, Volume 90, Issue 2, pp 160-166

Ultrastructural characteristics of cellular reaction after experimentally induced lesions in the arterial vessel

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Abstract

Method

Vessel segments of 30 pigs underwent injury using a directional atherectomy catheter. Vessels were assigned according to the extent of injury to Group 1 (intima lesion) or Group 2 (media injury). 2 hours to 7 days after injury, 68 arteries showing 41 intimal and 27 media lacerations were excised and processed for histology and transmission electron microscopy.

Results

Immediately after injury, thrombus formation was found at the site of the altered segment. A marked, transient infiltration of polymorphonuclear leukocytes (PMN) occurred only if the media was lacerated, starting within the first hours and increasing up until the 12 hours time point. The cellular infiltration was followed by a transformation of contractile myocytes to a synthetic subtype. The ratio of myofilaments to organelles decreased. A pronounced myoproliferative response was found in Group 2 after 7 days (p<0.01), whereas only moderate tissue hyperplasia was seen in Group 1.

Conclusion

The data presented provide evidence that the cellular alteration of injured vessels begins immediately. Subsequent to an initial temporary PMN infiltration, an activation of local myocytes occurs at a very early stage. In particular, a myoproliferative response was found only after deep injury with rupture of the internal elastic lamina.

Supported by Sanderstiftung grant No. 90.026.1/2, Friedrich Baur Stiftung grant No. 58-94, German Heart Foundation and Deutsche Forschungsgemeinschaft (1076/1–2)