PEGylated DNA/transferrin-PEI complexes: reduced interaction with blood components, extended circulation in blood and potential for systemic gene delivery

We investigated the in vitro and in vivo properties of DNA/transferrin-polyethylenimine (800 kDa) complexes before and after covalent coupling of poly(ethylene glycol) (PEG). Upon incubation with plasma, the positively charged non-PEGylated DNA complexes form aggregates. Plasma proteins such as IgM, fibrinogen, fibronectin and complement C3 were found to bind to non-PEGylated DNA complexes. At DNA concentrations relevant for in vivo gene delivery a strong aggregation of erythrocytes was also observed. PEGylation of the complexes strongly reduces plasma protein binding and erythrocyte aggregation. Furthermore, PEGylated complex size was stabilized and had a reduced surface charge. Prolonged circulation in the blood of the PEGylated complexes was also observed when injected intravenously. In tumor bearing mice, application of non-PEGylated complexes through the tail vein resulted in reporter gene expression in tail and lung, but severe toxicity was observed in some mice. In contrast, PEGylated complexes mediated reporter gene transfer to the tumor without significant toxicity.

Increased accumulation of the glycoxidation product N(epsilon)-(carboxymethyl)lysine in human tissues in diabetes and aging

N(epsilon)-(Carboxymethyl)lysine (CML), a major product of oxidative modification of glycated proteins, has been suggested to represent a general marker of oxidative stress and long-term damage to proteins in aging, atherosclerosis, and diabetes. To investigate the occurrence and distribution of CML in humans an antiserum specifically recognizing protein-bound CML was generated. The oxidative formation of CML from glycated proteins was reduced by lipoic acid, aminoguanidine, superoxide dismutase, catalase, and particularly vitamin E and desferrioxamine. Immunolocalization of CML in skin, lung, heart, kidney, intestine, intervertebral discs, and particularly in arteries provided evidence for an age-dependent increase in CML accumulation in distinct locations, and acceleration of this process in diabetes. Intense staining of the arterial wall and particularly the elastic membrane was found. High levels of CML modification were observed within atherosclerotic plaques and in foam cells. The preferential location of CML immunoreactivity in lesions may indicate the contribution of glycoxidation to the processes occurring in diabetes and aging. Additionally, we found increased CML content in serum proteins in diabetic patients. The strong dependence of CML formation on oxidative conditions together with the increased occurrence of CML in diabetic serum and tissue proteins suggest a role for CML as endogenous biomarker for oxidative damage.

Different behavior of branched and linear polyethylenimine for gene delivery in vitro and in vivo

BACKGROUND

Efficient gene transfer is a major challenge for non-viral gene therapy. Understanding how non-viral vectors initiate gene expression could lead to the development of new future vectors with enhanced efficacy.

METHODS

Linear or branched polyethylenimine (PEI)/DNA complexes were generated in varying salt conditions and their transfection efficiencies were compared in vitro and in vivo using reporter genes, luciferase and green fluorescent protein, and rhodamine labeled DNA (pGeneGrip).

RESULTS

The transfection efficiency of linear PEI22/DNA in vitro was generally greater than that of branched PEI/DNA when complexes were generated in salt containing buffer. However, PEI complexes generated under salt-free conditions generally had low transfection activity in vitro. In contrast, PEI22/DNA salt-free complexes were highly active in vivo. Branched PEI/DNA and salt containing PEI22/DNA complexes were generally 10-100-fold less active than the salt-free PEI22/DNA complexes. Salt-free PEI22/DNA complexes were small, but subsequently grew into aggregates when salt was added. In contrast, PEI25/DNA complexes remained small even after salt was added under the same conditions. Furthermore, PEI22/pGeneGrips complexes formed large aggregates associated with the cell membrane, cytoplasm and nucleus, while branched PEI complexes remained as small distinct particles associated with the cell membrane or in the cytoplasm.

CONCLUSIONS

Branched and linear PEI/DNA complexes differ in their ability to transfect cells. The greater efficiency of linear PEI might be due to an inherent kinetic instability under salt conditions. Understanding how to employ this kinetic instability of linear PEI could help in designing future vectors with greater flexibility and transfection efficiency in vivo.

