Preservation of Cardiac Tissue and B Cell Localization After B Cell Injection Into Infarcted Myocardium
Histological assessment of cellular apoptosis was performed using the TUNEL assay. Animals underwent sham (no ligation) (A) operation or ligation with B cell (B) or B cell cocultured with nonhematopoietic stem cell (NHSC) (C) injections. Animals were euthanized at 48 h after surgery, and hearts were processed for evaluation of apoptosis. Apoptotic cells within the peri-infarct domain were quantitated by visualization using 200× magnification. Scale bars are 100 μm. All nuclei were stained with hematoxylin. The percentage of cells staining positive for apoptosis was determined by comparison with the total number of cells visualized in a minimum of 5 fields. Ligation plus saline injection (open circles, n = 6) animals were included as control animals (D). Solid circles represent animals injected with B cells (n = 6), and B cells cocultured with NHSCs cultured overnight at 37°C (n = 4) are represented by solid squares. Each data point represents the percentage of TUNEL-positive cells counted in a single field in cardiac section with the largest infarction and horizontal bar is the mean ± SE. Significant differences in the mean values between control and experimental groups are denoted by *p < 0.05 using the Student t test, 2-tailed.