Somatic Cell Therapy

The word “somatic” is derived from the Greek word soma, meaning “body”. Hence, all body cells of an organism – apart from the sperm and egg cells, the cells from which they arise (gametocytes) and undifferentiated stem cells – are somatic cells. Examples of somatic cells are cells of internal organs, skin, bones, blood and connective tissues. In comparison, the somatic cells contain a full set of chromosomes whereas the reproductive cells contain only half. A somatic cell is generally taken to mean any cell forming the body of an organism.

About Human Gene Therapy

Human gene therapy is the replacement of an absent or faulty gene with a functioning gene. As a result, the body is able to produce the correct enzyme or protein, thereby eliminating the cause of the disease. There are essentially two types of gene therapy: somatic cell therapy and germ line therapy. Somatic cell therapy involves treating any cells of the individual, except the gametes, at the cellular level to correct an absent or malfunctioning gene. This can be accomplished in three ways: ex vivo, in situ, or in vivo. Ex vivo involves removing cells from the patient, altering the genetic material, and placing them back into the patient. In situ requires the vector be placed directly into the affected tissues. In vivo gene therapy involves injecting the vector into the bloodstream. The vector then must find the target tissue and deliver the therapeutic genes. Germ line gene therapy treats the gametes or an embryo, which would be used in the case of in vitro fertilization. The difference between somatic and germ line gene therapy may seem to be subtle; however, the alterations obtained through germ line therapy are not only found in that generation, but are passed on to the individuals progeny. That has serious repercussions when it comes to discussing the ethics of using germ line therapy.