Design and gene delivery activity of modified polyethylenimines

The polycation polyethylenimine (PEI) has recently been widely employed for the design of DNA delivery vehicles. Gene delivery using PEI involves condensation of DNA into compact particles, uptake into the cells, release from the endosomal compartment into the cytoplasm, and uptake of the DNA into the nucleus. Particularly for in vivo gene delivery, optimal coordination and timing between DNA complexation for protection of the DNA from nucleases and the disassembly of the complexes is essential. For in vivo application, DNA complexes have to pass a variety of anatomical and physiological barriers, and an environment of biological fluids and extracellular matrix before reaching their targets. Furthermore, targeted gene delivery is seriously hampered by non-specific interactions with non-target cells. Strategies have been developed to protect transfection complexes from non-specific interactions and to increase target specificity and gene expression.

The size of DNA/transferrin-PEI complexes is an important factor for gene expression in cultured cells

Under physiological salt concentration, plasmid DNA complexed with transferrin-conjugated or unmodified polyethylenimine (PEI, 800 kDa) forms huge (up to > 1000 nm) aggregates, unless the individual components are mixed at a highly positive nitrogen/phosphate (N/P) charge ratio. At low ionic strengths, however, small particles with an average size of 40 nm are formed over a broad range of N/P ratios. Interestingly, in transfection experiments these small particles result in a 10-fold (B16F10 cells) to more than 100-fold (Neuro2A cells, K562 cells) reduced luciferase gene expression efficiency in comparison to the large complexes formed in physiological salt solutions. Limited transport of the small particles to the cell surfaces is one possible reason for this effect. Application of the small particles in more concentrated form and over extended periods of time improves transfection activity. Reduced intracellular release may be another explanation for the decreased transfection efficiency; incubation with chloroquine or incorporation of the endosomolytic peptide INF5 into the small complexes enhances gene expression approximately 10-fold. Analysis of gene expression at the cellular level using a green fluorescence protein reporter gene and flow cytometry revealed that the differences in overall gene expression largely result from different intensities per expressing cell, while the difference in the percentage of expressing cells is less substantial.

Influenza virus hemagglutinin HA-2 N-terminal fusogenic peptides augment gene transfer by transferrin-polylysine-DNA complexes: toward a synthetic virus-like gene-transfer vehicle

Complexes containing plasmid DNA, transferrin-polylysine conjugates, and polylysine-conjugated peptides derived from the N-terminal sequence of the influenza virus hemagglutinin subunit HA-2 have been used for the transfer of luciferase or beta-galactosidase marker genes to K562 cells, HeLa cells, and BNL CL.2 hepatocytes. These DNA complexes mimic the entry of viruses into cells, as they contain functions for (i) the packaging of the nucleic acid with polylysine, (ii) the attachment to the cell and receptor-mediated endocytosis with transferrin as a ligand, and (iii) the release from endosomes by using membrane-disrupting influenza peptides. The presence of these influenza peptide conjugates in the DNA complexes renders the complexes active in membrane disruption in a liposome leakage assay and results in a substantial augmentation of the transferrin-polylysine-mediated gene transfer.

Transferrin-polycation conjugates as carriers for DNA uptake into cells

We have developed a high-efficiency nucleic acid delivery system that uses receptor-mediated endocytosis to carry DNA macromolecules into cells. We accomplished this by conjugating the iron-transport protein transferrin to polycations that bind nucleic acids. Human transferrin, as well as the chicken homologue conalbumin, has been covalently linked to the small DNA-binding protein protamine or to polylysines of various sizes through a disulfide linkage. These modified transferrin molecules maintain their ability to bind their cognate receptor and to mediate efficient iron transport into the cell. The transferrin-polycation molecules form electrophoretically stable complexes with double-stranded DNA, single-stranded DNA, and modified RNA molecules independent of nucleic acid size (from short oligonucleotides to DNA of 21 kilobase pairs). When complexes of transferrin-polycation and a bacterial plasmid DNA containing the gene for Photinus pyralis luciferase are supplied to eukaryotic cells, high-level expression of the luciferase gene occurs, demonstrating transferrin receptor-mediated endocytosis and expression of the imported DNA. We refer to this delivery system as "transferrinfection."

