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The aim of this study was to evaluate the effect of a fibrin-coating on the inner surface of a biodegradable poly(DL-lactide-E-caprolactone) nerve guide on the speed and quality of the nerve regeneration. The nerve regeneration and orientation of the nerve fibers, as well as the fibrous tissue formation were evaluated. On the short term, nerve regeneration was slightly faster in the non-coated nerve guide. After longer implantation periods (≥ 4 weeks), nerve regeneration in the fibrin-coated nerve guides was characterized by a severe inflammatory response with large numbers of macrophages and polymorphonuclear cells (PMN's). This study clearly demonstrates that nerve regeneration in a fibrin-coated nerve guide is not faster when compared with a non-coated nerve guide, and that nerve regeneration in the fibrin-coated nerve guide is even worse after longer implantation periods.

A new simple cut and fold technique is described, which allows precise shortening of extensor tendons in the hand by a few millimeters.

In this pilot study ADP-ase coated polyurethane (PL) vascular prostheses and noncoated (control) PU vascular prostheses (all vascular prostheses: ID 1.5 mm, length 1,5 cm) were implanted into the carotid artery of the rabbit to test wheter ADP-ase might function as an adequate anti-thrombogenic coating. The prostheses were evaluated after 1 hour (n = 4) and 3 weeks (n = 8). After 1 hour, there was extensive accumulation of thrombus on the inner surface of the control PU vascular prostheses, in contrast to the ADP-ase coated prostheses. At 3 weeks, all control PU vascular prostheses (n = 8) were occluded, whereas only 1 of the 8 ADP-ase coated PU vascular prostheses. The patent ADP-ase coated PU prostheses showed already extensive endothelial healing. These results indicate the potential of ADP-ase to function as an effective antithrombogenic coating of small-caliber and microvascular PU prostheses.

This report reviews our experiments that have been undertaken to test the hypothesis whether the induction of a clot layer on the graft surface of small-caliber polytetrafluoroethylene ( PTFE) prostheses might improve their healing. 1 2 PTFE prostheses with a fibril length of 30-mu-m, PTFE prostheses with a fibril length of 30-mu-m and either impregnated with Chitosan, or pretreated with alcohol or mechanically roughened, and PTFE prostheses with a fibril length of 60-mu-m (all prostheses: length 1 cm, ID 1.5 mm) were implanted into the abdominal aorta of rats and were evaluated from 1 day up till 6 weeks after implantation with regard to the presence or absence of a clot layer and with regard to the amount of graft healing. All untreated PTFE prostheses were never found to be covered with a clot layer and showed poor neoendothelial healing: even at 6 weeks after implantation, there were only endothelial cells near the anastomotic sides, directly on the graft surface. In contrast, all other PTFE prostheses were completely covered with a clot layer upon implantation and demonstrated almost complete neoendothelial healing after 6 weeks. Moreover, in these prostheses, the endothelial cells were present on a matrix of smooth muscle cells. These results confirm our hypothesis that the induction of a clot layer on the graft surface of PTFE prostheses improves their healing: the clot probably functions as a provisional matrix for the regeneration of arterial wall tissue, just as occurs in normal arterial wall repair.