Growth suppression of established human osteosarcoma lung metastases in mice by aerosol gene therapy with PEI-p53 complexes

Aerosol Inhalation of Gene Delivery Therapy for Pulmonary Diseases

Gene delivery therapy has emerged as a popular approach for the treatment of various diseases. However, it still poses the challenges of accumulation in target sites and reducing off-target effects. Aerosol gene delivery for the treatment of pulmonary diseases has the advantages of high lung accumulation, specific targeting and fewer systemic side effects. However, the key challenge is selecting the appropriate formulation for aerosol gene delivery that can overcome physiological barriers. There are numerous existing gene carriers under study, including viral vectors and non-viral vectors. With the development of biomaterials, more biocompatible substances have applied gene delivery via inhalation. Furthermore, many types of genes can be delivered through aerosol inhalation, such as DNA, mRNA, siRNA and CRISPR/Cas9. Aerosol delivery of different types of genes has proven to be efficient in the treatment of many diseases such as SARS-CoV-2, cystic fibrosis and lung cancer. In this paper, we provide a comprehensive review of the ongoing research on aerosol gene delivery therapy, including the basic respiratory system, different types of gene carriers, different types of carried genes and clinical applications.

Natural Products-Based Inhaled Formulations for Treating Pulmonary Diseases

Given the unique physiological and pathological characteristics of the lung, the direct, inhalable route is more conducive to pulmonary drug delivery and disease control than traditional systemic drug delivery, significantly circumventing drug loss, off-target effects, systemic and organ toxicity, etc., and is widely regarded as the preferred regimen for pulmonary drug delivery. However, very few lung diseases are currently treated with the preferred inhaled formulations, such as asthma, chronic obstructive pulmonary disease and pulmonary hypertension. And there is a lack of appropriate inhaled formulations for other critical lung diseases, such as lung cancer and pulmonary fibrosis, due to the fact that the physicochemical properties of the drugs and their pharmacokinetic profiles do not match the physiology of the lung, and conventional inhalation devices are unable to deliver them to the specific parts of the lung. Phytochemicals of natural origin, due to their wide availability and clear safety profile, hold great promise for the preparation of inhalable formulations to improve the current dilemma in the treatment of lung diseases. In particular, the preparation of inhalable formulations based on nano- and microparticulate carriers for drug delivery to deep lung tissues, which overcome the shortcomings of conventional inhalation therapies while targeting the drug activity directly to a specific part of the lung, may be the best approach to change the current dilemma of lung disease treatment. In this review, we discuss recent advances in nano- and micron-carrier-based inhalation formulations for the delivery of natural products for the treatment of pulmonary diseases, which may represent an opportunity for practical clinical translation of natural products.

shRNA-WT1 Potentiates Anticancer Effects of Gemcitabine and Cisplatin Against B16F10 Lung Metastases In Vitro and In Vivo

BACKGROUND/AIM

High expression level of Wilm's tumor gene (WT1) in several types of tumors appears to confer disruption of apoptosis and resistance to chemotherapeutic drugs, and correlate with poor outcome. The aim of this work was to determine if down-regulation of WT1 expression results in decreased cell proliferation and the increased action of different types of drugs, both in vitro in B16F10 cells, and in vivo in C57BL/6 mice.

MATERIALS AND METHODS

Inhibition of cell proliferation by short hairpin RNA against WT1 (shRNA-WT1), cisplatin, and gemcitabine in B16F10 cells in vitro was determined by the MTT assay and analysis of clonogenic survival. The apoptosis rate was determined by flow cytometry for annexin-V- fluorescein isothiocyante and propidium iodide.

RESULTS

Compared to treatment with shRNA-WT1 alone, treatment with shRNA-WT1 in combination with drugs had a synergistic inhibitory effect on B16F10 cell proliferation, particularly for the combination of cisplatin and gemcitabine at their 25% cytotoxic concentrations in vitro. Furthermore, mice treated with shRNA-WT1 in combination with cisplatin and gemcitabine were protected in the same way as those treated with the drugs alone, but were in better physical condition.

CONCLUSION

Decreased WT1 expression induces cell death and potentiates the action of anticancer drugs by inducing synergistic effects both in vitro and in vivo, which may be an attractive strategy in lung cancer therapy.

Chalcone Derivatives 4'-Amino-1-Naphthyl-Chalcone (D14) and 4'-Amino-4-Methyl-1-Naphthyl-Chalcone (D15) Suppress Migration and Invasion of Osteosarcoma Cells Mediated by p53 Regulating EMT-Related Genes

Osteosarcoma (OS) is a primary malignant bone tumor that mainly affects children, adolescents, and young adults. The inhibition of metastasis is a main strategy of OS therapy since the development of metastatic disease due to drug resistance remains the most important cause of death from this cancer. Considering the severe side effects of current OS chemotherapy, the identification of anti-metastatic drugs with reduced toxicity is of great interest. Chalcones are polyphenols with a basic structure consisting of an α-, β-unsaturated carbonyl system linking two aryl rings. These compounds exhibit anticancer activity against a variety of tumor cell lines through multiple mechanisms, including the regulation of the tumor-suppressor protein p53 and its target genes. An important process regulated by p53 is epithelial-mesenchymal transition (EMT), which facilitates tumor metastasis by conferring migratory and invasive properties to cancer cells. The activation of p53 can revert EMT and reduce migration and invasion. This study aimed to examine the inhibitory effects of two 4′-aminochalcones on the migration/invasion of the U2OS (p53+/+) and SAOS-2 (p53−/−) OS cell lines as well as the underlying molecular mechanisms. Cell viability was examined by MTT assay. Transwell assays were used to evaluate the migratory and invasive ability of the cells. The two 4′-aminochalcones showed low capacity to inhibit the viability of OS cells independent of p53 status, but preferentially suppressed the migration of U2OS cells and of a SAOS-2 cell line expressing p53. Invasion was strongly inhibited by both chalcones independent of p53 status. RT-PCR, zymography, and Western blot were used to study the expression of matrix metalloproteinases and EMT markers after treatment with the chalcones. The results indicated that the 4′-aminochalcone-induced antimigratory and anti-invasive effects are potentially associated with the inhibition of extracellular matrix (ECM) enzymatic degradation in OS cells and with the modulation of EMT genes. These effects probably result from the induced increase of p53 protein expression by the two chalcones. In conclusion, chalcones D14 and D15 have potential anti-metastatic activity mediated by p53 that can be exploited for OS treatment.

