Fibrillarin, a nucleolar protein, is required for normal nuclear morphology and cellular growth in HeLa cells

Fibrillarin is a key small nucleolar protein in eukaryotes, which has an important role in pre-rRNA processing during ribosomal biogenesis. Though several functions of fibrillarin are known, its function during the cell cycle is still unknown. In this study, we confirmed the dynamic localization of fibrillarin during the cell cycle of HeLa cells and also performed functional studies by using a combination of immunofluorescence microscopy and RNAi technique. We observed that depletion of fibrillarin has almost no effect on the nucleolar structure. However, fibrillarin-depleted cells showed abnormal nuclear morphology. Moreover, fibrillarin depletion resulted in the reduction of the cellular growth and modest accumulation of cells with 4n DNA content. Our data suggest that fibrillarin would play a critical role in the maintenance of nuclear shape and cellular growth.

Nucleolin functions in nucleolus formation and chromosome congression

A complex structure, designated the chromosome periphery, surrounds each chromosome during mitosis. Although several proteins have been shown to localize to the chromosome periphery, their functions during mitosis remain unclear. Here, we used a combination of high-resolution microscopy and RNA-interference-mediated depletion to study the functions of nucleolin, a nucleolar protein localized at the chromosome periphery, in interphase and mitosis. During mitosis, nucleolin was localized in the peripheral region including the vicinity of the outer kinetochore of chromosomes. Staining with an antibody specific for nucleolin phosphorylated by CDC2 revealed that nucleolin was also associated with the spindle poles from prometaphase to anaphase. Nucleolin depletion resulted in disorganization of the nucleoli at interphase. Furthermore, nucleolin-depleted cells showed a prolonged cell cycle with misaligned chromosomes and defects in spindle organization. The misaligned chromosomes showed syntelic kinetochore-microtubule attachments with reduced centromere stretching. Taken together, our results indicate that nucleolin is required for nucleolus formation, and is also involved in chromosome congression and spindle formation.

Bcl-2 engineered MSCs inhibited apoptosis and improved heart function

Engraftment of mesenchymal stem cells (MSCs) derived from adult bone marrow has been proposed as a potential therapeutic approach for postinfarction left ventricular dysfunction. However, limited cell viability after transplantation into the myocardium has restricted its regenerative capacity. In this study, we genetically modified MSCs with an antiapoptotic Bcl-2 gene and evaluated cell survival, engraftment, revascularization, and functional improvement in a rat left anterior descending ligation model via intracardiac injection. Rat MSCs were manipulated to overexpress the Bcl-2 gene. In vitro, the antiapoptotic and paracrine effects were assessed under hypoxic conditions. In vivo, the Bcl-2 gene-modified MSCs (Bcl-2-MSCs) were injected after myocardial infarction. The surviving cells were tracked after transplantation. Capillary density was quantified after 3 weeks. The left ventricular function was evaluated by pressure-volume loops. The Bcl-2 gene protected MSCs against apoptosis. In vitro, Bcl-2 overexpression reduced MSC apoptosis by 32% and enhanced vascular endothelial growth factor secretion by more than 60% under hypoxic conditions. Transplantation with Bcl-2-MSCs increased 2.2-fold, 1.9-fold, and 1.2-fold of the cellular survival at 4 days, 3 weeks, and 6 weeks, respectively, compared with the vector-MSC group. Capillary density in the infarct border zone was 15% higher in Bcl-2-MSC transplanted animals than in vector-MSC treated animals. Furthermore, Bcl-2-MSC transplanted animals had 17% smaller infarct size than vector-MSC treated animals and exhibited functional recovery remarkably. Our current findings support the premise that transplantation of antiapoptotic gene-modified MSCs may have values for mediating substantial functional recovery after acute myocardial infarction.

Clinical manifestations and computed tomography diagnosis for thoracostomach-airway fistula

AIM: To analyze the clinical manifestations and spiral computed tomography (CT) signs of thoracostomach-airway fistula (TSAF).

