| Abstract: |
A gene is a functional segment of DNA that specifies, or assists in the expression of a particular phenotype. Mutation is change in DNA sequence which usually leads to diseases if not repaired. br Gene vectors are agents that enable the cellular uptake of genetic material in such a way that its genetic information is expressed. Gene therapy vectors are either viral or non-viral. Viral vectors are either integrating viral vectors as Adeno-associated viruses or non-integrating viruses as the herpes simplex virus. Nonviral vectors as Cationic liposomes, gene gun, naked DNA and DNA-ligand complexes br Methods of gene therapy include ex vivo gene therapy and in vivo gene therapy. Ex vivo gene therapy ; transfer of genetic material to cells located outside the host then the cells are implanted back into the host. This term has also been called the indirect method of gene therapy. In vivo gene transfer; transfer of genetic material to cells located within host. This has also been termed the direct method of gene transfer. br Ex vivo gene therapies are predominantly concerned with gene delivery barriers presented by the cell itself. In vivo gene therapy and, to some extend, ex vivo therapies, must be concerned not only with intracellular barriers but also with extra cellular barriers. Intracellular barriers include the plasma membrane which is the first obstacle to be overcome, endosome and nuclear membrane. Extracellular barriers include tissue barriers; for example, any gene therapy aimed at treating CNS dis-#111;-#114;-#100;-#101;-#114;s must contend with the blood-brain barrier and immunological barriers which include serum component, cellular immune responses and humeral immune responses. br Gene therapy offers new possibilities for management of orthopaedic conditions that are difficult to treat by traditional surgical or medical means as; tumours, Osteogenesis imperfecta, repair of articular cartilage defect, meniscial tear, intervertebral disc prolapse, tear of ligaments and tendons. Also in rheumatoid arthritis, osteoarthritis, fracture healing, spinal fusion and others. br .
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