The transfer of genes into cells, both in vitro and in vivo, is critical for studying gene function and conducting gene therapy. Methods that utilize viral and nonviral vectors, as well as physical approaches, have been explored. Viral vector-mediated gene transfer employs replication-deficient viruses such as retro-virus, adenovirus, adeno-associated virus and herpes simplex virus. A major advantage of viral vectors is their high gene delivery efficiency. The nonviral vectors developed so far include cationic liposomes, cationic polymers, synthetic peptides and naturally occurring compounds. These nonviral vectors appear to be highly effective in gene delivery to cultured cells in vitro but are significantly less effective in vivo. Physical methods utilize mechanical pressure, electric shock or hydrodynamic force to transiently permeate the cell membrane to transfer DNA into target cells. They are simpler than viral-and nonviral-based systems and highly effective for localized gene delivery. The past decade has seen significant efforts to establish the most desirable method for safe, effective and target-specific gene delivery, and good progress has been made. The objectives of this review are to (i) explain the rationale for the design of viral, nonviral and physical methods for gene delivery; (ii) provide a summary on recent advances in gene transfer technology; (iii) discuss advantages and disadvantages of each of the most commonly used gene delivery methods; and (iv) provide future perspectives.

Image-guided, lobe-specific hydrodynamic gene delivery to liver was assessed in pigs. The procedure involved image-guided insertion of a balloon catheter to the hepatic vein of the selected lobe from the jugular vein and hydrodynamic injection of plasmid DNA using a newly developed computer-controlled injection device. We demonstrated that the impact of the procedure was regional with minimal effects on neighboring lobes. Level of gene expression resulted from the procedure was 107 RLU/mg in the targeted lobes and 102−105 RLU/mg in the non-targeted lobes 4 hr after hydrodynamic injection of pCMV-Luc plasmids. Occlusion of blood flow in the inferior vena cava or inferior vena cava plus portal vein was effective in elevating hydrodynamic pressure in the targeted vasculature but did not enhance gene delivery efficiency. Physiological examination on pigs with inferior vena cava occlusion revealed transient decreases of blood pressure and respiration rate. Removal of occlusion from inferior vena cava resulted in a rapid and transient increase in heart rate. Occlusion of the portal vein and hepatic vein showed no effect on physiological and cardiac activities. No major changes in serum composition were observed. These results suggest that: (1) image-guided, lobe-specific hydrodynamic procedure is safe and effective for regional gene delivery to liver; (2) blockade in inferior vena cava should be avoided for hydrodynamic gene delivery to the liver; and (3) clinic application of hydrodynamic gene delivery to liver is feasible.

Collagenous gastritis is a rare disease characterized by the subepithelial deposition of collagen bands thicker than 10 μm and the infiltration of inflammatory mononuclear cells in the lamina propria. Collagenous colitis and collagenous sprue have similar histological characteristics to collagenous gastritis and are thought to be part of the same disease entity. However, while collagenous colitis has become more common in the field of gastroenterology, presenting with clinical symptoms of chronic diarrhea in older patients, collagenous gastritis is rare. Since the disease was first reported in 1989, only 60 cases have been documented in the English literature. No safe and effective treatments have been identified from randomized, controlled trials. Therefore, better understanding of the disease and the reporting of more cases will help to establish diagnostic criteria and to develop therapeutic strategies. Therefore, here we review the clinical characteristics, endoscopic and histological findings, treatment, and clinical outcomes from case reports and case series published to date, and provide a summary of the latest information on the disease. This information will contribute to improved knowledge of collagenous gastritis so physicians can recognize and correctly diagnose the disease, and will help to develop a standard therapeutic strategy for future clinical trials.

Evidence in support of safety of a gene delivery procedure is essential toward gene therapy. Previous studies using the hydrodynamics-based procedure primarily focus on gene delivery efficiency or gene function analysis in mice. The current study focuses on an assessment of the safety of computer-controlled and liver-targeted hydrodynamic gene delivery in dogs as the first step toward hydrodynamic gene therapy in clinic. We demonstrate that the impacts of the hydrodynamic procedure were limited in the injected region and the influences were transient. Histological examination and the hepatic microcirculation measurement using reflectance spectrophotometry reveal that the liver-specific impact of the procedure involves a transient expansion of the liver sinusoids. No systemic damage or toxicity was observed. Physiological parameters, including electrocardiogram, heart rate, blood pressure, oxygen saturation, and body temperature, remained in normal ranges during and after hydrodynamic injection. Body weight was also examined to assess the long-term effects of the procedure in animals who underwent 3 hydrodynamic injections in 6 weeks with 2-week time interval in between. Serum biochemistry analysis showed a transient increase in liver enzymes and a few cytokines upon injection. These results demonstrate that image-guided, liver-specific hydrodynamic gene delivery is safe.