METHODS: The clinical manifestations and spiral CT signs were analyzed in 23 patients with TSAF.

RESULTS: The main clinical manifestations of TSAF were irritative choke after drinking or eating, fever, stubborn pulmonary infection, dyspnea, tachycardia and becoming thin, etc. The site and size of TSAF were shown exactly in 20 patients by spiral CT. According to spiral CT, the pulmonary infection and particular anatomic structures between the fistula and its adjoining air passage in details could be observed, and the inner diameters of the trachea and main bronchi could be measured.

CONCLUSION: TSAF has distinctive clinical manifestations. CT is a non-invasive and non-stimulative examination for TSAF.

Long-term outcome of elective stenting for symptomatic intracranial vertebrobasilar stenosis

Seventy-nine consecutive patients with symptomatic atherosclerotic stenosis > or = 50% of intracranial vertebrobasilar artery (VBA) were treated by elective stenting. There were five strokes within 30 days, and three strokes in the VBA territory after 30 days (mean of 812 days). The annual stroke rate in the VBA territory (including any stroke and death within 30 days) was 4.6%. At the last follow-up time, 73 patients were independent (modified Rankin scale grade < or = 2). The outcome compares favorably with medical therapy.

Comparison of elective stenting of severe vs moderate intracranial atherosclerotic stenosis

OBJECTIVE

To test whether symptomatic severe intracranial atherosclerotic stenosis was associated with a higher subsequent stroke risk than moderate stenosis after elective angioplasty with a balloon-expandable stent and to explore which factors were associated with the subsequent stroke.

METHODS

Between September 2001 and June 2005, there were 220 symptomatic intracranial atherosclerotic stenoses in 213 patients undergoing elective stenting at our institute. Of these stenoses, 126 in 121 patients were > or =70% severe stenoses, and 94 in 92 patients were 50% to 69% moderate stenoses. Primary endpoints included lesion-related ischemic stroke, and symptomatic brain or subarachnoid hemorrhage.

RESULTS

Ten primary endpoint events occurred in the severe stenosis group (six within 30 days and four in mean follow-up of 26.0 months after 30 days), and seven occurred in the moderate stenosis group (four within 30 days and three in mean follow-up of 27.6 months after 30 days). There was no significant difference in cumulative probability of primary endpoints between the severe (7.2% at 1 year and 8.2% at 2 years) and moderate (5.3% at 1 year and 8.3% at 2 years) stenosis groups. No single factor was found to be associated with primary endpoints in the moderate stenosis group. Multivariable analysis revealed that stent failure was the only predictor of primary endpoints in the severe stenosis group (hazard ratio 5.31, 95% CI 1.35 to 20.91).

CONCLUSION

Symptomatic severe intracranial atherosclerotic stenosis did not present a higher subsequent stroke risk than moderate stenosis after elective angioplasty with a balloon-expandable stent. Patients with severe stenosis may benefit from successful stent placement, and randomized trials are necessary to demonstrate this possible benefit.

Heterologous expression of the AtDREB1A gene in chrysanthemum increases drought and salt stress tolerance

DNA cassette containing an AtDREB1A cDNA and a nos terminator, driven by a cauliflower mosaic 35S promoter, or a stress-inducible rd29A promoter, was transformed into the ground cover chrysanthemum (Dendranthema grandiflorum) 'Fall Color' genome. Compared with wild type plants, severe growth retardation was observed in 35S:DREB1A plants, but not in rd29A:DREB1A plants. RT-PCR analysis revealed that, under stress conditions, the DREB1A gene was over-expressed constitutively in 35S:DREB1A plants, but was over-expressed inductively in rd29A:DREB1A plants. The transgenic plants exhibited tolerance to drought and salt stress, and the tolerance was significantly stronger in rd29A:DREB1A plants than in 35S:DREB1A plants. Proline content and SOD activity were increased inductively in rd29A:DREB1A plants than in 35S:DREB1A plants under stress conditions. These results indicate that heterologous AtDREB1A can confer drought and salt tolerance in transgenic chrysanthemum, and improvement of the stress tolerance may be related to enhancement of proline content and SOD activity.

