Efficiency, efficacy, and adverse effects of adenovirus vs. liposome-mediated gene therapy in cardiac allografts

Recent Advances in Liposomal-Based Anti-Inflammatory Therapy

Liposomes can be seen as ideal carriers for anti-inflammatory drugs as their ability to (passively) target sites of inflammation and release their content to inflammatory target cells enables them to increase local efficacy with only limited systemic exposure and adverse effects. Nonetheless, few liposomal formulations seem to reach the clinic. The current review provides an overview of the more recent innovations in liposomal treatment of rheumatoid arthritis, psoriasis, vascular inflammation, and transplantation. Cutting edge developments include the liposomal delivery of gene and RNA therapeutics and the use of hybrid systems where several liposomal bilayer features, or several drugs, are combined in a single formulation. The majority of the articles reviewed here focus on preclinical animal studies where proof-of-principle of an improved efficacy-safety ratio is observed when using liposomal formulations. A few clinical studies are included as well, which brings us to a discussion about the challenges of clinical translation of liposomal nanomedicines in the field of inflammatory diseases.

Establishment of a novel volume-loaded heterotopic heart transplantation model in rats

BACKGROUND

Non-volume-loaded (NL) donor hearts in the heterotopic heart transplantation model in rats undergo atrophy and thrombus formation in graft cavities after transplantation. The present study aimed to establish a novel model with volume-loaded donor hearts.

METHODS

We used Sprague-Dawley rats as donors and recipients. We established an NL model by anastomosing the donor ascending aorta and pulmonary artery end-to-side to the recipient abdominal aorta and inferior vena cava, respectively, and ligating the superior and inferior vena cava on the donor right atrium. The method of the volume-loaded (VL) model was the same as described above, except we performed an anastomosis of the donor left atrium to the recipient abdominal aorta to allow volume loading of the donor's left ventricle. We assessed the characteristics of the grafts by the surgical success rate, echocardiography, and histologic evaluation between the two models.

RESULTS

Echocardiography showed that donor left ventricle in VL models was volume loaded and had normal systolic and diastolic function compared with the NL models. The mean weight of NL hearts was significantly less than that of VL hearts. Morphologic observation revealed that thrombus formation in donor heart cavities in NL model was significantly higher than that in the VL model. The area of cardiomyocytes per high-power field in the NL model was significantly lower than that in the VL model.

CONCLUSIONS

We provide a novel VL heterotopic heart transplantation model in rats, in which hemodynamic performance of grafts is close to the normal cardiac physiologic situation; thus, the novel model will be more suitable for clinical research.

Prope tolerance to heart allografts in mice associated with persistence of donor interleukin-10-transduced stem cells

BACKGROUND

We previously reported that transduction of the human interleukin (IL)-10 gene into the total fetal liver stem cells (hIL-10-TFLs) of mice protects against their rejection in an allogeneic host. In this study, we explored the effects of these cells in two different models of organ transplantation.

METHODS

Balb/c mice were sublethally irradiated before receiving skin or vascularized heterotopic heart grafts from C57Bl/6 mice. TFLs from C57Bl/6 mice transduced with hIL-10 or untransduced TFLs were injected on the day of transplantation into recipient mice once or also every 20 days thereafter.

RESULTS

Skin allograft survival was prolonged for up to 17.8±0.6 days, vs. 9.0±0.4 days, in mice that received hIL-10-TFLs or untransduced TFLs, respectively. Allogeneic heart transplants survived for 86.25±13.8, 46.3±4.6, 28.1±6.1, or 11.5±0.6 days in mice that received repeated injections of hIL-10-TFLs, a single injection of hIL-10-TFLs, repeated injections of untransduced TFLs, or controls, respectively. Histological analyses of the grafts showed fewer inflammatory foci and CD8+ infiltrating cells in mice injected with hIL-10-TFLs compared with untreated mice. Expressions of H-2b and hIL-10 were found in several organs, including the thymus, liver, and the transplant, in hIL-10-TFL-injected mice. Finally, in hIL-10-TFL-injected mice, FoxP3 T cells were present inside the transplanted heart as late as 140 days after transplantation.

CONCLUSIONS

In this study, we showed that repeated injections of hIL-10-TFLs are efficient in mitigating transplant rejection. This "prope" tolerance was associated with survival of donor hematopoietic cells in the host.

