Oyster hydrolysate attenuates osteoarthritis progression by modulating inflammatory signaling and extracellular matrix homeostasis.

Neurodegenerative conditions affect millions of people worldwide and represent an important and growing cause of functional decline, long-term disability, and mortality []. Three leading causes of neurodegeneration are Alzheimer’s disease (AD), Parkinson’s disease (PD), and traumatic brain injury (TBI). In 2022, an estimated 416 million people worldwide were living across the AD continuum, encompassing individuals with preclinical AD, prodromal AD, and AD dementia. This number represents ~20% of the global population aged 50 and older []. Estimates from 2019 included more than 8.5 million individuals diagnosed with PD globally [,]. Moreover, the global incidence of TBI recently was estimated at ~21 million annually []. While these numbers represent people directly afflicted with these conditions, their impacts are felt much more broadly when one considers interpersonal relationships, the stresses on care providers, and the increases in healthcare demand and spending. To prevent and treat neurodegenerative disorders, there remains a need to better understand the molecular mechanisms underlying the regeneration of both neurons and glia. In this review, we define ‘neurogenesis’ as the generation of new neurons, and use ‘gliogenesis’ to describe the generation of new glial cells. We recognize that some authors refer to the generation of either neurons or glia as ‘neurogenesis’, most likely because some glia share precursors with neurons during development in vertebrates as well as in . However, we make the distinction because neurogenesis and gliogenesis represent different aspects of regeneration, with glial cells having unique roles in cleaning up cellular debris, providing scaffolding, improving signaling, and participating in immune responses [,]. We also note that gliogenesis is common during homeostasis of the vertebrate brain while neurogenesis is not [,]. A variety of laboratory models, including non-human primates, mice, zebrafish, , , and cultured mammalian neural stem cells, continue to provide insights into both neural degeneration and neural regeneration [,,,,,]. As in other regeneration models, injury can be used as a tool in the nervous system to initiate a regenerative response. This provides controlled spatial and temporal systems in which to study how specific tissues respond to damage, including relevant cellular and molecular mechanisms. Injury models allow researchers to investigate the importance of cell activation, cell cycle progression, blastema formation, morphogenesis, and wound healing during regeneration []. Additionally, studying the pathways involved in injury responses, including scarring and regeneration, can help us understand the complex processes that ensue upon tissue damage. Ultimately, injury models help bridge the gap between basic science and clinical applications, offering insights into how organisms repair themselves and how these processes can be harnessed for regenerative medicine.