Activation of the complement system by synthetic DNA complexes: a potential barrier for intravenous gene delivery

We have examined the complement-activating properties of synthetic cationic molecules and their complexes with DNA. Commonly used gene delivery vehicles include complexes of DNA with polylysine of various chain lengths, transferrin-polylysine, a fifth-generation poly(amidoamine) (PAMAM) dendrimer, poly(ethyleneimine), and several cationic lipids (DOTAP, DC-Chol/DOPE, DOGS/DOPE, and DOTMA/DOPE). These agents activate the complement system to varying extents. Strong complement activation is seen with long-chain polylysines, the dendrimer, poly(ethyleneimine), and DOGS (half-maximal at about 3 microM amine content in the assay used). Compared to these compounds, the other cationic lipids (in liposome formulations) are weak activators of the complement system (half-maximal approximately 50-100 microM positive charge in assay). Complement activation by polylysine is strongly dependent on the chain length. Short-chain oligolysines are comparable to cationic lipids in their activation of complement. Incubation of these compounds with DNA to form complexes reduces complement activation in virtually all cases. The degree of complement activation by DNA complexes is strongly dependent on the ratio of polycation and DNA (expressed as the charge ratio) for polylysine, dendrimer, poly(ethyleneimine), and DOGS. To a lesser degree, charge ratio also influences complement activation by monovalent cationic lipid-DNA complexes. For polylysine-DNA complexes, complement activation can be considerably reduced by modifying the surface of preformed DNA complexes with polyethyleneglycol (half-maximal approximately 20 microM amine content). The data suggests that, by appropriate formulation of DNA complexes, complement activation can be minimized or even avoided. These findings should facilitate the search for DNA complex formulations appropriate for reproducible intravenous gene delivery.

Transferrin-polycation-DNA complexes: the effect of polycations on the structure of the complex and DNA delivery to cells

We have previously described a gene delivery system based upon the receptor-mediated endocytosis of DNA complexed with transferrin-polycation conjugates. This delivery system has been found to be very effective for both the internalization and the expression of genetic material in cells that have many transferrin receptors. Upon scrutinization of the parameters involved in this method, which we have termed transferrinfection, we note two important features of the process: the polycation in polycation-transferrin conjugates, as expected, serves to attach the transferrin moiety to the DNA and, in addition, the polycation functions to condense the DNA into a doughnut structure. Electron microscopic analysis of a range of poorly active to highly active transferrinfection samples reveals a strong correlation between DNA condensation and cellular DNA uptake. Furthermore, we demonstrate that the transfection activity of the DNA complex can be increased by addition of free polycation as long as a sufficient quantity of polycation-transferrin conjugates remains in the complex to ensure its binding to the cellular receptor.

Coupling of adenovirus to transferrin-polylysine/DNA complexes greatly enhances receptor-mediated gene delivery and expression of transfected genes

We are developing efficient methods for gene transfer into tissue culture cells. We have previously shown that coupling of a chimeric adenovirus with polylysine allowed the construction of an adenovirus-polylysine-reporter-gene complex that transferred the transporter gene with great efficiency into HeLa cells. We have now explored simpler, biochemical means for coupling adenovirus to DNA/polylysine complexes and show that such complexes yield virtually 100% transfection in tissue culture cell lines. In these methods adenovirus is coupled to polylysine, either enzymatically through the action of transglutaminase or biochemically by biotinylating adenovirus and streptavidinylating the polylysine moiety. Combination complexes containing DNA, adenovirus-polylysine, and transferrin-polylysine have the capacity to transfer the reporter gene into adenovirus-receptor- and/or transferrin-receptor-rich cells.

Cell cycle dependence of gene transfer by lipoplex, polyplex and recombinant adenovirus

The aim of this study was to investigate the influence of cell cycle on transfection efficiency. Counterflow centrifugal elutriation was used which avoids possible side-effects from chemical treatment of cells. With this method, cell populations were fractionated by means of size and density, and fractions corresponding to discrete cell cycle phase-specific populations were transfected with various nonviral methods (Lipofectamine, TfpLys and TfPEI), adenovirus-enhanced transferrinfection (AVET system) and recombinant adenovirus. Transfection efficiency was found to be strongly dependent on the cell cycle stage at the time of transfection. Luciferase activity from cells transfected with polycation- or lipid-based transfection systems was 30- to more than 500-fold higher when transfection was performed during S or G2 phase compared with cells in G1 phase which have the lowest expression levels. In contrast, this effect was not observed with recombinant adenovirus which varied only four-fold. Our results indicate that mitotic activity enhances transfection not only by lipoplexes but also by polyplexes, but not a viral system which has an efficient nuclear entry machinery, suggesting that transfection close to M phase is facilitated perhaps by nuclear membrane breakdown. Furthermore, low transfection success into G1 cells indicates that DNA complexes deposited in G1 cells are probably not retained long enough to take advantage of mitosis effects or that passage of transfected cells through S phase is inhibitory. Gene Therapy (2000) 7, 401-407.

