Gene TherapyPhung Nguyen

Brief Overview1. What Gene Therapy Is

a. The Different Methods of Gene Therapyi. Ex vivo: indirect injection

i. Types of tissue removed and processi. Viral and Non-viral

ii. In vivo: direct injection1. Viral and Non-Viral

2. Uses and Costs of Gene Therapy

What is Gene Therapy?• Purpose: treating genetic disorders

with the use of vectors to introduce healthy DNA in a host with damaged DNA.

Viralo Retrovirus

o Murine leukemia viruso RNA to DNAo Tends to cause cancer

o Lentiviruso Made from more dangerous viruses

o Ebola, HVI, and others.o Can effect non-dividing cells

o Adenoviruso Such as the common cold virsuso Requires readministration

o Adeno-associated virus o Not lethal to humano Can infect dividing and non-diving cells alike

Adeno-associated virus • Has not been found to cause illness in humans.

o No immune response from humans• Has been shown to infect chromosome 19 with a

100% success rate with the help of a rep gene.o Makes the infection more predictable and

lessen chances of complications• Has a very low uptake frequency

o Usually does not combine with host genome• Needs a helper virus to replicate

o A lysogenic pathway unlikely without that helper virus

Non-Viral• Naked DNA

o DNA simply goes into cell (much like transformation) Safest method but least efficient

• Lipid Carrierso Genetic information shuttled in a liposome

• Gene Guno Genes covered and gold and shot into the body

• Electroporationo Shock of electricity to cause pores to form in

cell

Lipid Carriers (lipoplex)

• Most commonly used are cationic lipidso Have a positive charge to compact negative

DNA Forms complex with DNA

• Lipoplex

• Promotes Endocytosis• Protects DNA from degradation

Mechanism of Infection• Lipoplex

o Enters host cell through Endocytosiso Lipoplex is degraded and DNA is releasedo DNA is taken up into the nucleuso Recombination occurs and DNA is in genome

• Adeno-associated viruso Binds to receptors on cell membraneo Virus particles injected into cell

(process not fully understood)o Gene is expressed by host cell

But usually not taken up into genome

Lipoplex Cationic lipid

complex with DNA (Lipoplex)

Adeno-associated virus

Practical Uses and Cost• Has already been implemented in many

clinical trials all around the world since 1990.

• Has been shown to treat cystic fibrosis, cancer, arthritis, Parkinson’s, and other illnesses caused by genetic mishaps.

• Cost is not yet known.o Not readily available to the masseso Mostly still only seen in clinical trails

No Bioshock quite yeto Ethical Cost?

Alternative Methods

•Protein TherapyoSimply injects needed protein into patients body

oTemporary SolutionoDifficult to deliver proteins into cellsHard to get proteins into cell

The Future of Gene Therapy?

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(1997): 239-242.

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