Current Gene Therapy - Volume 7, Issue 1, 2007

Cell Transplantation is one of the powerful tools to ameliorate the capillary flow in ischemic condition. EPC (Endothelial Progenitor Cell) was identified in adult peripheral blood and thought to be a suitable candidate for cell transplantation. Also, gene therapy is already promising choice for enhancing angiogenic property. The combination of cell transplantation and gene therapy should be more effective way to regenerate vasculature in ischemic region. Recently, several research reports have come out regarding gene modified cell transplantation. We will mainly focus on the background of EPC, and then gene modified EPC findings in this review.

Cardiovascular diseases are the major cause of morbidity and mortality in both men and women in industrially developed countries. These disorders may result from impaired angiogenesis, particularly in response to hypoxia. Despite many limitations, gene therapy is still emerging as a potential alternative for patients who are not candidates for traditional revascularization procedures, like angioplasty or vein grafts. This review focuses on recent approaches in the development of new gene delivery vectors, with great respect to newly discovered AAV serotypes and their modified forms. Moreover, some new cardiovascular gene therapy strategies have been highlighted, such as combination of different angiogenic growth factors or simultaneous application of genes and progenitor cells in order to obtain stable and functional blood vessels in ischemic tissue.

Ocular neovascularization is a major cause of blindness and visual disability in developed countries. There has been considerable recent progress identifying molecular signals that participate in ocular neovascularization and it appears that imbalances between stimulatory and inhibitory proteins contribute. Re-establishing balance by ocular gene transfer to block stimulators or increase expression of endogenous inhibitors is an appealing therapeutic approach, because it provides a potential means to achieve sustained intraocular effects with little impact on the rest of the body. Proof-of-concept has been provided in animal models using several vector systems and several transgenes and completion of a phase I study testing intraocular injection of an adenoviral vector expressing pigment epithelium-derived factor is an important milestone that will help to accelerate future progress. It is likely that additional vectors and transgenes will enter clinical trials in the near future. This report discusses the rationale and experimental evidence regarding several candidate transgenes.

Current pharmacologic interventions in lipid metabolism are insufficient in a subset of patients at increased risk of cardiovascular disease. In particular, several monogenetic disorders of lipid metabolism with diverse clinical complications are beyond treatment to date. Somatic gene transfer is a potential approach to treat these disorders. This review describes the efforts made thus far to develop gene therapy for 3 major classes of dyslipidemia: Increased levels of lowdensity lipoprotein cholesterol, reduced levels of high-density lipoprotein cholesterol and increased plasma triglyceride levels. For many of the genetic causes underlying these conditions, proof-of-principle studies have been performed and in combination with improved vectors some of these strategies may be feasible for clinical use in the future.

Meganucleases are sequence-specific endonucleases recognizing large (>12 bp) sequence sites and several laboratories have used these proteins to induce highly efficient gene targeting in mammalian cells. The recent development of artificial endonucleases with tailored specificities has opened the door for a wide range of new applications, including therapeutic ones: redesigned endonucleases cleaving chosen sequences could be used to in gene therapy to correct mutated genes or introduce transgenes in chosen loci. Such “targeted” approaches markedly differ from current gene therapy strategies based on the random insertion of a complementing virus-borne transgene. As a consequence, they should bypass the odds of random insertion. Artificial fusion proteins including Zinc-Finger binding domains have provided important proofs of concept, however the toxicity of these proteins is still an issue. Today custom-designed homing endonucleases, the natural meganucleases, could represent an efficient alternative. After a brief description of the origin of the technology, current systems based on redesigned endonucleases will be presented, with a special emphasis on the recent advances in homing endonuclease engineering. Finally, we will discuss the main issues that will need to be addressed in order to bring this promising technology to the patient.

Over the last few decades, various vectors have been developed in the field of gene therapy. There still exist a number of important unresolved problems associated with the use of viral as well as non viral vectors. These techniques can suffer from secondary toxicity or low gene transfer efficiency. Therefore an efficient and safe method of DNA delivery still needs to be found for medical applications. DNA electrotransfer is a physical method that consists of the local application of electric pulses after the introduction of DNA into the extra cellular medium. As electrotransfer has proven to be one of the most efficient and simple non viral methods of delivery, it may provide an important alternative technique in the field of gene therapy. The present review focuses on questions related to the mechanism of DNA electrotransfer, i.e. the basic physical processes responsible for the electropermeabilisation of lipid membranes. It also addresses the current limitations of the method as applied to DNA transfer, in particular its efficiency in achieving in vitro gene expression in cells and also its potential use for in vivo gene delivery.