Gene Therapy 2: Nitty Gritty Cell Stuff

Rise of the Planet of the Apes (or as I like to mockingly call it 'Beginning of the Story of the Rise of the Planet of the Apes') was surprisingly good. No spoilers here, however, in light of the fact that the main storyline involves the use of viral gene therapy to enhance (or heal) ape brains, I figured it would be appropriate to write instalment number two of the gene therapy introduction.

Viruses are used to deliver the correct genetic material to cells in the hopes that this genetic material will be incorporated as part of the cells own genetic code. But how does this actually work?

The above diagram shows a virus (called a vector because it is basically a transport vehicle) attching to a cell. It is an adenovirus vector. Adenovirus is associated with respiratory, intestinal, and eye infections in humans (especially the common cold). As shown in the diagram, the virus is taken into the cell and then travles to the nuclues (the pink thing). It attaches to the surface of the nucleus and injects the DNA into to core of the nucleus. Remember that the nucleus of the cell is where we hold all our own genetic material.

The DNA molecule isn't a double-stranded molecule, but instead is a single strand, and can thus be read by the cells replication molecules. These molecules are called messenger RNA, and they are part of the process by which new proteins are formed. Thus, if the correct DNA is present, the correct proteins will be made, and so any disfunction that occured before may be rectified.

That's the nitty gritty of what is happening in the cells when infected with a virus vector carrying the corret DNA sequence. Next up we'll look at what diseases and disorders have been cured or treated to date, and what side effects have occured.

Will gene therapy one day become the ultimate application of genetic technology? Gene Therapy, the newest booklet in the Special Topics in Biology Series, addresses this question by exploring gene therapy as a complex technology for delivering therapeutic genes as a way to treat and cure human genetic diseases.
Author Mary Colavito provides an overview of the basic science involved in gene therapy methods and chronicles the history of gene therapy by discussing successful and ongoing gene therapy treatments as well as adverse outcomes in some cases of gene therapy. Also discussed are challenges that must be overcome for gene therapy to become a more reliable and readily accessible approach for treating a multitude of genetic diseases that affect humans.

A Brief Introduction to Gene Therapy

I haven’t written an article on Gene Therapy, and seeing as it is something a vaguely specialise in, I think it’s about time I do. So here it is.

Gene Therapy is an umbrella term for many types of treatments. Ultimately it involves changing or fixing or replacing genes that are defective or mutated in someone’s cell such that the cells can function again. Remember that genes represent the code by which just about everything that happens in the body follows. It’s like the instruction manual for the body. So if some of that code is missing, or incorrect, the body won’t work properly.

Examples of such diseases would be cystic fibrosis, Huntington’s disease, Sickle-cell anaemia and a huge range of immunity disorders. Even cancer is caused by genetic mutations. So if there was a way to fix the code, repair it in some way, this would have huge benefits to thousands of people.

More here: http://offthemark.com/

One way to fix a broken code involves using viruses. This may sound alarming, but it is actually quite effectively used. The basic principal revolves around using a harmless virus i.e. one that will only infect certain cells and won’t replicate, to carry the corrected gene code to cells. Viruses do this anyway – when they infect a person, they are often actually infecting the cells, their own gene codes being incorporated into the host cell. Usually this is detrimental, but by controlling what gene sequences are included in the virus, you can make tailor what happens when a virus infects a cell.

There are a few ways to ‘infect’ the cells with the virus. Say you have someone who has cystic fibrosis; their lung cells have defective genes that code correct mucous production. So if these genes were fixed, the cells would work correctly. Ideally, the virus could be injected into someone’s lungs, where they would infect the lung cells. These lung cells would ultimately then start performing the way they should. This is termed ‘In Vivo gene transduction’ i.e. you are placing the virus directly into the human, into the cells. Another method is to take the defective cells OUT of the body, and then infect them, only to put the hopefully fixed cells back into the body. This could work for any disorders that involve bone marrow (e.g immunity diseases or blood disorders). This is ‘Ex Vivo gene transduction’.

So there is the introduction to gene therapy. I could write a book on it. But there will be more posts soon... huge inroads are being made all the time in this field.