Cationic liposomes as gene delivery system: transfection efficiency and new application

As it has been generally reported that oppositely charged cationic liposomes (CLs) are superior to either neutral or anionic liposomes as gene delivery carrier, interest in the properties, structures, transfection mechanism of CLs and so forth arises unprecedentedly. However, our understanding about the mechanism of CLs-gene complexes (lipoplex)-cell interaction and factors influencing the transfection efficiency (TE) of CLs remains poor. In this article, we describe some new results aimed at elucidating the relationship between the chemical-physical properties of lipoplex with TE and introducing recent applications of CLs in gene therapy.

Module-based prediction approach for robust inter-study predictions in microarray data

MOTIVATION

Traditional genomic prediction models based on individual genes suffer from low reproducibility across microarray studies due to the lack of robustness to expression measurement noise and gene missingness when they are matched across platforms. It is common that some of the genes in the prediction model established in a training study cannot be matched to another test study because a different platform is applied. The failure of inter-study predictions has severely hindered the clinical applications of microarray. To overcome the drawbacks of traditional gene-based prediction (GBP) models, we propose a module-based prediction (MBP) strategy via unsupervised gene clustering.

RESULTS

K-means clustering is used to group genes sharing similar expression profiles into gene modules, and small modules are merged into their nearest neighbors. Conventional univariate or multivariate feature selection procedure is applied and a representative gene from each selected module is identified to construct the final prediction model. As a result, the prediction model is portable to any test study as long as partial genes in each module exist in the test study. We demonstrate that K-means cluster sizes generally follow a multinomial distribution and the failure probability of inter-study prediction due to missing genes is diminished by merging small clusters into their nearest neighbors. By simulation and applications of real datasets in inter-study predictions, we show that the proposed MBP provides slightly improved accuracy while is considerably more robust than traditional GBP.

AVAILABILITY

http://www.biostat.pitt.edu/bioinfo/

CONTACT

ctseng@pitt.edu

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Cationic and tissue-specific protein transduction domains identification, characterization, and therapeutic application

Protein transduction domains (PTDs) are small peptides able to transverse plasma membranes, able to carry proteins, nucleic acid, and viral particles into cells. PTDs can be broadly classified into three types; cationic, hydrophobic, and cell-type specific. The cationic PTDs, comprised of arginines, lysines, and ornithines, and hydrophobic PTDs can efficiently transduce a variety of cell types in culture and in vivo. The tissue-specific transduction domains, identified by screening of peptide display phage libraries for peptides able to confer internalization, have more restricted transduction properties. Here we provide a review of PTDs, focusing on methods for identifying and characterizing both cationic and tissue-specific transduction peptides. In particular, we describe the use of screening peptide phage display libraries to identify tissue-specific transduction peptides.

Effects of estradiol metabolites on cAMP production and degradation

(Full text is available at http://www.manu.edu.mk/prilozi). 17beta-Estradiol is metabolized to 2-hydroxyestradiol, and 2-hydroxyestradiol is converted to 2-methoxyestradiol. These steroids reduce proliferation of, migration of and collagen production by vascular smooth muscle cells with an order of potency of 2-methoxyestradiol > 2-hydroxyestradiol > 17beta-estradiol, i.e. the converse of their estrogenic potency. Since cAMP also inhibits cell growth, it is conceivable that these steroids alter cAMP synthesis or degradation, and this hypothesis was addressed in this study. In cultured preglomerular vascular smooth muscle cells pretreated with a high concentration of a broad spectrum phosphodiesterase inhibitor (3-isobutyl-1-methylxanthine, 1 mM) to eliminate phosphodiesterase activity as a confounding variable, high (100 microM), but not low (10 microM), concentrations of 17beta-estradiol, 2-hydroxyestradiol and 2-methoxyestradiol attenuated isoproterenol-induced cAMP by 15%, 19% and 55%, respectively. 2-Hydroxyestradiol (100 microM) also attenuated forskolin-induced cAMP by 31% in cells treated with 3-isobutyl-1-methylxanthine. In cells not pretreated with 3-isobutyl-1-methylxanthine and using concentrations of steroids (10 microM) that did not interfere with adenylyl cyclase, 17beta-estradiol decreased by 34%, 2-hydroxyestradiol did not alter and 2-methoxyestradiol increased by 60% isoproterenol-induced cAMP. These results indicate that in preglomerular vascular smooth muscle cells, high concentrations of 2-hydrxoyestradiol markedly inhibit adenylyl cyclase whereas 17beta-estradiol and 2-methoxestradiol only modestly inhibit adenylyl cyclase even at high concentrations. Our results also indicate that lower concentrations of 17beta-estradiol, 2-hydroxyestradiol and 2-methoxyestradiol activate, have no effect on and inhibit, respectively, phosphordiesterase activity. The effects of these compounds on phosphodiesterase activity may account in part for the greater potency of 2-methoxyestradiol as an anti-growth compound compared with 17beta-estradiol and 2-hydroxyestradiol. Key words: Estradiol, Estradiol metabolites, 2-Methoxyestradiol, Cyclic adenosine monophosphate.

