Genetic Therapy that focuses on hemophilia
Gene therapy is reinserting certain genes that helps deal with genetic diseases. There are three basic forms of this gene therapy. The first is Gene Inactivation Therapy in which the transferred gene neutralizes the proteins and evens out the amount or rids of the defective proteins. Another type is Gene Augmentation Therapy where the original form of the gene or the normal form of the gene is inserted into one of the cells chromosomes. This procedure is used normally when a gene with little activity or a deleted gene is the cause for the genetic disease. The third type of gene therapy is Gene Replacement Therapy. This form is used when the genetic disease involved specific genes that are necessary for proper functioning. The normal gene being put in place of the mutant gene accomplishes this form of gene therapy.
Either transduction or transfection can be used to get the therapeutic genes into the patients system. Transfection is when the genes are introduced physically or chemically in a way that allows the cell membrane to be temporarily permeable to a foreign DNA. In the second method used for gene therapy, transduction, there is a beneficial gene added into the genetic material of the virus, which then is allowed to infect the target cell which is the indirect transfer method for gene therapy.
There have been four somewhat recent successful gene therapy treatments. The four deal with correcting hemophilia, bone marrow transplants, skin cancer, and vessel growth. In the success with the bone marrow transplants, French researchers collected bone marrow cells from patients, used gene therapy to correct the bone marrow, and then returned the bone marrow to the patient. This was 80% successful as reports 16 months after the transplants showed. Squamous cell carcinoma, skin cancer of the head and neck, was treated using gene therapy as well. The fourth trial was where DNA was used to carry a substance that stimulates blood vessel growth to damaged heart tissue and in this trial there was much success noted.
The beginning of Gene Therapy began in the late 1980s, which was completely unsuccessful. In the fall of 1999 the death of University of Pennsylvania trial participant, Jesse Gelsinger was followed by much public outcry and legal problems that put an immediate halt on all gene therapy research. The reason Jesse was being treated with Gene therapy was to attempt to cure the teenagers rare liver disease. In the long run, the outcome of a government investigation concluded that researchers had not followed the rules. The FDA had all research put to a stand still until an appropriate monitoring and reporting system had been approved and was in place.
As you can guess, each of these gene therapy procedures was first tested on animals. First, the virus, hemophilia B was injected into the dogs in the form of a virus. Then the dogs were treated with gene therapy and given the appropriate missing genes and adding them to muscle cells, which would accept the genes, and then produce the proper clotting factor and the clotting of the dogs blood would be about back on track. The result show that the blood-clotting times decreased from more than on hour down to about 15-20 minutes where as a normal dogs blood-clotting time is approximately six minutes. No side effects or problems were reported as a result of the treatment. Researchers at Stanford University School of Medicine had a similar outcome when they experimented, first on mice, then on dogs as well.
(The process here shows how the new gene or foreign DNA is added into the nucleus of the chromosome with the help of the virus, represented here as AAV Vector)
Gene therapy that treats hemophilia has been an increasingly popular method to take cure hemophilia A and B. Hemophilia A is the more common form that is caused by a missing gene used as a blood-clotting factor. A single gene introduced into an affected person can treat the disease. Hemophilia B is much easier to treat, and often preferred by some therapy labs. The reason that it is easier to treat is because the defected gene found in hemophilia B, is smaller than the gene found in hemophilia A. Another reason it is easier to treat is that simply getting missing clotting factors injected into the blood stream can cure hemophilia.
There are a few basic steps used in gene therapy. The desired gene must first be isolated which is done through gene therapy and gene engineering. The gene must then be transferred into the cells. Four methods are available to transfer the gene into the cell. Fusion, chemical injections, physical methods, and vector viral use. The vector viruses are used to infect almost every cell in the target population and can deliver the gene to the cell that was trying to be treated.
There are concerns in this technology when added to other forms of technology that the world may end up all in the same. I mean that the world may try and do with gene therapy what they want to do with cloningthey will make identical copies that they believe are "perfect". "Although its not a present worry and its certainly not the focus of research, as gene therapy progresses and we have the technology to put genes in to treat disease, there must also be safeguards put in (place) or we will end up with people trying to put genes in to make designer babies," said French Anderson, M.D. "Its a worry that needs to stay right up front in peoples minds." On a personal note, I feel that there has been some tremendous work with gene therapy in the past twenty years and it seems we are nearing a future of hemophilia-free humans. Gene therapy seems to be making some wonderful improvements in other fields as well, although treating hemophilia seems to be easier and quicker than any other treatment used to attempt to take control of hemophilia.
Fidos Gene Therapy Success Bodes Well, Henahan, Sean, www.accessexcellence.cm/WN/SUA12/hemophilia199.html.
For Gene Therapy, It Was a Very Good Year, Maltin, Liza Jane, my.webmd.com/content/article/1728.68173.
Gene Therapy: Hemophilia, Friedman, Yali, biotech.about.com/industry/biotech/library/weekly/aa080299.htm?terms=hemophilia.
Genetic disease, Levine, Louis, World Encyclopedia, 1996, p 85-86.
How is Genetic Engineering used to cure or prevent Hemophilia?, Joseph, Jaky J., http://campus.fortunecity.com/baked/110/jaky_20nyu.html#Gene%20Therapy