Fig. 1.

Myocardial content and differentiation of transplanted CPCs in a rat model of chronic ischemic cardiomyopathy (old MI). C-kit+ CPCs were labeled with EGFP and injected 30 days after MI. (A) Representative confocal microscopic images from a CPC-treated rat showing presence of transplanted CPCs in the risk (infarcted) and noninfarcted regions, as evinced from immunoreactivity for EGFP (green). Some EGFP^pos cells also express α-sarcomeric actin (α-sarc actin; red). (B) Quantitation of EGFP^pos cells in the risk and noninfarcted region, expressed as percent EGFP^pos myocardial area and as total calculated number of EGFP^pos cells per heart. The number of EGFP^pos cells per heart was estimated by multiplying the number of EGFP^pos cells per unit area by the estimated number of EGFP^pos cells present through the thickness of each slice in which EGFP^pos cells were found (estimated 100 cells per 2 mm thickness of slice). (C) Representative confocal microscopic images showing colocalization of EGFP and α-sarcomeric actin in several cells in the border zone (the area in the white box is magnified in the three panels on the right). Yellow arrowheads indicate EGFP^pos cells that do not express α-sarcomeric actin. (D) Quantitative analysis of α-sarcomeric actin^pos/EGFP^pos cells. The figure illustrates the fact that very few CPCs (or CPC-derived cells) remained in the heart that expressed markers of cardiogenic commitment such as sarcomeric proteins; furthermore, these cells were small and did not exhibit the typical morphology and sarcomeric structure of mature cardiac myocytes. Data are means ± SEM. Reproduced with permission from Tang et al. (2010).