Iv Delivery Research Articles

Improved intravenous lentiviral gene therapy based on endothelial-specific promoter-driven factor VIII expression for hemophilia A

BackgroundHemophilia A (HA) is an X-linked monogenic disorder caused by deficiency of the factor VIII (FVIII) gene in the intrinsic coagulation cascade. The current protein replacement therapy (PRT) of HA has many limitations including short term effectiveness, high cost, and life-time treatment requirement. Gene therapy has become a promising treatment for HA. Orthotopic functional FVIII biosynthesis is critical to its coagulation activities.MethodsTo investigate targeted FVIII expression, we developed a series of advanced lentiviral vectors (LVs) carrying either a universal promoter (EF1α) or a variety of tissue-specific promoters, including endothelial-specific (VEC), endothelial and epithelial-specific (KDR), and megakaryocyte-specific (Gp and ITGA) promoters.ResultsTo examine tissue specificity, the expression of a B-domain deleted human F8 (F8BDD) gene was tested in human endothelial and megakaryocytic cell lines. Functional assays demonstrated FVIII activities of LV-VEC-F8BDD and LV-ITGA-F8BDD in the therapeutic range in transduced endothelial and megakaryocytic cells, respectively. In F8 knockout mice (F8 KO mice, F8null mice), intravenous (iv) injection of LVs illustrated different degrees of phenotypic correction as well as anti-FVIII immune response for the different vectors. The iv delivery of LV-VEC-F8BDD and LV-Gp-F8BDD achieved 80% and 15% therapeutic FVIII activities over 180 days, respectively. Different from the other LV constructs, the LV-VEC-F8BDD displayed a low FVIII inhibitory response in the treated F8null mice.ConclusionsThe LV-VEC-F8BDD exhibited high LV packaging and delivery efficiencies, with endothelial specificity and low immunogenicity in the F8null mice, thus has a great potential for clinical applications.

TAK-676 in combination with pembrolizumab after radiation therapy in patients (pts) with advanced non–small cell lung cancer (NSCLC), triple-negative breast cancer (TNBC), or squamous-cell carcinoma of the head and neck (SCCHN): Phase 1 study design.

TPS2698 Background: The cyclic GMP-AMP Synthase (cGAS)–STimulator of INterferon Genes (STING) pathway is an important modulator of the innate immune system via induction of type I interferon (IFN-I). Cytosolic DNA generated as a result of tumor cell death following radiation therapy has been demonstrated to activate the cGAS-STING signaling axis resulting in antitumor immunogenicity. TAK-676 is a novel, synthetic STING agonist and it has been shown in preclinical studies to potently modulate the innate immune system and subsequently activate the adaptive immune system to produce antitumor responses. TAK-676 is designed for prolonged half-life in serum and enhanced tissue permeability compared with other STING agonists designed for intratumoral injection, allowing for systemic IV delivery with access to tumor sites and lymphatic tissue. IFN signaling impairment has been linked to checkpoint inhibitor (CPI) resistance in tumors. Treatment with TAK-676 after radiation therapy has the potential to stimulate T cell-mediated antitumor immunity via STING-mediated IFN-I release, particularly when used with anti-PD-1/PD-L1 therapies. Preclinical data support the addition of STING agonists to reverse resistance in tumors with prior exposure to CPIs. TAK-676 is being investigated (+/- pembrolizumab) in an ongoing first-in-human phase 1 study (NCT04420884). Here, we describe another phase 1 trial to investigate the safety and preliminary antitumor activity of TAK-676 plus pembrolizumab following radiation therapy in pts with advanced or metastatic NSCLC, TNBC, or SCCHN (NCT04879849). Methods: Adult pts with progressive disease (PD) following CPI treatment and who have ≥2 lesions, 1 of which can be targeted with radiation, are being enrolled. Pts receive 8 Gy x 3 fractions of image-guided radiation followed (after ≥40 hours) by IV pembrolizumab 200 mg on day 1 plus escalating doses of IV TAK-676 on days 1, 8, and 15 of a 21-day cycle. TAK-676 dose escalation is guided by the Bayesian optimal interval design. Pts receive TAK-676 plus pembrolizumab until PD, intolerance to treatment, or withdrawal. Pts enrolled at TAK-676 dose levels shown to have pharmacodynamic activity, and who have a safely accessible lesion outside the radiation field, will have paired biopsies collected at screening and between days 15 and 21 of cycle 1. The primary objective is to determine the safety and tolerability of TAK-676 plus pembrolizumab following radiation therapy; secondary objectives are to establish the recommended phase 2 dose of TAK-676 plus pembrolizumab following radiation therapy, and to assess preliminary antitumor activity both locally (within the radiation field) and systemically (non-radiated lesions). As of February 2022, we have enrolled ̃10% of the planned pts. Clinical trial information: NCT04879849.

