Strain-Dependent Diffusivity of Small and Large Molecules in Meniscus

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Orthopedics

Background:

• The meniscus, crucial for knee joint health, lacks full vascularization, relying on diffusion for nutrient and protein delivery.
• Understanding solute transport under physiological compressive strains is vital for comprehending meniscus pathophysiology.

Purpose of the Study:

• To investigate how compressive strain affects the diffusive properties of meniscus fibrocartilage.
• To quantify the strain-dependent diffusion of small and large molecules within the meniscus extracellular matrix.

Main Methods:

• Porcine medial meniscus samples were subjected to 0%, 10%, and 20% compressive strain.
• Fluorescence recovery after photobleaching was used to measure the diffusivity of fluorescein (332 Da) and 40 kDa dextran (D40K).
• Diffusion coefficients and anisotropic ratios were determined under varying strain levels.

Main Results:

• Fluorescein diffusivity was consistently faster than that of D40K.
• Diffusion coefficients for both molecules significantly decreased by up to ~45% as compressive strain increased.
• The anisotropic ratios remained unaffected by applied strain, suggesting preserved diffusive pathways.

Conclusions:

• Compressive strain significantly impedes solute diffusion within the meniscus fibrocartilage.
• Findings highlight the impact of mechanical loading on meniscus transport properties.
• This research provides critical data for understanding meniscus dysfunction and developing regenerative therapies.