Fundamentals of Gene Therapy



illustration of DNA and the units that compose it (cell, nucleus, chromosomes) and illustration of a vector, target cell, and repaired cell
You look a little like your mother and a little like your father because of the genes they gave to you. Genes, those conceptual units composed of deoxyribonucleic acid—DNA, carry the information needed to make proteins, the building blocks of our bodies. The body buries genes deep in the heart of every cell, the nucleus, and organizes them in the chromosomes that hold the DNA. But when your DNA is damaged, it no longer makes all the needed proteins and disease results.

To reverse disease caused by genetic damage, researchers isolate normal DNA and package it into a vector, a molecular delivery truck usually made from a disabled virus. Doctors then infect a target cell —usually from a tissue affected by the illness, such as liver or lung cells—with the vector. The vector unloads its DNA cargo, which then begins producing the missing protein and restores the cell to normal.
illustration of vectors with SCID-repaired genes being joined with bone marrow cells and the resulting repaired cells
Recently, French researchers reported dramatic results in treating a disease called severe combined immune deficiency (SCID), the disorder suffered by David, The Boy in the Bubble. A broken gene eliminates the production of an enzyme essential for the development of a normal immune system. Scientists isolated the normal copy of the gene and packaged it into a vector. In the laboratory, they then used the vector to transport the gene into the patient's own bone marrow cells. Bone marrow cells create the immune system. The treated bone marrow cells are then given back to the patient in a germ-free isolation room, where they reconstitute a normal, functioning immune system, freeing the patient from the need to remain in isolation.


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