Targeting the hallmarks of ageing: Pharmacological challenges and breakthroughs in CRISPR delivery systems and future prospects.

CRISPR has emerged as a next-generation gene-editing tool with the potential to target the molecular pathways associated with ageing and related disorders. It functions through RNA-guided Cas nucleases, directing DNA cleavage and utilizing the native DNA repair machinery for genetic manipulations. Advances in CRISPR technology have significantly enhanced the precision and flexibility of techniques for genome editing. The enzyme Cas9's ability to cut DNA at exact site has revolutionized genome editing by enabling accurate modifications within living eukaryotic cells. This review critically examines recent developments in CRISPR-based technologies, including Cas9, Cas12, base editing, prime editing, and CRISPR-mediated gene regulation. It highlights their rising applications in ageing research, with more emphasis on neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. The review also discusses the major pharmacological and translational challenges that currently limit clinical applications, including inefficient tissue-specific delivery, off-target genome editing, immunogenicity, manufacturing complexity, and long-term safety concerns. Also, recent progress in both, viral and non-viral delivery methods are critically evaluated, including adeno-associated viruses, lentivirus vectors, lipid nanoparticles, gold nanoparticles, exosomes, electroporation, and microinjection, is thoroughly discussed to highlight their therapeutic potential and translational limitations. Current studies indicate that CRISPR-based approaches have preclinical potential for targeting important hallmarks of ageing, particularly genomic instability, telomere attrition, and mitochondrial dysfunction. Other hallmarks of ageing, such as stem cell exhaustion, epigenetic modifications, and microbiome changes, are at earlier stages of development. Overall, this review describes future strategies for developing safe, precise, and clinically translatable CRISPR-based treatments to promote healthy ageing.