Genetic Modification of the Lung Directed Toward Treatment of Human Disease

Genetic modification therapy is a promising therapeutic strategy for many diseases of the lung intractable to other treatments. Lung gene therapy has been the subject of numerous preclinical animal experiments and human clinical trials, for targets including genetic diseases such as cystic fibrosis and α1-antitrypsin deficiency, complex disorders such as asthma, allergy, and lung cancer, infections such as respiratory syncytial virus (RSV) and Pseudomonas, as well as pulmonary arterial hypertension, transplant rejection, and lung injury. A variety of viral and non-viral vectors have been employed to overcome the many physical barriers to gene transfer imposed by lung anatomy and natural defenses. Beyond the treatment of lung diseases, the lung has the potential to be used as a metabolic factory for generating proteins for delivery to the circulation for treatment of systemic diseases. Although much has been learned through a myriad of experiments about the development of genetic modification of the lung, more work is still needed to improve the delivery vehicles and to overcome challenges such as entry barriers, persistent expression, specific cell targeting, and circumventing host anti-vector responses.

New dry powders for inhalation containing temozolomide-based nanomicelles for improved lung cancer therapy

Besides the numerous advantages of a chemotherapy administered by the inhalation route for lung cancer therapy, dry powder for inhalation (DPI) offers many advantages compared to other techniques and seems to be a technique that is well-adapted to an anticancer treatment. DPI formulations were developed using the cytotoxic drug temozolomide and a new folate-grafted self-assembling copolymer, a conjugate of three components, folate-polyethylene glycol-hydrophobically-modified dextran (F-PEG-HMD). F-PEG-HMD was synthesized using carbodiimide-mediated coupling chemistry in three main steps. F-PEG-HMD was characterized by 1H-NMR, mass spectrometry and thermal analysis. F-PEG-HMD presented a critical micellar concentration in water of 4x10-7 M. F-PEG-HMD nanomicelles were characterized by a trimodal particle size distribution with Z-average diameter of 83±1 nm in water. Temozolomide-loaded nanomicelles were prepared by solubilization of F-PEG-HMD in the presence of temozolomide. Temozolomide solubility in water was increased in the presence of F-PEG-HMD (2-fold increase in molar solubility) which could potentially lead to increased local concentrations in the tumor site. The temozolomide-loaded F-PEG-HMD nanomicelles were characterized by a Z-average diameter of ~50 to ~60 nm, depending on the F-PEG-HMD concentration used. The nanomicelles were then spray-dried to produce dry powders. Temozolomide remained stable during all the formulation steps, confirmed by similar in vitro anticancer properties for the DPI formulations and a raw temozolomide solution. Two of the developed DPI formulations were characterized by good aerodynamic properties (with a fine particle fraction of up to 50%) and were able to release the F-PEG-HMD nanomicelles quickly in aqueous media. Moreover, in vitro, the two DPI formulations showed wide pulmonary deposition in the lower respiratory tract where adenocarcinomas are more often found. The present study, therefore, shows that F-PEG-HMD-based dry powders for inhalation could constitute an interesting drug delivery system able to release nanomicelles that are useful in adenocarcinomas that overexpress folate receptors.

Screening for metastatic osteosarcoma biomarkers with a DNA microarray

OBJECTIVE

The aim of this study was to screen for possible biomarkers of metastatic osteosarcoma (OS) using a DNA microarray.

METHODS

We downloaded the gene expression profile GSE49003 from Gene Expression Omnibus database, which included 6 gene chips from metastatic and 6 from non-metastatic OS patients. The R package was used to screen and identify differentially expressed genes (DEGs) between metastatic and non-metastatic OS patients. Then we compared the expression of DEGs in the two groups and sub-grouped into up-regulated and down-regulated, followed by functional enrichment analysis using the DAVID system. Subsequently, we constructed an miRNA-DEG regulatory network with the help of WebGestalt software.

RESULTS

A total of 323 DEGs, including 134 up-regulated and 189 down-regulated, were screened out. The up-regulated DEGs were enriched in 14 subcategories and most significantly in cytoskeleton organization, while the down-regulated DEGs were prevalent in 13 subcategories, especially wound healing. In addition, we identified two important miRNAs (miR-202 and miR-9) pivotal for OS metastasis, and their relevant genes, CALD1 and STX1A.

CONCLUSIONS

MiR-202 and miR-9 are potential key factors affecting the metastasis of OS and CALD1 and STX1A may be possible targets beneficial for the treatment of metastatic OS. However, further experimental studies are needed to confirm our results.

Recent advances in the management of osteosarcoma and forthcoming therapeutic strategies

Osteosarcoma is the most frequent primary bone tumor and occurs mainly in young patients (average age: 18 years). No evolution of the survival rates has been recorded for two decades in response to current treatment, associating often toxic and badly tolerated cures of chemotherapy (given a significant rate of bad responders) with preserving surgery. Among the proposed innovative strategies, immune-based therapy, antiangiogenesis agents, tumor-suppressor or suicide gene therapy, or anticancer drugs not commonly used in osteosarcoma are presented. A further strategy is to target the tumor microenvironment rather than the tumor itself.

Inhaled gene therapy in lung cancer: proof-of-concept for nano-oncology and nanobiotechnology in the management of lung cancer

Lung cancer still remains one of the leading causes of death among cancer patients. Although novel targeted therapies have been established in everyday treatment practice, and conventional platinum-based doublets have demonstrated effective results regarding overall and progression-free survival, we have still failed to achieve long-term survival. Therefore, several strategies of applying locoregional therapy are under investigation. Aerosol chemotherapy is already under investigation and, taking this a step further, aerosol gene therapies with multiple delivery systems are being developed. Several efforts have demonstrated its efficiency and effectiveness, but there are still multiple factors that have to be considered and combined to achieve an overall more effective multifunctional treatment. In the current review, we present data regarding aerosol delivery systems, transporters, carriers, vectors, genes, toxicity, efficiency, specificity, lung microenvironment and delivery gene therapy systems. Finally, we present current studies and future perspectives.