RNA-Templated Semiconductor Nanocrystals

The use of a biomolecular RNA template for the synthesis of CdS semiconductor nanocrystals is described. Transfer RNA, with a well-defined three-dimensional structure, is used as a scaffold and ligand system in the aqueous synthesis of CdS. We have found that nanocrystal structures can be modulated by the structure of the templating tRNA. When possessing a folded three-dimensional structure, tRNA-templated synthesis yields a single product. If the same tRNA is rendered unstructured through the introduction of destabilizing mutations, a range of products are observed. The results reported indicate that biomolecules can be used to systematically engineer the structures and properties of semiconductor-based materials, and that the synergy between the dimensions of nanostructures and biomolecules provides a means to tune the properties of materials with nanoscale precision.

Umbilical cord blood cell transplantation for myocardial regeneration

Bone marrow remains the most frequently used source of adult stem cells, but its angiogenic and possibly also myogenic potentials are likely to regress with increasing donor age and morbidity. Recently, cord blood has been suggested as a readily available source for non-embryonic stem cells with high regenerative capacity. We first tested the capacity of mononuclear cells obtained from human umbilical cord blood (UCB(mn)) to migrate to the heart on IV delivery in NOD/Scid mice. As evidenced by the presence of human DNA by PCR analysis, UCB(mn) cells migrated to the heart in 50% of the mice with myocardial infarctions, but in none of the sham-operated control mice. In UCB(mn) cell-positive injured hearts, the infarct size was smaller and capillary density higher in the ischemic myocardium. By immunohistology, we observed endothelial cell differentiation of UCB(mn) cells in the heart but there was no colocalization of UCB cell-specific antibodies with markers of myocyte-type cells. In a second series of experiments, we injected 5 x 10(5) UCB cells enriched for CD133 directly into the necrotic myocardium of NOD/Scid mice. Comparisons were performed with an equivalent number of CD133+ bone marrow (BM) cells or a sham injection in the respective control groups. Both BMCD133+ and UCBCD133+ cells abolished postoperative mortality and improved capillary density in the injured myocardium, but only BMCD133+ cells led to a detectable improvement in myocardial contractility in vivo. We conclude that human UCB cells facilitated neovascularization of ischemic myocardium, but their capacity for formation of contractile neotissue needs further investigation.

NGR enhanced the anti-angiogenic activity of tum-5

Tumstatin is an angiogenesis inhibitor. The anti-angiogenic activity of tumstatin is localized to the 54-132 amino acids. NGR motif is a marker of angiogenic endothelial cells. We synthesized the gene fragment encoding the amino acids 45-132 of tumstatin (tum-5) and coupled a NGR (CNGRCVSGCAGRC) motif to the C-terminal of tum-5 (tum-5-NGR). The both were inserted into pQE30 expression vector and expressed in Escherichia coli. The anti-angiogenic effects of tum-5-NGR and tum-5 were examined in vivo. The results demonstrated the effect of the former was more significant than the latter. After S180 murine cancer xenografts in BALB/c mice were treated with tum-5-NGR or tum-5, tum-5-NGR displayed more significant tumor growth inhibition than tum-5. Binding of tum-5-NGR to normal and tumor tissues was also evaluated. The results showed that the accumulation of tum-5-NGR in tumor tissue was much more than in normal tissues. These data suggest that NGR enhance the anti-angiogenic activity of tum-5.

