Mitochondrial disorders are so far categorized as incurable diseases. Several medical research and experiments have been conducted in the past (and in the present) for these disorders.
A recent research paper published on January 18, 2022, by Dr. Minczuk, a postdoctoral researcher, and his colleagues at the MRC Mitochondrial Biology Unit of the University of Cambridge claims that mitochondrial disorders are curable with new treatments developed using gene-editing techniques.
The research has resulted in the development of a biological tool known as a mitochondrial base editor. The claim can be proven with the recent experiments that manipulated the mitochondrial genome in living mice using the mitochondrial base editor and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR).
Mitochondrial-Based Editor - Overview
The mitochondrial-based editor is also dubbed a double-stranded DNA deaminase (DddA) -derived cytosine base editor (DdCBE). It can make the desired amount of changes to the mitochondrial DNA in humans, according to the research.
The DdCBE looks for a specific base pair sequence, which is made up of the A, C, G, and T molecules that make up DNA. It then switches the DNA base, in this case from C to T. This would allow the editor to fix particular cells that cause mitochondrial dysfunction.
Similar results were achieved in another experiment that was made using the CRISPR gene editing method.
The Experiment Using CRISPR Gene-Editing
CRISPR is a strong genome editing and targeting technology based on c molecules, which is a portion of bacterial immune systems that identify DNA sequence and defected DNA sequence. It has a high possibility of curing hereditary mitochondrial diseases.
CRISPR (Cas9) and single-guide RNA (sgRNA) are the most extensively used constructs of CRISPR gene editing. This and other upcoming CRISPR-based gRNA editing techniques could be extremely useful for modifying mitochondrial DNA.
However, because mRNA import into the mitochondria is challenging, a key roadblock in the development of CRISPR-Cas9-mediated gene editing of the mitochondrial genome is the absence of effective techniques to transfer gRNA through the mitochondrial membrane.
CRISPR is a revolutionary technological advancement in the life science business that has paved the way for various medical discoveries aimed at addressing primary issues of chronic diseases around the world. CRISPR gene editing has revolutionized gene editing by lowering response time and complexity, improving accuracy, safety, and efficiency, and spurring a slew of new ideas.
CRISPR gene editing has the potential to alter the human genome and adjust disease states, but it is fraught with ethical and social considerations. The global CRISPR gene editing market was worth $1.08 billion in 2020, and it's predicted to grow to $18.85 billion by 2031, with a CAGR of 29.60% during the forecast period.
Previous Research Developments
In 2018, researchers from the University of Cambridge's MRC Mitochondrial Biology Unit used an experimental gene therapy treatment on mice and were partially successful in targeting and destroying defective mitochondrial DNA in heteroplasmic cells, allowing healthy mitochondria to take their place.
Why Mitochondrial DNA Needs Editing?
Mitochondria are known as the powerhouse of the cell. It exists in every cell of the body. The mitochondria consist of minute mitochondrial DNA that forms 0.1% of the human DNA.
Each cell contains approximately 1,000 duplicates of mitochondrial DNA, and the fraction of these that are damaged or altered determines whether or not a person will develop the mitochondrial disease.
The significance of this DNA is that it passes down, as it is, through generations. If this DNA turns out to be faulty, then it becomes a hereditary disease. Mitochondrial diseases have fatal consequences that affect 1 in 5,000 people.
The presence of normal and defective mutants in the mitochondrial genes in cells is known as heteroplasmy. Whereas, a cell is homoplasmic if it lacks healthy mitochondrial DNA. It can be connected to mitochondrial illnesses caused by abnormalities in mitochondrial systems.
For a mitochondrial disease to emerge, more than 60% of the mitochondria in a cell must be defective. The more defective mitochondria are present in the cells, the more serious the diseases will be. The disease could be treated if some faulty DNA could be reduced.
Mitochondrial abnormalities are usually caused by mutations in the mitochondrial genome (mtDNA) or changes in nuclear genes that code for mitochondrial proteins.
Mitochondrial disorders can appear as a wide range of illnesses, ranging from modest hearing loss to severe progressive multisystem disorders, depending on the level of heteroplasmy. Due to genetic mutations, genetic illnesses such as hemophilia, sickle cell anemia, and beta-thalassemia are the leading causes of death worldwide.
The advances in the healthcare and medicine industry are opening avenues for the treatment of incurable diseases.