ABSTRACT
Gene therapy is a breakthrough treatment strategy against several intractable and lethal diseases that previously lacked established treatments. Viral and nonviral vectors have been studied to realize higher gene transfection efficiencies and to suppress the degradation of gene by nucleolytic enzymes in vivo. However, it is often the case that the addition of a vector results in adverse effects. In this study, we identified formulations of dry naked plasmid DNA (pDNA) powders with no vector showing significantly higher gene expression than pDNA solutions including vectors such as polyethylenimine (PEI) in the lungs of mice. We prepared the naked pDNA powders by spray-freeze-drying with various excipients. The gene expression of naked pDNA powders exceeded those of pDNA solutions containing PEI, naked pDNA solution, and reconstituted pDNA powder. Gene expression of each naked pDNA powder was dependent on the composition of excipients. Among them, the mice that were administered the pDNA powder composed of low-molecular-weight hyaluronic acid (LHA) as an excipient showed the highest gene expression. The lactate dehydrogenase activity and concentration of inflammatory cytokines in bronchoalveolar lavage fluid were comparable to those caused by ultrapure water. The results suggest that useful dry naked nucleic acid powders for inhalation could be created by optimizing the excipients, offering new insights into the development of pulmonary gene therapy.
Subject(s)
Genetic Therapy/methods , Hyaluronic Acid/administration & dosage , Hyaluronic Acid/chemistry , Lung/metabolism , Plasmids/genetics , Plasmids/metabolism , Administration, Inhalation , Animals , Female , Genetic Vectors/chemistry , Mice , Molecular Weight , Polyethyleneimine/chemistry , Powders/administration & dosage , Powders/chemistryABSTRACT
Little is understood about the usefulness of sulfur isotopic ratios (sigma 34S) in tree rings because the sulfur content in rings is generally insufficient for analysis using conventional methods. We present sigma 34S values of the water-soluble and the organically bound sulfur fractions in rings of coniferous trees grown in Japan, analyzed using a large-volume oxygen bomb. Comparing the sigma 34S values of the organically bound fraction in tree rings with past atmospheric sulfur concentrations and with those of their sources, we find clear evidence that the sigma 34S values of the organically bound fraction in the rings are dependent upon the values of the atmospheric sulfur sources. The evidence suggests that the sigma 34S values in tree rings are a useful chronological proxy for evaluating possible causes of past atmospheric sulfur pollution.
