CRISPR Cas9: Answers to Questions

[Farhad-.-]

Hello guy, been a while since I was here, recently I've been studying biology and we had a brief explanation on what cripsr cas9 is.

My teacher does not have answers to the questions I need so I will ask them here and sorry If there is misspelling here and there, I am on my phone.

First of, does the crispr cas9 move from one cell to the other? Or just be in the same cell?

If it doesn't, does that imply we won't be able to edit an adult human? But just a few cells of a growing human before it reaches full maturity?

And if so, I think there were 200 of different types of cells in the human body, can we just edit a few cells and let it replicate and after a few months/years all the old types die out and be replaced by the new mutation that has been inserted into the cells?

 

[jedishrfu]

The wiki articles gets into your questions under the genome engineering section

https://en.m.wikipedia.org/wiki/CRISPR

They might create virus entities to infect target cells by injecting. Crispr cas9 into the cell to do its magic.

 

[Farhad-.-]

The wiki articles gets into your questions under the genome engineering section

https://en.m.wikipedia.org/wiki/CRISPR

They might create virus entities to infect target cells by injecting. Crispr cas9 into the cell to do its magic.

Thanks, will read it

 

[Ygggdrasil]

First of, does the crispr cas9 move from one cell to the other? Or just be in the same cell?

On it's own, the CRISPR-Cas9 system would not have a way of moving from one cell to another.

If it doesn't, does that imply we won't be able to edit an adult human? But just a few cells of a growing human before it reaches full maturity?

This depends on the exact biology of the disease being treated. Sometimes, fixing a small number of cells may be sufficient to cure or alleviate the disease. For example, hemophilia is due to mutations that make platelets unable to produce blood clotting factors. Correcting these mutations even in a small fraction of cells could help alleviate the disease. Similar approaches are also being tested in cancer immunotherapy, where doctors would engineer one's own immune cells to help fight cancer.

In the case of blood, it is also possible to extract and edit stem cells from an individual's bone marrow, treat the individual with drugs and radiation to remove all of their unedited blood stem cells, then introduce the edited stem cells. This type of bone marrow transplantation therapy has been proposed to potentially cure individuals of HIV by editing the blood stem cells to produce T-cells resistant to HIV infection.

And if so, I think there were 200 of different types of cells in the human body, can we just edit a few cells and let it replicate and after a few months/years all the old types die out and be replaced by the new mutation that has been inserted into the cells?

This depends a lot on whether the gene editing produces cells that have increased fitness (which would outgrow the old, unedited cells and eventually replace them) or whether the fitness of the cells is reduced (where it is very likely that the edited cells would eventually replaced by the old, preexisting cells). Cells could be edited to increase their fitness, but doing so would also likely increase their potential for becoming cancerous.

All of these questions touch on very difficult challenges that we would need to addressed for CRISPR-Cas9 to be applied in the clinic. Some issues could be solved by editing genes in embryos, so that the edits will be present in every single cell of the adult individual, but germline gene editing carries many ethical concerns (see the following Physics Forums thread for more discussion: https://www.physicsforums.com/threads/first-human-embryos-edited-in-u-s.921238/).

For a longer, more technical discussion of the issues you address, I suggest the following review article from Feng Zhang's lab, published in the journal Nature Medicine: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4492683/