The use of CRISPR genome editing system to treat human diseases
Clustered Regularly Interspaced Short Palindromic Repeats known as CRISPR, is a powerful technology that plays an important role in genome editing and widely used in the biomedical research field to explore gene function. The CRISPR sequences were initially found in microbiomes to function as an adaptive immune defense that destroyed viral pathogens by cutting the DNA of the invader with Cas nucleases. A unique property of the Cas nucleases is the requirement for an RNA guide sequence that both activates the enzyme and selectively targets the nuclease to complementary DNA sequences. This distinctive property of the Cas Nucleases allows DNA breaks or nicks at essentially any location desired in genomic DNA. While CRISPR is mainly used in basic science research, the application of this technology has expanded to translational disease focused research as an area of intensive investigation.
The gene editing technology requires the generation of a double stranded break at the targeted DNA sequence. The double stranded break activates two competing DNA repair systems such as homology directed repair or non-homologous end joining. Non-homologous end joining is an error prone process in mammalian cells which generate insertions or deletions that could change the proteins coding sequence. On the other hand, homology directed repair includes homologous recombination with a donor DNA sequence that introduces precise DNA mutations or the insertion of specific sequence. The involvement of two essential components such as Cas nuclease and required gRNA give rise to the specificity of the CRISPR technology. The specificity for a target DNA sequence is determined by the gRNA which bind bases pairs to complementary DNA sequences. Due to this binding of the gRNA, Cas9 is located at the same specific site that leads to cuts in the DNA backbone and the generation of the double stranded break at the targeted site.
CRISPR technology has been recently used to disease-focused research through the production and characterization of patient-derived iPS cell from individuals with specific genetic diseases. IPS cells have been generated and used as a “disease-in-a-dish” in vitro model for diseases including muscular dystrophy, Parkinson’s disease, Huntington’s disease and Down Syndrome. Moreover, enhanced DNA sequencing technologies can recognize genetic mutations in an affected individual, and then gene editing with CRISPR can be used to show that the identified mutation is directly responsible for the disease. This strategy has been used in the study of Barth syndrome, an X-linked genetic heart disease resulting from mutation affecting the Tafazzin gene. In cancer immunotherapy, CRISPR has been applied in autologous T-cells that can be engineered in vitro to express chimeric antigen receptors that specially recognize cancer cells. This has proven to be useful in treating lymphoma, leukemia and melanoma in mice.
Furthermore, the CRISPR approach has also been potentially applied to the in vivo treatment of various genetic diseases. Duchenne muscular dystrophy, a fatal genetic muscle disease is affected by in frame deletions affecting the dystrophin gene. Research laboratories of Charles A. Gersgacy, Eric Olson and Amy Wagers used an adeno associated virus to deliver the CRISPR editing system into the mouse with the purpose of removing the deleterious DNA sequences and restoring the reading frame of DMD gene in muscle stem cells. Genome editing in IPS cells or vitro cultured cells holds great potential to treat human diseases, especially single gene diseases. Patient derived IPS cells can be alter via CRISPR technology, selected in vitro and delivered back to a patient to replace defective cells or tissues.
-How are you recording your video? Include the material you will be preparing, the equipment you would be using, the applications you need, etc.
The material I will be preparing for my video will be a PowerPoint presentation that will be projected into a smart board and from there, I will record myself presenting the major points and the information I have found in regards to CRISPR.
-A general, broad outline of how you want to present your project
• Introduction
• History of CRISPR
• How does CRISPR work?
• Human diseases treated by CRISPR
• CRISPR Biomedical Trials
• Bioethics in regards to CRISPR
• Conclusion