2-diethylaminoethyl-dextran methyl methacrylate copolymer nonviral vector: still a long way toward the safety of aerosol gene therapy

Revealing the lung tumor genome has directed the current treatment strategies toward targeted therapy. First line treatments targeting the genome of lung tumor cells have been approved and are on the market. However, they are limited by the small number of patients with the current investigated genetic mutations. Novel treatment administration modalities have been also investigated in an effort to increase the local drug deposition and disease control. In the current study, we investigated the safety of the new nonviral vector 2-diethylaminoethyl-dextran methyl methacrylate copolymer (DDMC; Ryujyu Science), which belongs to the 2-diethylaminoethyl-dextran family by aerosol administration. Thirty male BALBC mice, 2 month old, were included and divided into three groups. However, pathological findings indicated severe emphysema within three aerosol sessions. In addition, the CytoViva technique was applied for the first time to display the nonviral particles within the pulmonary tissue and emphysema lesions, and a spectral library of the nonviral vector was also established. Although our results in BALBC mice prevented us from further investigation of the DDMC nonviral vector as a vehicle for gene therapy, further investigation in animals with larger airways is warranted to properly evaluate the safety of the vector.

Vectors for inhaled gene therapy in lung cancer. Application for nano oncology and safety of bio nanotechnology

Novel aerosol therapeutic modalities have been investigated for lung cancer. Inhaled gene therapy has presented safety and effectiveness previously in cystic fibrosis. However, safety concerns have been raised regarding the safety of non-viral vectors for inhaled gene therapy in lung cancer, and therefore small steps have been made towards this multifunctional treatment modality. During the last decade, numerous new nanocomplexes have been created and investigated as a safe gene delivery nano-vehicle. These formulations are multifunctional; they can be used as either local therapy or carrier for an effective inhaled gene therapy for lung cancer. Herein, we present current and future perspectives of nanocomplexes for inhaled gene therapy treatment in lung cancer.

Aerosolized BC-819 inhibits primary but not secondary lung cancer growth

Despite numerous efforts, drug based treatments for patients suffering from lung cancer remains poor. As a promising alternative, we investigated the therapeutic potential of BC-819 for the treatment of lung cancer in mouse tumor models. BC-819 is a novel plasmid DNA which encodes for the A-fragment of Diphtheria toxin and has previously been shown to successfully inhibit tumor growth in human clinical study of bladder carcinoma. In a first set of experiments, we examined in vitro efficacy of BC-819 in human lung cancer cell-lines NCI-H460, NCI-H358 and A549, which revealed >90% reduction of cell growth. In vivo efficacy was examined in an orthotopic mouse xenograft lung cancer model and in a lung metastasis model using luminescent A549-C8-luc adenocarcinoma cells. These cells resulted in peri- and intra-bronchiolar tumors upon intrabronchial application and parenchymal tumors upon intravenous injection, respectively. Mice suffering from these lung tumors were treated with BC-819, complexed to branched polyethylenimine (PEI) and aerosolized to the mice once per week for a period of 10 weeks. Using this regimen, growth of intrabronchially induced lung tumors was significantly inhibited (p = 0.01), whereas no effect could be observed in mice suffering from lung metastasis. In summary, we suggest that aerosolized PEI/BC-819 is capable of reducing growth only in tumors arising from the luminal part of the airways and are therefore directly accessible for inhaled BC-819.

The effect of CpG motifs on gene expression and clearance kinetics of aerosol administered polyethylenimine (PEI)-plasmid DNA complexes in the lung

Presence of CpG motifs within pDNA is widely reported to influence transgene expression as well as inflammatory response to nonviral gene vector complexes. Here, we analyzed gene expression kinetics and lung clearance after aerosol delivery of polyethylenimine (PEI) complexes with two different plasmid vectors: a first generation plasmid, pCMVLuc, and a plasmid with depleted CpG motifs, pCpG-free-Luc. After aerosol delivery, equal nanogram amounts of PEI-pDNA complexes were deposited in murine lungs. Luciferase expression observed at day one post administration of PEI-pCpG-free-Luc complexes was 60-fold higher than for PEI-pCMVLuc complexes and decreased 16-fold at day 7 post application. In contrast, luciferase expression from PEI-pCMVLuc particles remained at levels comparable to day 1 post application. In agreement with these observations, PEI-pCpG-free-Luc complexes were cleared from the lungs at rates 6-fold faster than those observed for PEI-pCMVLuc particles. A more detailed analysis of pDNA distribution within bronchoalveolar lavage fluid (BALF), BALF cells and lung tissue showed 660-fold higher amounts of pCpG-free-Luc in BALF cells compared to pCMVLuc, whereas the amount of pCpG-free-Luc in lung tissue was 15-fold lower compared to pCMVLuc 1h after administration. Our results demonstrate that complexes of PEI with CpG-motif-free DNA are taken up more extensively by BALF cells, while the clearance of pCMVLuc from the lung tissue is significantly slower than for the CpG-free plasmid. Administration of PEI-pCpG-free-Luc caused transient decrease in number of resident lung cells, while their activation was more pronounced with PEI-pCMVLuc particles. Our results demonstrate that the level of transgene expression is increased with CpG-motif-free pDNA but the longevity of expression correlates with pDNA clearance pattern depending on the presence of CpG motifs within the plasmid.

