We must remember that chromosomes are like cookbooks that contain our recipes. We receive these recipes in equal numbers from our progenitors at the time of fertilisation.
These recipes contain all our genetic information. That is they express our traits. They specify the colour of our eyes, the colour of our skin, the colour of our hair, the shape of our nose or our teeth, ears, nails, the shape of our fingers, our toes, and each and every element that make us up.
Sometimes the information we inherit is wrong and sometimes this can lead to an array of different pathological conditions that manifest as malformations or diseases.
Sometimes, however, the information inherited is correct but for some reason throughout the course of our lives, it goes wrong ending in disease such as cancer.
Having clarified this point, we should now ask ourselves the question:
What is gene therapy?
Gene therapy is a laboratory procedure the aim of which is to repair wrong or incorrect recipes.
And, how is this done?
- By correcting the error directly.
- By replacing the bad recipes for good recipes.
- By blocking the expression of the bad recipes.
And, how can we repair the sick cells?
Very easily, by using any of these strategies.
- Ex vivo strategy: Damaged cells are extracted from a patient and repaired in a laboratory setting; then, once repaired, the cells are reimplanted into the body of the affected individual.
- In situ strategy: The repairing gene or recipe is introduced directly in the actual defective organ of the affected individual.
- In vivo strategy: The repairing gene is administered to the patient so that it reaches the exact point to be treated.
Why is gene therapy so important?
Because it can help cure disease, regardless of whether or not these are hereditary.
How far has gene therapy been developed?
It is at an investigational stage.
What are the problems faced by this technology?
- Transport method
How can the genetic information contained in the recipes be transported until its final destination without being destroyed or damaged in the journey? We have to remember that nature is very wise and tends to destroy any thing that is unknown to it in order to protect us, so the trick is to bypass several cell recognition systems during the journey.
- To incorporate the recipes in the right place
This means that once the recipe has reached its destination, that is the organ or part of the body that concerns us (lung, heart, brain, etc,) it must enter the organ and occupy the place where it should be.
In this regard, breakthroughs have been and are still being achieved in this field worldwide (genetic engineering and medicine). In 2012, some researchers, while observing how bacteria manage to cut up viruses that try to invade them into small tiny pieces/fragments, discovered an strategy known as CRISPR (Cluster regularly interspaced short palindromic repeats). CRISPR-Cas 9 is a genetic engineering tool of enormous potential that uses enzymes as “molecular scissors” to “cut and splice” DNA at specific points.
Once the information or recipe has reached its destination within the cell, the information must undergo the established internal cell control for it to function properly. In other words, the recipes should only become expressed when due and only under certain stimuli.
Any recipe acting on its own could alter the order and cause even further problems.
When will this technology be ready for use?
When we know how our recipes function and interact amongst themselves under normal conditions and how they act under altered conditions.
When we know how to transport and insert them in the right place and how to maintain their stability and functions.
Has this technique been tried on humans?
Yes, the first experiments started back in 1989 and since then it has been tried in several different disorders.
Why is this therapy allowed to be applied only in somatic cells and not in germinal cells?
The answer is simple. Let’s start by differentiating between somatic and germinal cells. Then, we will examine the exception.
Somatic cells are those cell groups that form part of our body, with the exception of the cells involved in reproduction: the ovum and the spermatozoon.
Germinal cells are cells that only take part in the reproductive process, namely the ovum in females and the spermatozoon in males.
Gene therapy is only allowed to be applied in somatic cells. In doing this, the modification is born with and dies with the individual, preventing from being passed on to future generations.
We have no right to modify the genetic heritage of future generations and even less through the use of new and advanced technologies, the effects of which are still not completely known, such as for instance the behavior of these recipes when they are transmitted from generation to generation.
Next topic: Cloning and stem cells
Reviewed: 13th of June 2016