Collagen coatings as biological sealants for textile arterial prostheses

Two collagen-coated grafts were studied: Hemashield (bovine collagen cross-linked with formaldehyde vapours and softened by exposure to glycerol) and Tascon (collagen fibres cross-linked with glutaraldehyde solution). The weight of the coating was 310 +/- 5 mg/g for Hemashield and 45 +/- 2.5 mg/g for Tascon. However, notwithstanding these differences, both coatings were efficient in making the walls of the grafts impervious to blood. The water permeabilities for the Hemashield and the Tascon were 8.7 and 5.9 ml.min-1.cm-2 at 120 mmHg respectively. The Hemashield collagen coating was rapidly eroded in vitro (4 h) after exposure to buffer, trypsin or pancreatin solutions, whereas the Tascon collagen coating remained well preserved after 7 d incubation. Both coatings were safe and did not interfere with the physical properties of the graft which was used as a skeleton. The healing properties of the Hemashield were similar to that observed with preclotted polyester prostheses, except in the early hours following graft implantation. On the other hand, the absence of erosion in the coating of the Tascon seemed to contribute to early antithrombogenicity. It also induced marked inflammatory reactions in the surrounding tissues and thus the healing appeared to be delayed.