CLINICAL AND HISTOLOGICAL DETERMINANTS OF SMOOTH-MUSCLE CELL OUTGROWTH IN CULTURED ATHERECTOMY SPECIMENS - IMPORTANCE OF THROMBUS ORGANIZATION

Background: Coronary atherectomy provides a unique opportunity to obta in plaque tissue from a wide variety of clinical syndromes. We investi gated the relation between the clinical status and histopathological s ubstrate of tissue retrieved during directional coronary atherectomy a nd the proliferative and migratory potential of smooth-muscle cells ju dged from successful outgrowth during cell culture. Methods: After dir ectional coronary atherectomy, tissue samples were examined macroscopi cally, divided into two equal pieces, and separately subjected to cell culture and histopathological study. Cell culture was performed using an explant technique. In-vitro smooth-muscle cell outgrowth was relat ed to clinical and histological variables. Results: Atherosclerotic ti ssue was obtained from 98 consecutive atherectomy procedures. Histolog ical examination revealed a broad spectrum of appearances, ranging fro m complex atheroma containing dense fibrous tissue, calcium deposits, macrophages, and necrotic debris to neointimal proliferation and organ ized thrombi. Smooth-muscle cell outgrowth was observed in 43 of the 9 8 samples (44%). Although not affected by any of the clinical variable s, cell outgrowth was influenced by histological variables, in particu lar the presence of organizing thrombi. Outgrowth was successful in ei ght out of 10 samples with thrombus (80%) and in only 35 out of 88 (40 %) without (P = 0.03). Conclusion: The presence of organizing thrombi in the retrieved tissue facilitates smooth-muscle cell outgrowth and s uggests an enhanced proliferative and migratory potential. These findi ngs may be relevant to the understanding of neointimal proliferation i n coronary syndromes where mural thrombosis is likely to occur.