Nanomedicine in pulmonary delivery

The lung is an attractive target for drug delivery due to noninvasive administration via inhalation aerosols, avoidance of first-pass metabolism, direct delivery to the site of action for the treatment of respiratory diseases, and the availability of a huge surface area for local drug action and systemic absorption of drug. Colloidal carriers (ie, nanocarrier systems) in pulmonary drug delivery offer many advantages such as the potential to achieve relatively uniform distribution of drug dose among the alveoli, achievement of improved solubility of the drug from its own aqueous solubility, a sustained drug release which consequently reduces dosing frequency, improves patient compliance, decreases incidence of side effects, and the potential of drug internalization by cells. This review focuses on the current status and explores the potential of colloidal carriers (ie, nanocarrier systems) in pulmonary drug delivery with special attention to their pharmaceutical aspects. Manufacturing processes, in vitro/in vivo evaluation methods, and regulatory/toxicity issues of nanomedicines in pulmonary delivery are also discussed.

Osteosarcoma treatment: state of the art

Osteosarcoma (OS) is a class of cancer originating from bone, mainly afflicting children or young adults. It is the second highest cause of cancer-related death in these age groups, mainly due to development of often fatal metastasis, usually in the lungs. Survival for these patients is poor despite the aggressive use of surgery, chemotherapy, and/or radiotherapy. Thus, new effective drugs and other forms of therapy are needed. This article reviews the biology and the state of the art management of OS. New experimental drugs and potential therapies targeting molecular pathways of OS are also discussed.

Polyethylenimine-mediated gene delivery to the lung and therapeutic applications

Nonviral gene delivery is now considered a promising alternative to viral vectors. Among nonviral gene delivery agents, polyethylenimine (PEI) has emerged as a potent candidate for gene delivery to the lung. PEI has some advantages over other polycations in that it combines strong DNA compaction capacity with an intrinsic endosomolytic activity. However, intracellular (mainly the nuclear membrane) and extracellular obstacles still hamper its efficiency in vitro and in vivo, depending on the route of administration and the type of PEI. Nuclear delivery has been increased by adding nuclear localization signals. To overcome nonspecific interactions with biological fluids, extracellular matrix components and nontarget cells, strategies have been developed to protect polyplexes from these interactions and to increase target specificity and gene expression. When gene delivery into airway epithelial cells of the conducting airways is necessary, aerosolization of complexes seems to be better suited to guarantee higher transgene expression in the airway epithelial cells with lower toxicity than observed with either intratracheal or intravenous administration. Aerosolization, indeed, is useful to target the alveolar epithelium and pulmonary endothelium. Proof-of-principle that PEI-mediated gene delivery has therapeutic application to some genetic and acquired lung disease is presented, using as genetic material either plasmidic DNA or small-interfering RNA, although optimization of formulation and delivery protocols and limitation of toxicity need further studies.

Non-viral methods for gene transfer towards osteosarcoma therapy

Osteosarcoma, a class of cancer that originates from bone, afflicts mainly young people usually in their teenage years of life. Despite surgery and chemotherapy, the outlook for sufferers is not that positive, with a third of patients with metastatic disease not surviving past the 10-year mark. Like other neoplasms, other forms of therapeutics are being evaluated, and amongst these is gene therapy. This review discusses approaches for gene therapy of osteosarcoma using cationic liposomes and polyethylenimine in vivo. The field is still in its infancy as far as osteosarcoma is concerned and much more needs to be done to test its true potential as a feasible therapeutic modality.

Gene therapy for osteosarcoma: steps towards clinical studies

Gene therapy, an applied form of biotechnology, relies on the delivery of foreign DNA into cells. More than 50% of all reported clinical trials for gene therapy are for cancer, though only a scant number for osteosarcoma. Osteosarcoma is a neoplasm afflicting young adults, who in their prime years of life suffer debilitation if not death. The disease is not entirely curable, even with surgery combined with aggressive chemotherapy. Thus, other forms of therapies are being evaluated, including gene therapy. There exist two major forms of gene transfer: viral and non-viral. This review only covers proof-of-principle work carried out in cancer beyond the cell culture stage, in animals. Drawing from the experiences of gene therapy against other cancers, studies for which have already reached the clinical phase, the review discusses potential pitfalls and solutions to enhance gene therapy for osteosarcoma.

Identification and characterization of a novel peptide ligand of Tie2 for targeting gene therapy

Tyrosine kinase with immunoglobulin and epidermal growth factor homology domain-2 (Tie2) has been considered as a rational target for gene therapy in solid tumors. In order to identify a novel peptide ligand of Tie2 for targeted gene therapy, we screened a phage display peptide library and identified a candidate peptide ligand NSLSNASEFRAPY (designated GA5). Binding assays and Scatchard analysis revealed that GA5 could specifically bind to Tie2 with a dissociation constant of 2.1x10(-8)M. In addition, we showed that GA5 was internalized into tumor cells highly expressing Tie2. In the biodistribution assay, (125)I-GA5 was mainly accumulated in SPC-A1 xenograft tumors that express Tie2. In gene delivery studies, GA5-conjugated polyethylenimine vector could achieve greater transgene transduction than non-targeted vectors both in vitro and in vivo. Tumor growth inhibition was observed in SPC-A1 xenograft-bearing mice that received eight intratumoral injections of GA5-polyethylenimine/p53 complexes in 3 weeks. The difference in tumor volume between the experiment and control groups was significant (P<0.05). Our results showed that GA5 is a potentially efficient targeting element for cancer gene or molecular therapy.

p53 Aerosol Formulation with Low Toxicity and High Efficiency for Early Lung Cancer Treatment

PURPOSE

To develop an optimal nonviral aerosol formulation for locoregional treatment of early lung cancer.

EXPERIMENTAL DESIGN

The formulation was made of polylysine/protamine combination (AND) as the carrier and p53 gene (p53sm) as therapeutic agent. To estimate the aerosol deposition, the aerodynamic size of the AND-p53sm was measured with extrusion-precipitation method. To accurately determine the dose, the aerosol efficiency in mice was measured with a fluorescent dye. The transfection efficiency and DNA protection function of the aerosolized formulation in cultured cells and mouse lungs were detected with reporter gene assays and/or reverse transcription-PCR. The preclinical safety and efficacy of AND-p53sm were studied in healthy mice and mice bearing orthotopic human non-small-cell lung cancer (NSCLC) xenograft.

