Diabetes-induced morphological, biomechanical, and compositional changes in ocular basement membranes

Area of Science:

• Ophthalmology
• Diabetic Retinopathy Research
• Biomaterials Science

Background:

• Diabetic complications affect ocular tissues, particularly basement membranes (BMs).
• Long-term diabetes mellitus is associated with structural alterations in retinal vascular BMs and the inner limiting membrane (ILM).
• Understanding these changes is crucial for managing diabetic eye disease.

Purpose of the Study:

• To investigate the structural, compositional, and biomechanical changes in ocular basement membranes (BMs) in long-term diabetes.
• To compare retinal vascular BMs and the ILM from diabetic and non-diabetic human eyes.
• To identify specific protein alterations contributing to BM changes in diabetes.

Main Methods:

• Light and transmission electron microscopy (TEM) for structural analysis.
• Atomic force microscopy (AFM) to assess ILM thickness and stiffness.
• Immunocytochemistry and western blots to analyze protein composition (agrin, fibronectin, tenascin).

Main Results:

• A significant increase in the thickness of retinal vascular BMs and ILM was observed in diabetic eyes.
• Atomic force microscopy confirmed increased ILM thickness and stiffness in diabetic eyes.
• Diabetic BMs showed increased concentrations of agrin, fibronectin, and tenascin, with fibronectin and tenascin elevated in microaneurysms.
• BM thickening resulted from both upregulated standard proteins and the expression of diabetes-specific extracellular matrix proteins.

Conclusions:

• Long-term diabetes induces significant morphological, biomechanical, and compositional alterations in retinal vascular BMs and the ILM.
• These changes are characterized by increased BM thickness and stiffness, alongside altered protein composition.
• The findings highlight the complex matrix remodeling in diabetic ocular tissues, involving both known and novel extracellular matrix proteins.