Predictors of inpatient outcomes in hospitalized patients after left heart catheterization

Clinical and laboratory factors predicting inpatient outcomes, specifically in-hospital mortality and length of stay (LOS), have not been defined for hospitalized patients specifically referred for left heart catheterization and coronary angiography (LHC). The objective of the study was to determine these outcomes and their predictors in hospitalized patients after LHC. Multivariate logistic regression models were used to identify risk factors for in-hospital mortality and Cox proportional hazards models were used to identify factors determining LOS in 9,420 consecutive patients hospitalized for LHC. Odds ratio for in-hospital mortality and hazard ratio for prolonged LOS were derived. The strongest predictors of mortality were advanced age, left ventricular (LV) end-diastolic pressure (EDP), LV ejection fraction (EF), systemic blood pressure, and renal insufficiency. Predictors of prolonged LOS were LVEDP, LVEF, 3-vessel coronary artery disease, and valvular disease. Clinical and laboratory characteristics of patients with an LVEF > or =50% were also compared with those of patients with an LVEF <50%. Predictors of mortality and LOS remained the same for patients with an LVEF <50%. For an LVEF > or =50%, LVEDP also determined LOS and chronic renal insufficiency provided predictive power to mortality and LOS in this subgroup. In conclusion, several readily attainable clinical and laboratory parameters predict inpatient mortality and LOS in hospitalized patients referred for LHC.

PTD-mediated loading of tumor-seeking lymphocytes with prodrug-activating enzymes

Using the approach of peptide transduction domain (PTD)-mediated loading of interleukin-2(IL-2)-activated natural killer (A-NK) cells, tumor-seeking lymphocytes, with prodrug-activating enzymes, we primarily aim to generate a cytotoxic drug selectively within tumors and minimize damage to normal tissues. A-NK cells are able to accumulate selectively at tumor sites. While these cells by themselves possess significant antitumor effect in vivo, we suggest that they can also serve as Trojan horses, by bringing anticancer agents, such as prodrug-activating enzymes, selectively to tumors. We have successfully demonstrated in a mouse model that A-NK cells can be rapidly loaded with prodrug-activating enzymes, such as alkaline phosphatase (AP) and beta-galactosidase (beta-gal), in vitro using enzyme-conjugated peptide PTD5. Upon adoptive transfer into lung-tumor-bearing animals, the loaded A-NK cells are able to bring their cargo of the prodrug-activating enzymes selectively to pulmonary metastases. The targeting of the AP to the tumor tissues is highly specific, since more than a fivefold higher concentration of AP was found in the tumor tissues compared to the surrounding normal lung tissue at 24 h after injection. The approach of transporting prodrug-activating enzymes selectively into tumors clearly shows potential for future targeted chemotherapy. Ongoing studies in our laboratory are evaluating the antitumor efficacy of cellular-dependent enzyme prodrug therapy.

Chaperone displacement from mutant cystic fibrosis transmembrane conductance regulator restores its function in human airway epithelia

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis (CF). The most common mutation, DeltaF508, omits the phenylalanine residue at position 508 in the first nucleotide binding domain (NBD1) of CFTR. The mutant protein is retained in the endoplasmic reticulum and degraded by the ubiquitin-proteasome system. We demonstrate that expression of NBD1 plus the regulatory domain (RD) of DeltaF508 CFTR (DeltaFRD) restores the biogenesis of mature DeltaF508 CFTR protein. In addition, DeltaFRD elicited a cAMP-stimulated anion conductance response in primary human bronchial epithelial (HBE) cells isolated from homozygous DeltaF508 CF patients. A protein transduction domain (PTD) could efficiently transduce (approximately 90%) airway epithelial cells. When fused to a PTD, direct addition of the DeltaFRD peptide conferred a dose-dependent, cAMP-stimulated anion efflux to DeltaF508 HBE cells. Hsp70 and Hsp90 associated equally with WT and DeltaF508 CFTR, whereas nearly twice as much of the Hsp90 cochaperone, Aha1, associated with DeltaF508 CFTR. Expression of DeltaFRD produced a dose-dependent removal of Aha1 from DeltaF508 CFTR that correlated with its functional rescue. These findings indicate that disruption of the excessive association of the cochaperone, Aha1, with DeltaF508 CFTR is associated with the correction of its maturation, trafficking and regulated anion channel activity in human airway epithelial cells. Thus, PTD-mediated DeltaFRD fragment delivery may provide a therapy for CF.

