DNA/dendrimer complexes mediate gene transfer into murine cardiac transplants ex vivo

mRNA therapy for myocardial infarction: A review of targets and delivery vehicles

Cardiovascular diseases are the leading cause of death in the world. This is partly due to the low regenerative capacity of adult hearts. mRNA therapy is a promising approach under development for cardiac diseases. In mRNA therapy, expression of the target protein is modulated by delivering synthetic mRNA. mRNA therapy benefits cardiac regeneration by increasing cardiomyocyte proliferation, reducing fibrosis, and promoting angiogenesis. Because mRNA is translated in the cytoplasm, the delivery efficiency of mRNA into the cytoplasm and nucleus significantly affects its therapeutic efficacy. To improve delivery efficiency, non-viral vehicles such as lipid nanoparticles have been developed. Non-viral vehicles can protect mRNA from enzymatic degradation and facilitate the cellular internalization of mRNA. In addition to non-viral vehicles, viral vectors have been designed to deliver mRNA templates into cardiac cells. This article reviews lipid nanoparticles, polymer nanoparticles, and viral vectors that have been utilized to deliver mRNA into the heart. Because of the growing interest in lipid nanoparticles, recent advances in lipid nanoparticles designed for cardiac mRNA delivery are discussed. Besides, potential targets of mRNA therapy for myocardial infarction are discussed. Gene therapies that have been investigated in patients with cardiac diseases are analyzed. Reviewing mRNA therapy from a clinically relevant perspective can reveal needs for future investigations.

Preparation and characterization of polyamidoamine dendrimers conjugated with cholesteryl-dipeptide as gene carriers in HeLa cells

Improving the transfection efficiency of non-viral carriers by using cationic polymers is a useful approach to addressing several challenges in gene therapy, such as cellular uptake, endosomal escape, and toxicity. Among the various cationic polymers, polyamidoamine (PAMAM) dendrimers have been widely utilized because of the abundance of terminal functional groups, thereby enabling further functionalization and enhancing DNA condensation and internalization into cells. The combination of various functional groups is required for these PAMAM dendrimer derivatives to function appropriately for gene delivery. Herein, we synthesized PAMAM G2-HRChol by conjugating dipeptide (histidine-arginine) and cholesterol at different ratios (6% or 23%) on the surface of PAMAM dendrimer generation 2 (PAMAM G2). Both PAMAM G2-HRChol 6% and PAMAM G2-HRChol 23% have buffering capacity, leading to improved endosomal escape after entering the cells. PAMAM G2-HRChol 6% and PAMAM G2-HRChol 23% dendrimers were condensed with pDNA to form nano-polyplexes at a weight ratio of 4 (polymer/pDNA). Polyplexes are positively charged, which facilitates cellular uptake. The transfection efficiency of PAMAM G2-HRChol 6% and PAMAM G2-HRChol 23% dendrimers was similar to that of PEI 25 kDa under optimum conditions, and the cytotoxicity was much lower than that of PEI 25 kDa in HeLa cells. In addition, after apoptin gene transfection was performed, cell death ratios of 34.47% and 22.47% were observed for PAMAM G2-HRChol 6% and PAMAM G2-HRChol 23%, respectively. The results show that a suitable amount of cholesterol can improve gene transfection efficiency, and the PAMAM G2-HRChol 6% dendrimer could be a potential gene carrier in HeLa cells.

