Their in vitro genetic modification and selection followed byAl-Allaf et al.
Their in vitro genetic modification and selection followed byAl-Allaf et al. International Archives of Medicine 2010, 3:36 http://www.intarchmed.com/content/3/1/Page 6 ofreimplantation of the transduced cells, or it can be done in vivo, where the vector is delivered directly to the organ [83]. The advantage of the ex vivo approach is that the transduction/transfection conditions can be carefully controlled and optimised and individual clones with the most PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28506461 desirable characteristics can be isolated to eliminate unmodified cells or cells with deleterious mutations before re-implantation. While this approach is laborious and time consuming, it may also offer significantly greater safety and control with respect to vector mediated mutagenesis and possible germline transmission of the transferred genes, which is a risk of in vivo gene delivery. The disadvantages of the ex vivo approach are failure of cell engraftment and difficulties in returning the cells to the patient due to disease manifestations such as portal vein hypertension [83,84]. The in vivo approach eliminates the need for engraftment after AprotininMedChemExpress Aprotinin re-implantation and is therefore easier to perform, more cost effective and may be more applicable for use in countries with limited laboratory resources. The gene transfer vector is injected into the bloodstream (systemic delivery) aiming at somatic cell delivery only or by use of specific cell targeting, preferentially to the tissues of interest (targeted delivery). Organ specific delivery of the gene transfer vector includes intrahepatic injection or selective intravasular application routes. Disadvantages of in vivo gene transfer are vector dilution, ectopic transgene expression and non-targeted, random, potentially genotoxic insertion into the host genome.Gene transfer systems In addition to the method chosen for delivery, successful treatment of FH would ideally require safe and efficient gene transfer vectors that provide appropriate and sustained levels of transgene expression and long-term survival of treated cells. The use of a liver specific promoter would be the most physiological approach to achieve this. However, because of present problems in transfection-efficiency, strong heterologous promoters are commonly used instead for proof of principles studies on the effectiveness of lipid-lowering. The development of more effective vectors to achieve this remains a formidable challenge to gene therapy. The properties required of such a vector system and those that should be avoided are listed in Table PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/27864321 1. Gene transfer vectors are generally classified under two categories; they are either non-viral or virus mediated gene transfer systems. Non-viral gene transfer systems Gene therapy vectors based on modified viruses are unquestionably the most effective gene delivery systems in use today. Their efficacy at gene transfer is howevertempered by their potential toxicity [85,86]. An ideal vector for human gene therapy should deliver sustainable therapeutic levels of gene expression without compromising the viability of the host (at either the cellular or somatic level) in any way. Non-viral vectors are attractive alternatives to viral gene delivery systems because of their low toxicity, relatively easy production and great versatility [87]. Most of the non-viral vectors that have been described for gene therapy are based on complimentary DNA (cDNA) gene sequences driven by highly active promoters. The DNA in these vectors is typically form.