CRISPR-mediated genome editing and human diseases

Abstract

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) technology has emerged as a powerful technology for genome editing and is now widely used in basic biomedical research to explore gene function. More recently, this technology has been increasingly applied to the study or treatment of human diseases, including Barth syndrome effects on the heart, Duchenne muscular dystrophy, hemophilia, β-Thalassemia, and cystic fibrosis. CRISPR/Cas9 (CRISPR-associated protein 9) genome editing has been used to correct disease-causing DNA mutations ranging from a single base pair to large deletions in model systems ranging from cells in vitro to animals in vivo. In addition to genetic diseases, CRISPR/Cas9 gene editing has also been applied in immunology-focused applications such as the targeting of C-C chemokine receptor type 5, the programmed death 1 gene, or the creation of chimeric antigen receptors in T cells for purposes such as the treatment of the acquired immune deficiency syndrome (AIDS) or promoting anti-tumor immunotherapy. Furthermore, this technology has been applied to the genetic manipulation of domesticated animals with the goal of producing biologic medical materials, including molecules, cells or organs, on a large scale. Finally, CRISPR/Cas9 has been teamed with induced pluripotent stem (iPS) cells to perform multiple tissue engineering tasks including the creation of disease models or the preparation of donor-specific tissues for transplantation. This review will explore the ways in which the use of CRISPR/Cas9 is opening new doors to the treatment of human diseases.

Keywords: CRISPR; DNA double-stranded break; Genome editing; Human diseases; iPS cells.

Fig. 1

CRISPR working mechanism. Guide RNA hybridizes with 20bp genomic DNA sequence and directs Cas9 endonuclease (colored in pink) to generate a double strand break which is usually located between 16 and 17bp region in the target sequence. Subsequently, DNA Mutagenesis is generated from DNA repair process, through either the non-homologous end-joining (NHEJ) or the homology-directed repair (HDR) mechanism. The final mutation could include insertion or deletion with several base pairs of DNA sequences (NHEJ pathway), or replacement with a particular DNA sequence used as a marker for further study (encoding for a fluorescence protein, tag protein, antibiotics, or the recognition sequence for a restriction enzyme digestion).

Fig. 2

CRISPR engineering for the clinics. Advances in DNA sequencing technology make it easier to identify the disease-driving genetic mutations. Meanwhile, the patient-derived iPS cells have been established to model human diseases and drug discovery in vitro. The deteriorating mutations can be corrected via the use of CRISPR-mediated gene editing, and the modified cells can be then utilized as patient-specific medicine.