Micronuclei: origins, assays, mechanisms, diseases and treatments.

Micronuclei are small, independent cytoplasmic structures containing nuclear material. They typically form during cell division due to DNA damage or division abnormalities, serve as biomarkers of genetic damage, and are closely associated with chromosomal instability (CIN). Emerging evidence suggests that micronuclei actively promote and exacerbate CIN, with significant implications in disease pathology and potential therapeutic applications. This review provides a comprehensive overview of micronuclei by exploring their origins, formation mechanisms, and functional consequences, and detailing the fate of micronuclei post-formation, which is essential for elucidating their role in genomic instability and potential therapeutic implications. Furthermore, micronuclei can contribute to extreme chromosomal shattering and genomic instability. These processes are increasingly recognized as critical contributors to disease progression, particularly in cancer. Although micronuclei have traditionally been viewed as markers of genomic instability, recent evidence suggests that they may also serve functional roles. Their potential use as treatments for certain diseases appears theoretically feasible; however, challenges remain in selectively targeting cells to induce the formation of favorable micronuclei and maintain optimal immune responses. Addressing these questions could open new avenues for therapeutic interventions.