Feasibility assessment of a chemoresponse assay to predict pathologic response in neoadjuvant chemotherapy for breast cancer patients

BACKGROUND

For chemosensitivity and resistance assays to be clinically useful in predicting patient outcome, they should require small amounts of tissue and be highly reproducible and reliable.

PATIENTS AND METHODS

Expanded tumor cells from transcutaneous biopsies of breast lesions (n=62) were tested for chemoresponse using the cell-based ChemoFx assay. Pathologic complete response (pCR) was determined on a subset of patients (n=34). Assay score and pCR were determined independently in a blinded manner. Logistic regression models were used to select predictors for response.

RESULTS

Tumor cells were successfully isolated from 83.9% of patients. Chemoresponse profiles were robust and reproducible with coefficient of variance of <3%. In a limited initial patient outcome correlation, assay score of docetaxel/capecitabine significantly predicted pCR; the cross-validated model was 75% accurate.

CONCLUSION

It is feasible to assess the chemoresponsiveness of small breast lesions using the ChemoFx assay to assist in choosing neoadjuvant chemotherapy for breast cancer patients.

Multiwavelength ultralow-threshold lasing in quantum dot photonic crystal microcavities

We demonstrate multiwavelength lasing of resonant modes in linear (L3) microcavities in a triangular-lattice 2D photonic crystal (PC) slab. The broad spontaneous emission spectrum from coupled quantum dots, modified by the PC microcavity, is studied as a function of the intensity of incident optical excitation. We observe lasing with an ultralow-threshold power of approximately 600 nW and an output efficiency of approximately 3% at threshold. Two other resonant modes exhibit weaker turnon characteristics and thresholds of approximately 2.5 and 200 microW, respectively.

Targeting of products of genes to tumor sites using adoptively transferred A-NK and T-LAK cells

Despite successes in animals, cytokine gene expression selectively in human tumors is difficult to achieve owing to lack of efficient delivery methods. Since interleukin (IL)-2-activated natural killer (A-NK) and phytohemagglutinin and IL-2 activated killer T (T-LAK) cells, as previously demonstrated, localize and accumulate in murine lung tumor metastases following adoptive transfer, we transduced them to test their ability to deliver products of genes selectively to tumors. Assessments of transduction efficiency in vitro demonstrated that adenoviral transduction consistently resulted in high (>60%) transduction rates and substantial expression of transgenes such as GFP, Red2, luciferase, beta-galactosidase and mIL-12 for at least 4 days. In vivo experiments illustrated that Ad-GFP transduced A-NK and Ad-Red2 (RFP) transduced T-LAK or mIL-12 transduced A-NK cells localized 10-50-fold more or survived significantly better than mock transduced cells, respectively, within lung metastases than in the surrounding normal lung tissue. Most importantly, mIL-12 transduced A-NK cells provided a significantly greater antitumor response than non-transduced A-NK cells. Thus, adoptive transfer of A-NK and T-LAK cells represents an efficient method for targeting products of genes to tumor sites.

Intra-articular injection of recombinant TRAIL induces synovial apoptosis and reduces inflammation in a rabbit knee model of arthritis

We demonstrated previously that local, intra-articular injection of an adenoviral vector expressing human tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in a rabbit knee model of inflammatory arthritis stimulated synovial apoptosis and reduced inflammation. To examine whether intra-articular injection of recombinant chimeric human TRAIL protein (rTRAIL) also induces apoptosis of proliferating rabbit synovium and reduces inflammation, we used an experimental rabbit arthritis model of rheumatoid arthritis, induced by intra-articular introduction of allogeneic fibroblasts genetically engineered to secrete human IL-1beta. Analysis of synovium isolated from the rabbits treated with intra-articular injection of rTRAIL, relative to saline control, showed areas of extensive acellular debris and large fibrous regions devoid of intact cells, similar to adenoviral mediated TRAIL gene transfer. Extensive apoptosis of the synovial lining was demonstrated using TUNEL analysis of the sections, corresponding to the microscopic findings in hematoxylin and eosin staining. In addition, leukocyte infiltration into the synovial fluid of the inflamed knee joints following rTRAIL treatment was reduced more than 50% compared with the saline control. Analysis of the glycosaminoglycan synthetic rate by cultured cartilage using radiolabeled sulfur and cartilage histology demonstrated that rTRAIL did not adversely affect cartilage metabolism and structure. Analysis of serum alanine aminotransferase showed that intra-articular injection of rTRAIL did not have adverse effects on hepatic function. These results demonstrate that intra-articular injection of rTRAIL could be therapeutic for treating pathologies associated with rheumatoid arthritis.

