Small-caliber, long-fibril ePTFE vascular grafts with covalent bonding of fibronectin achieved almost complete neointimal healing by the time of retrieval at 12 weeks. This indicates that, with further modifications, our new technique for covalent bonding of fibronectin has great potential in the development of small-caliber arterial prosthetic grafts.

Cambial cells dierentiate into secondary xylem cells through a process of expansion or elongation, cell wall thickening, cell wall sculpturing, lignification, and cell death (formation of wood). The secondary xylem cells develop modifications of the cell wall such as pits, helical thickenings, perforations and warts, through the localized deposition of cell wall materials. Recent observations have revealed that the localized appearance or disappearance of cortical microtubules is related to the localized deposition of cellulose microfibrils in secondary xylem cells. Cortical mi-crotubules play an important role in the morphogenesis of secondary xylem cells, thereby controlling the structure of wood. Therefore, cortical microtubules provide a target for biotechnological applications to change the quality of wood.

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Better endothelial healing of ePTFE vascular grafts is correlated with more cellular and capillary ingrowth, but more cellular and capillary ingrowth is not correlated with longer fibril length or higher air porosity.

Purpose: To manufacture high-porosity expanded polytetrafluoroethylene (ePTFE) vascular grafts with the same internodal distance but different node-fibril morphology, and to evaluate their biologic behaviors in a canine carotid artery implantation model. Materials and Methods: Several types of high-porosity ePTFE vascular grafts with the same inside diameter (4 mm) and wall thickness (650 µm) were manufactured under different heating, stretching conditions. The luminal surface and cross section of the grafts were photographed by scanning electron microscopy and the node-fibril structure was examined. Two typical types of high-porosity ePTFE vascular grafts were then selected and proceeded to an animal study. The test grafts were explanted after an interval of 12 weeks and subjected to histomorphometric analyses. Results: The following two types of high-porosity ePTFE vascular grafts were selected; one had a through-pore structure extending from the outer to the inner surface and the other had a random-node architecture with tortuous path channels extending from the outer to the inner surface. The histomorphometric analyses of thrombus-free surface, thickness of pseudointima, cellular ingrowth, capillary ingrowth, and cellular proliferation revealed no significant differences between the grafts. Conclusion: In high-porosity ePTFE vascular grafts, graft healing enhanced by transmural tissue ingrowth may be not largely dependent on node-fibril morphology. This knowledge will be helpful to design a new type of high-porosity ePTFE vascular grafts available for clinical use.