Randomised trial of monitoring, feedback, and management of care by telephone to improve treatment of depression in primary care

OBJECTIVE

To test the effectiveness of two programmes to improve the treatment of acute depression in primary care.

DESIGN

Randomised trial.

SETTING

Primary care clinics in Seattle.

PATIENTS

613 patients starting antidepressant treatment.

INTERVENTION

Patients were randomly assigned to continued usual care or one of two interventions: feedback only and feedback plus care management. Feedback only comprised feedback and algorithm based recommendations to doctors on the basis of data from computerised records of pharmacy and visits. Feedback plus care management included systematic follow up by telephone, sophisticated treatment recommendations, and practice support by a care manager.

MAIN OUTCOME MEASURES

Blinded interviews by telephone 3 and 6 months after the initial prescription included a 20 item depression scale from the Hopkins symptom checklist and the structured clinical interview for the current DSM-IV depression module. Visits, antidepressant prescriptions, and overall use of health care were assessed from computerised records.

RESULTS

Compared with usual care, feedback only had no significant effect on treatment received or patient outcomes. Patients receiving feedback plus care management had a higher probability of both receiving at least moderate doses of antidepressants (odds ratio 1.99, 95% confidence interval 1.23 to 3.22) and a 50% improvement in depression scores on the symptom checklist (2.22, 1.31 to 3.75), lower mean depression scores on the symptom checklist at follow up, and a lower probability of major depression at follow up (0.46, 0.24 to 0.86). The incremental cost of feedback plus care management was about $80 ( pound50) per patient.

CONCLUSIONS

Monitoring and feedback to doctors yielded no significant benefits for patients in primary care starting antidepressant treatment. A programme of systematic follow up and care management by telephone, however, significantly improved outcomes at modest cost.

Adenovirus enhancement of transferrin-polylysine-mediated gene delivery

Gene transfer may be accomplished by the receptor-mediated endocytosis pathway using transferrin-polylysine conjugates. For some target cells, however, gene transfer by this vector is extremely limited, despite the presence of the appropriate surface receptors, a phenomenon attributed to lysosomal degradation of endosome-internalized conjugate-DNA complexes. To enhance DNA escape from the cell vesicle system and thus augment gene transfer by this route, we have used the capacity of adenoviruses to disrupt endosomes as part of their entry mechanism. Adenoviral infection augmented levels of gene transfer by transferrin-polylysine conjugates in a dose-dependent manner: levels of gene transfer of greater than 2000-fold above baseline were achieved. Use of the adenovirus in this context allowed enhanced levels of gene transfer in a variety of target cells, including cell lines otherwise refractory to gene transfer by transferrin-polylysine conjugates. This augmentation was based on adenoviral-mediated vesicle disruption, a process independent of viral gene expression. Thus, the development of specific mechanisms to effect release from the endosome in combination with gene transfer by the receptor-mediated endocytosis pathway will increase the utility of this delivery system by allowing high levels of gene expression in target cells.

Distressed high utilizers of medical care. DSM-III-R diagnoses and treatment needs

Among a sample of 767 high utilizers of health care, 51% were identified as distressed by an elevated score on the SCL anxiety and depression scales, the SCL somatization scale, or by their primary-care physician. These distressed high utilizers were found to have a high prevalence of chronic medical problems and significant limitation of activities caused by illness. In the prior year, they made an average of 15 medical visits and 15 telephone calls to the clinic. The Diagnostic Interview Schedule was completed on 119 distressed high utilizers randomly assigned to an intervention group in a controlled trial of psychiatric consultation. The following DSM-III-R disorders were most common: major depression 23.5%, dysthymic disorder 16.8%, generalized anxiety disorder 21.8%, and somatization disorder 20.2%. Two thirds had a lifetime history of major depression. The examination resulted in an improved diagnostic assessment for 40% of intervention patients and a revised treatment plan for 67%.

