Chronological and Replicative Aging of CD51+/PDGFR-α+ Pulp Stromal Cells

Senescence and fibrosis in salivary gland aging and disease

Salivary gland hypofunction is highly prevalent in aged and diseased individuals leading to significant discomfort and morbidity. One factor that contributes to salivary gland hypofunction is cellular aging, or senescence. Senescent cells can impair gland function by secreting paracrine-acting growth factors and cytokines, known as senescence-associated secretory phenotype (SASP) factors. These SASP factors stimulate inflammation, propagate the senescent phenotype through the bystander effect, and stimulate fibrosis. As senotherapeutics that target senescent cells have shown effectiveness in limiting disease manifestations in other conditions, there is interest in the use of these drugs to treat salivary gland hypofunction. In this review, we highlight the contribution of senescence and fibrosis to salivary gland pathologies. We also discuss therapeutic approaches to eliminate or modulate the senescent SASP phenotype for treating age-related salivary gland diseases and extending health span.

The Role of Sensory Nerves in Dental Pulp Homeostasis: Histological Changes and Cellular Consequences after Sensory Denervation

Homeostatic maintenance is essential for pulp function. Disrupting pulp homeostasis may lead to pulp degeneration, such as fibrosis and calcifications. Sensory nerves constitute a crucial component of the dental pulp. However, the precise involvement of sensory nerves in pulp homeostasis remains uncertain. In this study, we observed the short-term and long-term histological changes in the dental pulp after inferior alveolar nerve transection. Additionally, we cultured primary dental pulp cells (DPCs) from the innervated and denervated groups and compared indicators of cellular senescence and cellular function. The results revealed that pulp fibrosis occurred at 2 w after the operation. Furthermore, the pulp area, as well as the height and width of the pulp cavity, showed accelerated reductions after sensory denervation. Notably, the pulp area at 16 w after the operation was comparable to that of 56 w old rats. Sensory denervation induced excessive extracellular matrix (ECM) deposition and increased predisposition to mineralization. Furthermore, sensory denervation promoted the senescence of DPCs. Denervated DPCs exhibited decelerated cell proliferation, arrest in the G2/M phase of the cell cycle, imbalance in the synthesis and degradation of ECM, and enhanced mineralization. These findings indicate that sensory nerves play an essential role in pulp homeostasis maintenance and dental pulp cell fate decisions, which may provide novel insights into the prevention of pulp degeneration.

Aging and Oral Health: Biological and Sociobehavioral Perspectives

As the life expectancy and growth of the aging population increase globally, efforts to promote healthy longevity become more important. Holistic policy guidelines and actions have been designed to advocate and fortify healthy aging at multiple levels. Oral health, a fundamental contributor of overall health and well-being, forms a core part of the noncommunicable disease agenda within the sustainable development goals set by the World Health Organization. Aging significantly heightens the risk of myriad oral disorders and other noncommunicable diseases. As of 2019, oral disorders accounted for 8.9 million disability-adjusted life-years in individuals older than 60 y. In addition to the development of multidisciplinary aging-friendly policies to promote healthy aging, basic biology and translational research has been encouraged that focuses on deciphering the underlying mechanisms involved in age-related physical and cognitive decline or dysregulation of oral tissues. Given the relevance of oral health aging as a critical component of the One Health Initiative, this special issue encompasses a collection of articles dedicated to recent advances in the behavioral and social implications of age-related oral diseases and tooth loss on several aspects of the quality of life of adults as they age. Furthermore, it includes articles detailing molecular mechanisms associated with cellular aging and their implications for oral tissue health, periodontal disease severity, and the regenerative potential of stem cells.