Flow through interstitium and other fibrous matrices.

Area of Science:

• Biomedical Engineering
• Tissue Engineering
• Biophysics

Background:

• Interstitial hydraulic conductivity is a critical biophysical property of tissues.
• Understanding the factors governing interstitial conductivity is essential for tissue engineering and understanding physiological processes.
• Previous hypotheses suggested glycosaminoglycan (GAG) concentration as the primary determinant of interstitial conductivity.

Purpose of the Study:

• To review the relationship between interstitial hydraulic permeability and tissue chemical composition.
• To evaluate the role of GAG concentration in governing interstitial conductivity.
• To elucidate the contributions of various fibrous elements to interstitial conductivity.

Main Methods:

• Porous matrix theory was employed to analyze interstitial hydraulic permeability.
• Quantitative considerations of in vitro GAG matrices were used.
• Correlation analysis between conductivity and concentrations of GAG and collagen was performed.

Main Results:

• Interstitial conductivity shows a negative correlation with both GAG and collagen concentrations across diverse tissues.
• In vitro studies indicate that no single fibrous element (e.g., GAG) at high concentration alone explains low tissue conductivity.
• Low interstitial conductivity arises from the interactive effects of collagen fibrils, GAG, and proteoglycan core protein.

Conclusions:

• The low interstitial conductivity observed in most tissues is a multifactorial phenomenon.
• Proteoglycan complexes play a major role, significantly amplified by the collagen fibril network.
• A comprehensive understanding of fibrous element interactions is necessary to fully explain interstitial conductivity.