Endothelial nitric oxide synthase mediates protective effects of hypoxic preconditioning in lungs

To elucidate the protective mechanism of whole-body hypoxic preconditioning (WHPC) on pulmonary ischemia-reperfusion injury focussing on nitric oxide synthases (NOS), mice were placed in a hypoxic chamber (FIO(2)=0.1) for 4h followed by 12h of normoxia. Then, pulmonary ischemia for 1h followed by 5h of reperfusion was performed by clamping the left hilum in vivo (I/R). WHPC protected WT mice from pulmonary leukocyte infiltration as assessed by myeloperoxidase (MPO) activity, associated with a mild further increase in endothelial permeability (Evans Blue extravasation). When all NOS isoforms were inhibited during WHPC by L-NAME, mortality and MPO activity after I/R markedly increased. To determine the responsible NOS isoform, quantitative RT-PCR was performed for eNOS and iNOS mRNA, showing that only eNOS was upregulated in response to WHPC. While eNOS total protein expression remained unchanged, the amount of phosphorylated eNOS also increased. The WHPC/IR experiments were then repeated with eNOS knockout mice. Here, we found that the protective effect of WHPC on pulmonary leukocyte sequestration was abrogated, and endothelial leakage was further exacerbated. We conclude that WHPC limits neutrophil sequestration via an eNOS-dependent mechanism, and that eNOS helps preserve endothelial permeability during hypoxia and I/R.

Intramyocardial delivery of human CD133+ cells in a SCID mouse cryoinjury model: Bone marrow vs. cord blood-derived cells

OBJECTIVE

The regenerative potential of endothelial and hematopoietic progenitor cells in the heart may vary according to their origin. This study was designed to compare the functional effects of CD133+ cells from human cord blood and bone marrow in a mouse model of myocardial injury.

METHODS

5 x 10(5) CD133+ cells from bone marrow (BM(CD133)) or cord blood (UCB(CD133)) were injected in the necrosis border zone of NOD/SCID (non-obese diabetic/severe combined immunodeficiency) mice with left ventricular cryoinjury (CI+). Transplanted cells were tracked by immunostaining for hNuclear antigen and by PCR for hDNA. Echocardiography was used to measure contractility. Scar size, capillary density, and cardiomyocyte apoptosis were evaluated by histology. In addition, the myogenic and endothelial differentiation capacity of BM(CD133) and UCB(CD133) was compared in vitro.

RESULTS

DNA was detected 4 weeks after cell injection by PCR, but hNuc+ cells were found by immunostaining only after 48 h. Capillary density in both BM(CD133) and UCB(CD133) cell-treated CI+ mice was higher than in control CI+ mice, but not different between BM(CD133) and UCB(CD133) cell-treated hearts. There were no differences in scar size and myocardial mass among BM(CD133), UCB(CD133) and control CI+ mice, but cardiomyocyte apoptosis was reduced by both BM(CD133) and UCB(CD133) cells. The post-injury deterioration of shortening fraction (46.2+/-1% in sham-operated mice and 41.3+/-0.8% in control CI+ mice) was prevented by BM(CD133) cells (45.4+/-0.9%), but not by UCB(CD133) cells (40.8+/-0.7%). On the other hand, both BM(CD133) and UCB(CD133) cells abolished post-injury mortality. In vitro, neither cultivated BM(CD133) or UCB(CD133) cells developed into myocytes, but both readily differentiated towards an endothelial cell phenotype.

CONCLUSIONS

While both cord blood and marrow CD133+ cells have some beneficial effects on post-injury angiogenesis and survival, only marrow cells appear to improve myocardial contractility.

