Graft Heart Rates May Grossly Indicate Development Of Immunotolerance Induced By Isolated Vascularized Bone Marrow Transplantation

Introduction: Our laboratory has been using rat heterotopic femoral heart transplantation to study tolerance induction. We hypothesized that heart rate over time could be quantitatively correlated with tolerance induction and absence of rejection. We studied this in recipients receiving a concomitant isolated vascularized bone marrow transplant (iVBMT). Methods and Materials: ACI rats served as donors for both iVBMT and heart transplants. Lewis rats were recipients of either a heart [group HI, n=4] or both a heart and a femur-iVBMT [group HFI, n=4]. All transplants were heterotopic to the groin. The recipients received FK506 for a total of 14 days. Heart rates were recorded daily until POD 10, then 3 times/week. Statistical analysis was performed for the data between the two groups. Results: A 2-way ANOVA demonstrated a significant difference for average heart rates during the first 10 days post-operatively between HI and HFI (192+/−28.4 vs. 204+/−18, p<0.009). Conclusion: The significant difference in heart rates between the HI and HFI groups may indicate that the iVBMT in the HFI group, as an engrafted bone marrow transplant, modulates the host immune response and affords immunoprotection to the graft heart. Supported by American Heart Association Grant #0555795T. Dr Hewitt is recipient of the Ellen Marmer research fellowship from the AHA for 2006.