Localized Interleukin-12 for Cancer Immunotherapy

Interleukin-12 (IL-12) is a potent, pro-inflammatory type 1 cytokine that has long been studied as a potential immunotherapy for cancer. Unfortunately, IL-12's remarkable antitumor efficacy in preclinical models has yet to be replicated in humans. Early clinical trials in the mid-1990's showed that systemic delivery of IL-12 incurred dose-limiting toxicities. Nevertheless, IL-12's pleiotropic activity, i.e., its ability to engage multiple effector mechanisms and reverse tumor-induced immunosuppression, continues to entice cancer researchers. The development of strategies which maximize IL-12 delivery to the tumor microenvironment while minimizing systemic exposure are of increasing interest. Diverse IL-12 delivery systems, from immunocytokine fusions to polymeric nanoparticles, have demonstrated robust antitumor immunity with reduced adverse events in preclinical studies. Several localized IL-12 delivery approaches have recently reached the clinical stage with several more at the precipice of translation. Taken together, localized delivery systems are supporting an IL-12 renaissance which may finally allow this potent cytokine to fulfill its considerable clinical potential. This review begins with a brief historical account of cytokine monotherapies and describes how IL-12 went from promising new cure to ostracized black sheep following multiple on-study deaths. The bulk of this comprehensive review focuses on developments in diverse localized delivery strategies for IL-12-based cancer immunotherapies. Advantages and limitations of different delivery technologies are highlighted. Finally, perspectives on how IL-12-based immunotherapies may be utilized for widespread clinical application in the very near future are offered.

Transferrin-polycation-mediated introduction of DNA into human leukemic cells: stimulation by agents that affect the survival of transfected DNA or modulate transferrin receptor levels

We have subverted a receptor-mediated endocytosis event to transport genes into human leukemic cells. By coupling the natural iron-delivery protein transferrin to the DNA-binding polycations polylysine or protamine, we have created protein conjugates that bind nucleic acids and carry them into the cell during the normal transferrin cycle [Wagner, E., Zenke, M., Cotten, M., Beug, H. & Birnstiel, M. L. (1990) Proc. Natl. Acad. Sci. USA 87, 3410-3414]. We demonstrate here that this procedure is useful for a human leukemic cell line. We enhanced the rate of gene delivery by (i) increasing the transferrin receptor density through treatment of the cells with the cell-permeable iron chelator desferrioxamine, (ii) interfering with the synthesis of heme with succinyl acetone treatment, or (iii) stimulating the degradation of heme with cobalt chloride treatment. Consistent with gene delivery as an endocytosis event, we show that the subsequent expression in K-562 cells of a gene included in the transported DNA depends upon the cellular presence of the lysosomotropic agent chloroquine. By contrast, monensin blocks "transferrinfection," as does incubation of the cells at 18 degrees C.

Coupling of cell-binding ligands to polyethylenimine for targeted gene delivery

Recently the high transfection potential of the cationic polymer polyethylenimine (PEI) was described (Boussif O et al. Proc Natl Acad Sci USA 1995; 92: 7297-7301). To combine the promising DNA delivering activity of PEI with the concept of receptor-mediated gene delivery, cell-binding ligands (transferrin or antiCD3 antibody) were incorporated by covalent linkage to PEI. DNA complexes of PEI or ligand-PEI conjugates were tested for transfection of cultured neuroblastoma Neuro 2A cells, melanoma B16 or H225 cells, erythroid leukemic K562 cells and T cell leukemia Jurkat E6.1 cells. Depending on the cell line, incorporation of the cell-binding ligand resulted in an up to 1000-fold increased transfection efficiency. This activity depends on ligand-receptor interaction and was observed also at low PEI cation:DNA anion ratios where ligand-free PEI lacks efficiency. Depending on the cell-binding ligand, specific targeting (CD3 antibody, Jurkat cells) can be achieved. Gene transfer can be augmented by the addition of an endosome-destabilizing influenza peptide, but is not dependent on the presence of additional endosomolytic agents. Application of transferrin-PEI for the production of murine interleukin-2 in B16 cells resulted in exceptionally high secretion rates of 19 micrograms IL-2 protein per 10(6) cells per 24 h.