Microbubble drug conjugate and focused ultrasound blood brain barrier delivery of AAV-2 SIRT-3

Background Delivery of viral vectors as gene therapies to treat neurodegenerative diseases has been hampered by the inability to penetrate the blood brain barrier (BBB) and invasive or non-targeted delivery options prone to inducing immune responses. MR guided focused ultrasound (MR-g-FUS) and microbubbles have demonstrated safe, temporary, targeted BBB permeabilization clinically. Methods We developed clinically scalable, microbubble drug conjugates (MDCs) for the viral gene therapy, AAV.SIRT3-myc [adeno-associated virus expressing myc-tagged SIRT3], which has previously been shown to have disease modifying effects in animal models of Parkinson’s disease (PD). The lipid shells of the perfluorocarbon gas MDCs were covalently conjugated to antibodies with binding specificity to AAVs. Following systemic (iv) delivery of AAV.SIRT3-myc MDCs, MR-g-FUS was used to deliver SIRT3-myc to brain regions affected in PD. SIRT3-myc expression was determined post mortem, using immunohistochemistry. Results An in vitro, SH-SY5Y cell culture model was used to show that the localized destruction of MDCs using ultrasound exposures within biological safety limits dissociated AAV2-GFP (green fluorescent protein) from the MDCs in the targeted area while maintaining their transduction capacity. In rats, MR-g-FUS resulted in BBB permeabilization in the striatum and substantia nigra (SNc). SIRT3-myc was expressed in the striatum, but not the SNc. Conclusion These studies demonstrate that MDCs combined with MR-g-FUS are an effective method for delivery of viral vector gene therapies, such as AAV.SIRT3, to brain regions affected in PD. This technology may prove useful as a disease-modifying strategy in PD and other neurodegenerative disorders.

High-efficacy targeting of colon-cancer liver metastasis with Salmonella typhimurium A1-R via intra-portal-vein injection in orthotopic nude-mouse models.

Liver metastasis is the main cause of colon cancer-related death and is a recalcitrant disease. We report here the efficacy and safety of intra-portal-vein (iPV) targeting of Salmonella typhimurium A1-R on colon cancer liver metastasis in a nude-mouse orthotopic model. Nude mice with HT29 human colon cancer cells, expressing red fluorescent protein (RFP) (HT29-RFP), growing in the liver were administered S. typhimurium A1-R by either iPV (1×104 colony forming units (CFU)/100 μl) or, for comparison, intra-venous injection (iv; 5×107 CFU/100 μl). Similar amounts of bacteria were delivered to the liver with the two doses, indicating that iPV delivery is 5×103 times more efficient than iv delivery. Treatment efficacy was evaluated by tumor fluorescent area (mm2) and total fluorescence intensity. Tumor fluorescent area and fluorescence intensity highly correlated (p<0.0001). iPV treatment was more effective compared to both untreated control and iv treatment (p<0.01 and p<0.05, respectively with iPV treatment with S. typhimurium arresting metastatic growth). There were no significant differences in body weight between all groups. The results of this study suggest that S. typhimurium A1-R administered iPV has potential for peri-operative adjuvant treatment of colon cancer liver metastasis.

Conjugation to Poly(amidoamine) Dendrimers and Pulmonary Delivery Reduce Cardiac Accumulation and Enhance Antitumor Activity of Doxorubicin in Lung Metastasis.

Lung is one of the most common sites to which almost all other primary tumors metastasize. The major challenges in the chemotherapy of lung metastases include the low drug concentration found in the tumors and high systemic toxicity upon systemic administration. In this study, we combine local lung delivery and the use of nanocarrier-based systems for improving pharmacokinetics and biodistribution of the therapeutics to fight lung metastases. We investigate the impact of the conjugation of doxorubicin (DOX) to carboxyl-terminated poly(amidoamine) dendrimers (PAMAM) through a bond that allows for intracellular-triggered release, and the effect of pulmonary delivery of the dendrimer-DOX conjugate in decreasing tumor burden in a lung metastasis model. The results show a dramatic increase in efficacy of DOX treatment of the melanoma (B16-F10) lung metastasis mouse model upon pulmonary administration of the drug, as indicated by decreased tumor burden (lung weight) and increased survival rates of the animals (male C57BL/6) when compared to iv delivery. Conjugation of DOX further increased the therapeutic efficacy upon lung delivery as indicated by the smaller number of nodules observed in the lungs when compared to free DOX. These results are in agreement with the biodistribution characteristics of the DOX upon pulmonary delivery, which showed a longer lung accumulation/retention compared to iv administration. The distribution of DOX to the heart tissue is also significantly decreased upon pulmonary administration, and further decreased upon conjugation. The results show, therefore, that pulmonary administration of DOX combined to conjugation to PAMAM dendrimer through an intracellular labile bond is a potential strategy to enhance the therapeutic efficacy and decrease systemic toxicity of DOX.