Human, viral or mutant human IL-10 expressed after local adenovirus-mediated gene transfer are equally effective in ameliorating disease pathology in a rabbit knee model of antigen-induced arthritis

IL-10 is a Th2 cytokine important for inhibiting cell-mediated immunity while promoting humoral responses. Human IL-10 (hIL-10) has anti-inflammatory, immunosuppressive as well as immunostimulatory characteristics, whereas viral IL-10 (vIL-10), a homologue of hIL-10 encoded by Epstein Barr virus (EBV), lacks several immunostimulatory functions. The immunostimulatory characteristic of hIL-10 has been attributed to a single amino acid, isoleucine at position 87, which in vIL-10 is alanine. A mutant hIL-10 in which isoleucine has been substituted (mut.hIL-10) is biologically active with only immunosuppressive, but not immunostimulatory, functions, making it a potentially superior therapeutic for inflammatory diseases. To compare the efficacy of mut.hIL-10 with hIL-10 and vIL-10 in blocking the progression of rheumatoid arthritis, we used replication defective adenoviral vectors to deliver intra-articularly the gene encoding hIL-10, vIL-10 or mut.hIL-10 to antigen-induced arthritic (AIA) knee joints in rabbits. Intra-articular expression of hIL-10, vIL-10, and mut.hIL-10 resulted in significant improvement of the pathology in the treated joints to similar levels. These observed changes included a significant reduction in intra-articular leukocytosis and the degree of synovitis, as well as normalization of cartilage matrix metabolism. Our results suggest that hIL-10, vIL-10, and mut.hIL-10 are all equally therapeutic in the rabbit AIA model for treating disease pathology.

Exosomes Derived from IL-10-Treated Dendritic Cells Can Suppress Inflammation and Collagen-Induced Arthritis

We have demonstrated previously that local, adenoviral-mediated gene transfer of viral IL-10 to a single joint of rabbits and mice with experimental arthritis can suppress disease in both the treated and untreated contralateral joints. This contralateral effect is mediated in part by APCs able to traffic from the treated joint to lymph nodes as well as to untreated joints. Moreover, injection of dendritic cells (DC) genetically modified to express IL-4 or Fas ligand was able to reverse established murine arthritis. To examine the ability of exosomes derived from immunosuppressive DCs to reduce inflammation and autoimmunity, murine models of delayed-type hypersensitivity and collagen-induced arthritis were used. In this study, we demonstrate that periarticular administration of exosomes purified from either bone marrow-derived DCs transduced ex vivo with an adenovirus expressing viral IL-10 or bone marrow-derived DCs treated with recombinant murine IL-10 were able to suppress delayed-type hypersensitivity responses within injected and untreated contralateral joints. In addition, the systemic injection of IL-10-treated DC-derived exosomes was able suppress the onset of murine collagen-induced arthritis as well as reduce severity of established arthritis. Taken together, these data suggest that immature DCs are able to secrete exosomes that are involved in the suppression of inflammatory and autoimmune responses. Thus DC-derived exosomes may represent a novel, cell-free therapy for the treatment of autoimmune diseases.

Immunization with lentiviral vector-transduced dendritic cells induces strong and long-lasting T cell responses and therapeutic immunity

Dendritic cell (DC) therapies are currently being evaluated for the treatment of cancer. The majority of ongoing clinical trials use DCs loaded with defined antigenic peptides or proteins, or tumor-derived products, such as lysates or apoptotic cells, as sources of Ag. Although several theoretical considerations suggest that DCs expressing transgenic protein Ags may be more effective immunogens than protein-loaded cells, methods for efficiently transfecting DCs are only now being developed. In this study we directly compare the immunogenicity of peptide/protein-pulsed DCs with lentiviral vector-transduced DCs, and their comparative efficacy in tumor immunotherapy. Maturing, bone marrow-derived DCs can be efficiently transduced with lentiviral vectors, and transduction does not affect DC maturation, plasticity, or Ag presentation function. Transduced DCs efficiently process and present both MHC class I- and II-restricted epitopes from the expressed transgenic Ag OVA. Compared with peptide- or protein-pulsed DCs, lentiviral vector-transduced DCs elicit stronger and longer-lasting T cell responses in vivo, as measured by both in vivo killing assays and intracellular production of IFN-gamma by Ag-specific T cells. In the B16-OVA tumor therapy model, the growth of established tumors was significantly inhibited by a single immunization using lentiviral vector-transduced DCs, resulting in significantly longer survival of immunized animals. These results suggest that compared with Ag-pulsed DCs, vaccination with lentiviral vector-transduced DCs may achieve more potent antitumor immunity. These data support the further development of lentiviral vectors to transduce DCs with genes encoding Ags or immunomodulatory adjuvants to generate and control systemic immune responses.