Stephanie M. Delgado Biol. 3095, Section 140, Student No. 804-09-2123<br />Dr. Díaz Monday, September 28, 2009 <br />Annotated Bibliography<br /><ul><li>Davies JC. 2006. Gene and cell therapy for cystic fibrosis. Paediatric Respiratory Reviews 7(1):S163-S165.
Abstract:</li></ul>Since the discovery of the CF gene over a decade ago, several groups worldwide have explored the potential of gene therapy, the insertion of a normal copy of the gene into the respiratory epithelium. Both viral and synthetic gene transfer agents have been designed to this end, although problems with repeat application have occurred with the former have occurred. Here, we will briefly review success in clinical trials to date. Cell therapy, replacement of the CF cell with a healthy, normal cell, is at a much earlier stage of development, studies mainly being preclinical or observational. Some evidence of plasticity of, for example, bone marrow cells, has been demonstrated, although for the airway, levels of correction appear to be extremely low and a degree of damage seems to be a prerequisite. Whether this approach will be able to achieve clinical success remains to be seen.<br />Annotation:<br />This article starts by mentioning the pathology of Cystic Fibrosis (CF) that using gene therapy addresses. It also provides basic information of what using gene therapy in patients with cystic fibrosis consists of, and the different vectors used. Davies (2006) also discusses the techniques currently used in measuring the success that gene therapy has in clinical trials, and based on studies, answers the questions of how much of the CFTR gene (cystic fibrosis transmembrane conductance regulator; gene responsible for cystic fibrosis) should be corrected by using gene therapy to eliminate the physiology of the disease. The article also focuses on cell therapy, as a new treatment, even more promising than gene therapy. Althougn cell therapy is still in a preclinical and observational stage, the author mentions some of the advantages that this new therapy could have on patients with CF, by using stem cells to replace CF cells with healthy counterparts. <br /><ul><li>Griesenbach U, Eric WF. 2008. Gene transfer to the lung: Lessons learned from more than 2 decades of CF gene therapy. Advanced Drug Delivery Reviews 61: 128–139.</li></ul> Abstract:<br />Gene therapy is currently being developed for a wide range of acute and chronic lung diseases. The target cells, and to a degree the extra and intra-cellular barriers, are disease-specific and over the past decade the gene therapy community has recognized that no one vector is good for all applications, but that the gene transfer agent (GTA) has to be carefully matched to the specific disease target. Gene therapy is particularly attractive for diseases that currently do not have satisfactory treatment options and probably easier for monogenic disorders than for complex diseases. Cystic fibrosis (CF) fulfils these criteria and is, therefore, a good candidate for gene therapy-based treatment. This review will focus on CF as an example for lung gene therapy, but lessons learned may be applicable to other target diseases.<br />Annotation:<br />In this review paper the authors give a deatiled description of the advantages that using gene therapy in cystic fibrosis has. They also describe the disease and some of the history of gene therapy in CF. Then they describe the different vectors used in gene therapy, and some of their advantages and disadvantages. Appart from the traditional viral vectors, and non-viral vectors, the article also discusses other promising vectors like the lentivial vector, and viruses with an RNA negative strand like the Sendain virus, the human resppiratory syncytial virus, and the human parainfluenza virus. The authors also reviewed other alternatives like gene repair, gene silencing, and using stem cells. The article also provides as references varios clinical trials and their results. <br /><ul><li>Ziady AG, Davis PB. 2006. Current prospects for gene therapy of cystic fibrosis. Current Opinion in Pharmacology 6(5):515-521</li></ul> Abstract:<br />Conventional therapy for cystic fibrosis has extended the median survival age, but the disease is still fatal. Gene therapy can correct the primary and secondary defects associated with cystic fibrosis, but limited extent and duration of the corrections as well as concerns about the safety of some current delivery systems have prevented gene therapy from being curative. For viral vectors, the main challenges are access to target cells and host immunity, which prevents efficient re-administration. Masking viral particles from the immune system, the use of alternative serotypes, or retargeting have been employed to address these issues. Non-viral vectors have dramatically improved over the past five years but improvements in efficacy are needed. In lung, naked DNA has been inefficient and lipid-based vectors have only achieved efficient gene transfer at doses that elicit limiting inflammatory responses. Molecular conjugates or polymer-based delivery overcomes some limitations, with good ability to transfect non-dividing cells. Improvements of viral and non-viral vectors continue to advance the construction of stable, safe and efficacious vectors that can be re-administered.