Difference Between Ex Vivo and In Vivo Gene Therapy

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 patient’s tissues or cells without culturing the cells in vitro in in vivo gene therapy.

CONTENTS
1. Overview and Key Difference
2. What is Ex Vivo Gene Therapy
3. What is In Vivo Gene Therapy
4. Side by Side Comparison – Ex Vivo vs In Vivo Gene Therapy
5. Summary

What is Ex Vivo Gene Therapy?

Ex vivo gene therapy is a type of gene therapy which involves exterior modification of a patient’s cell and reintroduction of it to the patient. The cells are cultured in the labs (outside the patient’s 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.

Procedure of Ex Vivo Gene Therapy

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

1. Cells with defective genes are isolated from the patient.
2. Isolated cells are grown in cultures in the laboratory.
3. Therapeutic genes are inserted or introduced to the grown cell cultures using vectors.
4. Transformed cells are selected from the nontransformants and grown.
5. Selected cells are transplanted into the patient.

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 patient’s 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.

What is In 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 patient’s 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.

What is the difference between Ex Vivo and In Vivo Gene Therapy?

Summary – Ex Vivo vs In Vivo Gene Therapy

Therapeutic genes are introduced into patient’s 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 patient’s 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. 2017
3. 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 pl”By Pisum na podstawie pracy Lizanne Koch – Own work (CC BY-SA 3.0) via Commons Wikimedia 
2. “In vivo gene therapy pl” By Pisum na podstawie pracy Lizanne Koch – Own work (CC BY-SA 3.0) via Commons Wikimedia