Genetic modification of somatic stem cells

Some of the illnesses that plague mankind are directly related to our genes. Severe genetic disorders with no current therapeutic options—immunodeficiencies, haemophilia, thalassaemia, muscular dystrophies and cystic fibrosis, for example—could potentially be treated with gene therapy, which uses genetic information to correct a mutation or to provide new functions for human cells. The aim of gene therapy for the past two decades has been to fix the genetic defects in diseased cells of the body, or in the stem cells that can regenerate a diseased tissue or organ.> A precise correction of a genetic defect, or the replacement of one or more genes in the human genome, will not be technically possible for years to comeThe spectacular development of genetic technologies—such as gene targeting and homologous recombination—now allows scientists to routinely generate transgenic animals with defined genetic modifications. The clinical application of this technology, however, is still in its infancy. A precise correction of a genetic defect, or the replacement of one or more genes in the human genome, will not be technically possible for some years to come. Currently, the only therapeutic option is gene replacement or the transfer and expression of therapeutic genes through virus‐derived vectors. Clinical studies carried out in the past 10 years have proven that gene transfer into the organs of a patient— in vivo gene therapy—or the transplantation of genetically modified somatic cells— ex vivo gene therapy—is feasible and might cure severe diseases or notably improve existing therapies. Other studies, however, have been less successful, and have shown limited efficacy and serious safety problems associated with the use of viral vectors, both in vivo and ex vivo .The main reason why in vivo gene therapies have failed is the human immune system, which rejects the therapeutic vector or the genetically corrected cells …