A sterically stabilized immunolipoplex for systemic administration of a therapeutic gene

Chemically modified short interfering hybrids (siHYBRIDS): nanoimmunoliposome delivery in vitro and in vivo for RNAi of HER-2

A blunt-ended 19-mer short interfering hybrid (siHybrid) (H) comprised of sense-DNA/antisense-RNA targeting HER-2 mRNA was encapsulated in a liposomal nanoplex with anti-transferrin receptor single-chain antibody fragment (TfRscFv) as the targeting moiety for clinically relevant tumor-specific delivery. In vitro delivery to a human pancreatic cell line (PANC-1) was shown to exhibit sequence-specific inhibition of 48-h cell growth with an IC50 value of 37 nM. The inhibitory potency of this siHybrid was increased (IC50 value of 7.8 nM) using a homologous chemically modified siHybrid (mH) in which the 19-mer sense strand had the following pattern of 2 '-deoxyinosine (dI) and 2 '-O-methylribonucleotide (2 '-OMe) residues: 5'-d(TITIT)-2'OMe(GCGGUGGUU)-d(GICIT). These modifications were intended to favor antisense strand-mediated RNAi while mitigating possible sense strand-mediated off-target effects and RNase H-mediated cleavage of the antisense RNA strand. The presently reported immunoliposomal delivery system was successfully used in vivo to inhibit HER-2 expression, and thus induce apoptosis in human breast carcinoma tumors (MDA-MB-435) in mice upon repeated i.v. treatment at a dose of 3 mg/kg of H or mH. The in vivo potency of modified siHybrid mH appeared to be qualitatively greater than that of H, as was the case in vitro.

Gene therapy progress and prospects: non-viral gene therapy by systemic delivery

Non-viral vectors continue to be an attractive alternative to viral vectors due to their safety, versatility and ease of preparation and scale-up. Over the past few years, investigators have been successful in developing gene carriers that can be targeted to the disease site. Several different delivery vectors for systemic use have been developed by different groups for plasmid DNA and oligonucleotide. Most of them are designed for targeted tumor therapy. The mechanism of inflammatory toxicity, the major toxicity of cationic lipoplex, has been studied and managed. In this review, we focus on the progress made over the last 2 years. We also discuss some future prospects for gene delivery.

The transferrin receptor part II: targeted delivery of therapeutic agents into cancer cells

Traditional anti-cancer treatments consist of chemotherapeutic drugs that effectively eliminate rapidly dividing tumor cells. However, in many cases chemotherapy fails to eliminate the tumor and even when chemotherapy is successful, its systemic cytotoxicity often results in detrimental side effects. To overcome these problems, many laboratories have focused on the design of novel therapies that exhibit tumor specific toxicity. The transferrin receptor (TfR), a cell membrane-associated glycoprotein involved in iron homeostasis and cell growth, has been explored as a target to deliver therapeutics into cancer cells due to its increased expression on malignant cells, accessibility on the cell surface, and constitutive endocytosis. The TfR can be targeted by direct interaction with conjugates of its ligand transferrin (Tf) or by monoclonal antibodies specific for the TfR. In this review we summarize the strategies of targeting the TfR in order to deliver therapeutic agents into tumor cells by receptor-mediated endocytosis.

Cationic lipids, lipoplexes and intracellular delivery of genes

As a consequence of several setbacks encountered by viral technology in achieving efficient and safe gene therapy in clinical trials, non-viral gene delivery vectors are considered to date as a valuable alternative and to hold promise for future therapeutic applications. Nevertheless, the transfection efficiency mediated by these non-viral gene delivery vectors has to be improved, especially in vivo, to benefit fully from their advantages. Cationic lipid/nucleic acid complexes or lipoplexes have been the subject of intensive investigations in recent years to understand the parameters governing the efficiency of transfection. Specifically, the comprehension of such mechanisms, from the formation of the complexes to their intracellular delivery, will lead to the design of better adapted non-viral vectors for gene therapy applications. Here, we will discuss some recent developments in the field on the structure/function relationship of cationic lipids in the mechanism of transfection, and where appropriate, we will make a comparison with mechanisms of viral and polyplex-mediated gene delivery. Cationic lipids are often used in combination with helper lipids such as DOPE or cholesterol. The effect of DOPE on lipoplex assembly and the relevance of the structural properties of the lipoplexes in destabilizing endosomal membranes and mediating endosomal escape of DNA will be discussed.

