Peritransplant ischemic injury is associated with up-regulation of stromal cell-derived factor-1

OBJECTIVES We evaluated chimerism and stromal cell-derived factor-1 (SDF-1) expression in response to peritransplant ischemic injury following human heart transplantation. BACKGROUND Myocardial ischemia has been shown to trigger mobilization of stem cells to the heart in animal experiments. METHODS Between January 1998 and April 2002, a total of 114 male recipients received hearts from female donors. Of these 114 recipients, 26 had evidence of ischemic injury on their initial heart biopsies (ischemia group). These were compared to the remaining 88 patients (control group). Heart biopsy specimens obtained initially at one week and at one year after transplant were evaluated from 20 matched patients of each group for the presence of Y chromosome-containing nuclei. The SDF-1 messenger ribonucleic acid (mRNA) and protein expression were also evaluated on initial heart biopsy specimens. RESULTS At one week, Y chromosome-containing nuclei were significantly increased in the ischemia group (0.68% vs. 0.04%; p < 0.0001) compared to the control group. These were positive for the stem cell factor receptor c-kit. A significant 3.3-fold increased mRNA expression (p = 0.001) and 2.8-fold increased protein expression (p = 0.01) of SDF-1 was noted in the ischemia group. At one year, Y chromosome was detected in 0.29% of cardiomyocyte nuclei in the ischemia group but none in the control group. The ischemia group had poorer survival and increased vasculopathy. CONCLUSIONS This is the first report to describe chimerism and up-regulation of SDF-1 in human heart transplantation in response to ischemic injury.