An in vivo model of somatic cell gene therapy for human severe combined immunodeficiency

Article Abstract:

Scientists have long speculated that genetic diseases might eventually be cured by the introduction of a normal gene into the cells of the patient, a technique referred to as gene therapy. For many diseases, however, gene therapy is not yet practical. The rare lethal disorder severe combined immunodeficiency can result from a deficiency in the enzyme adenosine deaminase (ADA). ADA deficiency may be an ideal disease for the exploration of genetic therapy, since unlike most body cells, immune system cells can be removed, manipulated in the laboratory, and then replaced with relative ease. Using special mutant strains of mice, scientists have now shown that the principle of genetic therapy is sound and may prove to be of therapeutic benefit. The BNX strain of mice are immunodeficient, but these mice may be successfully populated with functioning immune cells taken from humans. To show that gene therapy may actually restore immune function, the researchers began with lymphocytes obtained from the blood of patients with severe combined immunodeficiency who were lacking the enzyme ADA. Genes for the normal, functioning ADA enzyme were obtained from healthy cells and incorporated into the genome of retrovirus vectors. This permits the researchers to let the retrovirus do most of the important work. The virus containing the ADA gene infects the human cells, and as the virus incorporates its own genes into the cells, it incorporates the ADA genes as well. The resulting recombinant cells can then be injected into the immunodeficient mice. Six to 10 weeks after injection, seven of eight mice were found to have human antibodies in their blood and functional antigen specific T cells could be detected in three of five animals examined. These results indicate not only that the functional ADA gene permitted the long-term survival of the patient's lymphocytes when injected into immunodeficient mice, but that these recombinant cells were capable of carrying out immune responses. The observations suggest that the retroviral method of placing functional ADA genes into cells of patients with severe combined immunodeficiency may indeed have therapeutic potential. (Consumer Summary produced by Reliance Medical Information, Inc.)

Immunological deficiency syndromes, Immunologic deficiency syndromes, Genetic disorders

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Experimental therapy of human glioma by means of a genetically engineered virus mutant

Article Abstract:

Malignant gliomas (tumors made up of glial cells, which form the supporting tissue of the brain) are the most common type of malignant brain tumors that occur in humans. Even though treatment for the tumors, including surgery, chemotherapy, and radiotherapy, exists, glioblastomas are usually fatal. The expected survival is less than a year, and the five-year survival rate is less than 5.5 percent. The tumor often recurs in the area of the primary tumor. Metastasis (spread) to other parts of the body is rare. A new form of treatment involving a genetically altered form of the herpes simplex virus is being studied. The resulting mutant virus is deficient in the enzyme thymidine kinase, which is involved in the replication of DNA, the genetic material of cells. This new form of the virus can replicate in cells that are dividing, such as the tumor cells, but not in cells that are nondividing, such as cells in the brain and nervous system. It is thought that the virus could infect and kill the glioma cells but would not affect the normal cells of the brain. This was tested in tissue culture (cells grown outside of the body). The mutant virus was able to kill five different types of human glioma cells. Human gliomas were implanted into mice and the mutant virus was injected into the gliomas. The treated mice tended to develop smaller tumors and to survive longer than untreated mice with gliomas. This genetically engineered virus may eventually be further developed as a type of therapy against malignant human gliomas. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Microbial genetic engineering, Herpes simplex virus, Gliomas

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Liposomes revisited

Article Abstract:

Advances in membrane biophysics have enabled scientists to design nonreactive and polymorphic liposomes. The nonreactive liposomes are useful in cancer chemotherapy, while the polymorphic liposomes are likely to be useful in genetic therapy.

Innovations, Drugs, Drug delivery systems, Liposomes

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