Circulating bone marrow cells can contribute to neointimal formation

To examine the source of smooth muscle-like cells during vascular healing, C57BL/6 (Ly 5.2) female mice underwent whole body irradiation followed by t ransfusion with 10(6) nucleated bone marrow cells from congenic (Ly 5.1) ma le donors. Successful repopulation (88.4 +/- 4.9%) by donor marrow was demo nstrated in the female mice by flow cytometry with FITC-conjugated A20.1/Ly 5.1 monoclonal antibody after 4 weeks. The arteries of the female mice wer e then subjected to two types of insult: (1) The iliac artery was scratch-i njured by 5 passes of a probe causing severe medial damage. After 4 weeks, the arterial lumen was obliterated by a cell-rich neointima, with cells con taining a smooth muscle actin present around the residual lumen. Approximat ely half of these cells were of male donor origin, as evidenced by in situ hybridization with a Y-chromosome-specific probe. (2) In an organized arter ial thrombus formed by inserting an 8-0 silk suture into the left common ca rotid artery, donor cells staining with alpha smooth muscle actin were foun d in those arteries sustaining serious damage but not in arteries with mini mal damage, Our results suggest that bone marrow-derived cells are recruite d in vascular healing as a complementary source of smooth muscle-like cells when the media is severely damaged and few resident smooth muscle cells ar e available to effect repair. Copyright (C) 2001 S. Karger AG, Basel.