Creation of myocardial fibrosis by transplantation of fibroblasts primed with survival factors

One of the major obstacles in the creation of myocardial fibrosis using fibroblasts is massive cell death after cell injection. To overcome this problem, a method that delivers fibroblasts primed with survival factors was studied. Cardiac fibroblasts were isolated from wild-type male C57BL/6 mice. Female mice were randomly placed into the following three groups: 1) fibroblasts transfected with β-galactosidase-containing adenovirus (control group), 2) fibroblasts treated with a necrosis inhibitor (NI group), and 3) fibroblasts transfected with Akt-containing adenovirus (Akt group). Pretreated cells were transplanted into the recipient heart by direct injection after a thoracotomy. Quantitative real-time PCR and morphometric analysis were performed to investigate the effects of survival factor priming on the induction of cell engraftment and fibrosis. In addition, a canine model was used to investigate the development of fibrosis and conduction modification using autologous dermal fibroblasts. The NI and Akt groups showed a better engraftment rate: 13 (NI group) and 7 (Akt group) times greater at 21 days compared with the control group. Increased fibrosis and conduction delay were also observed in the NI and Akt groups compared with the control group. Survival factor priming increased cellular engraftment and enhanced the efficacy of cell transplantation. Delivery of fibroblasts primed with survival factors might be a promising approach to develop conduction modification as a novel strategy to treat arrhythmias.

Silk-elastin-like hydrogel improves the safety of adenovirus-mediated gene-directed enzyme-prodrug therapy

Recombinant silk-elastin-like protein polymers (SELPs) are well-known for their highly tunable properties on both the molecular and macroscopic hydrogel levels. One specific structure of these polymers, SELP-815K, has been investigated as an injectable controlled delivery system for the treatment of head and neck cancer via a gene-directed enzyme prodrug therapy (GDEPT) approach. Due to its pore size and gelation properties in vivo, SELP restricts the distribution and controls the release of therapeutic viruses for up to one month. It has been shown that SELP-mediated delivery significantly improves therapeutic outcome of the herpes simplex virus thymidine kinase (HSVtk)/ganciclovir (GCV) system in xenograft models of human head and neck cancer. However little is known about potential benefits of this approach with regard to toxicity in the presence of a fully intact immune system. The studies presented here were designed to assess the change in toxicity of the SELP-mediated viral delivery compared to free viral injection in a non-tumor-bearing immune competent mouse model. Toxicity was assessed at 1, 2, 4, and 12 weeks via body weight monitoring, complete blood count (CBC), and blood chemistry. It was found that in the acute and subacute phases (weeks 1-4) there is significant toxicity in groups combining the virus and the prodrug, and matrix-mediated gene delivery with SELP demonstrates a reduction in toxicity from the 2 week time point through the 4 week time point. At the end of the subchronic phase (12 weeks), signs of toxicity had subsided in both groups. Based on these results, recombinant SELPs offer a significant reduction in toxicity of virus-mediated GDEPT treatment compared to free virus injection in the acute and subacute phases.

Non-viral gene therapy for myocardial engineering

Despite significant advances in surgical and pharmacological techniques, myocardial infarction (MI) remains the main cause of morbidity in the developed world because no remedy has been found for the regeneration of infarcted myocardium. Once the blood supply to the area in question is interrupted, the inflammatory cascade, among other mechanisms, results in the damaged tissue becoming a scar. The goals of cardiac gene therapy are essentially to minimize damage, to promote regeneration, or some combination thereof. While the vector is, in theory, less important than the gene being delivered, the choice of vector can have a significant impact. Viral therapies can have very high transfection efficiencies, but disadvantages include immunogenicity, retroviral-mediated insertional mutagenesis, and the expense and difficulty of manufacture. For these reasons, researchers have focused on non-viral gene therapy as an alternative. In this review, naked plasmid delivery, or the delivery of complexed plasmids, and cell-mediated gene delivery to the myocardium will be reviewed. Pre-clinical and clinical trials in the cardiac tissue will form the core of the discussion. While unmodified stem cells are sometimes considered therapeutic vectors on the basis of paracrine mechanisms of action basic understanding is limited. Thus, only genetically modified cells will be discussed as cell-mediated gene therapy.

Overexpressed exogenous IL-4 And IL-10 paradoxically regulate allogenic T-cell and cardiac myocytes apoptosis through FAS/FASL pathway

BACKGROUND

The authors' previous study has shown that liposome-mediated ex vivo intracoronary interleukin (IL)-4 and IL-10 combined gene therapy suppressed the allo-immune responses and prolonged the cardiac allograft survival by 15 folds. However, the mechanism for promoting long-term allograft survival remains unknown.

