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When is Gene Therapy Useful?
Although most diseases in humans are caused by pathogens, there are cases when a genetic defect causes a particular pathology. It is in these instances that gene therapy may be an effective treatment. In a typical case requiring gene therapy, an important functional gene is lost or becomes dysfunctional. This gene is then expressed by a genetically engineered construct and introduced into the tissue to substitute the defective copy. Such therapeutic copies of genes are engineered and introduced using DNA viruses and other non-viral vectors. It should also noted that viral vectors provide a higher efficiency of transfection.
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Gene Therapy Research for Cardiovascular Diseases
As mentioned previously, most gene therapy treatments make use of viral vectors for efficient expression of the introduced copy of the gene, and therefore pose some risk. Most gene therapy trials are constrained to the labaratory where the experiments are performed on human cell lines cultured in controlled conditions. Given these constraints, however, researchers have produced some encouraging data. In 1996, gene therapy worked successfully in curing Pompe's disease. Pompe's disease is a defect caused by the absence of a protein in the muscle cells of the heart, and it is generally found in children. Scientists were able to successfully produce the absent protein by expressing the gene from a genetically engineered construct and showed how the disease can be cured using human cells obtained from deceased patients.
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From the Labs to the Clinics: Human Trials of Gene Therapy for Heart Diseases
Although there have been encouraging results and data from research carried out in the lab, are there any actual real life applications of gene therapy to date? The answer is yes! The NewYork-Presbyterian Hospital/Columbia University Medical Center carried out clinical phase I trials in human patients enrolled in the CUPID trial (Calcium Up-Regulation by Percutaneous Administration of Gene Therapy in Cardiac Disease). These test patients were introduced with a genetically engineered gene that allows the formation of a protein that enhances the blood pumping rate of the human heart.
The data presented from this clinical trial was presented at the American Heart Association (AHA) Scientific Sessions 2008 in New Orleans. The results show that seven of the nine patients who were administered the therapy have shown significant improvements which were observed in a six month monitoring program. The patients shows across the board improvements in symptoms, function and biomarkers to varying degrees. The success of the trial not only involves the improvement shown by the patients, but has also made clear that biosafety concerns have also been addressed sufficiently. The test subjects who did not show any improvements were indentified to have antibodies against the viral delivery vector used in the therapy and hence could not obtain the same benefits as their peers.
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Brighter Future Ahead for Gene Therapy for Cardiac Defects
Phase II of this trial is expected to start soon where 46 new patients will be enrolled from around 13 hospitals in the US. Given that heart diseases and as a result heart failure is a serious problem, such treatments can be expected to raise the life span of human beings considerably. This clinical trial was funded by the Celladon Corporation of La Jolla, California and the company has already released information that this therapy has been shown to be safe during large scale animal trials as well.
The time is not too far when cardiac defects will be treated as effectively as any other uman disease and with further research into gene therapy based treatment might open doors for hundreds or may be even thousands of lives across the world.