Dendrimer as a momentous tool in tissue engineering and regenerative medicine

Dendrimers have been comprehensively used for cargo delivery, nucleic acid delivery (genes, miRNA/siRNAs), delivery of macromolecules, and other various biomedical applications. Dendrimers are highly versatile in function and can be engineered as multifunctional biomacromolecules by modifying the surface for fulfilling different applications. Dendrimers are being used for crosslinking of existing synthetic and natural polymeric scaffolds to regulate their binding efficiency, stiffness, biocompatibility, transfection, and many other properties to mimic the in vivo extracellular matrix in tissue engineering and regenerative medicine (TERM). Dendritic inter-cellular linkers can enhance the linkages between cells and result in scaffold-independent tissue constructs. Effectively engineered dendrimers are the ideal molecules for delivering bioactive molecules such as cytokines, chemokines, growth factors, etc., and other metabolites for efficaciously regulating cell behavior. Dendrimeric nanostructures have shown tremendous results in various TERM fields like stem cells survival, osteogenesis, increased crosslinking for eye and corneal repair, and proliferation in cartilage. This review highlights the role and various aspects of dendritic polymers for TERM in general and with respect to specific tissues. This review also covers novel explorations and insights into the use of dendrimers in TERM, focusing on the developments in the past decade and perspective of the future.

Nanomaterials: A Promising Therapeutic Approach for Cardiovascular Diseases

Cardiovascular diseases (CVDs) are a primary cause of death globally. A few classic and hybrid treatments exist to treat CVDs. However, they lack in both safety and effectiveness. Thus, innovative nanomaterials for disease diagnosis and treatment are urgently required. The tiny size of nanomaterials allows them to reach more areas of the heart and arteries, making them ideal for CVDs. Atherosclerosis causes arterial stenosis and reduced blood flow. The most common treatment is medication and surgery to stabilize the disease. Nanotechnologies are crucial in treating vascular disease. Nanomaterials may be able to deliver medications to lesion sites after being infused into the circulation. Newer point-of-care devices have also been considered together with nanomaterials. For example, this study will look at the use of nanomaterials in imaging, diagnosing, and treating CVDs.

Adsorption of mixtures of poly(amidoamine) dendrimers and sodium dodecyl sulfate at the air-water interface

We relate the adsorption from mixtures of well-defined poly(amidoamine) (PAMAM) dendrimers of generations 4 and 8 with sodium dodecyl sulfate (SDS) at the air-water interface to the bulk solution properties. The anionic surfactant shows strong attractive interactions with the cationic dendrimers at pH 7, and electrophoretic mobility measurements indicate that the association is primarily driven by electrostatic interactions. Optical density measurements highlight the lack of colloidal stability of the formed bulk aggregates at compositions close to charge neutrality, the time scale of which is dependent on the dendrimer generation. Adsorption at the air-water interface was followed from samples immediately after mixing using a combination of surface tension, neutron reflectometry, and ellipsometry measurements. In the phase separation region for dendrimers of generation 4, we observed high surface tension corresponding to a depleted surfactant solution but only when the aggregates carried an excess of surfactant. Interestingly, these depleted adsorption layers contained spontaneously adsorbed macroscopic aggregates, and these embedded particles do not rearrange to spread monomeric material at the interface. These findings are discussed in relation to the interfacial properties of mixtures involving dendrimers of generation 8 as well as polydisperse linear and hyperbranched polyelectrolytes where there is polyelectrolyte bound to a surfactant monolayer. The results presented here demonstrate the capability of dendrimers to sequester anionic surfactants in a controllable manner, with potential applications as demulsification and antifoaming agents.

Interactions of PAMAM dendrimers with SDS at the solid-liquid interface

This work addresses structural and nonequilibrium effects of the interactions between well-defined cationic poly(amidoamine) PAMAM dendrimers of generations 4 and 8 and the anionic surfactant sodium dodecyl sulfate (SDS) at the hydrophilic silica-water interface. Neutron reflectometry and quartz crystal microbalance with dissipation monitoring were used to reveal the adsorption from premixed dendrimer/surfactant solutions as well as sequential addition of the surfactant to preadsorbed layers of dendrimers. PAMAM dendrimers of both generations adsorb to hydrophilic silica as a compact monolayer, and the adsorption is irreversible upon rinsing with salt solution. SDS adsorbs on the dendrimer layer and at low bulk concentrations causes the expansion of the dendrimer layers on the surface. When the bulk concentration of SDS is increased, the surfactant layer consists of aggregates or bilayer-like structures. The adsorption of surfactant is reversible upon rinsing, but slight changes of the structure of the preadsorbed PAMAM monolayer were observed. The adsorption from premixed solutions close to charge neutrality results in thick multilayers, but the surface excess is lower when the bulk complexes have a net negative charge. A critical examination of the pathway of adsorption for the interactions of SDS with preadsorbed PAMAM monolayers and premixed PAMAM/SDS solutions with hydrophilic silica revealed that nonequilibrium effects are important only in the latter case, and the application of a thermodynamic model to such experimental data would be inappropriate.

