Ageing is a complex biological process characterised by the accumulation of molecular and cellular damage leading to functional decline and an increased risk of chronic disease and geriatric syndromes. Despite data showing that lifestyle modifications, such as caloric restriction and exercise, can lead to healthy ageing and greatly reduce the incidence of chronic disorders, no medical therapies exist to delay or prevent these conditions effectively. We also lack tools to effectively track the ageing process in a manner that predicts an individual's risk of chronic disease and assess response to lifestyle or medical interventions. This review explores the emerging role of microRNAs (miRNAs), which are small non-coding RNAs that regulate gene expression, as a unifying mechanism underlying the biology of ageing and age-related conditions, including cardiovascular and neurodegenerative diseases, metabolic syndromes, musculoskeletal disorders such as sarcopenia, osteoarthritis and osteoporosis, and various cancers. We also examine the interactions of miRNAs with various hallmarks of ageing, such as DNA damage, cellular senescence, and mitochondrial dysfunction. We then explore the challenges of translating miRNA-based approaches from preclinical promise to clinical utility, emphasizing the need for trial-level validation to correlate miRNA profiles with clinically meaningful, patient-centred endpoints. By consolidating these findings, this article puts miRNAs forward as a pivotal mechanism in geroscience, offering a novel framework to mitigate ageing-related multimorbidity and bridge the gap between lifespan and healthspan.

Mesenchymal stem cells (MSCs) of placental origin hold great promise in tissue engineering and regenerative medicine for diseases affecting cartilage and bone. However, their utility has been limited by their tendency to undergo premature senescence and phenotypic drift into adipocytes. This study aimed to explore the potential involvement of a specific subset of aging and antiaging genes by measuring their expression prior to and following in vitro-induced differentiation of placental MSCs into chondrocytes and osteoblasts as opposed to adipocytes. The targeted genes of interest included the various LMNA/C transcript variants (lamin A, lamin C, and lamin A∆10), sirtuin 7 (SIRT7), and SM22α, along with the classic aging markers plasminogen activator inhibitor 1 (PAI-1), p53, and p16^INK4a. MSCs were isolated from the decidua basalis of human term placentas, expanded, and then analyzed for phenotypic properties by flow cytometry and evaluated for colony-forming efficiency. The cells were then induced to differentiate in vitro into chondrocytes, osteocytes, and adipocytes following established protocols. The mRNA expression of the targeted genes was measured by RT-qPCR in the undifferentiated cells and those fully differentiated into the three cellular lineages. Compared to undifferentiated cells, the differentiated chondrocytes demonstrated decreased expression of SIRT7, along with decreased PAI-1, lamin A, and SM22α expression, but the expression of p16^INK4a and p53 increased, suggesting their tendency to undergo premature senescence. Interestingly, the cells maintained the expression of lamin C, which indicates that it is the primary lamin variant influencing the mechanoelastic properties of the differentiated cells. Notably, the expression of all targeted genes did not differ from the undifferentiated cells following osteogenic differentiation. On the other hand, the differentiation of the cells into adipocytes was associated with decreased expression of lamin A and PAI-1. The distinct patterns of expression of aging and antiaging genes following in vitro-induced differentiation of MSCs into chondrocytes, osteocytes, and adipocytes potentially reflect specific roles for these genes during and following differentiation in the fully functional cells. Understanding these roles and the network of signaling molecules involved can open opportunities to improve the handling and utility of MSCs as cellular precursors for the treatment of cartilage and bone diseases.