METHODS

This study tested the hypothesis that this combined cytokine gene targeting may promote alloreactive T-cell apoptosis or prevent apoptosis of cardiac allograft myocytes through Fas/Fas ligand (FasL) pathway. A rabbit functional cervical heterotopic heart transplantation model was used, and plasmid human recombinant IL-4 and IL-10 gene complexed with cationic liposome (GAP/DLRIE) was delivered into cardiac allografts by intracoronary infusion ex vivo.

RESULTS

This liposome-mediated IL-4 and IL-10 combined gene therapy significantly increased apoptotic T cells detected by TUNEL staining. The caspase-8 or caspase-3 expressing T cells were also significantly increased. The Fas+ apoptotic T cells dominated in the population of apoptotic CD4+ T cells, but FasL+ CD4+ T-cell population was less effected in the combined gene therapy group. The effect of combined gene therapy on the infiltrative Fas+ CD8+ T-cell population is much less than that on Fas+ CD4+ cells, and there was almost no effect on the FasL+ CD8+ T-cell population. Furthermore, localized IL-4 and IL-10 combined gene therapy protected cardiac allograft myocytes by down-regulating its FasL expression, but not Fas.

CONCLUSIONS

These results suggest that this combined gene targeting strategy which induced localized overexpression of exogenous IL-4 and IL-10 may promote alloreactive T-cell apoptosis and prevent myocytes apoptosis through Fas/FasL cell surface interaction, therefore inducing cardiac allograft tolerance.

Sodium iodide symporter (hNIS) permits molecular imaging of gene transduction in cardiac transplantation

BACKGROUND

We evaluated the feasibility of noninvasive micro-single photon emission computed tomography (SPECT)/computed tomography (CT) imaging and quantification of cardiac gene expression after sodium iodide symporter (hNIS) gene transfer in cardiac transplantation.

METHODS

Donor rat hearts were perfused ex vivo with adenovirus expressing hNIS (Ad-hNIS), Ad-Null, or University of Wisconsin (UW) solution prior to heterotopic transplantation into syngeneic recipients. In the first group of recipients, imaging of the transplanted hearts with micro-SPECT/CT on day 5 was followed by immediate explant of the organs for ex vivo analyses. Radioactivity counts in the explanted hearts were obtained ex vivo and expressed as a percentage of the injected dose per gram of tissue (%ID/g). Intensities of the SPECT images of the transplanted hearts were quantified and converted to radioactive counts using a standard equation. The second group of recipients was imaged sequentially after injection of I on days 2 to 14 after transplantation.

RESULTS

Higher ex vivo radioiodine counts were noted in the hearts perfused with Ad-hNIS (1.04+/-0.2) compared to either the UW group (0.31+/-0.11, P<0.001) or the Ad-Null group (0.32+/-0.08, P<0.001). Image intensity in the Ad-NIS group (0.9+/-0.2) was also significantly higher than in the UW group (0.4+/-.03, P=0.003) or the Ad-Null group (0.5+/-0.1, P<0.05). Sequential imaging of Ad-NIS-perfused hearts between postoperative days 2 and 14 revealed peak image intensity at day 5. Overall, image intensities correlated with ex vivo counts of radioactivity (rho=0.74, P<0.05).

CONCLUSIONS

These data demonstrate that hNIS gene transfer permits sequential real-time detection and quantification of reporter gene expression in the transplanted heart with micro-SPECT/CT imaging.

Exogenous IL-10 overexpression reduces perforin production by activated allogenic CD8+cells and prolongs cardiac allograft survival

