Cardioprotective c-kit⁺ cells are from the bone marrow and regulate the myocardial balance of angiogenic cytokines
J. Clin. Invest. Shafie Fazel, et al. 116:1865 doi:10.1172/JCI27019 [Go to this article.]

Figure 1
c-kit⁺ cells increase in infarcted myocardium. (A) Quantification of EPCs over a time course after MI in wild-type mice. Upperpanels, flow cytometry for VEGFR2⁺ cells. Lower panels, in vitro splenocyte fibronectin (Fib.) adhesion, acetylated LDL uptake (Ac-LDL), and lectin-binding assay results. Total number of cells was calculated by multiplying percentage of positive cells by total number of cells isolated from both tibia and femur of 1 mouse. n = 3–5 per time point. *P < 0.05 compared to day 0 values. (B) MI causes an increase in VEGFR2⁺c-kit⁺Sca-1⁺ subset of PBMCs. (C) Increase of c-kit⁺ cells is specific to the injured myocardium (arrowhead). Seven days after MI, c-kit⁺ cells were not detected in other organs and the peripheral circulation. Gray, isotype control; red, c-kit. (D and E) The c-kit⁺ cells detected after MI in the heart were homogeneously VEGFR2⁺ but heterogeneous with respect to CD45 expression. –ve con, negative control. (F) Quantification of the number of c-kit⁺ cells. Lowerpanel shows that the majority of the c-kit⁺ cells in the heart were CD45^–. n = 3 per time point. (G–J) Confocal microscopic images. (G) c-kit⁺ cells visualized at the infarct border zone both as isolated cells (arrowheads) and in clusters (arrow). Scale bar: 100 μm. (H) The majority of the c-kit⁺ cells did not express CD45 (arrowhead) although some of the clusters contained CD45-expressing cells (arrow). Scale bar: 50 μm. (I) c-kit⁺ cells present in the clusters are shown to express Ki67 cell cycling–associated nuclear antigen. Scale bar: 10 μm. (J) c-kit⁺ cells in the cell cycle (arrowhead) did not coexpress CD45 (arrow). Scale bar: 10 μm.