Concomitant intravenous nitroglycerin with intracoronary delivery of AAV1.SERCA2a enhances gene transfer in porcine hearts

SERCA2a gene therapy improves contractile and energetic function of failing hearts and has been shown to be associated with benefits in clinical outcomes, symptoms, functional status, biomarkers, and cardiac structure in a phase 2 clinical trial. In an effort to enhance the efficiency and homogeneity of gene uptake in cardiac tissue, we examined the effects of nitroglycerin (NTG) in a porcine model following AAV1.SERCA2a gene delivery. Three groups of Göttingen minipigs were assessed: (i) group A: control intracoronary (IC) AAV1.SERCA2a (n = 6); (ii) group B: a single bolus IC injection of NTG (50 µg) immediately before administration of intravenous (IV) AAV1.SERCA2a (n = 6); and (iii) group C: continuous IV NTG (1 µg/kg/minute) during the 10 minutes of AAV1.SERCA2a infusion (n = 6). We found that simultaneous IV infusion of NTG and AAV1.SERCA2a resulted in increased viral transduction efficiency, both in terms of messenger RNA (mRNA) as well as SERCA2a protein levels in the whole left ventricle (LV) compared to control animals. On the other hand, IC NTG pretreatment did not result in enhanced gene transfer efficiency, mRNA or protein levels when compared to control animals. Importantly, the transgene expression was restricted to the heart tissue. In conclusion, we have demonstrated that IV infusion of NTG significantly improves cardiac gene transfer efficiency in porcine hearts.

The ability of a collagen/calcium phosphate scaffold to act as its own vector for gene delivery and to promote bone formation via transfection with VEGF(165)

Collagen/calcium phosphate scaffolds have been used for bone reconstruction due to their inherent similarities to the bone extracellular matrix. Calcium phosphate alone has also been used as a non-viral vector for gene delivery. The aim of this study was to determine the capability of a collagen/calcium phosphate scaffold to deliver naked plasmid DNA and mediate transfection in vivo. The second goal of the study was to deliver a plasmid encoding vascular endothelial growth factor(165) (pVEGF(165)) to promote angiogenesis, and hence bone formation, in a mouse intra-femoral model. The delivery of naked plasmid DNA resulted in a 7.6-fold increase in mRNA levels of beta-Galactosidase compared to the delivery of plasmid DNA complexed with a partially degraded PAMAM dendrimer (dPAMAM) in a subcutaneous murine model. When implanted in a muirne intra-femoral model, the delivery of pVEGF(165) resulted in a 2-fold increase in bone volume at the defect site relative to control scaffolds without pVEGF(165). It was concluded that a collagen/calcium phosphate scaffold can mediate transfection without the use of additional transfection vectors and can promote bone formation in a mouse model via the delivery of pVEGF(165).

Degradable poly(amino ester) based on poly(ethylene glycol) dimethacrylate and polyethylenimine as a gene carrier: molecular weight of PEI affects transfection efficiency

The aim of the research is to study the effect of polyethylenimine (PEI) molecular weight on the gene transfection efficiency of degradable poly(amino ester) based on poly(ethylene glycol) dimethacrylate (PEGDMA) and polyethylenimine (PEG-cr-PEI) as a gene carrier. Various low molecular weight (LMW) branched PEI based PEG-cr-PEI was synthesized via Michael addition. The degradation half-life of PEG-cr-PEI was longer at pH 5.6 than that at pH 7.4. The plasmid condensation and protection ability of the PEG-cr-PEI were confirmed by agarose gel electrophoresis assay. PEG-cr-PEI/DNA nanoparticles showed high positive zeta potential (>+20 mV), narrow size distribution, and spherical shapes with size below 250 nm when N/P ratios of PEG-cr-PEI to DNA were above 10, suggesting that they have endocytosis potential. The cytotoxicity of PEG-cr-PEI/DNA complexes was lower than that of PEI 25K/DNA complexes, and the transfections mediated by PEG-cr-PEI were checked in 293T, HeLa and HepG2 cell lines. The report gene expression was increased with increasing the molecular weight of LMW PEI. The "proton sponge effect" was proposed as the mechanism of PEG-cr-PEI mediated gene transfection.