Clusterin plays an important role in hepatocellular carcinoma metastasis

To identify genes associated with tumor metastasis in hepatocellular carcinoma (HCC), gene expression profiles between a pair of primary HCC (H2-P) and their matched metastatic HCC (H2-M) were compared. Overexpression of clusterin (CLU) was found in H2-M cells. To determine the roles CLU played in HCC metastasis, CLU was transfected into H2-P cells. Overexpression of CLU in H2-P cells increased cell migration by twofold in vitro and formation of metastatic tumor nodules in liver by eightfold in vivo. To evaluate the correlation of CLU expression with HCC metastasis, the expression levels of CLU in HCCs were investigated using a tissue microarray (TMA) containing 104 pairs of primary HCCs and their matched metastases. The frequency of CLU overexpression increased significantly in metastatic HCCs (59.1%) compared with that in primary tumors (32.6%, P<0.001). To gain additional insight into the function of CLU, the expression profile of H2P-CLU was compared with vector-transfected H2-P cells by cDNA microarray. A total of 35 upregulated and 14 downregulated genes were detected in H2P-CLU. One of the upregulated genes known as YKL-40, which is implicated in matrix-remodeling and metastasis, was further studied using TMA. A significant correlation (P<0.001) between the expression levels of YKL-40 and CLU was observed, implying that the CLU-YKL-40 pathway may play an important role in HCC metastasis.

Transcriptional regulation of ethylene receptor and CTR genes involved in ethylene-induced flower opening in cut rose (Rosa hybrida) cv. Samantha

In this work, the effect of ethylene on flower opening of cut rose (Rosa hybrida) cv. Samantha was studied. However, although ethylene hastened the process of flower opening, 1-MCP (1-methylcyclopropene), an ethylene action inhibitor, impeded it. Ethylene promoted ethylene production in petals, but 1-MCP did not inhibit this process. Of the four ethylene biosynthetic genes tested, Rh-ACS1 and Rh-ACS2 were undetectable; Rh-ACS3 and Rh-ACO1 expression was enhanced by ethylene slightly and greatly, respectively. However, their mRNA amounts were not inhibited by 1-MCP compared with controls. Expression of seven signalling component genes was also studied, including three ethylene receptors (Rh-ETR1, Rh-ETR3, and Rh-ETR5), two CTRs (Rh-CTR1 and Rh-CTR2), and two transcription factors (Rh-EIN3-1 and Rh-EIN3-2). Transcripts of Rh-ETR5, Rh-EIN3-1, and Rh-EIN3-2 were accumulated in a constitutive manner and had no or little response to ethylene or 1-MCP, while transcript levels of Rh-ETR1 and Rh-CTR1 were substantially elevated by ethylene, and those of Rh-ETR3 and Rh-CTR2 were greatly enhanced by ethylene; 1-MCP reduced all the four genes to levels much less than those in control flowers. These results show that ethylene triggers physiological responses related to flower opening in cut rose cv. Samantha, and that continued ethylene perception results in flower opening. Ethylene may regulate flower opening mainly through expression of two ethylene receptor genes (Rh-ETR1 and Rh-ETR3) and two CTR (Rh-CTR1 and Rh-CTR2) genes.

Human cord blood cells induce angiogenesis following myocardial infarction in NOD/scid-mice

OBJECTIVE

We tested the hypothesis that intravenously administered human umbilical cord blood (hUCB) cells contribute to repair processes following myocardial infarction.

METHODS

hUCB mononuclear cells containing 0.11% to 1.1% CD34(+) cells were injected in the tail vein of NOD/scid mice that had (MI+) or had not (MI-) previously undergone ligation of the left anterior coronary artery (LAD). Homing to bone marrow and solid organs was determined by polymerase chain reaction (PCR) for human DNA (hDNA) using human-specific primers of Locus D7Z1. Immunostaining was used for phenotypic analysis, and capillary density as well as myocardial scar formation was assessed. Moreover, expression of stromal cell-derived factor-1 (SDF-1) was studied in infarcted and in normal hearts.