Perforin is a cytolytic mediator produced by cytotoxic T cells (CD8+cells) and natural killer cells. We previously reported that ex vivo IL-10 gene therapy induced apoptosis of allogenic infiltrative CD8+cells and significantly prolonged cardiac allograft survival. To further test the hypothesis that localized IL-10 overexpression in cardiac allografts may also effect the alloreactive CD8+T cell function by downregulating its perforin production, we used a rabbit functional heterotopic allograft heart transplant model. Human recombinant IL-10 gene complexed with liposome was intracoronary delivered into the cardiac allografts ex vivo. The percentage of apoptotic infiltrative CD8+cells in cardiac allografts was increased 6-fold in the gene therapy group vs. the control group, whereas the percentage of perforin-positive CD8+cells was decreased 2.9-fold ( P < 0.01). Perforin expression level in the allograft myocardium of the gene therapy group was deceased 3.2-fold ( P < 0.01). The amount of infiltrative perforin-positive CD8+cells and perforin expression level were inversely correlated with IL-10 transgene and protein expression level in the myocardium of cardiac allografts ( P < 0.01), the percentage of apoptotic cardiac myocytes ( P < 0.01), and the peak left ventricular systolic pressure of cardiac allografts ( P < 0.01) but significantly correlated with the infiltrative T cell cytotoxicity ( P < 0.01) and allograft rejection score ( P < 0.01). These results suggest that localized IL-10 gene therapy prolongs cardiac allograft survival, at least in part, through downregulation of perforin production by activated allogenic CD8+T cells. Reduction of cytolytic function of cytotoxic effector cells prevents the apoptosis of cardiac myocytes.

Ex vivo hypothermic recirculatory adenoviral gene transfer to the transplanted pig heart

BACKGROUND

To facilitate the application of adenoviral gene therapy in clinical heart transplantation, we developed an ex vivo hypothermic recirculatory adenoviral gene transfer method to the transplanted pig heart.

METHODS

Experimental animals were assigned into three groups; controls, 1x10(8) plaque-forming units (pfu)/ml group and 1x10(9) pfu/ml group. During the 30 min gene transfer perfusion, 200 ml of University of Wisconsin solution containing the adenoviral vector was recirculated through the coronary vessels. The myocardial temperature was maintained below 4 degrees C and the perfusion pressure was adjusted at 50 mmHg.

RESULTS

Cardiac myocyte transduction efficiencies in the 1x10(8) pfu/ml group were 0.04% and 0.07%, whereas transduction efficiencies in the 1x10(9) pfu/ml group were widely distributed from 0.45% to 22.62%. The gene transduction efficiency increased with the virus titer. Additionally, no difference in the transduction efficiency was observed between different segments of the left ventricle. The current gene transfer method at 1x10(9) pfu/ml of adenovirus titer enabled homogeneous gene transduction into the transplanted pig heart up to a maximum of 22.62%.

CONCLUSIONS

This model can be applied to a large isolated heart and will greatly facilitate the investigation of gene therapy in large animal models of heart transplantation.

Attenuated alloreactivity of dendritic cells engineered with surface-modified microspheres carrying a plasmid encoding interleukin-10

In the present study, we investigated MS(O10H6) as a carrier system to introduce a plasmid encoding murine interleukin-10 (pIL-10) to modulate alloreactivity of dendritic cells (DC). Results indicate that MS(O10H6) formed stable and protective nano-sized particles with pIL-10. Gene-modified DC elicited weak proliferation of allogeneic CD4 and CD8 T cells in vitro. Using cell-embedded Matrigel as a surrogate graft, we also showed that DC transfected with MS(O10H6) complexed with pIL-10 suppressed host cell infiltration in vivo. These data demonstrate that the self-assembled system of MS(O10H6) is an effectual delivery vehicle for plasmid-based modulation of DC-dependent allogeneic T cell responses.

Low molecular weight dextrans stabilize nonviral vectors during lyophilization at low osmolalities: concentrating suspensions by rehydration to reduced volumes

Stabilization of nonviral vectors during freezing and drying requires formulation with protective excipients such that transfection rates and physical characteristics are maintained upon reconstitution. While many studies have demonstrated the ability of disaccharides (e.g., sucrose) to effectively protect nonviral vectors during lyophilization, the sucrose/DNA weight ratios required to achieve stability result in formulations that are not osmotically compatible with the subcutaneous (SC) or intramuscular (IM) injection of a typical dose of plasmid DNA. In an effort to reduce the formulation osmolality, dextrans possessing a range of molecular weights were investigated for their ability to serve as protectants. Dextran 3000 proved to be the most effective of the dextrans tested, and offered similar protection to sucrose on a weight basis. However, the advantage of employing this excipient is that the resulting osmolality is reduced by approximately 40% as compared to an equivalent weight of sucrose. Moreover, the use of dextran allows lyophilized vector preparations to be rehydrated to reduced volumes, essentially concentrating vectors prior to administration. Utilizing a combination of dextran 3000 and sucrose, we demonstrate that complexes of polyethylenimine (PEI) and DNA lyophilized at 0.1 mg/mL can be concentrated tenfold upon rehydration, resulting in an isotonic formulation containing 1 mg/mL DNA that can provide more realistic injection volumes for animal studies, and is compatible with clinical trials involving SC and IM injection.

