Vitreous Fibrillar Structure and Interfibrillar Composition in Adult Mice.

Area of Science:

• Ophthalmology
• Biomedical Science
• Extracellular Matrix Research

Background:

• Mice are crucial models for human eye diseases, yet their vitreous humor structure and composition remain poorly understood.
• The vitreous fibrillar network is vital for biomechanical integrity, but its specific components and organization in mice are largely uncharacterized.

Purpose of the Study:

• To comprehensively characterize the structure and composition of mouse vitreous fibrils and their interfibrillar space.
• To investigate the impact of intravitreal injections on vitreous architecture and cellular responses.

Main Methods:

• Utilized classical histology, picrosirius red-polarization, immunofluorescence, lectin histochemistry, and hyaluronic acid binding protein assays.
• Employed Airyscan microscopy for high-resolution analysis of component distribution along vitreous fibrils.
• Studied healthy adult C57/BL6J mice for vitreous characterization and intravitreal injection impact.

Main Results:

• Mouse vitreous fibrils are composed of collagen cores wrapped in glycoproteins (fibrillin 1, fibronectin, laminin, collagen IV), N-acetyl galactosamine, and hyaluronan.
• The interfibrillar space was found to be devoid of these components.
• Intravitreal saline injection triggered inflammation, increasing fibril density and leading to macrophage/hyalocyte infiltration, suggesting phagocytosis and vitreous remodeling.

Conclusions:

• Mouse vitreous fibrils consist of glycoprotein-sheathed collagen, with hyaluronan and glycoproteins absent between fibrils, potentially explaining lower viscosity than humans.
• Intravitreal injections act as an inflammatory insult, disrupting the vitreous fibril network and activating resident immune cells like macrophages and hyalocytes.
• This research provides a detailed structural understanding of the mouse vitreous, crucial for interpreting disease models and therapeutic interventions.