RESULTS

hDNA was detected in marrow, spleen, and liver of both MI+ and MI- mice 24 h, 1 week, and 3 weeks after cell injection. In the heart, however, hDNA was detected in 10 of 19 MI+ mice but in none of the MI- mice (p=0.002). Infarct size was smaller in cell-treated MI+ mice than in untreated MI+ hearts (38.7 versus 47.8%, P<0.05), and there was also less collagen deposition. In cell-treated MI+ mice, capillary density in the infarct border zone was approximately 20% higher (p=0.03), and clusters of hUCB-derived cells were detected in the perivascular interstitium. Occasionally, chimeric capillaries composed of human and mouse endothelial cells were found, but the vast majority of neo-vessels appeared to consist of mouse cells only. Up to 70% of the cord blood-derived cells in the heart were CD45(+). There was no evidence of cardiomyocyte differentiation as determined by co-localization of HNA or HLA-I with GATA-4 or Connexin 43. In infarcted myocardium, expression of SDF-1 mRNA was approximately 7-fold higher than in normal hearts.

CONCLUSIONS

hUCB cells migrate to infarcted, not to normal myocardium, where they engraft, participate in neoangiogenesis, and beneficially influence remodelling processes. Cord blood cells may hence be useful for cell therapy of ischemic heart disease.

Exogenous Eethylene influences flower opening of cut roses (Rosa hybrida) by regulating the genes encoding ethylene biosynthesis enzymes

The purpose of this paper is to investigate the differential responses of flower opening to ethylene in two cut rose cultivars, 'Samantha', whose opening process is promoted, and 'Kardinal', whose opening process is inhibited by ethylene. Ethylene production and 1-aminocyclopropane-1-carboxylate (ACC) synthase and oxidase activities were determined first. After ethylene treatment, ethylene production, ACC synthase (ACS) and ACC oxidase (ACO) activities in petals increased and peaked at the earlier stage (stage 3) in 'Samantha', and they were much more dramatically enhanced and peaked at the later stage (stage 4) in 'Kardinal' than control during vasing. cDNA fragments of three Rh-ACSs and one Rh-ACO genes were cloned and designated as Rh-ACS1, Rh-ACS2, Rh-ACS3 and Rh-ACO1 respectively. Northern blotting analysis revealed that, among three genes of ACS, ethylene-in- duced expression patterns of Rh-ACS3 gene corresponded to ACS activity and ethylene production in both cultivars. A more dramatic accumulation of Rh-ACS3 mRNA was induced by ethylene in 'Kardinal' than that of 'Samantha'. As an ethylene action inhibitor, STS at concentration of 0.2 mmol/L generally inhibited the expression of Rh-ACSs and Rh-ACO in both cultivars, although it induced the expression of Rh-ACS3 transiently in 'Kardinal'. Our results suggests that 'Kardinal' is more sensitive to ethylene than 'Samantha'; and the changes of Rh-ACS3 expression caused by ethylene might be related to the acceleration of flower opening in 'Samantha' and the inhibition in 'Kardinal'. Additional results indicated that three Rh-ACSs genes were differentially associated with flower opening and senescence as well as wounding

Up-regulation of endothelial nitric oxide synthase inhibits pulmonary leukocyte migration following lung ischemia-reperfusion in mice

Endogenous nitric oxide (NO) is known to modulate post-ischemic inflammatory response in various organs. However, the role of nitric oxide synthase isoforms (NOS) in mediating pulmonary post-ischemic inflammatory response is poorly understood. We therefore studied post-ischemic endothelial adhesion molecule expression and leukocyte migration in endothelial NOS knockout (eNOS-KO) mice subjected to pulmonary ischemia and reperfusion in vivo. Under anesthesia and mechanical ventilation, the left pulmonary hilum in wild-type (WT) and eNOS-KO mice was clamped for 1 hour, followed by reperfusion for up to 24 hours. In WT mice, we observed a selective up-regulation of both eNOS mRNA and protein in lung tissue, while inducible NOS (iNOS) and neuronal NOS (nNOS) remained unchanged. Survival in eNOS-KO mice was reduced due to severe pulmonary edema, underlining an increased susceptibility to ischemia-reperfusion (I/R) injury. Interstitial tissue infiltration by CD18- and CD11a-positive white blood cells as well as lung tissue water content peaked at 5 hours of reperfusion and were found significantly higher than in WT mice. Enhanced leukocyte-endothelial interaction was associated with pronounced up-regulation of vascular cell adhesion molecule (VCAM) in eNOS-KO mice during post-ischemic reperfusion. We conclude that eNOS attenuates post-ischemic inflammatory injury to the lung most probably via inhibition of endothelial adhesion molecule expression.

