Intravascular Electroporation Markedly Attenuates Neointima Formation After Balloon Injury of the Carotid Artery in the Rat

Irreversible electroporation attenuates neointimal formation after angioplasty

Restenosis following coronary angioplasty represents a major clinical problem. Irreversible electroporation (IRE) is a nonthermal, nonpharmacological cell ablation method. IRE utilizes a sequence of electrical pulses that produce permanent damage to tissue within a few seconds.

METHODS AND RESULTS

The left carotid arteries of eight rats underwent in vivo intimal damage using two Fogarty angioplasty catheters. The procedure was immediately followed by IRE ablation in four rats, while the remaining four were used as the control group. The IRE ablation was performed using a sequence of ten dc pulses of 3800 V/cm, 100 micros each, at a frequency of ten pulses per second, applied across the blood vessel between two parallel electrodes. The electrical conductance of the treated tissue was measured during the electroporation to provide real-time feedback of the process. Left carotid arteries were excised and fixated after a 28-day follow-up period. Neointimal formation was evaluated histologically. The use of IRE was successful in three out of four animals in a way that is consistent with the measurements of blood vessel electrical properties. The integrity of the endothelial layer was recovered in the IRE-treated animals, compared with control. Successful IRE reduced neointima to media ratio (0.57 +/-0.4 versus 1.88 +/-1.0, P = 0.02).

CONCLUSIONS

We report for the first time the in vivo results of attenuation of neointimal formation using IRE. Our study shows that IRE might be able to attenuate neointimal formation after angioplasty damage in a rodent model of restenosis. This approach may open new venues in the treatment of coronary artery restenosis after balloon angioplasty.

Applicator and electrode design for in vivo DNA delivery by electroporation

As in vivo electroporation advances from the preclinical phase to clinical studies and eventually to routine medical practice, the design of electroporation devices becomes increasingly important. Achieving safety and efficacy levels that meet regulatory requirements, as well as user and patient friendliness, are major design considerations. In addition, the devices will have to be economical to manufacture. This chapter will focus on the design of applicators and electrodes, the pieces of hardware in direct contact with the user and the patient, and thus key elements responsible for the safety and efficacy of the procedure. The two major foreseeable applications of the technology in the DNA field are for gene therapy and DNA vaccination. Design requirements differ considerably for these applications and for the diseases to be treated or prevented. In addition to the trend of device differentiation, there is also a trend to build devices capable of performing both the step of delivering the DNA to the target tissue and the subsequent step of electroporation. This chapter presents the electrical and biological principles underlying applicator and electrode design, gives an overview of existing devices, and discusses their advantages and disadvantages. The chapter also outlines major design considerations, including regulatory pathways, and points out potential future developments.

Nonviral gene transfer to skeletal, smooth, and cardiac muscle in living animals

The study of muscle physiology has undergone many changes over the past 25 years and has moved from purely physiological studies to those intimately intertwined with molecular and cell biological questions. To ask these questions, it is necessary to be able to transfer genetic reagents to cells both in culture and, ultimately, in living animals. Over the past 10 years, a number of different chemical and physical approaches have been developed to transfect living skeletal, smooth, and cardiac muscle systems with varying success and efficiency. This review provides a survey of these methods and describes some more recent developments in the field of in vivo gene transfer to these various muscle types. Both gene delivery for overexpression of desired gene products and delivery of nucleic acids for downregulation of specific genes and their products are discussed to aid the physiologist, cell biologist, and molecular biologist in their studies on whole animal biology.

Electroporation of the vasculature and the lung

Electroporation has proven to be a highly effective technique for the in vivo delivery of genes to a number of solid tissues. In most of the reported methods, DNA is injected into the target tissue and electrodes are placed directly on or in the tissue for application of the electric field. While this works well for solid tissues, there are many tissues and organs that are not amenable to such an approach. In this review I will focus on the development of electroporation protocols for two such tissues: the vasculature and the lung. Several methods for in vivo electroporation of the vasculature have been developed in recent years that deliver DNA to vessel segments from either the inside or outside of the vessel. The advantages and disadvantages of each are discussed, as are the applications for which they have been used. In more recent work, our laboratory has developed a novel method to deliver genes to the rodent lung that results in high level, uniform, gene expression throughout all cell types of the lung. Most importantly, this technique is safe, and causes no inflammatory response or alterations in normal physiology of the organs. Taken together, these studies demonstrate the utility of electroporation for gene transfer to non injectible tissues.