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Biotech / Medical : Cell Genesys (CEGE) -- Ignore unavailable to you. Want to Upgrade?

To: david james who wrote (750)	3/12/2000 2:06:00 AM
From: Mike Learner	Read Replies (1) \| Respond to of 1298

For info: Jim Wilson What is Gene Therapy? Gene therapy is a novel approach to treating diseases based on modifying the expression of a person's genes toward a therapeutic goal. Gene therapy has been discussed in the context of treating lethal and disabling diseases although it also has a potential for disease prevention. Gene therapy is in its formative stages, being investigated in basic research laboratories. A number of early human clinical trials have been initiated to test important concepts that have emerged in these laboratory studies. The rationale for gene therapy lies in our understanding of the genetic basis of human disease. It is probably safe to say that genes we inherit from our parents influence virtually every human disease. A composite of approximately 150,000 individual genes constitutes a human being. Several years ago, an international effort was launched to identify every single human gene. This effort, called the Human Genome Project, is well underway and should be completed soon after the turn of the century. Variation in the structure of a person's genes collectively helps define us as individuals such as how tall we are to the color our eyes. Some of this genetic heterogenetics unfortunately leads to the development of disease. The genetics of many diseases are passed from one generation to the next by inheriting a single gene. An example is Huntingdon's disease. Many other diseases and traits are influenced by a collection of genes. The premise of gene therapy is based on correcting disease at its root - the abnormal genes. There are essentially two forms of gene therapy, one of which is called somatic gene therapy. Somatic gene therapy involves the manipulation of gene expression in cells that will be corrective to the patient but not inherited to the next generation. This is the type of gene therapy that is currently being investigated at the Institute for Human Gene Therapy, as well as other laboratories across the world. The other form of gene therapy is called germline gene therapy, this involves the genetic modification of germ cells that will pass the change on to the next generation. Little, if any, research is currently being conducted in germline intervention largely for technical and ethical reasons. Delivery The basic challenge in gene therapy is to develop approaches for delivering genetic material to the appropriate cells of the patient in a way that is specific, efficient and safe. This problem of "drug delivery," where the gene is a drug, is particularly challenging for genes which are large and complex and require targeting to the nuclei of cells. If genes are appropriately delivered they can persist for the life of the cell and potentially lead to a cure. The enabling technology of gene therapy is based on strategies for delivering genes. To do this we have developed gene delivery vehicles called vectors, which encapsulate therapeutic genes for delivery to cells. Many of the vectors currently in use are based on attenuated or modified versions of viruses. Over billions of years of evolution, viruses have developed extraordinarily efficient ways of targeting cells and delivering genome, which unfortunately leads to disease. Our challenge is to remove the disease causing components of the virus and insert recombinant genes that will be therapeutic to the patient. The modified viruses cannot replicate in the patient, but do retain the ability to efficiently deliver genetic material. Another strategy is based on synthetic vectors in which complexes of DNA, proteins, or lipids are formed in particles capable of efficiently transferring genes. The first human trials of gene therapy began in 1990 using a strategy of ex vivo gene therapy. In this approach, the patient cells were harvested and cultivated in the laboratory and incubated with vectors to modify their genes. The cells were then harvested and transplanted back into the patient from whom they derived. The first therapeutic trials utilizing this approach attempted to treat two genetic disorders, including children with an inherited form of immune deficiency as well as children and adults with extremely high levels of serum cholesterol. The field has quickly moved into more practical approaches for delivering genes based on so-called "in vivo" gene therapy in which the virus is directly administered to the patients. The first model for in vivo gene therapy was based on an attenuated version of the adenovirus in the treatment of cystic fibrosis. Adenoviruses have a natural tropism for lungs in that they are associated with respiratory diseases. Many other types of diseases are currently being investigated as candidates for gene therapy including cardiovascular diseases, infectious diseases such as AIDS, and cancer. Institute for Human Gene Therapy The Institute for Human Gene Therapy (IHGT) was formed in 1993 with the recruitment of Dr. James M. Wilson as its Director. The IHGT is the first academic based program dedicated solely to gene therapy. Over the last four years, the Institute has grown and established research programs in virtually all areas of medicine. Over 170 faculty at the University of Pennsylvania participate in Institute sponsored activities. The foundation of the Institute lies in its basic investigation, which is making discoveries necessary for gene therapy to be truly effective in the coming years. This work in discovery is coupled with a fully integrated Translational Research Program capable of bringing fundamental discoveries to proof-of-concept experiments in humans. The Institute has initiated over seven clinical trials of gene therapy in the last four years. The potential for gene therapy is huge and likely to impact on all aspects of medicine. The concept is fundamental although the technical challenges are tough. The real question is when genetic cures will be available. We are confident gene therapy will cure diseases and the IHGT will be a major participant in this cutting edge research.