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Porous polyurethane tubes as vascular graft
K Fujimoto1, M Minato, S Miyamoto
1Research Center for Biomedical Engineering, Kyoto University, Japan.
Journal of Applied Biomaterials : an Official Journal of the Society for Biomaterials
|January 1, 1993
Summary
Porous polyurethane vascular grafts show promise, with larger pore sizes (≥5.5 µm) correlating to longer patency. Further research is needed to optimize neointima formation for improved long-term performance.
Area of Science:
- Biomaterials Science
- Regenerative Medicine
- Vascular Surgery
Background:
- Vascular grafts are crucial for replacing damaged or diseased blood vessels.
- Developing synthetic grafts with appropriate mechanical properties and biocompatibility remains a challenge.
- Polyurethanes offer tunable properties but require optimization for vascular applications.
Purpose of the Study:
- To fabricate and characterize porous poly (ether urethane) vascular grafts.
- To evaluate the influence of pore size on graft patency and tissue integration.
- To assess the long-term biocompatibility and cellular response within the grafts.
Main Methods:
- Segmented poly (ether urethane) vascular grafts were fabricated using extrusion and salt leaching techniques.
- Pore size was controlled by incorporating NaCl particles into the polyurethane solution.
- Graft compliance and Young's modulus were measured.
- Grafts were implanted in canine carotid arteries and explanted at various time points for analysis.
Main Results:
- Vascular grafts with pore sizes of 5.5, 7.4, and 30 µm remained patent for over 4 weeks, unlike those with smaller pores (≤4.4 µm) which occluded within 2 weeks.
- The mechanical properties (compliance, Young's modulus) of the grafts were comparable to native canine carotid arteries.
- Long-term implantation (6 months) of 30 µm pore size grafts showed neointima coverage, but with immature endothelium-like cells and modified smooth muscle cells, particularly at anastomotic sites.
Conclusions:
- Pore size is a critical factor influencing the patency of porous polyurethane vascular grafts.
- Grafts with larger pores demonstrate improved initial patency.
- Further optimization is needed to promote mature neointima formation and prevent anastomotic intimal hyperplasia for enhanced long-term clinical success.