Neurogenesis and glial impairments in congenital hydrocephalus: insights from a BioGlue-induced fetal lamb model.

Abstract

Background: Congenital hydrocephalus (HCP) is a prevalent condition, that leads to fetal cerebral ventricle dilation and increased intracranial pressure. It is associated with significant neurological impairments, partly due to the disruption of neurogenesis and gliogenesis. This study aims to investigate alterations in the proliferation and differentiation of neural progenitor cells (NPCs) in a fetal lamb model of obstructive HCP induced by intracisternal BioGlue injection, to identify the potential optimal intervention time for prenatal surgery.

Methods: This study involved 22 fetal lambs, divided into control (n = 10) and HCP (n = 12) groups with hydrocephalus induced at approximately 85-90 gestational days. Histological and molecular techniques, including hematoxylin and eosin staining, triple immunofluorescence, Western blot analysis, and RT-qPCR, were utilized to assess changes in NPCs, astrocytes, and oligodendrocytes across three different gestational stages (E105, E125, and E140). The analysis of data was done by using multiple (unpaired) two-sample t-test and was represented as mean and standard deviation.

Results: HCP led to significant disruptions in the ventricular zone (VZ), with the translocation of NPCs into the intraventricular CSF and formation of periventricular heterotopias. This study revealed an initial surge in the expression of NPC markers (Pax6 and Sox2), which decreased as HCP progressed. Astroglia reaction intensified, as indicated by increased expression of GFAP, vimentin, and aquaporin 4, particularly at later stages of pregnancy (p < 0.001, p < 0.001 and p < 0.001, control and HCP E140, respectively). Myelin formation was also adversely affected, with reduced expression of oligodendrocyte markers (Olig2 and Sox10, p = 0.01 and p = 0.009, control and HCP E140, respectively) and myelin proteins (MOBP, MOG and MBP, p = 0.02, p = 0.049 and p = 0.02 control and HCP E140, respectively).

Conclusions: This study contributed to clarify the profound impact of congenital HCP on neurogenesis and gliogenesis in an experimental fetal lamb model. The VZ disruption and altered expression of key neurogenic and glial markers suggested a significant pathological process underlying neurodevelopmental abnormalities. The findings suggested a potential window for prenatal surgical intervention between E105 and E125 in the sheep model, offering new avenues for prenatal therapeutic approaches and improving surgical outcomes in affected fetuses and neonates.