New lymphatic cell formation is associated with damaged brain tissue clearance after penetrating traumatic brain injury

Cellular and molecular mechanisms in vascular repair after traumatic brain injury: a narrative review

Traumatic brain injury (TBI) disrupts normal brain function and is associated with high morbidity and fatality rates. TBI is characterized as mild, moderate or severe depending on its severity. The damage may be transient and limited to the dura matter, with only subtle changes in cerebral parenchyma, or life-threatening with obvious focal contusions, hematomas and edema. Blood vessels are often injured in TBI. Even in mild TBI, dysfunctional cerebral vascular repair may result in prolonged symptoms and poor outcomes. Various distinct types of cells participate in vascular repair after TBI. A better understanding of the cellular response and function in vascular repair can facilitate the development of new therapeutic strategies. In this review, we analyzed the mechanism of cerebrovascular impairment and the repercussions following various forms of TBI. We then discussed the role of distinct cell types in the repair of meningeal and parenchyma vasculature following TBI, including endothelial cells, endothelial progenitor cells, pericytes, glial cells (astrocytes and microglia), neurons, myeloid cells (macrophages and monocytes) and meningeal lymphatic endothelial cells. Finally, possible treatment techniques targeting these unique cell types for vascular repair after TBI are discussed.

Firearm-Related Traumatic Brain Injury Homicides in the United States, 2000-2019

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of homicide-related death in the United States. Penetrating TBI associated with firearms is a unique injury with an exceptionally high mortality rate that requires specialized neurocritical trauma care.

OBJECTIVE

To report incidence patterns of firearm-related and nonfirearm-related TBI homicides in the United States between 2000 and 2019 by demographic characteristics to provide foundational data for prevention and treatment strategies.

METHODS

Data were obtained from multiple cause of death records from the National Vital Statistics System using Centers for Disease Control and Prevention's Wide-Ranging Online Data for Epidemiologic Research database for the years 2000 to 2019. Number, age-adjusted rates, and percent of firearm and nonfirearm-related TBI homicides by demographic characteristics were calculated. Temporal trends were also evaluated.

RESULTS

During the study period, there were 77 602 firearm-related TBI homicides. Firearms were involved in the majority (68%) of all TBI homicides. Overall, men, people living in metro areas, and non-Hispanic Black persons had higher rates of firearm-related TBI homicides. The rate of nonfirearm-related TBI homicides declined by 40%, whereas the rate of firearm-related TBI homicides only declined by 3% during the study period. There was a notable increase in the rate of firearm-related TBI homicides from 2012/2013 through 2019 for women (20%) and nonmetro residents (39%).

CONCLUSION

Firearm-related violence is an important public health problem and is associated with the majority of TBI homicide deaths in the United States. The findings from this study may be used to inform prevention and guide further research to improve treatment strategies directed at reducing TBI homicides involving firearms.

The lymphatic system: a therapeutic target for central nervous system disorders

The lymphatic vasculature forms an organized network that covers the whole body and is involved in fluid homeostasis, metabolite clearance, and immune surveillance. The recent identification of functional lymphatic vessels in the meninges of the brain and the spinal cord has provided novel insights into neurophysiology. They emerge as major pathways for fluid exchange. The abundance of immune cells in lymphatic vessels and meninges also suggests that lymphatic vessels are actively involved in neuroimmunity. The lymphatic system, through its role in the clearance of neurotoxic proteins, autoimmune cell infiltration, and the transmission of pro-inflammatory signals, participates in the pathogenesis of a variety of neurological disorders, including neurodegenerative and neuroinflammatory diseases and traumatic injury. Vascular endothelial growth factor C is the master regulator of lymphangiogenesis, a process that is critical for the maintenance of central nervous system homeostasis. In this review, we summarize current knowledge and recent advances relating to the anatomical features and immunological functions of the lymphatic system of the central nervous system and highlight its potential as a therapeutic target for neurological disorders and central nervous system repair.

Insights into nervous system repair from the fruit fly

Millions of people experience injury to the central nervous system (CNS) each year, many of whom are left permanently disabled, providing a challenging hurdle for the field of regenerative medicine. Repair of damage in the CNS occurs through a concerted effort of phagocytosis of debris, cell proliferation and differentiation to produce new neurons and glia, distal axon/dendrite degeneration, proximal axon/dendrite regeneration and axon re-enwrapment. In humans, regeneration is observed within the peripheral nervous system, while in the CNS injured axons exhibit limited ability to regenerate. This has also been described for the fruit fly Drosophila. Powerful genetic tools available in Drosophila have allowed the response to CNS insults to be probed and novel regulators with mammalian orthologs identified. The conservation of many regenerative pathways, despite considerable evolutionary separation, stresses that these signals are principal regulators and may serve as potential therapeutic targets. Here, we highlight the role of Drosophila CNS injury models in providing key insight into regenerative processes by exploring the underlying pathways that control glial and neuronal activation in response to insult, and their contribution to damage repair in the CNS.