Abstract 17459: Donor Organ Specific Exosome Platform for Monitoring Transplant Organ Rejection in an in vivo Mouse Heterotopic Heart Transplant Model
Introduction: In heart transplantation, there is a critical need for development of serum biomarkers to monitor for donor organ rejection/ injury, which remains a major cause of morbidity and mortality. Exosomes are tissue and major histocompatibility complex (MHC) specific microvesicles (30-200 nm) with stable RNA cargo reflecting conditional state of the tissue releasing them. Their application in biomarker discovery is implicated in several fields.
Hypothesis: We hypothesize that transplant organ releases donor tissue-specific exosomes into the recipient blood that can be serially monitored. Characterization of donor organ specific exosome profiles and their RNA cargo can serve as potential novel biomarkers for monitoring transplant organ rejection/ injury.
Methods: In mouse acute rejection model of full MHC mismatch heterotopic heart transplantation (BALB/c into B6, n=10), plasma exosome pool was isolated from recipient blood using Sepharose gel filtration chromatography, and was assessed at different post-transplant time points for donor heart-specific exosome signal utilizing NanoSight nanoparticle tracking analysis technology with quantum dot labeled anti-donor MHC specific antibodies. Western blot was also performed for confirmation. Syngeneic B6 transplants served as negative control (n=3).
Results: NanoSight tracking confirmed donor specific exosome signal in the recipient serum with 100% sensitivity and specificity at all time-points post-transplant (p=0.003): 4 hours, 2, 5, 9, and 11 days. Histology and clinical exam confirmed progression of donor rejection. Western blot of recipient exosomes confirmed donor MHC protein. Donor MHC specific signal was absent by NanoSight and Western blot exosome analysis of negative controls, although recipient MHC signal was evident.
Conclusions: We are the first to report that transplanted heart releases stable and detectable donor tissue-specific exosomes into recipient blood that can be serially tracked. We propose that characterization of transplant organ-specific exosome signatures from recipient’s blood would lay the foundation for development of a novel, non-invasive biomarker assay to monitor donor organ rejection/ injury in heart transplant patients.
- © 2013 by American Heart Association, Inc.