Monitoring of transplanted liver health by quantification of organ-specific genomic marker in circulating DNA from receptor

Abstract

Background: Health assessment of the transplanted organ is very important due to the relationship of long-term survival of organ transplant recipients and health organ maintenance. Nowadays, the measurement of cell-free DNA from grafts in the circulation of transplant recipients has been considered a potential biomarker of organ rejection or transplant associated complications in an attempt to replace or reduce liver biopsy. However, methods developed to date are expensive and extremely time-consuming. Our approach was to measure the SRY gene, as a male organ biomarker, in a setting of sex-mismatched female recipients of male donor organs.

Methods: Cell-free DNA quantization of the SRY gene was performed by real-time quantitative PCR beforehand, at the moment of transplantation during reperfusion (day 0) and during the stay at the intensive care unit. Beta-globin cell-free DNA levels, a general cellular damage marker, were also quantified.

Results: Beta-globin mean values of patients, who accepted the graft without any complications during the first week after surgery, diminished from day 0 until patient stabilization. This decrease was not so evident in patients who suffered some kind of post-transplantation complications. All patients showed an increase in SRY levels at day 0, which decreased during hospitalization. Different complications that did not compromise donated organs showed increased beta-globin levels but no SRY gene levels. However, when a donated organ was damaged the patients exhibited high levels of both genes.

Conclusion: Determination of a SRY gene in a female recipient's serum is a clear and specific biomarker of donated organs and may give us important information about graft health in a short period of time by a non-expensive technique. This approach may permit clinicians to maintain a close follow up of the transplanted patient.

Figure 1. Concentration of serum beta-globin levels in patients without complications.

Mean concentration of serum beta-globin circulating levels from patients who accepted transplanted livers without any complications during the first week of stay at ICU (patient 1 to 6, mean +SEM). (*) Kruskall Wallis test, p<0.05; Dunn's Multiple Comparison Test, p<0.05 vs day 0.

Figure 2. Comparison of serum beta-globin levels in patients with and without complications.

Early mean concentration of serum beta-globin circulating levels from patients who accepted transplanted livers without any complications (white bars; n = 6) and patients suffering any kind of post-transplantation complications during their stay at ICU (shadow bars; n = 4).

Figure 3. Serum SRY gene and beta-globin gene circulating levels in two re-transplanted female patients.

Concentration of serum SRY gene and beta-globin gene circulating levels in two female patients who underwent two consecutive transplantations, one sex-mismatched donor–recipient and the other sex-matched. A) woman who underwent a liver transplantation from a male donor and re-transplanted from a female donor due to hepatic veins thrombosis complication. B) woman who underwent a liver transplantation from a woman donor and re-transplanted from a male donor due to a hepatic artery thrombosis. PT: pre-transplantation sample before organ reperfusion.

Figure 4. Concentration of serum SRY levels in patients without complications.

SRY gene circulating levels of six patients after successful male liver transplantation without any additional complications during one month of follow up.

Figure 5. Profile of SRY and beta-globin genes circulating levels of two patients with severe complications after transplantation.

A) Patient 7 was transplanted due to a co-infection of HBV and delta virus and after arterial thrombosis was urgently re-transplanted. B) Patient 8 suffered sustained a biliary complication after transplantation that ended in cholestasis. Patient was discharged on day 23 but she was re-admitted to the ICU and suffered a multi-organic failure (MF) on day 37. Patient died on day 70 after transplantation.