Monitoring pig-to-primate cardiac xenografts with live internet images of recipients and xenograft telemetric signals: Histologic and immunohistochemical correlations

Background: Monitoring pig-to-primate cardiac xenografts is often difficult in awake and uncooperative primates. We investigated the possibility of mo nitoring xenotransplantation through internet broadcasting of (1) continuou s video images of transplant recipients and (2) xenograft telemetric signal s detected by an implanted device. The telemetric readings were later compa red with histology and immunohistochemistry for signs of rejection. Methods: Heterotopic baboon-to-baboon (n = 2) and transgenic pig (human com plement regulatory proteins CD59/DAF, n = 3; MCP, n = 1)-to-baboon transpla nts were performed with serial biopsies for hematoxylin-and-eosin staining and immunohistochemical detection of immunoglobulin M (IgM) and complement membrane attack complex (MAC) deposition. Baboon recipients were continuous ly monitored with a QuickCamPro digital camera, whereas grafts were monitor ed with a Data Science International implantable telemetric system. Video i mages and telemetric signals were broadcast over the Internet through a lap top computer. Results: Baboon allografts remained healthy until explant on Day 14, wherea s pig xenografts were rejected on Day 5, 6, 7, and 11. Telemetry of allogra fts and xenografts documented regular rhythm with an average heart rate of 80 to 120, but xenografts developed bradycardia and widened/dampened QRS co mplexes 24 to 48 hours before graft loss. Continuous video monitoring of re cipient activities was vital in differentiating between graft arrhythmias a nd telemetric artifacts. Allograft biopsies showed little cellular infiltra te, whereas xenograft biopsies showed increasing IgM and MAC deposition, wi th extensive thrombi and myocardial damage 24 hours before cessation of car diac activities. Conclusions: Combined video surveillance of recipient activities and graft telemetric signals is a useful method to continuously monitor abdominal car diac grafts in large, uncooperative, awake primates. QRS-complex widening a ssociated with progressive bradycardia correlated with histologic and immun ohistochemical evidence of xenograft rejection.