2, and 10. However, the biological functions of TbdR1 in R. anatipestifer remain unclear. In the present study, a tbdR1 (Riean_1607) deletion mutant CH3ΔtbdR1 of R. anatipestifer strain CH3 was constructed and characterized for iron-limited growth, biofilm formation, and pathogenicity to ducklings. Our results showed that TbdR1 was involved in hemin iron acquisition and the tbdR1 deletion significantly reduced biofilm formation and adhesion to and invasion of Vero cells. Animal experiments indicated that the median lethal dose of the CH3ΔtbdR1 mutant in ducklings was about 45-fold higher than that of the wild-type CH3 strain. Additional analysis indicated that bacterial loads in blood, liver, and brain tissues in CH3ΔtbdR1-infected ducklings were decreased significantly compared to those in wild-type CH3-infected ducklings. Thus, our results demonstrated that TbdR1 was involved in hemin iron acquisition and necessary for optimal bacterial virulence.

[Association between dysplastic development of ventricular wall and primary cardiomyopathy: pathomorphological observations on 92 hearts from transplant recipients.].

OBJECTIVE: To investigate the morphological characteristics and types of ventricular wall with dysplastic development and their associations to primary cardiomyopathy. METHODS: Ninety-two hearts from heart transplant patients were studied soon after explanation from 2004 to 2007. Gross examination/measurement, histopathology and photography were performed. RESULTS: Dysplastic development of ventricular wall could be evidenced in patients with various heart diseases but more often in patients with primary cardiomyopathy, though the extension and distribution of dysplastic development of ventricular wall varied between patients with or without primary cardiomyopathy. Severe dysplastic development of ventricular wall is associated with clinical dysplastic cardiomyopathy. The range of extension and degree of dysplasia in the ventricular wall correlated positively to heart dilation/failure and time point of heart failure development. The incidence of severe ventricular wall dysplasia was 27.17% in all transplanted hearts and was 43.1% (25/58) in hearts diagnosed as primary cardiomyopathy (P < 0.05). The main pathological changes of dysplastic hearts were: (1) extensive proliferative hypertrophy of the heart wall, (2) fibrous/fat or fat/fibrous tissue replacement of normal myocardium, (3) disarrangement of myocardial fibers, (4) dysplastic change in the medium-sized intramural arteries. Dysplastic cardiomyopathy was presented mainly as a combination of several forms of dysplasia. The same clinical manifestations of dysplastic cardiomyopathy patients did not always show the same pathologic changes. Fibrous-fat tissue replacement was commonly found in dilated cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. Disarrangement of myocardium was often accompanied by hypertrophic cardiomyopathy. Dysplasia of intramural arteries could result in heart dilatation due to myocardial ischemia. CONCLUSION: Dysplasia of ventricular wall is a common variation of heart structure. Only severe or diffuse types of dysplasia is associated with cardiomyopathy, especially primary cardiomyopathy.

[Pathologic features of arrhythmogenic right ventricular cardiomyopathy with severe heart failure].

OBJECTIVES: To study the pathologic features of arrhythmogenic right ventricular cardiomyopathy (ARVC) in the phase of heart failure. METHODS: Eight cases underwent heart transplantation in Fuwai Hospital during the period from May, 2004 to July, 2007 with pathologic diagnosis of ARVC were studied. The age of patients ranged from 15 to 54 years. They had history of palpitation and syncope for 1 to 22 years. Severe heart failure was diagnosed according to the New York Heart Association Classification System. The recipient hearts were examined and the following parameters were evaluated: weight of heart, presence of cardiac dilatation, myocardial hypertrophy, fatty infiltration, fibrosis, parietal thrombosis and myocarditis. The degree of left ventricular involvement was also analyzed. RESULTS: Of the 8 cases studied, 7 cases with prominent right ventricular lesion (fibrofatty replacement) were classified as classic type. One case with prominent left ventricle lesion and mild right ventricle involvement was classified as left predominant type. No biventricular type and no pure fatty infiltration were found. The cases of classic type showed moderate to severe dilatation of right ventricle, sometimes with aneurysm formation. Left ventricle was involved in 6 cases, which showed diffuse interstitial fibrosis, patchy fibrous replacement and subepicardial fatty infiltration. Mild to moderate dilatation of left ventricle, myocardial hypertrophy and vacuolation were also observed in these cases. The case of left predominant type had severe hypertrophy and dilatation of left ventricle, with prominent diffuse interstitial fibrosis and transmural fatty infiltration. Besides, 3 cases showed left ventricular hypertrophy and parietal thrombosis in both ventricles. Focal lymphocytic myocarditis was noted in 1 case. CONCLUSIONS: Left ventricular involvement is common in the heart failure phase of ARVC. Extensive interstitial fibrosis, marked hypertrophy and degeneration of myocardial fibers, as well as severe cardiac dilatation with organized thrombi, represent the major pathologic changes which resembles dilated cardiomyopathy.

