Persistent reelin-expressing Cajal-Retzius cells in polymicrogyria.

Area of Science:

• Neuroscience
• Developmental Biology
• Pathology

Background:

• Cajal-Retzius (CR) cells are crucial for mammalian corticogenesis, secreting reelin essential for neuronal migration and cortical lamination.
• Reelin deficiency causes 'reeler' phenotype in mice and lissencephaly in humans.
• Focal reelin/CR cell increases correlate with cortical malformations like microgyria in animal models.

Purpose of the Study:

• To investigate the role of CR cells and reelin expression in human polymicrogyria.
• To explore the occurrence, distribution, morphology, and reelin expression of CR cells in polymicrogyria.

Main Methods:

• Studied pathological sections from 12 human polymicrogyria cases (21 weeks gestation to 10 years).
• Compared CR cell characteristics and reelin expression with age-matched controls.
• Analyzed CR-like cell distribution, morphology, and reelin positivity in polymicrogyric and adjacent cortical areas.

Main Results:

• CR-like cells were more numerous and persisted longer (up to 10 years) in most polymicrogyria cases compared to controls.
• These cells clustered, particularly in fused molecular layers and overlying leptomeningeal heterotopia in polymicrogyria.
• Clusters were also observed in adjacent non-polymicrogyric cortex, but not in controls.

Conclusions:

• Increased numbers and prolonged persistence of reelin-expressing CR-like cells are associated with human polymicrogyria.
• The aggregation of these cells in specific malformed regions suggests a significant role in polymicrogyria pathogenesis.
• Findings support the involvement of reelin signaling in developmental dynamics underlying polymicrogyria.