<br />Annotation:<br />This review papers offers easy to understand background information on cystic fibrosis (CF), and the goal of using gene therapy to treat it. But this information is limited, as the paper focuses on the recent developments in the gene transfer agents or vectors for CF gene therapy. Mainly the paper is about the viral and non-viral vectors used in gene therapy. When talking about viral vectors, its focal points are adenoviral vectors (Ad), and adeno-associated viral vectors (AVV). The author describes the problems with these vectors, and some solutions that have been proposed in recent studies, however it only mentions other viral vectors that have been proposed like lintiviruses. Next, Davis and Ziady (2006) writes about non-viral vectors focusing on lipoplexes and polyplexes. They discuss clinical trials where this vectors where used and their results. They also go into the unique issues associated with each non-viral vector, and in his conclusions emphasizes the areas that need further research. <br /><ul><li>Dannhoffer L, Blouquit-Laye S, Regnier A, Chinet T. 2009. Functional Properties of Mixed Cystic Fibrosis and Normal Bronchial Epithelial Cell Cultures. American Journal of Respiratory Cell and Molecular Biology 40: 717–723. </li></ul>Abstract:<br />Cystic fibrosis (CF) airway epithelia exhibit altered Cl2 and Na1transport properties and increased IL-8 secretion. In the present study, we examined whether a small proportion of cells with a normal phenotype could normalize the ion transport and IL-8 secretion properties of a CF airway epithelial cell layer. We obtained three types of primary cultures of human bronchial epithelial cells: one composed of 100% non-CF cells, one of 100% CF cells, and one of 10% non-CF and 90% CF cells (‘‘cocultures’’). Measurement of the bioelectric properties in Ussing chambers revealed that the cocultures displayed Cl2 and Na1 transports similar to those observed in the 100% non-CF cultures and significantly different from CF cultures. IL-8 concentration in the coculture supernatant was not different from non-CF cultures, but was significantly lower than in CF cultures. This study provides evidence that 10% bronchial epithelial cells expressing a normal phenotype are sufficient to functionally correct a primary culture of CF bronchial epithelial cells in vitro. We postulate that 10% cells with a non-CF phenotype can be used as a goal for the design of gene therapy and cell therapy trials for CF lung disease.<br />Annotation:<br />This article is about the research of a group of French scientists who made cultures of 100% cystic fibrosis cells, cultures of cells a 100% non-cystic fibrosis, and cocultures that had 10% cystic fibrosis cells and 90% non-cystic fibrosis cells. They measured the Na+ and the CFTR dependent Cl- transport exposing the cultures to amiloride and forskolin, respectively in a Ussing chamber. They also measured their IL-8 secretion, whose increase, has been suggested is caused by CFTR dysfunction. The results indicate that cocultures exhibit similar bioelectric properties than non-CF cultures, and differed significantly from CF cultures. Their research shows that the cells cultures composed of 10% non-CF and 90% CF epithelial bronchial cells exhibit normal ion transport and IL-8 secretion as the 100% non-CF cells. This is significant because when using gene therapy it’s important to know the minimal percentage of cells with a non-CF phenotype that will be required to normalize the functions of the CF bronchial epithelial layer. <br /><ul><li>Buckley SMK , Howe SJ, Sheard V, Ward NJ, Coutelle C, Thrasher AJ, Waddington SN, McKay TR. 2008. Lentiviral transduction of the murine lung provides efficient pseudotype and developmental stage-dependent cell-specific transgene expression. Gene Therapy 15: 1167–1175</li></ul>Abstract:<br />Gene transfer for cystic fibrosis (CF) airway disease has been hampered by the lung’s innate refractivity to pathogen infection. We hypothesized that early intervention with an integrating gene transfer vector capable of transducing the lung via the lumen may be a successful therapeutic approach. An HIV-based lentiviral vector pseudotyped with the baculovirus gp64 envelope was applied to the fetal, neonatal or adult airways. Fetal intra-amniotic administration resulted in transduction of approximately 14% of airway epithelial cells, including both ciliated and non-ciliated epithelia of the upper, mid and lower airways; there was negligible alveolar or nasal transduction. Following neonatal intra-nasal administration we observed significant transduction of the airway epithelium (approximately 11%), although mainly in the distal lung, and substantial alveolar transduction. This expression was still detectable at 1 year after application. In the adult, the majority of transduction was restricted to the alveoli. In contrast, vesicular stomatitis virus glycoprotein pseudotyped virus transduced only alveoli after adult and neonatal application and no transduction was observed after fetal administration. Repeat administration did not increase transduction levels of the conducting airway epithelia. These data demonstrate that application at early developmental stages in conjunction with an appropriately pseudotyped virus provides efficient, high-level transgene expression in the murine lung. This may provide a modality for treatment for lung disease in CF.<br />Annotation:<br />This article describes the research of a group of scientists who administrated gp64 pseudotyped lentivirus to fetal, neonatal, and adult murines. Their study suggests that gp64 pseudotyped lentivirus efficiently transduces airway epithelial cells after both fetal and neonatal administration, whereas adult administration resulted in low level transduction in this tissue but efficient transduction of alveoli. These results are important because this vector could prove more useful in the delivery of the CFTR gene than other vectors and could provide prolonged expression throughout adolescent lung development. If the same pseudotype selectivity applies also to human fetal airway epithelia and safe techniques are developed to administer the vector to the airways in utero, it may become possible in the future to offer early intervention gene therapy in conjunction with prenatal diagnosis as an alternative preventative therapy to individuals with a family history of CF. <br />