[Clinicopathologic analysis of dilated heart in cardiac transplant recipients].

OBJECTIVE: To study the pathologic features of dilated heart in cardiac transplant recipients, with clinicoradiologic correlation. METHODS: Sixty recipient hearts from cardiac transplantation performed in Fuwai Hospital were analyzed by gross examination, histologic observation and electron microscopy. Clinicoradiologic correlation was available in 40 cases. RESULTS: Amongst the 40 cases of dilated heart, 52.5% (21/40) were due to dilated cardiomyopathy, 22.5% (9/40) due to arrhythmogenic right ventricular cardiomyopathy, 15.0% (6/40) due to ischemic cardiomyopathy, and the remaining 10.0% (4/40) due to miscellaneous causes, including local noncompaction of ventricular myocardium, giant cell myocarditis, alcoholic cardiomyopathy and hypertensive cardiomyopathy. The discrepancy rate between clinical and pathologic diagnosis was 37.5% (15/40). The erroneous categories included arrhythmogenic right ventricular cardiomyopathy (7 cases), ischemic cardiomyopathy (5 cases), and giant cell myocarditis (1 case), which were all mistaken clinically as dilated cardiomyopathy. While ischemic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, noncompaction of ventricular myocardium and giant cell myocarditis have distinctive pathologic features, the diagnosis of alcoholic and hypertensive cardiomyopathies required clinicopathologic correlation. Dilated cardiomyopathy due to viral myocarditis was not identified in the cases studied. CONCLUSION: Pathologic examination is essential in analysis of transplant recipient heart and helps to rectify clinical diagnostic discrepancy.

[Clinicopathologic studies of 11 cases of primary cardiac valve tumors].

OBJECTIVE: To study the clinicopathologic features of primary cardiac valve tumors. METHODS: Eleven cases of primary valve tumors collected from Fuwai Hospital during the period from 1983 to 2005 were enrolled into the study. The tumors were stained with hematoxylin and eosin and Weigert-Van Gieson stain. Immunohistochemistry was also carried out in selected examples. RESULTS: Primary cardiac valve tumors were uncommon and accounted for only 3% (11/426) of all primary cardiac tumors. Most of them (10/11) were benign and malignancy was rarely encountered (1/11). The tumor subtypes included papillary fibroelastoma (4/11), cavernous hemangioma (4/11), glomus tumor (1/11), angiosarcoma (1/11) and hamartoma (1/11). Of the 11 tumors studied, 4 involved the tricuspid valve, 4 involved the mitral valve, 2 involved the pulmonary valve and 1 involved the aortic valve. The diagnosis was established by preoperative echocardiography in 7 patients. The remaining 4 cases were either misdiagnosed or undiagnosed. CONCLUSIONS: Preoperative diagnosis of primary cardiac valve tumors can be difficult due to lack of detailed information related to this group of lesions. Although benign cardiac valve tumors carry a good prognosis, the clinical outcome may be disastrous as a result of hemodynamic disturbances. Intraoperative frozen section examination is advisable for guiding proper surgical management.

[The clinicopathological endomyocardial biopsy analysis in cardiac transplant recipients due to end-stage heart failure].

OBJECTIVE: Endomyocardial biopsies from 42 (35 males and 7 females, aged 43.3 years) heart transplant recipients due to end-stage heart failure between June 2004 and January 2006 in our institute were obtained for pathological studies. METHODS: Sixteen patients underwent 1 endomyocardial biopsy (right ventricular septum) between 13 days to 5 months, 13 patients underwent second biopsy between 1.5 to 8 months and 10 patients underwent third biopsy between 3 to 8.5 months post transplantation. Specimen were stained by hematoxylin-eosin (HE) and Phosphotungstic Acid Hematoxylin (PTAH) and observed under light microscope and cardiac allograft rejection were evaluated according to the Revision of the 1990 working formulation for the standardization of nomenclature in the diagnosis of heart rejection in 2004. RESULTS: The rejection grades were as follows: Grade 0 R in 31 biopsies; Grade 1 R (mild rejection 1990 grade 1A, 1B and 2.) in 30 biopsies; Grade 2 R (moderate rejection, 1990 grade 3A) in 3 biopsies; Grade 1 R cellular rejection companies with humoral rejection in 1 biopsy. Cellular rejection with Quilty effect was found in 2 biopsies. Ischemic myocardial injury presented in 4 biopsies. Quilty effect was observed in 1 biopsy. Cytomegalovirus or toxoplasmic myocarditis was not observed. CONCLUSIONS: Endomyocardial biopsy (EMB) is a valuable diagnostic procedure for rejection surveillance in heart allograft recipients. The observed low rejection incidence and mild rejection from specimens of our heart recipients were comparable to the results of developed countries.