Delayed cell death signaling in traumatized central nervous system: hypoxia

Area of Science:

• Neuroscience
• Cell Biology
• Pathology

Background:

• Cell death occurs via necrosis or apoptosis, traditionally distinguished by morphology.
• The roles of apoptosis and necrosis in central nervous system (CNS) trauma remain debated.
• Electron microscopy is a key tool for distinguishing cell death mechanisms.

Purpose of the Study:

• To evaluate the roles of apoptosis and necrosis in cell death following spinal cord injury, stroke, and hypoxia/ischemia (H/I).
• To reconcile conflicting morphological and biochemical data on cell death mechanisms in CNS trauma.

Main Methods:

• Systematic review of studies published since 1997 using electron microscopy.
• Analysis of morphological criteria for necrosis and apoptosis.
• Assessment of biochemical markers for cell death, including DNA degradation and histone presence.
• Evaluation of DNA damage, repair, gene expression (bcl-like), and cytokine production in H/I.

Main Results:

• Spinal cord injury showed evidence for both necrosis and apoptosis through morphological and biochemical markers.
• Stroke predominantly exhibited necrosis as the major cell death pathway, despite some apoptotic biochemical markers.
• Hypoxia/ischemia (H/I) demonstrated consistent results for both necrosis and apoptosis via morphological and biochemical analyses, similar to spinal cord injury.
• In H/I, DNA damage/repair, bcl-like gene products, and cytokine production significantly influenced cell death outcomes.

Conclusions:

• Necrosis is the predominant cell death mechanism in stroke.
• Both necrosis and apoptosis contribute to cell death in spinal cord injury and H/I.
• DNA damage, gene expression, and inflammation are critical in H/I-induced cell death.