A stereotactic injection method to establish a clinically relevant germinal matrix hemorrhage murine model

A germinal matrix hemorrhage (GMH) model that recapitulates both GMH-like tissue injury and intraventricular hemorrhage via injection of clostridial collagenase into the ganglionic eminence (GE; germinal matrix) has been well established in rats.

A dose-response injection study was performed using weight-based collagenase doses extrapolated from established rat models. Reproducible targeting of the right GE in neonatal mice was achieved by the following stereotactic injection protocol: needle entry 1.1 mm lateral and 1.5 mm anterior to lambda, insertion to a depth of 1.3 mm prior to collagenase injection.

High rates of ventriculomegaly were observed across collagenase injection groups compared with controls, with a significant dose-dependent effect. The weight-based equivalent dose of collagenase (0.024 collagenase digestion units [CDU] /μL) was identified as the optimal dose for this neonatal mouse model compared to lower or higher CDUs. Positive GFAP and CD68 labeling suggested accurate GE targeting. Intraventricular blood injection was used as a positive control.

A neonatal mouse model that recapitulates GMH-like tissue injury using stereotactic injection method and weight-based dosing extrapolated from prior reported rat models, while achieving high rates of hydrocephalus with minimal complications and mortality, has not yet been well established.

Our group developed a GMH/posthemorrhagic hydrocephalus (PHH) mouse model with reproducible stereotactic injection coordinates. This model provides a foundation for future studies using genetically modified mouse strains aimed to advance understanding of the inflammation-related molecular mechanisms underlying acquired hydrocephalus and to support the preclinical evaluation of potential therapeutic interventions.