Primary functions in stem cell maintenance include:Genome safeguarding: They silence transposable genetic elements (“jumping genes”), preventing DNA instability and maintaining cellular integrity. Guided differentiation: They regulate the exact pathways required for stem cells to mature into specialised cell types for tissue repair. Expanding scope in somatic tissues and pathologyWhile historically studied in reproductive biology, researchers have identified active PIWI/piRNA pathways across diverse somatic cell types. Their presence in adult tissues opens new avenues for therapeutic intervention:Cancer biology: Dysregulated PIWI/piRNA activity fuels cancer stem cell survival, driving treatment resistance and tumour progression. Neurodegeneration and ageing: Emerging evidence ties piRNA pathways to neural stem cell maintenance and healthy tissue longevity.