Question

Which is correct regarding ex vivo gene therapy?

• A. Therapeutic Genes are transferred to germ line cells
• B. Cells are modified outside body and transferred back to the body
• C. Genes are changed in cells when cells are inside the body
• D. Luxturna is an example of ex vivo gene therapy

Hint:

• Ex vivo Gene Therapy Cells removed from patient \(\rightarrow\) Genetically modified in lab \(\rightarrow\) Modified cells returned to patient. (Ex = Outside)
• In vivo Gene Therapy Therapeutic gene delivered directly into patient's body. (In = Inside)
• Somatic Gene Therapy Targets non-reproductive cells. Changes are not heritable. (Most current gene therapies).
• Germline Gene Therapy Targets reproductive cells (sperm, egg, embryo). Changes are heritable. Raises significant ethical concerns.

Answer 1

The Correct Option is B

Gene therapy involves introducing genetic material into an individual's cells to treat or cure a disease. There are two main approaches: 1. Ex vivo Gene Therapy:

• Cells are first removed from the patient's body (e.g., bone marrow cells, lymphocytes).
• These cells are then genetically modified in vitro (outside the body) in the laboratory, for example, by introducing a therapeutic gene using a viral vector or other gene delivery methods.
• The modified cells are selected, often expanded in culture, and then transferred back into the patient's body.

2. In vivo Gene Therapy:

• The therapeutic gene (often packaged in a vector) is directly delivered into cells inside the patient's body (e.g., by injection into a specific tissue or systemically).

Let's analyze the options: (a) "Therapeutic Genes are transferred to germ line cells": This describes germline gene therapy, which alters genes in sperm, eggs, or embryos, leading to heritable changes. Both ex vivo and in vivo approaches generally target somatic cells (non-reproductive cells) for ethical and safety reasons, though germline therapy is a separate concept. This option is not a definition of ex vivo specifically. (b) "Cells are modified outside body and transferred back to the body": This accurately describes the core procedure of ex vivo gene therapy. (c) "Genes are changed in cells when cells are inside the body": This describes in vivo gene therapy. (d) "Luxturna is an example of ex vivo gene therapy": Luxturna (voretigene neparvovec) is an FDA-approved gene therapy for a rare inherited retinal dystrophy. It is administered via subretinal injection, meaning the therapeutic gene (in an AAV vector) is delivered directly to cells inside the eye. Therefore, Luxturna is an example of in vivo gene therapy, not ex vivo. Thus, option (b) correctly describes ex vivo gene therapy. \[ \boxed{\text{Cells are modified outside body and transferred back to the body}} \]