MONITORING OF PLASMA CIRCULATING DONOR DNA REFLECTS CARDIAC GRAFT INJURY

Background: Although improved surgical techniques and the development of new immunosuppressive drugs have significantly extended the survival of heart transplant recipients, acute rejection still represents a mortality risk during the first three years following cardiac transplantation. The current standard for graft rejection surveillance is endomyocardial biopsy (EMB), an invasive procedure with rare but potentially serious complications. Detection of circulating donor-derived cell-free DNA (ddcfDNA) is an option for noninvasive monitoring of graft injury and rejection.
Case report: Two patients (a 63-year-old man and a 65-year-old woman) were monitored (EMB) for allograft rejection status. Forty-eight single-nucleotide polymorphisms (SNPs; with minor allele frequency (MAF) range 0.4-0.5) were screened to distinguish donor and recipient DNA based on homozygosity, and digital droplet PCR (ddPCR) was used to analyze ddcfDNA concentrations. In both subjects, we detected increased levels of ddcfDNA during ongoing acute cellular (ACR) or antibody-mediated rejection (AMR). Moreover, two different digital PCR systems (digital droplet PCR and digital PCR) were used for the comparison of cfDNA quantification in 5 patients after orthotopic heart transplant.
Conclusion: Individual monitoring of ddcfDNA dynamics from the 1st to the 6th month posttransplant (post-Tx) reflected cardiac graft injury in patients suffering ACR or AMR. We identified similar plasma concentration of ddcfDNA using both digital PCR instruments with identical trend during time after orthotopic heart transplant.