RESULTS

After aerosolization, AND is 3- to 17-fold more effective than commonly used PEI or cationic lipid formulations in transfecting the NSCLC cells (relative light units, 1,494 versus 534 and 86; P < 0.003). Aerodynamic size of AND-p53sm ranged 0.2 to 3 mum is the optimal aerosol droplets for deposition in the entire human respiratory tract. Significant gene expression was detected in the lungs of mice given aerosolized AND-p53sm and AND-luciferase. Aerosolized AND-p53sm significantly prolonged the life of mice bearing orthotopic human NSCLC xenografts, and it was more effective than an optimal i.v. cisplatin chemotherapy (increased life span, 93% versus 25%; P = 0.014). Inhalation of AND produced low and reversible pulmonary toxicity and no systemic toxicity.

CONCLUSIONS

This optimal formulation is suitable for delivering biological materials to human lung with aerosol administration. This therapeutic strategy is an option for patients with early lung cancer and bronchoalveolar carcinoma.

Intraperitoneal linear polyethylenimine (L-PEI)-mediated gene delivery to ovarian carcinoma nodes in mice

Linear polyethylenimine (L-PEI) is an efficient transfection agent for ovarian carcinoma cells in vitro and ex vivo. In the present work, we go a step further and evaluate the efficacy of L-PEI in human ovarian tumor nodes developed in mice. PEI/DNA complexes were administered intraperitoneally instead of intravenously to avoid sequestering of complexes in the lung and liver and to allow transfection of nonvascularized tumor nodes. Plasmid biodistribution was studied by PCR and gene expression was characterized using complementary luciferase and beta-galactosidase assays. Intraperitoneal (i.p.) injection of L-PEI/DNA complexes allowed the straightforward distribution of plasmid in the whole peritoneal cavity. Gene expression occurred in many organs, but tumor nodes appeared as preferential sites for transgene expression. The i.p. delivery route allowed repeated injections and administration of large amounts of DNA (up to 400 mug) without signs of toxicity, even for doses well beyond the intravenous lethal dose. Transgene expression was dose-dependent and transient. However, multiple injections allowed its persistence to increase. These results provide encouraging elements towards the development of PEI-based gene therapy protocols for the treatment of advanced stage ovarian carcinoma.

Evolving gene therapy approaches for osteosarcoma using viral vectors: review

This review begins with an introduction to the malignant bone tumor, osteosarcoma [OS] and then moves to a discussion of the commonly used vectors for gene transfer. We first briefly highlight non-viral vectors including polymeric and liposomal delivery systems but concentrate predominantly on the 5 leading viral vectors used in cancer gene therapy, specifically retroviruses, adeno-associated viruses, herpes viruses and lentiviruses with the most detailed analysis reserved for adenoviruses. The 3 main strategies for gene therapy in osteosarcoma are next summarized. As part of this review, the several prodrug-converting enzymes utilized in OS suicide gene therapy are examined. The text then turns to a discussion of adenovirus-mediated gene transfer and the need for tumor targeting via transductional or transcriptional approaches. Because of practical problems with use of replication-incompetent viruses in achieving complete tumor kill in vivo, virotherapy utilizing replication competent viruses has come to the fore. This topic is, thus, next reviewed which allows for a natural transition to a discussion of armed therapeutic viruses many of which are conditionally replicating adenoviruses carrying transgenes with established anti-tumor efficacy. We recognize that several other issues have arisen which hamper progress in the field of cancer gene therapy. We, therefore, review viral-induced toxicity in the host and vector delivery issues which have been found to potentially influence safety. We end with a brief perspective including commenting on animal models used in examining delivery strategies for osteosarcoma gene therapy. The challenges remaining are touched upon most especially the need to deal with pulmonary metastatic disease from OS.

Ethanol enhanced in vivo gene delivery with non-ionic polymeric micelles inhalation

Modifications of both carriers and host barriers have been investigated for efficient inhalation gene delivery to lung. Here we used a biocompatible, non-ionic poly(ethyleneoxide)-poly(propyleneoxide)-poly(ethyleneoxide) (PEO-PPO-PEO) polymeric micelles (PM) as a carrier and combined it with ethanol to enhance membrane penetration of delivered DNA. The inhalation delivery with six 100 microg doses of pCMV-Lac Z with PM co-formulated with 10%-40% ethanol to nude mice in 2 days at 8 h interval was performed. The beta-galatosidase (beta-Gal) activity was assessed using chlorophenol red-beta-d galactopyranoside (CPRG) and X-gal staining for quantitative and qualitative analysis in tissues. The results showed that beta-Gal activity was significantly increased by 38% in lung around bronchioles when inhalation with PM and 10% ethanol was given. The 10% ethanol also increased the intracellular apparent permeability by 42% in stomach and by 141% in intestine at 48 h after the first dosage of delivery. Also delivery of DNA encoding a functional human cystic fibrosis transmembrane protein (CFTR) using the same inhalation delivery method co-formulated with 10% ethanol, an increased expression of CFTR in lung was detected by immunostaining. We concluded that 10% ethanol co-formulated with the PM system could enhance inhaled gene delivery to airway and gastrointestinal (GI) tract.

Unilateral Lung-Selective Gene Transfer Following the Administration of Naked Plasmid DNA onto the Pulmonary Pleural Surface in Mice

The purpose of the present study was to examine unilateral lung-selective gene transfer following the administration of naked plasmid DNA (pDNA) onto the pulmonary pleural surface in mice. Naked pDNA was administered intravenously, intraperitoneally, and instilled onto the right pulmonary pleural surface. Four hours later, right pulmonary pleural surface instillation of naked pDNA resulted in high gene expression in the right lung. On the contrary, intravenous and intraperitoneal administration of naked pDNA resulted in no detectable gene expression. After instilling naked pDNA onto the right or left pulmonary pleural surface, gene expressions in the applied lung were significantly higher than those in the other lung and tissues. In addition, gene expressions were detected only in the intrathoracic tissues, not in the intraperitoneal tissues. Four hours after instillation of naked pDNA onto the right pulmonary pleural surface, gene expression in the right lung was the highest, and thereafter gene expression in the right lung decreased gradually. This novel gene transfer method is expected to be a safe and effective treatment against serious lung diseases.