Targeting of small molecule anticancer drugs to the tumour and its vasculature using cationic liposomes: lessons from gene therapy

Cationic (positively charged) liposomes have been tested in various gene therapy clinical trials for neoplastic and other diseases. They have demonstrated selectivity for tumour vascular endothelial cells raising hopes for both antiangiogenic and antivascular therapies. They are also capable of being selectively delivered to the lungs and liver when administered intravenously. These vesicles are being targeted to the tumour in various parts of the body by using advanced liposomal systems such as ligand-receptor and antibody-antigen combinations. At present, the transferrin receptor is commonly used for cancer-targeted drug delivery systems including cationic liposomes. This review looks at the growing utility of these vesicles for delivery of small molecule anticancer drugs.

Selective gene delivery for cancer therapy using cationic liposomes: in vivo proof of applicability

Targeted gene therapy is essential if cancer treatment is to become a reality with this form of therapy. In the past few years, cationic liposomes, discovered 2 decades ago, and at present, the most commonly used class of transfection reagents, have been tested in various clinical trials for diseases not restricted to cancer. They have been shown to be selective for tumour vascular endothelial cells raising hopes for antiangiogenic and antivascular therapies. They are also capable of being selectively delivered to the lungs and liver when administered intravenously. These vesicles are also being targeted to the tumour in various parts of the body by using advanced liposomal systems such as antibody-antigen and ligand-receptor combinations. This review looks at the state of play in this rapidly growing field.

Role of nanobiotechnology in developing personalized medicine for cancer

Personalized medicine simply means the prescription of specific therapeutics best suited for an individual. Personalization of cancer therapies is based on a better understanding of the disease at the molecular level. Nanotechnology will play an important role in this area. Nanobiotechnology is being used to refine discovery of biomarkers, molecular diagnostics, drug discovery and drug delivery, which are important basic components of personalized medicine and are applicable to management of cancer as well. Examples are given of the application of quantum dots, gold nanoparticles, and molecular imaging in diagnostics and combination with therapeutics -- another important feature of personalized medicine. Personalized medicine is beginning to be recognized and is expected to become a part of medical practice within the next decade. Personalized management of cancer, facilitated by nanobiotechnology, is expected to enable early detection of cancer, more effective and less toxic treatment increasing the chances of cure.

Synthetic, self-assembly ABCD nanoparticles; a structural paradigm for viable synthetic non-viral vectors

Gene therapy research is still in trouble owing to a paucity of acceptable vector systems to deliver nucleic acids to patients for therapy. Viral vectors are efficient but may be too dangerous. Synthetic non-viral vectors are inherently safer but are currently not efficient enough to be clinically viable. The solution for gene therapy lies with improved synthetic non-viral vectors systems. This review is focused on synthetic cationic liposome/micelle-based non-viral vector systems and is a critical review written to illustrate the increasing importance of chemistry in gene therapy research. This review should be of primary interest to synthetic chemists and biomedical researchers keen to appreciate emerging technologies, but also to biological scientists who remain to be convinced about the relevance of chemistry to biology.

Recent Advances in Non‐viral Gene Delivery

Gene therapy has been deemed the medicine of the future due to its potential to treat many types of diseases. However, many obstacles remain before gene delivery is optimized to specific target cells. Over the last several decades, many approaches to gene delivery have been closely examined. By understanding the factors that determine the efficiency of gene uptake and expression as well as those that influence the toxicity of the vector, we are better able to develop new vector systems. This chapter will provide a brief overview of recent advances in gene delivery, specifically on the development of novel non-viral vectors. The following chapters will provide additional details regarding the evolution of non-viral gene delivery systems.

What Role Can Chemistry Play in Cationic Liposome‐Based Gene Therapy Research Today?

Gene therapy research is still in trouble owing to a paucity of acceptable vector systems to deliver nucleic acids to patients for therapy. Viral vectors are efficient but may be too dangerous for routine clinical use. Synthetic non-viral vectors are inherently much safer but are currently not efficient enough to be clinically viable. The solution for gene therapy lies with improved synthetic non-viral vectors based upon well-found platform technologies and a thorough understanding of the barriers to efficient gene delivery and expression (transfection) relevant to clinical applications of interest. Here we introduce and interpret synthetic non-viral vector systems through the ABCD nanoparticle structural paradigm that represents, in our view, an appropriate lens through which to view all synthetic, non-viral vector systems applicable to in vitro use or in vivo applications and gene therapy. Our intention in introducing this paradigm is to shift the focus of organic and physical chemists away from the design of yet another cytofectin, and instead encourage them to appreciate the wider challenges presented by the need to produce tool kits of meaningful chemical components from which to assemble viable, tailor-made nanoparticles for in vivo applications and gene therapy, both now and in the future.