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. 2012 Mar 7;1(3):248–260. doi: 10.5966/sctm.2011-0028

Figure 4.

Figure 4.

Histological analysis at day 45 of rat hearts transplanted with fibrin patches containing either superparamagnetic iron oxide (SPIO) nanoparticles (Iron-patch) or bone morphogenetic 2-primed, SPIO-loaded mouse embryonic stem cells (mESCs) (Cell-patch). (A): Representative Lendrum stains of transverse heart sections showing the remodeling of the myocardium after permanently occluding the left anterior descending coronary artery, displaying muscular fibers in red, collagen in blue, and fibrin in orange. Effects of different treatments are compared: sham-operated heart with a normal morphology (left), typical infarcted hearts with engrafted Iron-patch (center) or Cell-patch (right). A large part of the anterolateral wall is reduced to a paper-thin fibrous layer. The left ventricular wall is hypertrophied in the Iron-patch condition, in contrast to infarcted rats treated with Cell-patch (right). Scale bars = 1 mm. (B): Immunohistochemical analysis of normal heart sections at day 45 after the engraftment from the Iron-patch group (left) and the Cell-patch group (right). Landrum staining confirmed the presence of fibrotic tissue for both groups at the periphery of the left ventricle muscle where the patch was positioned. Iron presence is indicated by the Prussian blue coloration. Anti-MEF2 staining revealed the presence of ESC-committed cardiomyocytes in the epicardial area, as well as of rat cardiomyocytes in the left ventricular wall. Arrows indicate examples of cells positive for both MEF2 and Prussian blue staining in consecutive sections. (C): Histological analysis of the Cell-patch engraftment in the infarcted rat hearts. Collagen staining of the infarcted left ventricle wall (blue, collagen; red, cardiac muscle). Tissue sections in the lower row (Prussian blue) are consecutive to the sections in the upper row (MEF2). Identification of SPIO-loaded mESCs colonizing the left ventricular wall, as demonstrated by colocalization of Prussian blue (arrows) and MEF2-staining (orange, arrows) in consecutive sections. (D): Analysis of Iron-patch engraftment in infarcted rat hearts. Collagen staining of the infarcted left ventricle wall (blue, collagen; red, cardiac muscle). No consistent colocalization could be detected between SPIO nanoparticles, likely incorporated into the tissue via inflammatory cells, and the MEF2-positive staining. Abbreviations: MEF2, myocyte enhancer factor 2; MI, myocardial infarction; N, normal.