Effect of the Route of Administration and PEGylation of Poly(amidoamine) Dendrimers on Their Systemic and Lung Cellular Biodistribution

There are many opportunities in the development of oral inhalation (oi) formulations for the delivery of small molecule therapeutics and biologics to and through the lungs. Nanocarriers have the potential to play a key role in advancing oi technologies and pushing the boundary of the pulmonary delivery market. In this work we investigate the effect of the route of administration and PEGylation on the systemic and lung cellular biodistribution of generation 3, amino-terminated poly(amidoamine) (PAMAM) dendrimers (G3NH2). Pharmacokinetic profiles show that the dendrimers reach their peak concentration in systemic circulation within a few hours after pulmonary delivery, independent of their chemistry (PEGylated or not), charge (+24 mV for G3NH2 vs -3.7 mV for G3NH2-24PEG1000), or size (5.1 nm for G3NH2 and 9.9 nm for G3NH2-24PEG1000). However, high density of surface modification with PEG enhances pulmonary absorption and the peak plasma concentration upon pulmonary delivery. The route of administration and PEGylation also significantly impact the whole body and local (lung cellular) distribution of the dendrimers. While ca. 83% of G3NH2 is found in the lungs upon pulmonary delivery at 6.5 h post administration, only 2% reached the lungs upon intravenous (iv) delivery. Moreover, no measurable concentration of either G3NH2 or G3NH2-24PEG1000 is found in the lymph nodes upon iv administration, while these are the tissues with the second highest mass distribution of dendrimers post pulmonary delivery. Dendrimer chemistry also significantly impacts the (cellular) distribution of the nanocarriers in the lung tissue. Upon pulmonary delivery, approximately 20% of the lung endothelial cells are seen to internalize G3NH2-24PEG1000, compared to only 6% for G3NH2. Conversely, G3NH2 is more readily taken up by lung epithelial cells (35%) when compared to its PEGylated counterpart (24%). The results shown here suggest that both the pulmonary route of administration and dendrimer chemistry combined can be used to passively target tissues and cell populations of great interest, and can thus be used as guiding principles in the development of dendrimer-based drug delivery strategies in the treatment of medically relevant diseases including lung ailments as well as systemic disorders.

Abstract 19492: Adipose-Specific Gene Therapy Corrects Leptin Deficiency in vivo

Objective: To develop an in vivo , systemic method of gene therapy specifically targeting adipose tissue. We assessed the hypothesis that adipose-specific gene therapy using adeno-associated viruses (AAV) can correct leptin deficiency in vivo . Background: Obesity is a major risk factor for developing coronary heart disease. Adipose is an endocrine organ critical for energy intake and expenditure. Available data on adipose is limited, in part, because of the difficulties in adapting experimental techniques to tissue with high lipid content. Few studies have investigated in vivo gene transfer in adipose tissue, and these studies used subcutaneous injections in obese mice. Method and Results: Tail vein iv delivery of genes to adipose tissue was assessed in healthy C57BL/6 mice injected with AAV serotype 8 (AAV8) containing the expression vector of interest. Mice were sacrificed 2-3 weeks after injection, and tissues were analyzed for transgene expression. Systemic delivery of a vector containing the GFP gene under control of a CMV promoter induced GFP transgene expression in most tissues, including all adipose depots tested. Replacing the CMV promoter with an adiponectin enhancer/promoter unit and incorporating liver specific micro-RNA-122 target sites into the vector restricted GFP expression to adipose tissue. The leptin gene was put into the adipose-targeted expression vector and delivered by AAV8 to 9-10 week old ob/ob mice. Phenotypic changes were then measured for 8 weeks. Expression of leptin gene was detectable in multiple adipose tissue beds at both RNA and protein levels in mice receiving AAV8 leptin vector, but absent in control mice. Mice receiving leptin gene ate less food and had lower insulin levels compared to control mice. At sacrifice, average weight of mice receiving leptin gene was 14 g less than control mice. Glucose tolerance tests demonstrated adipose-targeted leptin gene therapy increased insulin sensitivity in ob/ob mice. Conclusion: AAV8-mediated systemic delivery of an adipose-targeted expression vector can replace a gene lacking in adipose tissue and thus correct for leptin deficiency in ob/ob mice. This novel approach has therapeutic potential in obesity and downstream complications such as insulin resistance and diabetes.