Anti-angiogenesis effect of generation 4 polyamidoamine/vascular endothelial growth factor antisense oligodeoxynucleotide on breast cancer in vitro

OBJECTIVE

To study the effects of the generation 4 polyamidoamine/vascular endothelial growth factor antisense oligodeoxynucleotide (G4PAMAM/VEGFASODN) compound on the expressions of vascular endothelial growth factor (VEGF) and its mRNA of breast cancer cells and on the inhibition of vascular endothelial cells.

METHODS

We examined the morphology of G4PAMAM/VEGFASODN compound and its pH stability, in vitro transfection efficiency and toxicity, and the expressions of VEGF and its mRNA. Methyl thiazolyl tetrazolium assay was used to detect the inhibitory function of the compound on vascular endothelial cells.

RESULTS

The compound was about 10 nm in diameter and was homogeneously netlike. From pH 5 to 10, it showed quite a buffered ability. The 48-h transfection rate in the charge ratio of 1:40 was 98.76%, significantly higher than that of the liposome group (P<0.05). None of the transfection products showed obvious toxicity on the cells. The expressions of both VEGF protein and its mRNA after G4PAMAM/VEGFASODN transfection decreased markedly.

CONCLUSION

With a low toxicity, high safety, and high transfection rate, G4PAMAM/VEGFASODN could be a promising gene vector. Specifically, it inhibits VEGF gene expression efficiently, laying a basis for further in vivo animal studies.

Stealth dendrimers for drug delivery: correlation between PEGylation, cytocompatibility, and drug payload

It is advantageous to utilize low generation polyamidoamine (PAMAM) dendrimers for drug delivery because low generations (generation 4.0 or below) have more biologically favorable properties as compared to high generations. Nevertheless, modification of low generation dendrimers with PEG to create stealth dendrimers is still necessary to avoid potential side effects by long term accumulation. However, low generation dendrimers have much fewer surface sites for drug loading as compared to higher generations. To efficiently utilize low generation dendrimer-based stealth dendrimers for drug loading, PEGylation needs to be optimized. In this study, we synthesized a series of stealth dendrimers based on low generation Starburst PAMAM dendrimers (i.e., G2.5, G3.0, G3.5, and G4.0) and quantitatively assessed PEGylation efficacy in modulating cytocompatibility of low generation PAMAM dendrimers. Cytocompatibility of stealth dendrimers was examined using endothelial cells. The results showed that PEGylation degree on low generation dendrimers could be dramatically reduced to leave as many unoccupied surface groups as possible for drug loading, while maintaining the drug carrier cytocompatibility. 3PEGs-G3.0 and 10PEGs-G4.0 were considered initially optimized stealth dendrimers that would be further modified to deliver drugs of interest. Correlation of PEGylation, cytocompatibility, and drug payload allowed us to optimize low generation dendrimer-based stealth dendrimers for drug delivery and advance the understanding of structure-property relationship of stealth dendrimers.

Gene delivery to vascular endothelium using chemical vectors: implications for cardiovascular gene therapy

The vascular endothelium is an attractive target for gene therapy because of its accessibility and its importance in the pathophysiology of a wide range of cardiovascular conditions. In general, viral methods have been shown to be very effective at delivering genes to endothelium. The immunogenicity and pathogenicity associated with viral vectors have led increased efforts to seek alternative means of 'ferrying' therapeutic genes to endothelium or to decrease the short-comings of viral vectors. This paper reviews developments in non-viral technology. In addition, discussion also covers the mechanisms whereby existing chemical vectors deliver DNA to cells. Understanding the pathways of vector internalisation and intracellular traffic is important in developing strategies to improve vector technology. The authors propose that the chemical vector may represent a robust and versatile technology to 'ferry' therapeutic genes to vascular endothelium in order to modify the endothelial dysfunction associated with many cardiovascular diseases.

