Figure 8. Cardiac commitment of endogenous CPCs after trasplantation of exogenous CPCs.

The commitment of endogenous CPCs (c-kit^pos/EGFP^neg cells) to cardiac lineage was assessed by quantitating endogenous CPCs that expressed Nkx2.5 and MHC in vehicle- and CPC-treated hearts. New myocytes formed in the last 2 weeks of life were identified by measuring α-sarcomeric actin^pos and BrdU^pos cells. (A) Representative confocal microscopic image of a c-kit^pos/EGFP^neg/Nkx2.5^pos/MHC^pos cell obtained in serial sections of a CPC-treated heart. (B) Quantitative analysis of c-kit^pos/EGFP^neg/Nkx2.5^pos/MHC^pos cells in the risk and noninfarcted regions of vehicle- and CPC-treated hearts (the CPC-treated group is subdivided into two subgroups, one with EGFP^pos cells [EGFP^pos] and one without EGFP^pos cells [EGFP^neg]). The number of c-kit^pos/EGFP^neg/Nkx2.5^pos/MHC^pos cells is normalized to both number of cells (10⁴ nuclei, upper panels) and area (mm², lower panels). Because cell density in CPC-treated, EGFP^pos hearts was higher (due to presence of clusters of EGFP^pos cells), the magnitude of the increase in endogenous CPCs in CPC-treated, EGFP^pos hearts was greater when the number of cells was normalized to area (mm²) than to number of nuclei. (C) Representative confocal microscopic image of α-sarcomeric actin^pos/BrdU^pos cells in a CPC-treated heart. (D) Quantitative analysis of the number of α-sarcomeric actin^pos/BrdU^pos cells in the risk and noninfarcted regions of vehicle- and CPC-treated hearts (subdivided into EGFP^neg and EGFP^pos subgroups). Data are means ± SEM.