A gene is a length of a DNA in which instructions for protein synthesis are processed. A specific gene codes this information to postulate the order in which the amino acid should form a specific protein molecule. The ability of DNA to replicate exactly the same copy is fundamental for proper functions and health of the organism (Kelemen, Z et al, 2015).
Likewise, chromosome consists of protein and a single molecule of DNA. During the cell division chromosomes ensures that DNA codes correctly to avoid mistakes.Gene Therapy for Heart Failure Paper Nevertheless during replication process occasionally mistakes happen. When a gene is unable to code amino acids correctly, the incorrect and harmful protein molecules will be formed. In this case a gene is said to have undergone mutation and the hereditary disorder will occur.
It is believed that gene therapy can resolve these shortcomings by delivering DNA remedies to faulty human cells to correct these genetic defects (Carl H et al, 2014). Regarding to the recent preclinical studies in animals models which identified molecular pathways in the pathophysiology of the heart failure, this therapy will provide hope in treating inherited and acquired cardiovascular diseases (Rincon et al, 2015).
This comparative study aims at assessing relative efficacy of the MCARD-AAV and IM-AAV injection approaches in delivering foreign genes to the host cells. It will determine the effectiveness of stranded adeno-associated virus (ssAAV) and self-complementary adeno-associated virus (scAAV) for gene transfer.
GENE THERAPY FOR HEART FAILURE
Heart failure occurs when the heart fails to pump inadequate blood required for the body metabolism. This disorder eventually prompts calcium cycle dysregulation to the myocytes resulting in disruptions of other body functions. The cardiovascular related diseases such as hypertension, coronary artery disease, diabetes and infection are thought to influence this ailment (Carl H et al, 2014).
The Heart failure gene therapy involves insertion of copies of a heathy peripheral gene into the chromosomes of an individual who carries a faulty allele to replace faulty genes to the heart.Gene Therapy for Heart Failure Paper This practice is renowned to correct the major pathologies which are out of reach for conventional drugs and the application of gene therapy has shown some success in tackling heart failure ( Gwathmey K et al,.2011; Pleger et al 2013).
FUNDAMENTALS OF GENE THERAPY
It is crucial to identify a gene that will match its modification with a target pathophysiology to produce expected results to avoid undesirable changes in heart failure trials that would result in an adverse cardiac adjustment (Carl H et al, 2014).
Vector selection and gene delivery
In recombinant DNA technology, various genetic engineering techniques are involved in the formulation of recombinant DNA. The restriction enzymes are used to cut a DNA molecule into small pieces. Simple microinjection, bioballistics, electro and chemical poration are among techniques used in gene delivery. It is important to understand that gene therapy is not a separate procedure; instead it is a genetic engineering method which uses these genetic tools to correct the DNA for medical purposes.
Specific virus and bacterial species are used as plasmid and vectors for preparing a recombinant DNA because of their ability to carry peripheral genes into the host cells and eventually releasing the chosen gene to replace the faulty gene.
In the preparation of a recombinant DNA, a gene is isolated from foreign DNA molecule by using restriction enzymes and then the gene is inserted into a vector to make multiple copies of the desired gene before a cloned genes being incorporated into the plasmid. An incorporated gene or DNA with the plasmid will be a recombinant DNA.Gene Therapy for Heart Failure Paper
The electro and chemical poration
The electro and chemical poration method is designed to create pores in the membrane of the cell so as genes can be transferred more easily. To achieve this, cells are exposed to chemical or to a very small electric current to make pores on the surface of the cells for the easy entry of genes.
In this method, small silver particles are combined with foreign genes and then inserted into the recipient cells. A small amount of mixture is then transferred is by a short gun in one projectile into the host cells.
The alternative gene delivery method to replace the use of vectors and plasmid for transferring peripheral genes into the host cells is microinjection. However, when this procedure involves large cell of plants and animals, a fine glass needle is applied to deliver the genes into the cell nucleus to merge with the host genetic material to start replication Gene Therapy for Heart Failure Paper
The common virus vectors used to repair and regenerate heart tissue in cardiovascular diseases in preclinical models of gene therapy and in human clinical trials are retrovirus, lentivirus, adenovirus, and adeno-associated virus (Naim C. et al, 2013; Mason D et al, 2015).
The recombinant viruses were reported to be the most successful virus vector in gene transfer. Some inflammatory responses have been known to contribute a cause of death in a clinical trial due to innate immune response during gene delivery. For that reason many preclinical studies use non- viral vectors therapeutic gene transfer to the heart. The plasmid DNA has been studied to find way for plasmid-mediated gene therapy vectors (Paul W and Paul K, 2011).
Non-viral vectors and Gene transfer without a vector (naked DNA)
Naked DNA has been uncommon gene transfer method due to its negatively charged membrane. The non-virus vectors have impressed many researchers for the reason that they are cost effective. Even if non-virus vectors are insufficient in transduction efficiency, they have no size limitation in transgene delivery systems (Carl H et al, 2014).Gene Therapy for Heart Failure Paper
The natural ability of viruses to deliver therapeutic genes to cells with greater transduction efficiency and cardiotropism has given them advantages over non-viral vectors. Adenoviruses are selected species and widely used in cardiovascular gene therapy clinical trials due to their wide target cell tropism and high transduction efficiency to cardiac cells (Carl H et al, 2014).
The studies portrayed the features of retrovirus that it contains single-stranded positive-sense RNA which generates double stranded DNA which uses to insert genetic sequences directly into the host genome. In contrast, it requires active mitosis for viral integration into the genome when it is used for cardiovascular gene therapy. Also it has been conveyed that the virus is incapable of transducing properly on non-dividing cell of cardiomyocytes and smooth muscle cells (Naim, C. et al,. 2013).
In vitro clinical trials, adeno-associated virus (AAV) have been used to transduce a variety of cells to respiratory epithelial cells, bone marrow and lymphocyte-derived cells. While in in vivo transduction and expression studies in the lungs, AAV has been observed in rodents and non-human primates after direct delivery to the airway surface without any detectable toxicity. Based on these findings, the use of AAV in human trial has been approved for gene therapy (Flotte and Carter, 1995).Gene Therapy for Heart Failure Paper
The simplest form of vector used to transfer the DNA into the cell reported is the plasmid. Itâs essential attributes include a circular DNA molecule and stability at room temperatures, and also its ability to produce proteins with antibiotic resistance. Moreover, the plasmid consists of only one transgene but its multiple polycitrionic expression cassettes have the capacity of encoding multiple proteins regardless of their sizes, although poor gene transfer efficiency in protein production has been perceived (Paul W and Paul K, 2011). Gene Therapy for Heart Failure Paper