Phase I clinical trial of a genetically modified and oncolytic vaccinia virus GL-ONC1 with green fluorescent protein imaging.

2530 Background: GL-ONC1 is a genetically engineered vaccinia virus attenuated by insertion of the RUC-GFP (Renilla luciferase and Aequorea green fluorescent protein fusion gene), beta-galactosidase (lacZ) and beta-glucuronidase (gusA) reporter genes into the F14.5L, J2R (thymidine kinase) and A56R (hemaglutinin) loci. A phase I clinical trial of iv GL-ONC1 was pursued to evaluate safety, tolerability, tumour delivery, neutralizing antibody development and anti-tumour activity. Methods: GL-ONC1 was administered to patients with advanced solid tumours at escalating doses (1×105, 1×106, 1×107, 1×108, 1×109, 3×109 plaque-forming units (pfu) on day 1; 1.667×107 and 1.667×108 pfu on day 1-3 of a 28-day cycle) using a 3+3 dose escalation design. Green fluorescent protein (GFP) imaging was performed on skin rash and mucosal tumour lesions at baseline and after each cycle. Optional tumour biopsies were obtained for pharmacodynamic and viral delivery evaluation. Results: 27 patients (21 males, median age 60 years) were treated. One of six patients at the 1x109 pfu dose level developed a dose-limiting, grade 3 rise in aspartate transaminase levels after a single infusion. Other reported adverse events (grade 1/2) included pyrexia (21), musculoskeletal pain (9), fatigue (8), nausea (7), and vomiting (4). Two patients developed skin rash during the first week of treatment, which appeared green by GFP and were positive to viral plaque assay (VPA). VPA of blood, urine, stool and sputum were negative for viral shedding in all but one patient who had positive shedding for 11 days. Increased neutralizing antibody titres were detected in all tested patients apart from one. Best response by RECIST was stable disease at 48 weeks (1), 24 weeks (3) and 8-12 weeks (5). A patient with squamous cell carcinoma of the tongue had a biopsy after 4 cycles which showed positive IHC staining of vaccinia virus. This is the first time that a virus is shown to be delivered to solid tumour after iv delivery. Conclusions: GL-ONC1 administered iv is well tolerated, with documented colonisation in patient tumour, and preliminary evidence of anti-tumour activity.

Optimization of Non-Viral Gene Therapeutics Using Bilamellar Invaginated Vesicles

Bilamellar invaginated vesicles (BIVs) are unique liposomal nanoparticles (NPs) that are highly efficient vehicles for intravenous (iv) delivery of encapsulated therapeutics including plasmid DNA. Systemic administration of therapeutics is required to effectively treat or cure metastatic cancer, certain cardiovascular diseases, and other acquired or inherited diseases. In addition to having extended half-life and stability in circulation, BIVs are nontoxic, nonimmunogenic, biodegradable and can be repeatedly administered without losing potency. Furthermore, BIVs encapsulating therapeutic agents can be modified to specifically enter the disease cells using small molecules that mimic beta turns incorporated on the surface of BIV complexes while focusing biodistribution by bypassing uptake in non-target organs and tissues using reversible masking. These modifications do not alter the unique properties of the BIV delivery system that provide for its robust treatment of disease demonstrated in small and large animal models and in Phase I clinical trials. This review will cover the unique properties of BIVs, including its fusogenic entry into cells and its ability to penetrate tight barriers in vivo. Methods to further improve the overall delivery-expression system including further purification of plasmid DNA to eliminate colanic acid from all current commercially produced preparations, and enhanced or prolonged expression provided by plasmid design will also be discussed.

Differences in tissue drug concentrations following intravenous versus intraperitoneal treatment with amphotericin B deoxycholate or liposomal amphotericin B

Amphotericin B formulations were compared in preclinical models by using intraperitoneal (ip) and intravenous (iv) delivery of amphotericin B deoxycholate (DAMB) or liposomal amphotericin B. We examined the effects on drug tissue penetration and retention resulting from different routes of drug administration. Mice were treated with equivalent total doses of AmBisome (AmBi) or DAMB (i.e.,15 mg/kg) given ip (3 mg/kg/day for 5 days) or iv (3 mg/kg/day AmBi for 5 days or 1 mg/kg/day DAMB for 15 days), with tissues collected 24 h post-treatment. For drug retention studies, mice were given iv or ip total doses of 30 mg/kg AmBi (10 mg/kg/day 3 x /week) or 60 mg/kg AmBi (20 mg/kg/day 3 x /week) with tissue collection 24 h or 7 days post-treatment. Blood samples were collected at 0.5 h, 2 h, 8 h, 12 h and 24 h after ip or iv drug dosing. A Paecilomyces variottii bioassay was used to determine drug concentrations. AmBi and DAMB were detected in the kidneys following iv, but not ip dosing. Significantly more DAMB than AmBi was detected in the lungs with ip dosing (P = 0.008), and more AmBi than DAMB (P = 0.056) was present with iv dosing. Unlike the lungs, the spleen and liver retained the AmBi for up to one week post-treatment regardless of the route of drug administration. Thus, there are significant differences in AmBi and DAMB tissue distribution depending upon the drug route and these differences could effect how the drugs perform in fungal infection models.