Two-layer simulation model of laser-induced interstitial thermo-therapy

A two-layer model using different properties for the pathological tissue and the normal tissue was developed to describe the spatial photon, temperature and thermal damage distributions during laser-induced interstitial thermo-therapy (LITT). The photon distribution was simulated using the Monte Carlo method. The optical tissue parameters and the blood perfusion were derived based on the Arrhenius rate process formulation of thermal damage and kinetics of vasodilatation. The corresponding temperature distribution was numerically calculated using the Pennes bio-heat equation. The calculated results showed that the two-layer model predicted different results on the temperature variation and distribution, the thermal damage distribution and the thermal damage volume etc. from the one-layer model. As a more reasonable physical model, the two-layer model can be used to optimize the therapeutic parameters for improved LITT treatments.

Nerve Growth Factor Receptor-Mediated Gene Transfer

One obstacle to effective gene therapies for neurological disorders lies in the cell-type diversity of the nervous system, making it difficult to direct gene delivery vectors to specific types of cells. To meet this challenge, we have developed a recombinant peptide-based gene delivery vector that targets nerve growth factor (NGF) receptors. The peptide comprises a cell-targeting domain derived from the NGF hairpin motif containing loops 1 and 2 linked to a DNA-binding domain composed of SPKR repeats. In PC12 cells, it activated the high-affinity NGF receptor, TrkA, and displayed NGF-like bioactivity by promoting neurite outgrowth and cell survival after serum deprivation. When combined with a low molecular weight of polyethylenimine (PEI), the peptide condensed plasmid DNA into nanoparticles that efficiently transferred exogenous genes into PC12 cells, enhancing reporter gene expression 5600-fold over peptide-free DNA/PEI complexes. Co-incubation with free NGF inhibited this effect. Furthermore, the peptide enhanced gene expression in NGF-receptor-rich rat primary cortex neurons but not glial cells. An in vivo experiment targeting TrkA-expressing dorsal root ganglia demonstrated that the peptide-containing complexes were 9- to 14-fold more efficient in transfection than controls. These properties make the chimeric peptide a promising gene delivery vector for targeting specific subtypes of neurons.

Safety issue of re-sterilization of polyurethane electrophysiology catheters: a cytotoxicity study

The reuse of electrophysiology catheters could result in significant cost savings. However, re-sterilization of catheters could lead to several adverse consequences, including toxicity related to potential chemical reactions that occur during sterilization due to toxic residues remaining on the surface of catheters. The objective of this study was to investigate in vitro cytotoxicity of polyurethane (PU)-based catheter extracts on macrophages after their re-sterilization. We have compared three sterilization methods: steam autoclave, ethylene oxide (EtO) and hydrogen peroxide plasma (Sterrad system). Our results showed that the viability of cells varied from 90% to 99% as a function of incubation time and number of sterilization cycle. While there was no statistical difference based on the sterilization procedure, the number of sterilization cycles (up to 10 cycles) presents a statistically significant effect on the viability of J774 macrophages. However, extract obtained after resterilization of PU-based catheters had a low cytotoxic effect on J774 macrophages, since the overall cell mortality remained under 10%. An inhibitory effect on cell growth was also observed, which was not significant either as a function of incubation time, sterilization technique or the number of sterilization cycles. Finally, extracts of PU-based catheters had no statistically significant effect on TNF-alpha release by J774 macrophage. Even though there were some statistically significant differences between the control and processed samples, and among processed samples, our data suggest that one single reprocessing of PU-based catheters may not induce clinically significant changes in their cytotoxicity behaviour.

