Key Difference Ex Vivo vs In Vivo Gene Therapy

Gene therapy is an important technique which is used to treat or prevent genetic diseases by introducing genes for missing or defective genes. Certain diseases can be cured by inserting the healthy genes in place of mutated or missing genes responsible for the disease. Gene therapy is mostly applied for somatic cells than germline cells, and it can be categorized into two major types named Ex vivo gene therapy and In vivo gene therapy. The key difference between Ex vivo and In vivo gene therapy is that therapeutic genes are transferred to in vitro cell cultures and reintroduced into a patient in ex vivo gene therapy while genes are delivered directly to patients tissues or cells without culturing the cells in vitro in in vivo gene therapy.

CONTENTS1. Overview and Key Difference2. What is Ex Vivo Gene Therapy3. What is In Vivo Gene Therapy4. Side by Side Comparison Ex Vivo vs In Vivo Gene Therapy5. Summary

Ex vivo gene therapy is a type of gene therapy which involves exterior modification of a patients cell and reintroduction of it to the patient. The cells are cultured in the labs (outside the patients body), and genes are inserted. Then the stable transformants are selected and reintroduced into the patient to treat the disease. Ex vivo gene therapy can be applied only to certain cell types or selected tissues. Bone marrow cells are the cells frequently used for ex vivo gene therapy.

There are several major steps involved in Ex vivo gene therapy as follows;

In ex vivo gene therapy, carriers or vectors are used to deliver genes into target cells. Successful gene delivery is dependent on the carrier system, and the important vectors used in ex vivo gene therapy are viruses, bone marrow cells, human artificial chromosome, etc. Compared to the in vivo gene therapy, ex vivo gene therapy does not involve adverse immunological reactions in the patients body since the genetic correction is done in vitro. However, the success depends on stable incorporation and expression of the remedial gene within the patient body.

Figure 01: Ex vivo gene therapy

In vivo gene therapy is a technique which involves direct delivery of genes into the cells of a particular tissue inside the patients body to treat genetic diseases. It can be applied to many tissues of the human body including liver, muscle, skin, lung, spleen, brain, blood cells, etc. The therapeutic genes are introduced by the viral or nonviral-based vectors into the patient. However, the success depends on several factors such as efficient uptake of the therapeutic gene carrying vectors by the target cells, intracellular degradation of the genes within the target cells and gene uptake by the nucleus, expression ability of the gene, etc.

Figure 02: In vivo gene therapy

Therapeutic genes are introduced into patients body as a treatment for certain diseases. It is known as gene therapy and can be done in two ways namely ex vivo gene therapy and in vivo gene therapy. The difference between ex vivo and in vivo gene therapy is that gene insertion in ex vivo gene therapy is done in the cell cultures exterior to patients body and the corrected cells are reintroduced to the patient while in in vivo gene therapy genes are introduced directly into the interior target tissues without isolating the cells. The success of the both processes depends on the stable insertion and transformation of the therapeutic genes into the patient cells.

Reference:1.What is gene therapy? Genetics Home Reference. U.S. National Library of Medicine. National Institutes of Health, n.d. Web. 24 Apr. 2017.2.Evaluation of the Clinical Success of Ex Vivo and In Vivo Gene Therapy | JYI The Undergraduate Research Journal. JYI The Undergraduate Research Journal. N.p., n.d. Web. 24 Apr. 20173. Crystal, Ronald G. In vivo and ex vivo gene therapy strategies to treat tumors using adenovirus gene transfer vectors. SpringerLink. Springer-Verlag, n.d. Web. 24 Apr. 2017

Image Courtesy:1. ExVivoGeneTherapy plBy Pisum na podstawie pracy Lizanne Koch Own work (CC BY-SA 3.0) via Commons Wikimedia2. In vivo gene therapy pl By Pisum na podstawie pracy Lizanne Koch Own work (CC BY-SA 3.0) via Commons Wikimedia

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Difference Between Ex Vivo and In Vivo Gene Therapy