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.

Prolonged skin allograft survival by IL-10 gene-introduced CD4 T cell administration

Both CD4 and CD8 T cells play crucial roles in immune responses in transplantation. Immunosuppressive drugs, such as FK506 and cyclosporin A, block the priming of alloreactive CD4 T(h) cells and the subsequent induction of allospecific CD8 cytotoxic effector T cells and inhibit allograft rejection. However, the desire to minimize chronic complications that may arise from the use of immunosuppressive agents drives the search for additional strategies for immunosuppression of allograft rejection. In this study, CD4 or CD8 T cells into which the IL-10 gene is introduced using an adenovirus vector containing human IL-10 (hIL-10) cDNA (Ad-hIL-10) and into mouse T cells transgenic for the Coxsackie virus and adenovirus receptor form a model system to study the effect of administration of IL-10-secreting T cells on the survival of the allogenic skin grafts. Ad-hIL-10-infected CD4 and CD8 T cells secreted a large amount of hIL-10 for 3-4 days in culture in vitro. Ad-hIL-10-infected CD4 T cells administered in vivo could be detected in the spleen for 7 days post-transfer. Significantly prolonged survival of grafts was observed in animals that received either Ad-hIL-10-infected activated CD4 T cells or T(h)2-skewed CD4 T cells as compared with controls. Furthermore, substantial enhancement of the effect was observed in B6.C-H2(bm1)/ByJ transplants. Thus, a direct manipulation of T cells through the introduction of the immunosuppressive cytokine gene IL-10 may be a novel strategy for the control of allograft rejection.

Lentivirus-mediated gene transfer of viral interleukin-10 delays but does not prevent cardiac allograft rejection

Human immunodeficiency virus (HIV)-based lentiviral vectors expressing viral interleukin-10 (vIL-10) were used to transduce rat cardiac allografts with the aim of extending graft survival. vIL-10 expression was first shown, by RT-PCR, to persist in transduced heart isografts for at least 28 days after transduction. Cardiac transplants were performed in a fully allogeneic rat strain combination (Lewis to DA); allografts transduced by vectors expressing vIL-10 showed significantly prolonged survival (14.5 vs 7.5 days median survival time). Mixed lymphocyte reactions (MLRs) were used to determine the influence, in vitro, of vIL-10 on alloantigen-induced T-cell proliferation. Bioactive vIL-10, produced by DA rat aortic endothelial cells transduced with HIV-PGK-vIL-10, was added to MLRs at different time points and lymphocyte proliferation was assessed by uptake of [3H]thymidine. T-cell proliferation was inhibited by >80% when vIL-10 was added to the MLR at day 1, 2 or 3 of coculture. The inhibitory effect was significantly decreased when addition of vIL-10 was delayed until day 4 or 5 (47 and 35% inhibition, respectively). The extended graft survival time is comparable to that using adenoviral vectors delivering vIL-10 in a similar rat strain combination. The limited improvement in survival may be due to lack of inhibition of the early phase of the alloimmune response as suggested by in vitro studies confirming that maximum suppression of the MLR by vIL-10 can only be achieved if the cytokine is present at the initiation of alloimmune recognition. The delay in expression of vIL-10 from the lentiviral vector means that protocols must be developed to suppress the early stages of alloimmune stimulation before vIL-10 is produced.

Fatal disseminated adenoviral infection in an adult heart transplant patient

In heart transplant recipients, infection is one of the leading causes of morbidity and mortality. In adult heart transplant patients, cytomegalovirus is the most frequently encountered viral pathogen. Conversely, disseminated adenoviral infection is observed mainly in children, where it is predictive of allograft rejection and coronary vasculopathy. The literature contains only a few reports of adenoviral infections in adult heart transplant recipients. Limited information is available concerning the diagnosis and epidemiology of such infections and their relationship to organ rejection, heart failure and overall outcomes in these patients. To promote an awareness of this potentially lethal complication, we present a case of fatal disseminated adenoviral infection in an adult heart transplant recipient.