Tissue kallikrein reverses insulin resistance and attenuates nephropathy in diabetic rats by activation of phosphatidylinositol 3-kinase/protein kinase B and adenosine 5'-monophosphate-activated protein kinase signaling pathways.

We previously reported that iv delivery of the human tissue kallikrein (HK) gene reduced blood pressure and plasma insulin levels in fructose-induced hypertensive rats with insulin resistance. In the current study, we evaluated the potential of a recombinant adeno-associated viral vector expressing the HK cDNA (rAAV-HK) as a sole, long-term therapy to correct insulin resistance and prevent renal damage in streptozotocin-induced type-2 diabetic rats. Administration of streptozotocin in conjunction with a high-fat diet induced systemic hypertension, diabetes, and renal damage in rats. Delivery of rAAV-HK resulted in a long-term reduction in blood pressure, and fasting plasma insulin was significantly lower in the rAAV-HK group than in the control group. The expression of phosphatidylinositol 3-kinase p110 catalytic subunit and the levels of phosphorylation at residue Thr-308 of Akt, insulin receptor B, and AMP-activated protein kinases were significantly decreased in organs from diabetic animals. These changes were significantly attenuated after rAAV-mediated HK gene therapy. Moreover, rAAV-HK significantly decreased urinary microalbumin excretion, improved creatinine clearance, and increased urinary osmolarity. HK gene therapy also attenuated diabetic renal damage as assessed by histology. Together, these findings demonstrate that rAAV-HK delivery can efficiently attenuate hypertension, insulin resistance, and diabetic nephropathy in streptozotocin-induced diabetic rats.

A novel therapeutic approach to 6-OHDA-induced Parkinson’s disease in rats via supplementation of PTD-conjugated tyrosine hydroxylase

The present study aimed to evaluate whether the protein transduction domain (PTD)-conjugated human tyrosine hydroxylase (TH) fusion protein was effective on the 6-hydroxydopamine (6-OHDA)-induced Parkinson’s disease (PD) model rats. An expression vector pET-PTD-TH harbouring the PTD-TH gene was constructed and transformed to the Escherichia coli BL21 cells for expression. The expressed recombinant PTD-TH with a molecular weight of 61 kD was successfully transduced (1 μM) into the dopaminergic SH-sy5y human neuroblastoma cells in vitro and visualized by immunohistochemical assay. An in vivo experiment in rats showed that the iv administered PTD-TH protein (8 mg/kg) permeated across the blood–brain barrier, penetrated into the striatum and midbrain, and peaked at 5–8 h after the injection. The behavioral effects of PTD-TH on the apomorphine-induced rotations in the PD model rats 8 weeks after the 6-OHDA lesion showed that a single bolus of PTD-TH (8 mg/kg) iv injection caused a decrement of 60% of the contralateral turns on day 1 and 40% on days 5–17. The results imply that iv delivery of PTD-TH is therapeutically effective on the 6-OHDA-induced PD in rats, the PTD-mediated human TH treatment opening a promising therapeutic direction in treatment of PD.