Aerosol gene delivery to the murine lung is mouse strain dependent

The cationic polymer polyethylenimine (PEI) has been previously demonstrated to efficiently deliver genes to the lungs of mice in vivo via nebulization. Although within these studies various mouse strains were used in individual experiments, no direct comparison of gene delivery to different mouse strains via aerosol application has been published to date. With respect to the widespread use of mice as animal models of inherited and acquired diseases, such data could be of relevance to select the most appropriate mouse genetic background for preclinical mouse models. We investigated PEI-based aerosol gene delivery in two commonly used mouse strains, BALB/c and NMRI, and mixed 129/Sv x C57BL/6 mice. Gene expression in BALB/c mice was significantly 3.2- and 3.8-fold higher than in NMRI and 129/Sv x C57BL/6 mice, respectively. Lung deposition rates of radioactively labeled plasmid DNA (I(123)) complexed with PEI were not significantly different between each of the mouse strains. The kinetics of pDNA clearance from the lungs of BALB/c mice was slightly faster than from NMRI mice. Whereas gene expression increased until day 3 after treatment, the levels of pDNA decreased over the same period of time. Repeated aerosol application in a 3-day time interval could maintain gene expression at high levels compared with a single application. Furthermore, PEI-pDNA aerosol application led to reproducible gene expression in independent experiments. These data suggest that the genetic background of mice could be important for nonviral aerosol gene delivery which should be considered in transgenic animal mouse models of inherited and acquired diseases for aerosol gene delivery studies.

Adenovirus-mediated p53 tumor suppressor gene therapy of osteosarcoma

The clinical outcome for osteosarcoma (OS) remains discouraging despite efforts to optimize treatment using conventional modalities including surgery, radiotherapy and chemotherapy. Novel therapeutic approaches based on our expanding understanding of the mechanisms of tumor cell killing have the potential to alter this situation. Tumor suppressor gene therapy aims to restore the function of a tumor suppressor gene lost or functionally inactivated in cancer cells. One such molecule, the p53 tumor suppressor gene plays a critical role in safeguarding the integrity of the genome and preventing tumorigenesis. Introduction of wild-type (wt) p53 into transformed cells has been shown to be lethal for most cancer cells in vitro, but clinical trials of p53 gene replacement have had limited success. Analysis of these clinical trials highlighted the insufficient efficacy of current vectors and low proapoptotic activity of wt p53 as a single agent in vivo. In this review, a contemporary summarization of the current status of adenovirus-mediated p53 gene therapy of OS is presented. Advancement in our understanding of p53 tumor suppressor activity, the molecular biology of chemoresistant OS, and recent advances in tumor targeting with adenoviral vectors are also addressed. Based on these parameters, prospects for future investigations are proposed.

Delivery systems for pulmonary gene therapy

Delivery of therapeutic genes to the lungs is an attractive strategy to correct a variety of pulmonary dysfunctions such as cystic fibrosis, alpha-1 antitrypsin deficiency, pulmonary hypertension, asthma, and lung cancer. Different delivery routes such as intratracheal instillation, aerosol and intravenous injection have been utilized with varying degrees of efficiency. Both viral and non-viral vectors, with their respective strengths and weaknesses, have achieved significant levels of transgene expression in the lungs. However, the application of gene therapy for the treatment of pulmonary disease has been handicapped by various barriers to the delivery vectors such as serum proteins during intravenous delivery, and surfactant proteins and mucus in the airway lumen during topical application of therapeutic genes. Immune and cytokine responses against the delivery vehicle are also major problems encountered in pulmonary gene therapy. Despite these shortcomings much progress has been made to enhance the efficiency, as well as lower the toxicity of gene therapy vehicles in the treatment of pulmonary disorders such as cystic fibrosis, lung cancer and asthma.

Polymers for DNA delivery

Nucleic acid delivery has many applications in basic science, biotechnology, agriculture, and medicine. One of the main applications is DNA or RNA delivery for gene therapy purposes. Gene therapy, an approach for treatment or prevention of diseases associated with defective gene expression, involves the insertion of a therapeutic gene into cells, followed by expression and production of the required proteins. This approach enables replacement of damaged genes or expression inhibition of undesired genes. Following two decades of research, there are two major methods for delivery of genes. The first method, considered the dominant approach, utilizes viral vectors and is generally an efficient tool of transfection. Attempts, however, to resolve drawbacks related with viral vectors (e.g., high risk of mutagenicity, immunogenicity, low production yield, limited gene size, etc.), led to the development of an alternative method, which makes use of non-viral vectors. This review describes non-viral gene delivery vectors, termed "self-assembled" systems, and are based on cationic molecules, which form spontaneous complexes with negatively charged nucleic acids. It introduces the most important cationic polymers used for gene delivery. A transition from in vitro to in vivo gene delivery is also presented, with an emphasis on the obstacles to achieve successful transfection in vivo.

Aerosol gemcitabine inhibits the growth of primary osteosarcoma and osteosarcoma lung metastases

Osteosacarcoma (OS) lung metastases are often resistant to chemotherapy. Most anticancer drugs are administered systemically. In many cases this is followed by dose-dependent toxicity, which may not allow the achievement of therapeutic levels in lungs to eradicate metastases. We determined the efficacy of gemcitabine (GCB) by administering it directly to the lungs via aerosol and studied the role of the Fas pathway in response to the therapy. We used 2 osteosarcoma lung metastases animal models: human LM7 cells that form lung metastases in mice following intravenous injection and murine LM8 cells, which grows subcutaneously in mice and spontaneously metastasize to the lung. Treatment was initiated when the presence of lung metastases had been established. Aerosol GCB inhibited the growth of lung metastases in mice. Intraperitoneal GCB administration at similar dosage had no effect on lung metastases. Besides its direct effect on lung metastases, aerosol GCB suppressed the growth of subcutaneous LM8 tumor. Histopathological examination of mice receiving aerosol GCB showed no evidence of toxicity. Lungs are distinguished from other tissues by the constitutive expression of FasL. Since exposure of tumor cells to GCB upregulated Fas expression, we hypothesized that the susceptibility of the tumor cells to ligand-induced cell death by resident lung cells may be increased. Therefore, the Fas pathway may contribute to the therapeutic effect of aerosol GCB.