Polyethylenimine/DNA complexes shielded by transferrin target gene expression to tumors after systemic application

Systemic application of positively charged polycation/DNA complexes has been shown to result in predominant gene expression in the lungs. Targeting gene expression to other sites, eg distant tumors, is hampered by nonspecific interactions largely due to the positive surface charge of transfection complexes. In the present study we show that the positive surface charge of PEI (25 kDa branched or 22 kDa linear)/DNA complexes can be efficiently shielded by covalently incorporating transferrin at sufficiently high densities in the complex, resulting in a dramatic decrease in nonspecific interactions, eg with erythrocytes, and decreased gene expression in the lung. Systemic application of transferrin-shielded PEI/DNA complexes into A/J mice bearing subcutaneously growing Neuro2a tumors via the tail vein resulted in preferential (100- to 500-fold higher) luciferase reporter gene expression in distant tumors as compared with the major organs including the lungs. Tumor targeting is also demonstrated by DNA uptake and beta-galactosidase gene expression in tumor cells. Assessing DNA distribution following systemic application significant amounts of DNA were found in the liver and tumor. However, in the liver, DNA was mainly taken up by Kupffer cells and degraded without significant transgene expression. In the tumor, DNA was associated mainly with tumor cells and frequently found near structures which resemble primitive blood vessels.

High-efficiency receptor-mediated delivery of small and large (48 kilobase gene constructs using the endosome-disruption activity of defective or chemically inactivated adenovirus particles

One limit to successful receptor-mediated gene delivery is the exit of the endocytosed material from the endosome. We demonstrate here the delivery of marker genes to tissue culture cells using a modification of the receptor-mediated gene delivery technique that exploits the endosomolytic activity of defective adenovirus particles. In particular, greater than 90% of the transfected-cell population is found to express a beta-galactosidase gene, and, most importantly, this high level of expression can be obtained with psoralen-inactivated virus particles. Furthermore, because the delivered gene is not carried within the genome of the adenovirus particle, the size constraints are relieved, and we can, therefore, show the delivery of a 48-kilobase cosmid DNA molecule.

Gene transfer into hepatocytes using asialoglycoprotein receptor mediated endocytosis of DNA complexed with an artificial tetra-antennary galactose ligand

We have constructed an artificial ligand for the hepatocyte-specific asialoglycoprotein receptor for the purpose of generating a synthetic delivery system for DNA. This ligand has a tetra-antennary structure, containing four terminal galactose residues on a branched carrier peptide. The carbohydrate residues of this glycopeptide were introduced by reductive coupling of lactose to the alpha- and epsilon-amino groups of the two N-terminal lysines on the carrier peptide. The C-terminus of the peptide, containing a cysteine separated from the branched N-terminus by a 10 amino acid spacer sequence, was used for conjugation to 3-(2-pyridyldithio)propionate-modified polylysine via disulfide bond formation. Complexes containing plasmid DNA bound to these galactose-polylysine conjugates have been used for asialoglycoprotein receptor-mediated transfer of a luciferase gene into human (HepG2) and murine (BNL CL.2) hepatocyte cell lines. Gene transfer was strongly promoted when amphipathic peptides with pH-controlled membrane-disruption activity, derived from the N-terminal sequence of influenza virus hemagglutinin HA-2, were also present in these DNA complexes. Thus, we have essentially borrowed the small functional domains of two large proteins, asialoglycoprotein and hemagglutinin, and assembled them into a supramolecular complex to generate an efficient gene-transfer system.

Gestational age-dependent expression of IL-10 and its receptor in human placental tissues and isolated cytotrophoblasts

Control of antifetal immune responses is thought to be regulated locally by the placenta. Because the physiologic programming of the placenta across gestation is likely to influence the local immunity, we hypothesize that a potent anti-inflammatory cytokine such as IL-10 may be produced in a gestational age-dependent manner. In the present study, we examined the expression of IL-10 and its receptor in placental explants or freshly isolated cytotrophoblasts from different gestational ages and compared it with the expression profiles of other cytokines. First and second trimester placental tissues from normal pregnancies predominantly expressed IL-10, whereas the levels of IL-2, IL-4, and IFN-gamma were mostly below detection throughout pregnancy. The expression of IL-10, but not its receptor, diminished significantly in term placental tissues collected "before" the onset of labor and did not change appreciably "after" labor. On the other hand, TNF-alpha and IL-1beta were significantly up-regulated in response to labor-associated conditions. IL-10 expression was transcriptionally attenuated at term as observed in cytotrophoblasts. In contrast to the placental cytokine milieu, autologous PBMCs, when activated with PHA, secreted significant amounts of IL-2, IL-4, IL-10, and IFN-gamma, albeit with a statistically significantly enhanced IL-10 production in first trimester compared with age-matched nonpregnant women. These data suggest that IL-10 is expressed in the placenta in a gestational age-dependent manner and that its down-regulation at term may be an important mechanism underlying the subtle changes associated with parturition.