377. Intravascular Delivery of Adenovirus Vectors Rapidly Targets Platelets to the Reticuloendothelial System

Top of pageAbstract Following intravenous (iv) delivery of an adenovirus (Ad) vector a severely adverse event was seen in a phase I clinical trial. Systemic inflammatory response syndrome (SIRS) and biochemically detectable disseminated intravascular coagulation (DIC) were among complications that ultimately resulted in multiple organ system failure 98 hours after iv delivery of a dose of 6 x 1011 viral particles/kg. DIC is a complex clinical syndrome characterized by a systemic activation of coagulation leading to the intravascular deposition of fibrin in the (micro) vasculature and the simultaneous consumption of coagulation factors and platelets. Since platelet consumption is a symptom of DIC and Ad vectors are known to induce thrombocytopenia after iv delivery we decided to investigate Ad- platelet interactions as part of a safety and toxicity study. We investigated the interactions of an Ad5 vector, chimeric Ad5 vectors possessing the CD46 interacting Ad11 or Ad35 fibers (Ad5/F11 or Ad5/F35), and an Ad11 vector, early after iv delivery to mice. Transgenic mice that express human CD46 were injected in the tail vein with a total of 1011 viral particles of each vector. Within 10 minutes of iv delivery we found Ad particles associated with circulating platelets, with the highest levels seen with Ad11 vectors. Subsequently, different organs where monitored by immunohistochemistry and transmission electron microscopy (TEM) for evidence of in vivo Ad-platelet interactions. Within 5 minutes of administration degranulated platelets containing Ad5, Ad5/F11, Ad5/F35 or Ad11 vector particles could be seen directly interacting with endothelial cells within the liver sinusoids by TEM. Ad particles could also be seen within platelet aggregates and inside Kupffer cells. Triple label immunohistochemistry revealed widespread co-labeling of platelets (CD41), Kupffer cells (F4/80) and Ad (hexon) throughout the liver. In the spleen immunohistochemistry showed Ad particles in macrophage and platelet-rich areas of the marginal zone within 5 minutes. In the lung Ad genomes were found within 5 minutes with higher numbers of Ad11 genomes present. Widespread platelet accumulation was seen after delivery of all Ad vectors, with platelet-endothelial interaction and platelet aggregates visible throughout the pulmonary vasculature by immunohistochemistry and TEM. Polymorphonuclear cells and leukocytes within the pulmonary vasculature were also seen interacting with platelet aggregates. These data suggest that Ad and platelets interact rapidly after iv Ad delivery and that this interaction causes rapid targeting of platelets to the reticuloendothelial system. We are currently investigating the mechanisms of Ad-platelet interaction and subsequent platelet reticuloendothelial targeting.

72. Intravascular Interaction between Adenovirus and Platelets Promotes Adenovirus Sequestration, Degradation and Toxicity

Intravascular (iv) delivery of adenovirus (Ad) vectors is hindered by acute toxicity that is triggered by trapping of virus in the reticuloendothelial system (RES) within minutes of administration, and subsequent production of pro-inflammatory cytokines/chemokines. While Ad localizes to tissue macrophages and endothelial cells of the liver, spleen and lung within minutes of iv delivery, the mechanism of this reticuloendothelial targeting is unknown. We have identified a novel pathway by which platelets mediate trapping of Ad in the RES. Rapidly after iv administration fiber independent interaction between Ad and circulating platelets can be seen by Southern blot, by transmission electron microscopy (TEM) of isolated platelets and blood cell fractionation of mice receiving radiolabeled Ad. Blood platelet levels drop after Ad administration, while serum levels of the platelet activation marker soluble CD62p rise. Within 5 minutes of administration, Ad and platelets co-localize in the liver sinusoids along with endothelial and Kupffer cells. TEM showed Ad particles inside degranulated platelets and platelet aggregates within the liver sinusoids. Ad particles could also be seen inside Kupffer cells. Immunohistochemistry (IHC) showed widespread co-labelling of platelets (CD41), Kupffer cells (F4/80) and Ad (hexon) throughout the liver. In the spleen, Ad genomes were found within 5 minutes and Ad particles were detected in CD41 and F4/80 rich regions of the marginal zone by IHC. In the lung, Ad genomes were found within 5 minutes. Platelet accumulation was seen by IHC after delivery of Ad vectors, with platelet-endothelial interactions visible in the pulmonary vasculature by TEM. To determine the contribution of Ad-platelet interactions towards toxicity, mice were pre-injected with a platelet depleting antibody prior to virus delivery. At 6 hours post virus delivery, vector genomes in liver, lung and spleen were detected by Southern blot, and circulating serum cytokine levels were determined. Serum levels of the pro-inflammatory cytokines/chemokines IFN-|[gamma]|, IL-6 and MCP- 1 were lower in platelet depleted mice. The effect of Ad neutralizing antibodies on Ad-platelet interactions was also determined in mice that had been pre-immunized with the same vector prior to iv Ad vector administration. Early after vector administration significantly lower levels of Ad genomes were associated with circulating platelets in pre-immunized mice. While the levels of Ad deposition in the liver were unchanged in pre-immunized mice, there was reduced Ad deposition within the lungs of pre-immunized mice. Taken together these data suggest that rapid interaction between Ad and platelets occurs after iv administration. Platelet-Ad interactions apparently play a role in RES sequestration and degradation of Ad, and subsequent toxicity. We are currently attempting to identify the structural components involved in Ad-platelet interactions in vivo and investigating the contribution of this interaction to sequestration, degradation and toxicity, after Ad administration.