Polyethylenimine (PEI)

Since the first edition of this book in 1999 the field of gene therapy has been the arena both for major advances that justified the early hopes placed in the concept, and for ever-present impatience with the slowness of overall progress. On the positive side, gene therapy obtained its first brilliant success, though not where most efforts were invested and not with a synthetic vector (Cavazzana-Calvo et al., 2000). Yet the search for efficient molecules is still very active, in part because the negative consequences of using viral vectors somewhat shadow the brilliant picture (Hacein-Bey-Abina et al., 2003). Clinical trial reports using the first generation of non-viral vectors, that is, cationic lipids, emphasize safety more than efficacy. The next generation, namely cationic polymers, is coming to maturity. This is illustrated in Fig. 8.1 by a literature survey that compares the most used "open source" vector in each category, the lipid DOTAP and polymer PEI. This "coming of age" is also highlighted by the number of planned clinical trials using PEI, trials we shall discuss in the last paragraph of this chapter. Advances have not only been made toward therapy, but also toward a better understanding of the mechanisms underlying gene delivery. Finally, PEI has become one of the most popular reagents for transfection of cells in culture, on a fast-growing market that is boosted by human and animal genome sequencing.

Osteosarcoma cell lines display variable individual reactions on wildtype p53 and Rb tumour-suppressor transgenes

BACKGROUND

One of the most widely studied gene therapeutic strategies for cancer is the introduction of tumour-suppressor genes-generally p53-into the target cells. As the genes of p53 and/or retinoblastoma (Rb) are mutated in the major part of osteosarcomas (OS), we aimed to study the effect of p53 and Rb transgenes on a panel of five different osteosarcoma cell lines.

METHODS

OS cell lines were transduced by adenoviral vectors delivering the transcription units of the wildtype p53 and the Rb gene. Effects of the transgenes alone and at additional cytostatic stress were studied by proliferation, alive/dead and cell cycle assays.

RESULTS

The individual cells lines displayed divergent reactions to p53- or Rb-transgene delivery reaching from cell death (SaOs-2, U2OS at p53 transduction) over stopped or lowered cell division (MG-63, K-HOS, SJSA-1 at p53 and Rb transduction) to nearly unhindered cell growth (U2OS at Rb transduction). In those OS cell lines reacting with lowered cell division to p53 or Rb delivery, cytostatics only moderately intensified the transgene effects. Surprisingly, these reactions were apparently not dependent on the functional status of the cellular p53 and/or Rb genes or on differences in the infectability of the cell lines by the adenoviral vectors. Most interestingly, the respective effects of the p53 or Rb transgenes were not multiplied by simultaneous transduction of both tumour-suppressor genes.

CONCLUSIONS

The application of wildtype tumour-suppressor gene therapy on genetically variable osteosarcomas may be efficient only in yet not identified genetic subgroups of this tumour entity. Hyperactive tumour-suppressor transgenes could be an alternative.

Polyethyleneimine-based gene therapy by inhalation

The delivery of genes by inhalation holds promise for the treatment of a wide range of pulmonary and non-pulmonary disorders and offers numerous advantages over more invasive modes of delivery. Subsequent to the cloning of the cystic fibrosis gene, there was great interest in the delivery of genes directly to the lung surfaces by aerosol, and most early efforts focused on the use of non-viral vectors, particularly cationic lipids. Unfortunately, nebulisation shear forces, inefficient penetration of mucous barriers and inhibitory effects of surfactant and other lung-specific features have generally resulted in a lack of therapeutic effect, and much of this work has diminished in recent years as a consequence. Polyethyleneimine (PEI)-based formulations have proven stable during nebulisation and result in nearly 100% efficient transfection throughout the airways, as well as significant, although lower, levels of transfection throughout the lung parenchyma. Most importantly, therapeutic responses have been obtained in several animal lung tumour models when PEI-based complexes of p53 and IL-12 genes were delivered by aerosol. This approach may also prove useful as a means of localised genetic immunisation. In addition, this mode of delivery seems to be associated with surprisingly low toxicity, and results in little or no CpG immunostimulatory response, which has presented a challenge to repeated gene therapy via other modes of delivery.

Gene therapy in orthopaedic surgery: the current status

The first successful gene therapy trial was reported in 1991. Since then, successful gene transfer in cultured cells and small animals has been reported by many studies, with achievement of at least transitory high levels of exogenous gene expression. Over 400 clinical protocols for gene therapy have been approved, involving over 4000 patients. However, publication of the results of these gene therapy trials has been limited, with only 80 published reports as of 2002. The majority of clinical gene therapy trials reported so far have been phase I or phase II trials, which are concerned mainly with safety issues and have focused on the treatment of malignancies and other potentially fatal conditions. The death of a patient in 1999 from systemic administration of an adenoviral vector and recent reports of leukaemia in two patients in a clinical gene therapy trial have led to a further re-evaluation of the safety of gene therapy and the role for gene therapy in clinical practice. This review outlines the current status of gene therapy as it relates to orthopaedic diseases and highlights the areas where progress is still to be made.

Biodistribution and pharmacokinetics of aerosol and intravenously administered DNA-polyethyleneimine complexes: optimization of pulmonary delivery and retention

This report describes the time-dependent biodistribution of human p53 plasmid delivered in aerosol with polyethyleneimine in mice compared to the distribution of this material following intravenous injection. Area-under-the-curve values for p53 plasmid after inhalation were 2.8-fold greater than values after intravenous administration, despite the fact that the delivered aerosol dose was one-fifth the intravenous dose. After aerosol administration, pulmonary concentrations of p53 plasmid were high and other organs showed amounts not distinguishable from untreated control. High concentrations of p53 plasmid in the lungs remained with negligible reduction for at least 24 h. Shortly after intravenous injection, organs exhibited the following relative levels of exogenously administered p53: liver > spleen > blood > or = lungs > heart > kidney. These results demonstrate effective pulmonary delivery of DNA in complex with PEI by aerosol, without significant systemic dissemination. In contrast, intravenous administration caused a prompt systemic distribution of DNA with a shorter half-life of the administered gene in the lungs.