The development and characterization of a glutathione-sensitive cross-linked polyethylenimine gene vector

A glutathione-sensitive cross-linked polyethylenimine gene vector CLPEI(50%) was specially designed via the cross-linking reaction between the low molecular weight polyethylenimine (PEI(1800)) and dimethyl 3.3'-dithiopropionimidate dihydrochloride (DTBP). The acid-base titration test indicated that CLPEI(50%) still possessed efficient proton sponge effect. The property of CLPEI(50%)-DNA complexes were investigated by atomic force microscopy (AFM) and dynamic light scattering (DLS). CLPEI(50%) induced DNA condensation and formed spherical nanoparticles. The diameter of polyplexes prepared at pH value of 6.0 and 7.4 was about 150 and 260 nm, respectively. It was interesting to find the polyplexes were sensitive to the reductive glutathione (GSH). The CLPEI(50%)-DNA polyplexes prepared at N/P ratio of 10 were unpacked at GSH concentration of 3mm, which was comparable to the intracellular environment. The in vitro cytotoxicity of CLPEI(50%) was also significantly reduced comparing with PEI(25k). The biomimetic CLPEI(50%)-DNA polyplexes with the low cytotoxicity and GSH-sensitive property could be a good candidate for gene delivery.

Amine terminated G-6 PAMAM dendrimer and its interaction with DNA probed by Hoechst 33258

Fluorescence characteristics of Hoechst 33258 bound to G-6 dendrimer, to the DNA-G-6 dendrimer complex, and to DNA were compared with that in an aqueous solution. The spectral properties including fluorescence emission spectrum, accessibility of anionic quencher, as well as the fluorescence decay time of the Hoechst 33258 are different for all three conditions, indicating that the environments in these conditions are different. Close analysis of the fluorescence properties led us to suggest that Hoechst 33258 located at or near the contact area of the dendrimer and DNA in the DNA-G-6 complex. In the complex, in the absence of Hoechst 33258, the shape of the circular dichroism in the DNA absorption region remained, indicating that DNA is in B form in the complex. On the other hand, the magnitude of linear dichroism (LD) decreased upon DNA-G-6 dendrimer complex formation. The decrease in LD magnitude reflects the shortening of the DNA contour length, which is expected from the fact that a large part of linear DNA is required to wrap the surface of G-6 dendrimer.

PAMAM dendrimers and model membranes: Differential scanning calorimetry studies

Dendrimers attract much attention as potential drug and gene carriers for intracellular delivery. From this point of view, it is crucial to extend our knowledge about their interactions with membranes. The influence of polyamidoamine (PAMAM) dendrimers on the thermotropic behavior of DPPC multilamellar vesicles and DMPC small unilamellar vesicles was examined by differential scanning calorimetry. We used three types of PAMAM dendrimers to determine how a dendrimer structure determines interactions with liposomes. We show that the strength of interactions depends on both the dendrimers' structure and degree of hydrophobicity. A model for the interaction of each type of dendrimer with liposomes was proposed.

Nonviral gene transfer to skeletal, smooth, and cardiac muscle in living animals

The study of muscle physiology has undergone many changes over the past 25 years and has moved from purely physiological studies to those intimately intertwined with molecular and cell biological questions. To ask these questions, it is necessary to be able to transfer genetic reagents to cells both in culture and, ultimately, in living animals. Over the past 10 years, a number of different chemical and physical approaches have been developed to transfect living skeletal, smooth, and cardiac muscle systems with varying success and efficiency. This review provides a survey of these methods and describes some more recent developments in the field of in vivo gene transfer to these various muscle types. Both gene delivery for overexpression of desired gene products and delivery of nucleic acids for downregulation of specific genes and their products are discussed to aid the physiologist, cell biologist, and molecular biologist in their studies on whole animal biology.