PTD–XIAP protects against cerebral ischemia by anti-apoptotic and transcriptional regulatory mechanisms

Caspases play a major role in the infarction process that follows occlusion of cerebral arteries and are important targets for stroke therapy. We have generated three fusion proteins that link various domains of the X chromosome-linked inhibitor of apoptosis (XIAP), a potent caspase inhibitor, to the protein transduction domain (PTD) of HIV-1/Tat, and have tested their efficacy after distal occlusion of the middle cerebral artery (dMCAO) in mice. PTD-XIAP failed to accumulate in brain structures after intravenous (iv) delivery, but properly transduced cortical cells when applied topically. Shorter constructs efficiently targeted the lesion after iv delivery. All proteins retained their caspase inhibitory activity and significantly reduced infarct volumes. PTD-XIAP reversed long-term impairments in the water maze test. Sequential activation of transcription factors was observed, suggesting that the effects of XIAP are mediated by both direct inhibition of apoptotic mechanisms and secondary regulation of transcription factors involved in neuronal survival.

44. Development of AAV-Mediated Gene Therapy for Murine Models of Genetic Diseases Affecting the Heart

The long term goal of this project is to develop a clinically relevant gene therapy approach for the treatment of genetic diseases affecting the heart. Due to its small size, safety and proven ability to persist for long periods of time in muscle, adeno-associated virus (AAV) has emerged as a promising cardiac gene delivery vehicle. We have sought to determine the most advantageous combination AAV serotype and vector delivery route for the transduction of cardiomyocytes in vivo. Both intra-venous (iv) and intra-cardiac (ic) injection routes were compared by injecting 1|[times]|1011 and 5|[times]|1010 (respectively) vector particles of AAV-CMV-LacZ per mouse neonate of 3 different serotypes AAV1, AAV8 and AAV9. Tissue analysis included both x-gal staining on tissue sections to visualize expression and the quantitative |[beta]|-galactosidase enzyme detection assay. Our results show that iv administration of AAV9 results in 30-fold more efficient transduction of cardiac tissue than AAV1. Moreover, hearts injected with AAV9 displayed a global distribution of transgene expression suggesting this serotype has no transduction site preference within cardiac tissue. 2 murine models for cardiac dysfunction; the alpha-sarcoglycan (asg-/-) knockout model for Limb Girdle Muscular Dystrophy Type 2D (LGMD-2D) and the acid-alpha glucosidase (gaa-/-) knockout model for Pompe Disease are currently being characterized functionally and morphologically using both non-invasive MRI and histological techniques. LGMD-2D is the result of mutations in the alpha sarcoglycan (ASG) gene. This model displays the development of dystrophic lesions in cardiac and skeletal muscle. We have developed a non-invasive assay using MRI that enables us to locate and measure the random development of lesions within the muscles of asg-/- mice. We have demonstrated functional correction and prevention of disease progression in skeletal muscles injected with AAV-ASG. Studies are currently underway to demonstrate the same effect in cardiac tissue. The cells of the gaa-/- mouse contain lysosomes enlarged with glycogen due to a GAA enzyme deficiency. Previously, our lab has demonstrated that delivery of the human GAA gene to the skeletal muscle of this model is therapeutically beneficial. To evaluate gene delivery to the cardiac tissue of this model we are currently characterizing the cardiac phenotype of disease and assessing our ability to prevent disease presentation following optimized delivery of the human GAA gene. In conclusion, our maker-gene study has established that iv delivery using AAV9 is the most clinically advantageous combination of AAV serotype and delivery route for the transduction of cardiac tissue in vivo. We are now in the process of using this delivery method to demonstrate disease correction in two mouse models of cardiomyopathy.

Stabilized Plasmid–Lipid Particles: Pharmacokinetics and Plasmid Delivery to Distal Tumors following Intravenous Injection

A previous study has shown that plasmid DNA can be encapsulated in lipid particles (SPLP, “stabilized plasmid lipid particles”) of approximately 70 nm diameter composed of 1,2-dioleoyl-3-phosphatidyl-ethanolamine (DOPE), the cationic lipid N,N-dioleoyl-N,N-dimethylammonium chloride (DODAC) and poly(ethylene glycol) conjugated to ceramide (PEG-Cer) using a detergent dialysis process (Wheeler et al. (1999) Gene Therapy 6, 271-281). In this work we evaluated the potential of these SPLPs as systemic gene therapy vectors, determining their pharmacokinetics and the biodistribution of the plasmid and lipid components. It is shown that the blood clearance and the biodistribution of the SPLPs can be modulated by varying the acyl chain length of the ceramide group used as lipid anchor for the PEG polymer. Circulation lifetimes observed for SPLPs with PEG-CerC14 and PEG-CerC20 were t1/2 = ± 1 and ± 10 h, respectively. The SPLPs are stable while circulating in the blood and the encapsulated DNA is fully protected from degradation by serum nucleases. The accelerated clearance of SPLPs with PEG-CerC14 is accompanied by increased accumulation in liver and spleen as compared to PEG-CerC20 SPLPs. Delivery of intact plasmid to liver and spleen was detected. Significant accumulation (approximately 10% of injected dose) of the long circulating SPLPs with PEG-CerC20 in a distal tumor (Lewis lung tumor in the mouse flank) was observed following iv application and delivery of intact plasmid to tumor tissue at approximately 6% injected dose/g tissue is demonstrated.