Aerosol gene therapy

Gene therapy is a novel field of medicine that holds tremendous therapeutic potential for a variety of human diseases. Targeting of therapeutic gene delivery vectors to the lungs can be beneficial for treatment of various pulmonary diseases such as lung cancer, cystic fibrosis, pulmonary hypertension, alpha-1 antitrypsin deficiency, and asthma. Inhalation therapy using formulations delivered as aerosols targets the lungs through the pulmonary airways. The instant access and the high ratio of the drug deposited within the lungs noninvasively are the major advantages of aerosol delivery over other routes of administration. Delivery of gene formulations via aerosols is a relatively new field, which is less than a decade old. However, in this short period of time significant developments in aerosol delivery systems and vectors have resulted in major advances toward potential applications for various pulmonary diseases. This article will review these advances and the potential future applications of aerosol gene therapy technology.

Prospects for cationic polymers in gene and oligonucleotide therapy against cancer

Gene and antisense/ribozyme therapy possesses tremendous potential for the successful treatment of genetically based diseases, such as cancer. Several cancer gene therapy strategies have already been realized in vitro, as well as in vivo. A few have even reached the stage of clinical trials, most of them phase I, while some antisense strategies have advanced to phase II and III studies. Despite this progress, a major problem in exploiting the full potential of cancer gene therapy is the lack of a safe and efficient delivery system for nucleic acids. As viral vectors possess toxicity and immunogenicity, non-viral strategies are becoming more and more attractive. They demonstrate adequate safety profiles, but their rather low transfection efficiency remains a major drawback. This review will introduce the most important cationic polymers used as non-viral vectors for gene and oligonucleotide delivery and will summarize strategies for the targeting of these agents to cancer tissues. Since the low efficiency of this group of vectors can be attributed to specific systemic and subcellular obstacles, these hurdles, as well as strategies to circumvent them, will be discussed. Local delivery approaches of vector/DNA complexes will be summarized and an overview of the principles of anticancer gene and antisense/ribozyme therapy as well as an outline of ongoing clinical trials will be presented.

Growth inhibition of established B16-F10 lung metastases by sequential aerosol delivery of p53 gene and 9-nitrocamptothecin

Growth inhibition of established tumor metastases in the lungs poses a difficult challenge for most clinical settings in spite of extensive multi-modality approaches. Aerosol delivery of drugs and genes holds promise for the treatment of disseminated lung metastases, since aerosol delivery can target the lungs specifically and uniformly. We previously demonstrated that aerosol delivery of dilauroylphosphatidylcholine liposome formulation of 9-nitrocamptothecin (9NC-DLPC) inhibits B16-F10 melanoma lung metastases. Aerosol delivery of polyethleneimine-p53 DNA (PEI-p53) complexes results in a similar anti-tumor effect in the B16-F10 model. In both these previous studies, the protocols were designed to inhibit development of lung metastases. In this study we demonstrate, using the B16-F10 melanoma lung metastasis model, that sequential aerosol delivery of PEI-p53 and 9NC-DLPC acts additively to inhibit growth of established B16-F10 tumor metastases in the lungs. Mice injected with B16-F10 cells and treated with a combination of 9NC-DLPC (twice weekly) and PEI-p53 (once weekly) aerosol complexes starting on day 11 after tumor inoculation, exhibited a highly significant (P < 0.01) reduction in the number of visible tumor foci as compared with untreated mice or mice treated with either single agent alone, or with a combination of 9NC and a control plasmid. There was a highly significant reduction in the tumor burden, as well as the lung weights for the 9NC and p53 combination group (P < 0.001 as compared with other groups). Moreover, the doses of p53 gene and 9NC in the combination group were reduced at least two-fold as compared with our previous single agent studies, but still achieved significant tumor inhibition. Furthermore, the sequential aerosol delivery of p53 and 9NC lead to a 30-40% increase in the mean survival time of these mice, as compared with animals in different control groups. The data suggest that the combination of 9NC and p53 gene delivered by aerosol is an attractive strategy for growth inhibition of established tumor metastases in the lungs.

Aerosol delivery of PEI-p53 complexes inhibits B16-F10 lung metastases through regulation of angiogenesis

Inhibition of pulmonary metastases poses a difficult clinical challenge for current therapeutic regimens. We have developed an aerosol system utilizing a cationic polymer, polyethyleneimine (PEI), for topical gene delivery to the lungs as a novel approach for treatment of lung cancer. Using a B16-F10 murine melanoma model in C57BL/6 mice, we previously demonstrated that aerosol delivery of PEI-p53 DNA resulted in highly significant reductions in the tumor burden (P < .001) in treated animals, and also lead to about 50% increase in the mean length of survival of the mice-bearing B16-F10 lung tumors. The mechanisms of this antitumor effect of p53 are investigated in this report. Here, we demonstrate that the p53 transfection leads to an up-regulation of the antiangiogenic factor thrombospondin-1 (TSP-1) in the lung tissue and the serum of the mice. Furthermore, there is a down-regulation of vascular endothelial growth factor (VEGF) in the lung tissue and serum of the B16-F10 tumor-bearing mice treated with PEI-p53 DNA complexes, compared with untreated tumor-bearing animals. In addition, staining for von Willebrand factor (vWF), a marker for the angiogenic blood vessels, revealed that p53 treatment leads to a decrease in the angiogenic phenotype of the B16-F10 tumors. Immunohistochemistry for transgene expression reveals that the PEI-p53 aerosol complexes transfect mainly the epithelial cells lining the airways, with diffuse transfection in the alveolar lining cells, as well as, the tumor foci in the lung tissue. There was also some evidence of apoptosis in the lung tumor foci of animals treated with p53. The data suggest that aerosol delivery of PEI-p53 complexes leads to inhibition of B16-F10 lung metastases, in part by suppression of angiogenesis.