Role of myofibroblasts in pseudointima formation

Area of Science:

• Vascular Surgery
• Biomaterials Science
• Cell Biology

Background:

• Dacron grafts are widely used for aortic repair.
• Understanding the cellular mechanisms of graft healing is crucial for improving outcomes.

Purpose of the Study:

• To investigate the cellular composition and ultrastructure of pseudointima in Dacron grafts.
• To determine the origin and differentiation of cells forming the luminal lining of Dacron prostheses.

Main Methods:

• Light microscopy, scanning electron microscopy, and transmission electron microscopy (TEM).
• Analysis of Dacron grafts explanted from canine thoracoabdominal aortas (1-10 months post-implantation).

Main Results:

• Fibroblast-derived pseudointima formed a smooth luminal lining.
• Crimped graft surfaces showed nonuniform cell alignment due to turbulent flow.
• TEM revealed infiltration of fibroblasts, macrophages, vasa, and nerves into graft interstices.
• Luminal cells were identified as myofibroblasts, not true endothelial cells, with a transitional gradient from fibroblasts.
• Myofibroblasts actively produced ground substances and extracellular matrix.

Conclusions:

• The cellular lining of healed Dacron grafts originates from modified fibroblasts or multipotential cells.
• These cells exhibit plasticity, transforming into endothelioid and myoblastoid phenotypes based on functional demands.
• This cellular adaptation is key to the successful integration and function of Dacron prostheses.