Next-Generation Gene Editing Technology Minimizing Double-Strand Breaks Expands Treatment Scope Beyond Blood Disorders to Chronic and Refractory Diseases
Background
The emergence of clustered regularly interspaced short palindromic repeats (CRISPR-Cas9) technology marked a new turning point in gene therapy research. First-generation gene scissors, which selectively cut target sequences, are considered to have opened the possibility of conquering intractable diseases. However, the double-strand break (DSB) method, which cuts both strands of target DNA, revealed clear limitations in clinical application.
This is because random base insertions or deletions occur during the cell's process of repairing the severed DNA. Risks of inducing genomic structural abnormalities, such as large-scale chromosomal deletions or translocations, have also been continuously raised. This is the background behind the delay in developing in vivo direct-injection therapeutics, which face high thresholds for safety verification.
Early therapeutic development remained limited to ex vivo methods, where patient cells are removed from the body for correction. Research has been concentrated on treating hematopoietic stem cell (HSC) diseases, which require cell culture. The technical challenge of directly delivering gene editing materials to in vivo solid organs has acted as a hurdle preventing the expansion of indications.
Key Findings
Recently, the field of genome editing has been shifting its focus toward next-generation technologies that overcome the safety issues of first-generation technology. Base editing (BE) and prime editing (PE) are representative examples. These two technologies work by replacing only specific target bases or precisely inserting/deleting desired sequences without completely cutting the DNA double strand. It is explained that they significantly reduce the frequency of DSB occurrence, thereby reducing the risk of chromosomal damage and genomic instability.
As precision in binding to target sequences has improved, off-target effects at non-target sites have also decreased noticeably. Progress in actual clinical pipelines is becoming evident.
A representative achievement in translational medicine is the treatment of hemoglobinopathies using ex vivo editing technology. The approach of correcting defects in patient-derived hematopoietic stem cells (HSCs) and reinfusing them into the body is establishing itself as a standard treatment. Clinical results have accumulated, demonstrating that inducing normal hemoglobin expression in patients with sickle cell anemia significantly reduces transfusion dependence.
In the field of in vivo delivery, achievements in genome editing using lipid nanoparticles (LNPs) are prominent. The LNP delivery system is a tool that has proven the possibility of targeting specific organs by safely transporting mRNA and guide RNA complexes. A representative example is the result of animal experiments that directly correct genes causing metabolic diseases in vivo by leveraging the liver's tissue-specific accumulation characteristics. The flow of gene editing targets is expanding beyond blood diseases to the area of complex chronic diseases such as diabetes, cancer, neurodegenerative diseases, and autoimmune diseases.
Limitations to be overcome still exist. The risk of minute residual off-target mutations and the in vivo immune response induced by bacteria-derived Cas proteins are major challenges. The limitation that LNP delivery efficiency to target tissues other than the liver is low is also an area for improvement. Additionally, the bioethical debate surrounding embryo or germline editing also requires social consensus.
Significance and Outlook
Next-generation genome editing technology is expected to establish itself as a precision medicine tool for controlling a wide range of chronic intractable diseases, going beyond single-gene defect therapeutics. The emergence of BE and PE technologies, which reduce DSB risks, has raised the safety standards of gene therapy by one level.
It is pointed out that detailed technological advancement must support the full clinical adoption of gene editing. The accuracy of guide RNA design and the level of enzyme engineering must be enhanced to exclude off-target mutations. Developing next-generation drug delivery systems capable of delivering editing tools to various target organs beyond the liver is also an essential task.
The establishment of an institutional management system is also an urgent matter. Regulatory guidelines that strictly distinguish between therapeutic somatic cell editing and germline genome manipulation are required. Once a long-term genome stability tracking system is established, precision genome editing technology is expected to become the key to treating human diseases.
The advent of CRISPR-Cas9 technology has revolutionized genome editing, enabling precise modifications to the human genome with unprecedented accuracy and sequence specificity. This review examines current mechanistic insights, translational advances, and clinical developments in gene editing, focusing on applications in diabetes mellitus, cancer, hematologic disorders, neurodegenerative diseases, and autoimmune pathologies. This study provides a comprehensive analysis of recent literature on CRISPR-based genome editing, emphasizing next-generation modalities like base editing and prime editing, and their impact on target specificity and genomic integrity. Therapeutic strategies involving ex vivo editing of hematopoietic stem cells and in vivo delivery approaches, including lipid nanoparticle-mediated systems, are evaluated. Base editing and prime editing have improved sequence specificity and reduced double-strand DNA breaks, enhancing safety profiles. Ex vivo editing of hematopoietic stem cells for hemoglobinopathies and in vivo genome editing via lipid nanoparticles show translational promise. However, limitations persist: off-target effects, immunogenicity, delivery inefficiencies, and ethical concerns surrounding germline editing require careful consideration. Gene editing technologies show potential for treating previously intractable diseases. Technical, safety, and ethical challenges must be addressed through continued refinement of editing platforms, rigorous scientific validation, and the establishment of robust governance frameworks to ensure safe and responsible translation into clinical medicine.
The convergence of next-generation genome editing and LNP delivery systems represents a key inflection point that will transform the landscape of clinical practice and the pharmaceutical industry. Existing ex vivo hematopoietic stem cell therapies inevitably require high-dose anticancer conditioning regimens to deplete the patient's bone marrow and months of hospitalization in sterile rooms, resulting in treatment costs reaching billions of won and imposing an extreme physical burden on patients.
On the other hand, if LNP-based in vivo direct-injection therapeutics are commercialized, it will become possible to correct genes related to liver disease or type 2 diabetes in a single visit via one intravenous injection at a general outpatient clinic. It is expected to lower manufacturing costs and significantly improve patient access to treatment by enabling the mass production and supply of drugs in an off-the-shelf form, without the need for expensive customized cell manipulation processes. This is a practical leap for gene editing technology, which was confined to rare genetic diseases, to expand into treatments for chronic diseases.