Question

Describe some specific failures of gene therapy trials, which have negatively affected public opinion and slowed the development of gene therapy techniques in medicine. How have researchers tried to solve the problems associated with these failures? What do you think the future of gene therapy will be?

Answer 1

THE FUTURE OF GENE THERAPY

• Identifying an appropriate target for gene therapy
• Getting a therapeutic transgene into the right cells in the right amount
• Delivering the transgene with a vector that doesn’t trigger an immune response .
• Providing the appropriate regulatory elements for turning the gene on and off at the correct time
• Keeping the transgene in the target cell long enough for it to do its job
• Keeping the transgene from causing damage elsewhere

DEFINITION OF GENE THERAPY

It is defined as the introduction of genetic material via techniques of molecular biology into somatic cells

Today both patients are alive and doing well, but conventional therapy can be given before, during, and after their gene therapy confounded the results and makes any claim of “cure” based on the gene therapy problematic. One patient has an ADA level that is 25 percent of normal with the therapeutic gene present in 15 percent of her peripheral blood mononuclear cells.

GENE THERAPY CAN BE DIVIDED INTO THREE GROUPS

1. Replacing a defective or mal-adaptive gene that’s responsible for some monogenic disease
2. Altering or killing an aberrant cell (e.g., infected by HIV or cancerous)
3. Inducing production of a therapeutic protein

RECENT DEVELOPMENTS ON GENE THERAPY

In April 2002 the BBC online news service in the United Kingdom caused by a defective gene on the X chromosome. This gene encodes the common ?C chain, an essential component of five cytokine receptors, all of which are necessary for the development of T cells and natural killer cells. Without the ?C chain, mature T cells and natural killer cells are completely absent, whereas B cells are usually present in normal or increased numbers. A collaboration of scientists from London, Paris, and Milan used a retroviral vector to introduce a functional copy of the defective gene into bone marrow stem cells taken from the patient in the hope that after re-infusion they would engraft and reconstitute a normal immune system.Integration and expression of the ?C transgene and development of the lymphocyte subgroups and their functions were analysed over a period of up to 2.5 years after gene transfer. No immediate adverse effects was hailed as a success and an important breakthrough for gene therapy as it pioneered an ex vivo procedure that avoided direct in vivo transfer of the vector.