Cre Expressor/Beta-Galactosidase Reporter Myocardial Infarction Studies

(A) Nests of Cre⁺ cells (green) are detected 1 wk after tail-vein injection into an acute infarct model.

(B) Nomarski image of (A).

(C) Merged image of (A) and (B). The clusters are located near a blood vessel (arrow).

(D) Infarcted tissue in a control MI model (infarction surgery but no donor-cell injection) showing a lack of staining for Cre (no green) and GATA-4 (no red).

(E) Control X-gal staining of ROSA mouse heart.

(F) In a sequential series of tissue sections, odd-numbered sections were immunostained for Cre, yielding the results seen in (A). These two clusters of cells were seen on five sections (sections 1, 3, 5, 7, and 9). Even-numbered sections (sections 2, 4, 6, and 8) were stained for X-gal. No X-gal⁺ cells were found. One slide was immunostained, showing the Cre⁺ cells present. This slide was then stained for X-gal and was found to be X-gal⁻. The lack of X-gal staining of the serial sections indicates that at 1 wk no fusion of donor and host cells has occurred in the infarct.

(G) Cluster of Cre⁺ donor cells detected in infarcted heart tissue of a 1-wk-old acute infarct model. Arrowheads indicate cells that also express GATA-4, as shown in (H).

(H) GATA-4 (red) is mostly present in some cells in the margin of the cluster. Arrowheads indicate cells that also express Cre, as shown in (G)

(I) Merged image showing co-localization (arrowheads) of Cre (green) with GATA-4 (red) in some cells of the cluster of Cre⁺ cells.

(J–L) Co-staining of donor cells with anti–Cre antibody (green) and MSC 21 (red) is apparent after 7 d in an acute infarct model.

(M) There is a lack of staining with MSC 21 (no red) in the infracted tissue of mice that have not received Spoc cell injections.