Immobilization of Nonviral Vectors During the Freezing Step of Lyophilization

The development of nonviral vectors as commercial therapeutics will require formulations that are sufficiently stable to allow shipping and storage for prolonged periods. Given the well-known instability of these systems as aqueous suspensions, it would be desirable to develop lyophilized formulations that are resistant to shipping stress and can be stored for extended periods at ambient temperatures. Previous studies have shown that aggregation and structural changes resulting in reduced transfection rates can occur during the freezing step of lyophilization. While it has been clearly demonstrated that freezing-induced damage is promoted by vector crowding that results from the reduced volume of unfrozen solution, the precise mechanism of damage has yet to be fully elucidated, i.e., damage may occur due to ice formation and/or during incubation in the frozen state. In this study, we investigate the time- and temperature-dependence of damage during freezing and demonstrate that aggregation can occur while frozen vector suspensions are incubated at a constant temperature. Aggregation is not seen during incubation at temperatures below T(g)', and can also be avoided above the glass transition temperature under some conditions. Our data are consistent with a model describing the mobility of vectors in the unfrozen sucrose solution being sufficiently restricted such that inter-particle interactions are prevented in the frozen state. Furthermore, the protection achieved during freezing at temperatures above T(g)' is applicable to a complete lyophilization cycle (i.e., freezing and drying), and provides stabilization at higher primary drying temperatures.

Dual upregulation of Fas and Bax promotes alloreactive T cell apoptosis in IL-10 gene targeting of cardiac allografts

Activation-induced cell death and cytokine deprivation are demonstrated by peripheral T cell populations at the conclusion of natural immune responses, and each of these processes is modulated by the immunosuppressive cytokine interleukin (IL)-10 in vitro. This study employs a clinically relevant in vivo model of IL-10 gene transfer with heterotopically transplanted cardiac allografts to determine the mechanisms of the effects of IL-10 on T cell survival. IL-10 protein overexpression within allografts 4-5 days after gene transfer augments apoptosis of CD4+ and CD8+ graft-infiltrating lymphocytes by 7.1-fold (P < 0.001) and 6.0-fold (P < 0.001), respectively. Graft-infiltrating T cells express 10-fold more proapoptotic Fas (P < 0.01) and 30-fold more Bax (P < 0.01) than controls. The fractions of activated caspase-8 (FADD-like IL-1beta-converting enzyme) and activated caspase-9 were increased 7- and 2.3-fold, respectively, in IL-10 gene-treated allografts at postoperative day 4-5. These changes in the Fas-Fas ligand pathway and Bcl-2 mitochondrial apoptosis regulation are enhanced by complete suppression of antiapoptotic FADD-like IL-1beta-converting enzyme inhibitory protein (FLIP) (from 30.5 to 0.0%, P < 0.01) and Bcl-xL (from 22.5 to 0.1%, P = 0.03) expression among these cells from the earliest days after gene transfer. Although changes in proteins of Fas- and Bcl-2-mediated apoptosis signaling occur, only the levels of Fas and FLIP correlate to the rate of apoptosis of graft-infiltrating CD3 lymphocytes and histological rejection scores. These results indicate that dichotomous apoptosis-regulatory pathways are affected by IL-10 gene therapy, but Fas-mediated mechanisms of activation-induced cell death more substantially contribute to the greater cell death of graft-infiltrating T cells after ex vivo IL-10 gene transfer.

AP-4F, antennapedia peptide linked to an amphipathic alpha helical peptide, increases the efficiency of Lipofectamine-mediated gene transfection in endothelial cells

Typically, endothelial cells are difficult to transfect. In this study, we report that antennapedia peptide (AP) linked to L-4F, a water-soluble, amphipathic alpha helical peptide that avidly binds lipids (AP-4F) increases Lipofectamine 2000-mediated transfection of bovine coronary endothelial cell cultures. Transfection efficiency was monitored by flow cytometry and fluorescent microscopy. Lipofectamine 2000 transfection of endothelial cell cultures with green fluorescence protein (GFP)-DNA typically yields transfection efficiencies of 35.4+/-3.3% with low levels of cell death (8.1+/-1.0%). Pre-treatment of the Lipofectamine 2000-GFP-DNA complexes with AP-4F for 5 min increased transfection to 58.2+/-2.8% without increasing cell death. AP-4F increases Lipofectamine 2000-mediated transfection in a time-dependent fashion (within 10-20 min). Systematic studies reveal that the individual components of AP-4F, i.e., AP and L-4F alone, are ineffective in increasing Lipofectamine 2000-mediated transfection and that AP-4F must be directly associated with DNA liposomes prior to transfection for optimal uptake by endothelial cells. These observations demonstrate that AP-4F may be useful for increasing the transfection efficiency of endothelial cell cultures with standard commercially available reagents.