Water-soluble polycationic dendrimers with a phosphoramidothioate backbone: preliminary studies of cytotoxicity and oligonucleotide/plasmid delivery in human cell culture

A series of water-soluble polycationic dendrimers with a phosphoramidothioate backbone (P-dendrimers) was studied in human cell culture. Preliminary studies have shown that P-dendrimers of series 1 and 2, possessing N,N-diethyl-ethylenediamine hydrochloride functions at the surface, show rather moderate cytotoxicity toward HeLa, HEK 293, and HUVEC cells in a standard MTT assay in serum-containing medium, generally lower than lipofectin. The experiments of cellular uptake have shown the necessity for the presence of serum for transfection with P-dendrimers of series 1 and 2. These compounds efficiently delivered fluorescein-labeled oligodeoxyribonucleotide into HeLa cells in serum-containing medium, but they failed to do so in HUVEC cell culture. The dendrimers were found to be successful mediators of transfection of the HeLa cells with a DNA plasmid containing the functional gene of enhanced green fluorescent protein (EGFP).

Endothelial cells present antigens in vivo

Background

Immune recognition of vascular endothelial cells (EC) has been implicated in allograft rejection, protection against pathogens, and lymphocyte recruitment. However, EC pervade nearly all tissues and predominate in none, complicating any direct test of immune recognition. Here, we examined antigen presentation by EC in vivo by testing immune responses against E. coli β-galactosidase (β-gal) in two lines of transgenic mice that express β-gal exclusively in their EC. TIE2-lacZ mice express β-gal in all EC and VWF-lacZ mice express β-gal in heart and brain microvascular EC.

Results

Transgenic and congenic wild type FVB mice immunized with β-gal expression vector DNA or β-gal protein generated high titer, high affinity antisera containing comparable levels of antigen-specific IgG1 and IgG2a isotypes, suggesting equivalent activation of T helper cell subsets. The immunized transgenic mice remained healthy, their EC continued to express β-gal, and their blood vessels showed no histological abnormalities. In response to β-gal in vitro, CD4⁺ and CD8⁺ T cells from immunized transgenic and FVB mice proliferated, expressed CD25, and secreted IFN-γ. Infection with recombinant vaccinia virus encoding β-gal raised equivalent responses in transgenic and FVB mice. Hearts transplanted from transgenic mice into FVB mice continued to beat and the graft EC continued to express β-gal. These results suggested immunological ignorance of the transgene encoded EC protein. However, skin transplanted from TIE2-lacZ onto FVB mice lost β-gal⁺ EC and the hosts developed β-gal-specific antisera, demonstrating activation of host immune effector mechanisms. In contrast, skin grafted from TIE2-lacZ onto VWF-lacZ mice retained β-gal⁺ EC and no antisera developed, suggesting a tolerant host immune system.

Conclusion

Resting, β-gal⁺ EC in transgenic mice tolerize specific lymphocytes that would otherwise respond against β-gal expressed by EC within transplanted skin. We conclude that EC effectively present intracellular "self" proteins to the immune system. However, antigen presentation by EC does not delete or anergize a large population of specific lymphocytes that respond to the same protein following conventional immunization with protein or expression vector DNA. These results clearly demonstrate striking context sensitivity in the immune recognition of EC, a subtlety that must be better understood in order to treat immune diseases and complications involving the vasculature.

Applications of gene transfer to cellular immunotherapy

Adoptive cellular therapy remains a potentially powerful method of eradicating established tumors. T-cells have been particularly potent effector cells, as demonstrated in animal models and clinical studies, and it is apparent that the stimulation of certain subpopulations of T-cells that are reactive to tumor antigens can lead to more therapeutic T-cells. The use of gene transfer techniques has resulted in more effective and specific methods to generate these tumor-specific T-cells. Another area of tremendous interest is in the adoptive transfer of DCs manipulated to present tumor antigen to resting, naive T-cells. Gene transfer techniques may offer more optimal ways to generate therapeutic DCs. Adoptive immunotherapy may ultimately [figure: see text] have its greatest use in patients undergoing cellular rescue after ablative chemotherapy; the infusion of immunocompetent T-cells, genetically modified stem cells, or programmed DCs may offer the opportunity to direct a patient's immune response to eliminate residual microscopic disease.

