 not incorporated into genome .and they are not replicated though Ex. Common cold
Gene therapy using an Adenovirus vector:
A new gene is inserted into an adenovirus vector, which is used to introduce the modified DNA into a human cell. If the treatment is successful, the new gene will make a functional protein.
- Direct introduction of therapeutic DNA: Its only with certain tissue and requires a
lots of DNA.
- Creation of artificial lipid sphere with aqueous core, liposome.
- Chemically linking DNA to molecule that will bind to special cell receptors but
DNA is engulfed by cell membrane and less effective.
- Trying to introduce a 47th chromosome it exist alongside the 46 othersand this
could carry a lot of information.
Successful Gene Therapy for Severe Combined Immunodeficiency:
- Infants with severe combined immunodeficiency are unable to mount an adaptive immune response; because they have a profound deficiency of lymphocytes.
- Severe combined immunodeficiency is inherited as an X-linked recessive disease, which for all practical purposes affects only boys. In the other half of the patients with severe combined immunodeficiency, the inheritance is autosomal recessive — and there are several abnormalities in the immune system when the defective gene is encoded on an autosome.
- A previous attempt at gene therapy for immunodeficiency was successful in children with severe combined immunodeficiency due to a deficiency of adenosine deaminase. In these patients, peripheral T cells were transduced with a vector bearing the gene for adenosine deaminase.
- The experiment was extremely labor intensive, because mature peripheral-blood T cells were modified rather than stem cells, and the procedure therefore had to be repeated many times to achieve success.
- A previous attempt at gene therapy for immunodeficiency was successful in children with severe combined immunodeficiency due to a deficiency of adenosine deaminase.
- In these patients, peripheral T cells were transduced with a vector bearing the gene for adenosine deaminase. The experiment was extremely labor intensive, because mature peripheral-blood T cells were modified rather than stem cells, and the procedure therefore had to be repeated many times to achieve success.
- 2. Parkinson’s Disease:
- Neurologix a biotech company announced that they have successfully completed its
- landmark Phase I trial of gene therapy for Parkinson’s Disease.
- This was a 12 patient study with four patients in each of three dose escalating
- cohorts. All procedures were performed under local anesthesia and all 12 patients
- were discharged from the hospital within 48 hours of the procedure, and followed
- for 12 months. Primary outcomes of the study design, safety and tolerability, were
- successfully met. There were no adverse events reported relating to the treatment
- The gene transfer procedure utilized the AAV (adeno-associated virus) vector, a virus
- that has been used safely in a variety of clinical gene therapy trials, and the vehicle that
- will be used in all of the company’s first generation products, including epilepsy and
- Huntington’s disease. In its Parkinson’s disease trial, Neurologix used its gene transfer
- Genes get into brain using liposomes coated in polymer called polyethylene glycol
potential for treating Parkinson’s disease
- RNA interference or gene silencing to treat Huntington’s
siRNAs was used to degrade RNA of particular sequence and so abnormal protein won’t be
- Create tiny liposomes that can carry therapeutic DNA through pores of nuclear
- Sickle cell successfully treated in mice
- Due to every method of gene transfer having shortcomings, there have been some hybrid methods developed that combine two or more techniques.
- Virosomes are one example; they combine liposomes with an inactivated HIV or influenza virus. This has been shown to have more efficient gene transfer in respiratory epithelial cells than either viral or liposomal methods alone. Other methods involve mixing other viral vectors with cationic lipids or hybridizing viruses.
Some of the p