Retroviral analysis of cardiac morphogenesis: discontinuous formation of coronary vessels.

In this report we present an application of retroviral cell tagging procedures for tracking smooth muscle, endothelial, and connective-tissue progenitors during coronary morphogenesis

T. Mikawa; D. A. Fischman

2006

Scholarcy highlights

  • Cellular progenitors of the coronary vasculature are believed to enter the chicken heart during epicardlal morphogenesis between stages 17 and 27 of egg incubation
  • Our data provide direct proof that vascular smooth muscle progenitors begin to enter the heart at stage 17, substantially after the heart begins propulsive contractions; cardiac myocytes, vascular smooth muscle, perivascular fibroblasts, and coronary endothelial cells all derive from independent precursors when these cells migrate into the heart;
  • Endothelial cells of the coronary vessels have a different clonal origin than endothelial cells of the endocardium; coronary arteries form by the coalescence of discontinuous colonies, each derived from a founder cell tagged at the time of retroviral injection; and coronary arteries contain discrete segments composed of
  • Up to stage 15, the heart is composed of only two cell types: myocytes and endothelial cells; neither connective tissue, coronary vessels, neural elements, nor the conduction system is evident histologically
  • When injections were performed at stage 15 or earlier, all blue-stained cell clusters were myocytes restricted to the myocardium
  • Of a more general nature, our work demonstrates that retroviral gene targeting to cardiac myocytes and cells of the coronary vasculature is feasible in the chicken embryo
  • Since the grape-like clusters of cells along the dorsal mesocardium which give rise to the epicardium can be dissected from an embryo and grafted to another host, gene transfer into the vascular precursors might be facilitated by tissue immersion in larger volumes of retroviral suspension than can be realized with intraembryonic injections

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