Induction of T-cell immunity against leukemia by dendritic cells pulsed with total RNA isolated from leukemia cells

OBJECTIVES

To assess the feasibility and efficacy of eliciting leukemia-specific T-cell responses in syngeneic mice in vitro and in vivo using dendritic cells (DCs) pulsed with total RNA from leukemia cells.

METHODS

DCs generated from bone marrow culture in vitro in the presence of combined cytokines were pulsed with cellular total RNA isolated from cultured L615 cells by cationic lipid 1,2-dioleoyloxy-3-(trimethylammonium) propane (DOTAP). T-cell responses were evaluated by in vitro proliferation, and cytotoxicity assay. And in vivo immune protection and prognosis of mice with leukemia were studied.

RESULTS

DCs pulsed with total RNA isolated from cultured L615 cells (DCs/RNA) were remarkably effective in stimulating L615-specific T-cell response in vitro, but did not cross-react with other leukemia cells from syngeneic mice. Vaccination of naive mice with viable DCs/RNA vaccine was able to partly protect from challenge with a lethal dose of live L615 cells, leading to low leukemia incidence and overall survival prolongation. Statistically significant survival was also observed in a low lethal dose of L615-bearing mice that received treatment using viable DCs/RNA vaccine alone, suggesting that systemic administration of IL-2 could enhance the anti-tumor efficacy of leukemia RNA/DCs vaccine.

CONCLUSIONS

These data support the use of DCs/RNA vaccine as a feasible and effective route to elicit leukemia immunity against unidentified leukemia-associated antigens for treatment of leukemia-bearing animals.

Cytotoxic reaction and TNF-alpha response of macrophages to polyurethane particles

Their unique mechanical and biological properties make polyurethanes (PUs) ideal materials for many implantable devices. However, uncertain long-term biostability in the human physiological environment limits their extensive clinical applications. Chronic inflammatory response associated with macrophage activation has been suggested as a prime factor; although the mechanism of macrophage activation in response to biomaterial surfaces and debris is still unknown. The overall objective of this work was to study the response of macrophages to PU materials in vitro by measuring cell viability and activity. The studies were carried out using phagocytozable-size PU particles from three types of commercially-available PUs: Pellethane 2363 80ABA (PL); Tecothane TT2065 (TC65); and Tecothane TT2085 (TC85). These polymers posess the same generic composition but differ in the length of hard and soft segments, as revealed by the FTIR and NMR studies. The results showed that PU particles affected both viability and activity of J774 macrophages. The percentage of mortality ranged from 1 to 15% with 10-100 microg ml(-1) of particles after 24 and 48 h incubation. These three types of particles induced different mortality on the macrophages. Specifically, the mortality with PL particles was 1-4% (p > 0.05), while the mortality with TC85 particles was 2-10% (p < 0.05) and 4-15% with TC65 (p < 0.05). Conversely, these particles also affected cell proliferation. Cell numbers increased by 132 and 167% after 24 and 48 h incubation, respectively, without particles, whereas the cell numbers increased only 46 and 78% with TC65, 66 and 105% with TC85, and 67 and 110% with PL in the presence of 100 microg ml(-1) of particles for the respective incubation times. PU particles also increased TNF-alpha release from macrophage. After having been incubated for 24 h with 100 microg ml(-1) particles of TC65, TC85, and PL, macrophages release TNF-alpha 7.4, 5.2, and 4.1 times more than the control. In conclusion, PU particles had cytotoxic effects on J774 macrophage at high concentrations. The order of macrophage response for three types of particles was TC65 > TC85 > PL. PU particles' effect on macrophage viability and activity depends on the concentration of particles and their chemical composition, especially on the ratio of hard to soft segments.