Monitoring of plasma circulating donor DNA reflects cardiac graft injury: Report of two cases

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. A 63-year-old man and a 65-year-old woman were monitored by EMB for allograft rejection. A total of 48 single-nucleotide polymorphisms with a minor allele frequency range of 0.4-0.5 were screened to distinguish donor and recipient DNA based on homozygosity, and digital droplet PCR was used to analyze ddcfDNA concentrations. Both subjects suffered rejection within the first 6 months after transplantation. The maximal ddcfDNA level of 270 copies (cp)/ml during EMB-confirmed acute cellular rejection (ACR; mild grade 1R/2, patient 1), and the maximal concentration of 1,846 cp/ml in the case of EMB-confirmed antibody-mediated rejection (AMR; grade 1+; patient 2), was detected. Individual monitoring of ddcfDNA dynamics from the 1st to the 6th month posttransplant reflected cardiac graft injury in patients suffering ACR or AMR, meaning that ddcfDNA may serve as a noninvasive biomarker.

Association between aortic telomere length and cardiac post-transplant allograft function

BACKGROUND

In patients having undergone orthotopic heart transplantation, a number of complications exist that are known to be connected to both telomerase activity and telomere length. The aim of this study was to determine how telomere length in aortic DNA correlates with the subsequent post-transplantation development of the patients.

MATERIALS AND METHODS

Between 2005 and 2015, we collected aortic samples from 376 heart recipients (age 50.8 ± 11.8 years) and 383 donors (age 38.6 ± 12.2 years). Relative telomere length in aortic tissue DNA was determined using quantitative PCR.

RESULTS

Shorter telomere length was detected in heart allograft recipients compared to donors (P < 0.0001). Patients suffering acute cellular rejection had significantly shorter telomere length (P < 0.01) than patients without rejection. Shorter telomere length was observed in patients with implanted mechanical circulatory support before heart transplantation (P < 0.03), as well as in subjects with cardiac allograft vasculopathy (P < 0.05). Overall survival time after heart transplantation was associated with shorter donor telomeres (P < 0.004).

CONCLUSIONS

Telomere length differed between donors and recipients independent of the sex and age of the patients. Our findings suggest a potential new linkage between the aortic telomere length of recipients and post-heart transplant complications. Further studies focusing on epigenetic modifications and gene regulation involved in telomere maintenance in transplanted patients should verify our results.

Comparison of relative telomere length measured in aortic tissue and leukocytes in patients with end stage heart failure

OBJECTIVES

Telomeres are repetitive non-coding DNA sequences on the ends of eukaryotic chromosomes. Relative leukocyte telomere length (LrTL) is considered to reflect biological ageing and fitness. Therefore, we examined whether LrTL would reflect rTL in aortic tissue (ArTL) and whether it could be used as a marker of biological heart age.

DESIGN

We analysed telomere length in aortic and leukocyte samples from 73 heart recipients (63 males, 10 females; age 52.2±11.7 years). Relative telomere length was measured using a quantitative PCR-based method.

RESULTS

Neither LrTL nor ArTL correlated significantly with the age of heart recipients. Mean ArTL was slightly shorter than LrTL (p=0.06) and there was a slight but significant inverse correlation between LrTL and ArTL (p=0.019).

CONCLUSIONS

The age of patients with end stage heart failure was not associated with leukocyte or aortic telomere length. An inverse correlation between LrTL and ArTL suggests that LrTL is unlikely to be an important predictor of biological ageing in these patients.