Unveiling the Secrets of Vascular Grafts: Chemistry, Surfaces, and Cell Growth

Recent research into the field of vascular grafts has shed light on how different materials and surface characteristics influence cell growth. Utilizing organotypic culture techniques, scientists have discovered that woven polyester structures outperformed polyurethane and PTFE (polytetrafluoroethylene) surfaces in promoting cellular proliferation. This finding aligns with earlier studies indicating that textured porous surfaces tend to stimulate both cell growth and metabolic activity more effectively than their smooth counterparts.

A crucial aspect of cell adhesion appears to be regulated by factors such as substrate wettability, surface charge, and roughness. For instance, investigations by Sank et al. highlighted that polyurethane foam, commonly used in breast implants, provides a suboptimal environment for fibroblast attachment and growth when compared to smoother or textured silicone surfaces. Interestingly, endothelial cells exhibited slightly better proliferation on polyurethane surfaces, suggesting that different cell types may respond variably to the same material.

Lee et al. emphasized two critical factors that influence cell attachment and proliferation on polyurethane surfaces: surface morphology and hydrophilic properties. The former is determined by the dispersion of the polymer's hard segment phase, while the latter is influenced by high chain mobility at physiological temperatures. Despite the promising properties of polyurethanes, including their mechanical strength and biocompatibility, there remains no definitive consensus on which surface characteristics are optimal for promoting desirable cell behavior.

In vivo studies of polyurethanes over the past three decades have documented their successful application in various biomedical devices, such as artificial hearts and vascular grafts. While many studies have corroborated the excellent mechanical properties and biofunctionality of these devices, fewer have addressed their long-term chemical stability and degradation issues. Modifications aimed at enhancing resistance to oxidation, mineralization, and environmental stress-cracking have been initiated to improve the performance of these materials in clinical settings.

The segmented polyether-urethane Biomer™ has been a focal point of research due to its relatively stable performance post-implantation, though some microscopic defects have been noted. Notably, Biomer™ has been associated with low inflammatory reactions in vivo, providing a promising avenue for further development. Recent studies underscore the complex interplay between cellular behavior and material properties, suggesting that localized surface cracking may be influenced by foreign body reactions, including the presence of macrophages and giant cells.

As the medical community continues to explore and refine polyurethane materials for vascular grafts, understanding the nuances of material chemistry and surface characteristics will be vital. This ongoing research promises to bridge the gap between in vitro findings and in vivo applications, ultimately enhancing the effectiveness and safety of vascular grafts in patient care.