Anaesthesia by intravenous emulsified isoflurane in mice.

An emulsion of isoflurane in Intralipid for intravenous (iv) injection was formulated and its anaesthetic properties determined in mice. The major advantage of iv delivery of volatile agents is to accelerate the induction of anaesthesia by circumventing the anesthetic circuitry and the lung's functional residual capacity. Isoflurane was added to Intralipid in varying concentrations. The ED50 (n = 34) and LD50 (n = 20) were determined by a single iv bolus injection. Anaesthesia was also induced and maintained for 30 min (n = 5) by continuous infusion and the time to emergence was measured. The ED50 and LD50 were 0.7 +/- 0.2 microliter and 2.4 +/- 0.2 microliter of isoflurane equivalent respectively. An average infusion rate of 1.6 +/- 0.4 microliters.min-1 of isoflurane equivalent was required for maintenance following which the average emergence time was 193 +/- 35 secs. The only negative effect was local skin ulceration with an inadvertent interstitial injection. We conclude that iv induction and maintenance with emulsified isoflurane in Intralipid can be carried out with safety and reproducibility in the mouse. Further larger animal studies are warranted assessing the haemodynamic, toxicological, physiochemical and pharmacokinetic characteristics of these and other similar preparations.

Respiratory depression associated with patient-controlled analgesia: a review of eight cases

Patient-controlled iv delivery of opioids for postoperative pain management is a popular alternative to the traditional im route of administration. However, occasional patients receiving opioids in this manner develop severe respiratory depression. The purpose of this paper is to determine the incidence of, and factors contributing to, the development of this complication. To do this, the Office of Medical Quality Improvement retrospectively searched for reports of respiratory depression in a database compiled from the charts of approximately 1600 patients who had received PCA at the University of Alberta Hospitals in 1992. Eight cases of serious respiratory depression were detected. Factors associated with the occurrence of respiratory depression included the concurrent use of a background infusion, advanced age, concomitant administration of sedative/hypnotic medications, and pre-existing sleep apnoea syndrome. No cases were attributed to operator error or equipment malfunction. In conclusion, the risk of respiratory depression with patient-controlled opioid administration is similar to that observed when opioids are delivered by the traditional im or spinal routes. The safe and effective use of patient-controlled analgesia depends upon knowledgeable medical and nursing staff, clearly defined nursing policy and procedures, and frequent patient follow-up.

Single Dose Blood Toxicokinetics of Methacrylonitrile in the F344 Rat

Methacrylonitrile (MAN) is a widely used industrial chemical. Minimal information is available on its effects or toxicokinetics; therefore, current investigations were undertaken as part of an overall effort to characterize MAN toxicity in laboratory animals. Groups of male F344 rats were administered MAN intravenously (29, 58, or 116 mg/kg) or perorally (58 mg/kg). Blood samples were collected at various time points after dosing and serum MAN concentrations were measured. Concentration versus time profiles were characterized by two phases and a two-compartment model was selected to fit the data. Toxicokinetic parameters were determined using Simusolv. The 39-min terminal half-life shows that 99% of an iv dose is eliminated in less than 5 hr, suggesting that the potential for MAN bioaccumulation is minimal. The volume of distribution at steady-state (747 ml/kg) indicates little distribution of MAN into tissues. Clearance is higher at 29 mg/kg than at the two other doses, suggesting that MAN elimination is saturable at doses above 29 mg/kg. MAN disposition is route-dependent. Approximately 36% of the iv dose was exhaled as unchanged MAN, while only 18% was eliminated via this route following po administration. MAN disposition data also suggest that a significant first-pass metabolism may occur because a higher percentage of metabolites was produced following oral vs iv administration. Perorally, 39% of the dose was exhaled as CO2 and 22% was excreted into the urine as metabolites over the 24-hr dosing interval. In comparison, following iv delivery, 26% of the dose was exhaled as CO2 and 16% was excreted into the urine as metabolites. About equal amounts of acetone were excreted following administration by either route. This information may prove useful in designing long-term toxicity studies for MAN by the National Toxicology Program and in interpreting the results of such studies.