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Genome Editing with CRISPR | An Introduction

It was the beginning of the Year 2016, when a revolutionary technology came into existence and started to be known as Genome Editing with CRISPR technology which stands for Clustered regularly interspaced short palindromic repeats was a ground breaking technology which helps in editing the genes of any speicies to improve it.

It was going to be used in a lot of research areas which would have yield a lot of new possibilites for human kind. The best example of which is in early 2018, a women was treated with CRISPR technology who was suffering from breast cancer in USA. 

She was treated with this technology and i was a new dawn in the era of human race. A technology so powerful that it can cure any disease in a fraction of time as compared to the regular methods known to Human Kind.

So let us first understand what is the technology and how it works.

What is CRISPR Cas9?

Crispr Cas 9 is the combination of technology and the enzyme used to perform the process. CRISPR is the technology which is used to edit the gene and with the help of a Cas Enzyme which works like a Molecular Scissors. 

The discovery of CRISPR repeats within the bacterial genome in 1987 by Ishino et al. marked a revolutionary change in the field of genome editing. However, many groups only began further research regarding CRISPR/Cas mechanisms in the early 2000s, after the identification of Cas genes, unique to prokaryotes with CRISPR loci.

First proposed by Markarova et al. in 2006 and later confirmed by Garneau et al. in 2010, the CRISPR/Cas systems originate from bacteria and Archaea as a defense mechanism within their adaptive immune system to protect themselves from foreign invaders, such as viruses and plasmids. These foreign invaders are identified when a guide RNA (gRNA) made by the bacteria binds to its complementary foreign DNA or RNA sequence.

Several methods exist for gene delivery, including viral and non-viral systems. Each of these approaches carry their own advantages and disadvantages, therefore, it is important to choose the most suitable vector depending on the nature of your experiment.

While there is no ‘perfect vector’ that can be used for all applications, considering the following parameters will help in selecting the most appropriate gene delivery vehicle: In vitro or in vivo research: the requirements for in vivo applications (i.e. as a gene therapy vector) is more extensive. For example, the vector should elicit minimal immune response after delivery and in many cases, the vector should have the ability to target specific tissue or cell types.

Gene of interest size: the genetic material that a viral vector can deliver is often limited to its genome size. Non-viral delivery methods provide the solution for expressing genes with larger coding sequences. Target cell type: some cell types such as neurons, hepatocytes and myocytes are post-mitotic, therefore vectors capable of delivering materials into non-dividing cells are necessary for those cells types.

Transient or permanent expression: some vectors offer stable long-term transgene expression while others are only capable of short-term expression. For example, many viral vectors can integrate into the host’s genome thereby establishing permanent gene expression in target cells. The key to a successful CRISPR Cas9 system-mediated genome editing is to efficiently deliver the gRNA and the Cas9 nuclease into living cells.

Several methods exist for gene delivery, including viral and non-viral systems. Each of these approaches carry their own advantages and disadvantages, therefore, it is important to choose the most suitable vector depending on the nature of your experiment. While there is no ‘perfect vector’ that can be used for all applications, considering the following parameters will help in selecting the most appropriate gene delivery vehicle:

In vitro or in vivo research: the requirements for in vivo applications (i.e. as a gene therapy vector) is more extensive. For example, the vector should elicit minimal immune response after delivery and in many cases, the vector should have the ability to target specific tissue or cell types.

Gene of interest size: The genetic material that a viral vector can deliver is often limited to its genome size. Non-viral delivery methods provide the solution for expressing genes with larger coding sequences.

Target cell type:  Some cell types such as neurons, hepatocytes and myocytes are post-mitotic, therefore vectors capable of delivering materials into non-dividing cells are necessary for those cells types.

Transient or permanent expression: some vectors offer stable long-term transgene expression while others are only capable of short-term expression. For example, many viral vectors can integrate into the host’s genome thereby establishing permanent gene expression in target cells.

The key to a successful CRISPR Cas9 system-mediated genome editing is to efficiently deliver the gRNA and the Cas9 nuclease into living cells.

The Problem

The biggest problem with the use of CRISPR Therapeutics technology is that it raises a lot of concerns related to a lot of possible misuses like creationof Super Humans, creation of Bio-Weapons Etc. A lot of people fear that that ultimatley this will be the technology of Rich that they will be able to choose what all charactersitcs they want in their childrens and in the womb itself the the changes can be induced so that the child will be born with all those characterstics.

Whether they are cosmetic updates like blue-colour of the eyes or lookings similar to any actor or any famous personality or having good skills like a great footballer or cricketer. So there are a lot of issue surrounding the use of this technology. 

The Solution 

The solution related to the use of CRISPR Cas9 Technology is simple that it needs to be heavily regulated and must be practiced under controlled environment. Right now the use of CRISPR technology is only limited to be used in agriculture only. So, that we can improve the quality of our crops by retaining the qualitry of the yield every year.

Rest for all other applications there are a lot of restrictions and guidelines are being layed down to start the use of CRISPT technology in a controlled manner.

To know more about the initial steps of starting the genome editing process using bioinformatics tools you can join us for a 3 Hour Short Course on Genome Analysis, register yourself HERE

A brief introduction to Genome Editing is available HERE

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