Question

Give a schematic representation of gene therapy.

Answer 1

The ex vivo gene therapy can be applied to only selected tissues (e.g., bone marrow) whose cells can be cultured in the laboratory. The technique of ex vivo gene therapy involves the following steps

• Isolate cells with genetic defect from a patient.
• Grow the cells in culture.
• Introduce the therapeutic gene to correct gene defect.
• Select the genetically corrected cells (stable trans-formants) and grow.
• Transplant the modified cells to the patient.

The procedure basically involves the use of the patient’s own cells for culture and genetic correction, and then their return back to the patient. This technique is therefore, not associated with adverse immunological responses after transplanting the cells. Ex vivo gene therapy is efficient only, if the therapeutic gene (remedial gene) is stably incorporated and continuously expressed. This can be achieved by use of vectors.