Endocytic Relay as a Potential Means for Enhancing Ligand Transport through Cellular Tissue Matrices: Analysis and...

Area of Science:

• Biophysics
• Mathematical Biology
• Tissue Engineering

Background:

• Peptide ligand transport in tissues faces challenges from cellular barriers and extracellular matrix.
• Understanding these transport mechanisms is crucial for drug delivery and developmental biology.

Purpose of the Study:

• To investigate if receptor-mediated endocytic trafficking can enhance peptide ligand transport through tissue.
• To develop a mathematical model simulating ligand flux in a two-phase tissue system (cell and matrix).

Main Methods:

• Modeled tissue as a packed bed reactor with distinct cell and matrix phases.
• Calculated steady-state flux of intact and degraded peptides through a 1D cell/tissue matrix.
• Analyzed the influence of environmental and molecular parameters on ligand transport.

Main Results:

• Ligand flux is significantly influenced by matrix to intracellular diffusivity ratio (D(m)/D(i)), extracellular proteolysis rate (k(prot)), and degradation fraction (f(1)).
• Enhancement is possible with D(m)/D(i) >= 1 at low degradation (f(1) <= 0.05) and no proteolysis.
• Higher degradation (f(1) up to 0.07) or significant proteolysis broadens the conditions for transport enhancement.

Conclusions:

• Receptor-mediated endocytosis can be a viable strategy to improve ligand transport in engineered tissues.
• Model provides insights into cytokine transport during embryonic development.
• Findings can inform strategies for delivering therapeutic ligands from controlled-release systems or engineered cells.