Community-level comparisons between the grocery store environment and individual dietary practices

BACKGROUND

This article examines the relationship at the community level between individual dietary practice and the grocery store environment.

METHODS

Individual dietary practice was measured in 12 communities using a telephone survey to obtain self-reported diet. A protocol was developed to measure two aspects of the grocery store environment in these same 12 communities: the relative availability of healthful (low-fat and high-fiber) products, and the amount of health-education information provided. Comparisons were made between individual and store-level measures at two levels of geographic aggregation: community (typically a county) and zip code within community (n = 34).

RESULTS

We found positive and statistically significant correlations at both the community and the zip code level between the availability of healthful products in stores and the reported healthfulness of individual diets. Positive correlations were also found between measures of the amount of health-education material provided by stores and the healthfulness of individual diets, but these correlations did not reach statistical significance.

CONCLUSIONS

The results provide support for including measures of the grocery store environment as part of a community-level assessment of dietary behavior.

Different strategies for formation of pegylated EGF-conjugated PEI/DNA complexes for targeted gene delivery

With the aim of generating gene delivery systems for tumor targeting, we have synthesized a conjugate consisting of polyethylenimine (PEI) covalently modified with epidermal growth factor (EGF) peptides. Transfection efficiency of the conjugate was evaluated and compared to native PEI in three tumor cell lines: KB epidermoid carcinoma cells, CMT-93 rectum carcinoma cells, and Renca-EGFR renal carcinoma cells. Depending on the tumor cell line, incorporation of EGF resulted in an up to 300-fold increased transfection efficiency. This ligand-mediated enhancement and competition with free EGF strongly suggested uptake of the complexes through the EGF receptor-mediated endocytosis pathway. Shielded particles being crucial for systemic gene delivery, we studied the effect of covalent surface modification of EGF-PEI/DNA complexes with a poly(ethylene glycol) (PEG) derivative. An alternative way for the formation of PEGylated EGF-containing complexes was also evaluated where EGF was projected away from PEI/DNA core complexes through a PEG linker. Both strategies led to shielded particles still able to efficiently transfect tumor cells in a receptor-dependent fashion. These PEGylated EGF-containing complexes were 10- to 100-fold more efficient than PEGylated complexes without EGF.

Polycation-based DNA complexes for tumor-targeted gene delivery in vivo

BACKGROUND

Efficient and target-specific in vivo gene delivery is a major challenge in gene therapy. Compared to cell culture application, in vivo gene delivery faces a variety of additional obstacles such as anatomical size constraints, interactions with biological fluids and extracellular matrix, and binding to a broad variety of non-target cell types.

METHODS

Polycation-based vectors, including adenovirus-enhanced transferrinfection (AVET) and transferrin-polyethylenimine (Tf-PEI), were tested for gene delivery into subcutaneously growing tumors after local and systemic application. DNA biodistribution and reporter gene expression was measured in the major organs and in the tumor.

RESULTS

Gene transfer after intratumoral application was 10-100 fold more efficient with Tf-PEI/DNA or AVET complexes in comparison to naked DNA. Targeted gene delivery into subcutaneously growing tumors after systemic application was achieved using electroneutral AVET complexes and sterically stabilized PEGylated Tf-PEI/DNA complexes, whereas application of positively charged polycation/DNA complexes resulted in predominant gene expression in the lungs and was associated by considerable toxicity.

CONCLUSION

For systemic application, the physical and colloidal parameters of the transfection complexes, such as particle size, stability, and surface charge, determine DNA biodistribution, toxicity, and transfection efficacy. By controlling these parameters, DNA biodistribution and gene expression can be targeted to different organs.