Transgenics refers to those specific genetic engineering processes that remove genetic material from one species of plant or animal and add it to a different species. Due to the high similarity in genetic sequences for proteins among species, transgenic organisms are able to effectively assimilate and express these trans-genes.
Viral vector In order to replicateviruses introduce their genetic material into the host cell, tricking the host's cellular machinery into using it as blueprints for viral proteins.
Retroviruses go a stage further by having their genetic material copied into the genome of the host cell. Scientists exploit this by substituting a virus's genetic material with therapeutic DNA. The term 'DNA' may be an oversimplification, as some viruses contain RNA, and gene therapy could take this form as well.
A number of viruses have been used for human gene therapy, including retrovirusesadenovirusesherpes simplexvacciniaand adeno-associated virus. Non-viral[ edit ] Non-viral methods present certain advantages over viral methods, such as large scale production and low host immunogenicity.
However, non-viral methods initially produced lower levels of transfection and gene expressionand thus lower therapeutic efficacy. Later technology remedied this deficiency.
Short-lived nature — Before gene therapy can become a permanent cure for a condition, the therapeutic DNA introduced into target cells must remain functional and the cells containing the therapeutic DNA must be stable. Problems with integrating therapeutic DNA into the genome and the rapidly dividing nature of many cells prevent it from achieving long-term benefits.
Patients require multiple treatments. Immune response — Any time a foreign object is introduced into human tissues, the immune system is stimulated to attack the invader.
Stimulating the immune system in a way that reduces gene therapy effectiveness is possible. The immune system 's enhanced response to viruses that it has seen before reduces the effectiveness to repeated treatments. Problems with viral vectors — Viral vectors carry the risks of toxicity, inflammatory responses, and gene control and targeting issues.
Multigene disorders — Some commonly occurring disorders, such as heart diseasehigh blood pressureAlzheimer's diseasearthritisand diabetesare affected by variations in multiple genes, which complicate gene therapy.
Some therapies may breach the Weismann barrier between soma and germ-line protecting the testes, potentially modifying the germline, falling afoul of regulations in countries that prohibit the latter practice.
This has occurred in clinical trials for X-linked severe combined immunodeficiency X-SCID patients, in which hematopoietic stem cells were transduced with a corrective transgene using a retrovirusand this led to the development of T cell leukemia in 3 of 20 patients. This may be problematic since the longer the DNA is, the harder it is to integrate into cell genomes.
The first was that of Jesse Gelsingerwho died in because of immune rejection response. Please consider summarizing the material while citing sources as needed.
November s and earlier[ edit ] In Friedmann and Roblin authored a paper in Science titled "Gene therapy for human genetic disease? The defective gene of the patient's blood cells was replaced by the functional variant.
Production of the missing enzyme was temporarily stimulated, but the new cells with functional genes were not generated. She led a normal life only with the regular injections performed every two months. The effects were successful, but temporary. This therapy also represents the beginning of cancer immunogene therapy, a treatment which proves to be effective due to the anti-tumor mechanism of IGF-I antisense, which is related to strong immune and apoptotic phenomena.
In Claudio Bordignonworking at the Vita-Salute San Raffaele Universityperformed the first gene therapy procedure using hematopoietic stem cells as vectors to deliver genes intended to correct hereditary diseases. The success of a multi-center trial for treating children with SCID severe combined immune deficiency or "bubble boy" disease from andwas questioned when two of the ten children treated at the trial's Paris center developed a leukemia-like condition.
Clinical trials were halted temporarily inbut resumed after regulatory review of the protocol in the US, the United Kingdom, France, Italy, and Germany.
Blood was removed from his mother's placenta and umbilical cord immediately after birth, to acquire stem cells. The allele that codes for adenosine deaminase ADA was obtained and inserted into a retrovirus.
Retroviruses and stem cells were mixed, after which the viruses inserted the gene into the stem cell chromosomes. Stem cells containing the working ADA gene were injected into Andrew's blood.
Injections of the ADA enzyme were also given weekly. After four years more treatment was needed. The approach has shown promising results in the treatment of six different malignant tumors: Trojan Trojan et al.
In humans, the use of hydroxyurea to stimulate the production of HbF temporarily alleviates sickle cell symptoms. The researchers demonstrated this treatment to be a more permanent means to increase therapeutic HbF production.The study of the ethical and moral implications of new biological discoveries and biomedical advances — as in the fields of genetic engineering and drug research The branch of ethics, philosophy and social commentary that discusses the life sciences and their potential impact on society.
In the UK, the most prestigious bioethics body has just green-lighted the genetic engineering of children. This has several significant problems.
The Guardian reported on their conclusions. The. The Effects of Genetic Engineering on Agriculture - Genetic engineering is a way in which specific genes for an animal or plant can be extracted, and reproduced to form a new animal or plant. Providing researchers with access to millions of scientific documents from journals, books, series, protocols and reference works.
The Nuffield Council on Bioethics is one of the most forward-thinking ethics boards in the world. Six years ago, the council approved a controversial fertility treatment requiring three genetic.
Sustainable agriculture practices can protect the environment and produce high-quality, safe, and affordable food. Our goal is to promote such practices while eliminating harmful “factory farming” methods and strengthening government oversight of genetically engineered food.