DNA assembly using bis-peptide nucleic acids (bisPNAs)

DNA nanostructures are ordered oligonucleotide arrangements that have applications for DNA computers, crystallography, diagnostics and material sciences. Peptide nucleic acid (PNA) is a DNA/RNA mimic that offers many advantages for hybridization, but its potential for application in the field of DNA nanotechnology has yet to be thoroughly examined. We report the synthesis and characterization of tethered PNA molecules (bisPNAs) designed to assemble two individual DNA molecules through Watson-Crick base pairing. The spacer regions linking the PNAs were varied in length and contained amino acids with different electrostatic properties. We observed that bisPNAs effectively assembled oligonucleotides that were either the exact length of the PNA or that contained overhanging regions that projected outwards. In contrast, DNA assembly was much less efficient if the oligonucleotides contained overhanging regions that projected inwards. Surprisingly, the length of the spacer region between the PNA sequences did not greatly affect the efficiency of DNA assembly. Reasons for inefficient assembly of inward projecting DNA oligonucleotides include non-sequence-specific intramolecular interactions between the overhanging region of the bisPNA and steric conflicts that complicate simultaneous binding of two inward projecting strands. These results suggest that bisPNA molecules can be used for self-assembling DNA nanostructures provided that the arrangement of the hybridizing DNA oligonucleotides does not interfere with simultaneous hybridization to the bisPNA molecule.

Nonviral gene transfer strategies for the vasculature

Major attention has been focused on the development of gene therapy approaches for the treatment of vascular diseases. In this review, we focus on an alternative use of gene therapy: the use of genetic means to study vascular cell biology and physiology. Both viral and nonviral gene transfer strategies have limitations, but because of the overwhelming inflammatory responses associated with the use of viral vectors, nonviral gene transfer methods are likely to be used more abundantly for future applications in the vasculature. Researchers have made great strides in the advancement of gene delivery to the vasculature in vivo. However, the efficiency of gene transfer seen with most nonviral approaches has been exceedingly low. We discuss how to circumvent and take advantage of a number of the barriers that limit efficient gene delivery to the vasculature to achieve high-level gene expression in appropriate cell types within the vessel wall. With such levels of expression, gene transfer offers the ability to alter pathways at the molecular level by genetically modulating the activity of a gene product, thus obviating the need to rely on pharmacological agents and their foreseen and unforeseen side effects. This genetic ability to alter distinct gene products within a signaling or biosynthetic pathway or to alter structural interactions within and between cells is extremely useful and technologically possible today. Hopefully, with the availability of these tools, new advances in cardiovascular physiology will emerge.

Combination of electroporation and DNA/dendrimer complexes enhances gene transfer into murine cardiac transplants

Electroporation is a new gene delivery method to increase gene transfer and expression in vivo. Starburst polyamidoamine dendrimers have been demonstrated to augment gene expression in vitro and in vivo. We hypothesized that the combination of electroporation and dendrimer could enhance the gene transfer and gene expression in cardiac transplants. After immersion in DNA/dendrimer complexes or intracoronary transfer of DNA/dendrimer complexes, both nonvascularized and vascularized syngeneic cardiac grafts, respectively, were subjected to serial electrical pulses before transplantation. beta-Galactosidase reporter gene expression in the graft was determined by X-Gal staining. Gene expression was enhanced 10- to 45-fold in grafts immersed in DNA/dendrimer complexes, or after intracoronary transfer of DNA/dendrimer complexes, and subjected to 20 square wave 25-ms pulses with a strength of 200 V/cm. The combination of electroporation and DNA/dendrimer complexes may provide a novel approach to enhance gene transfer and gene expression ex vivo.