Evaluation of Total Circulating Cell-Free DNA as a Biomarker in Liver Transplant Recipients: A Single-Center Pilot Study

Donor-derived cell-free DNA (dd-cfDNA) has shown promise as a sensitive non-invasive biomarker of graft injury following liver transplantation (LT). This pilot study assessed whether total cfDNA levels alone could reflect liver graft health and predict rejection events. To analyze this, 70 adult LT recipients were stratified by underlying liver disease etiology and monitored for 18 months. Total cfDNA was extracted from plasma samples collected 10 days post-LT and quantified fluorometrically. Associations between cfDNA levels and standard liver function biomarkers (ALT, AST, ALP or tacrolimus dosing) were analyzed using Kendall’s Tau. Differences in cfDNA levels among disease etiologies were assessed using the Kruskal-Wallis test. Median cfDNA concentration was 11 ng/ml (range: <3–70 ng/ml). Highest concentrations were noted in patients with autoimmune liver disease or hepatocellular carcinoma. No significant correlation was observed between cfDNA and ALT, AST, ALP, or tacrolimus levels. A subset of patients with cfDNA ≥ 20 ng/ml (n = 21) showed a moderate correlation with ALT (Tau = 0.46, p = 0.0105). cfDNA levels did not differ between etiological groups. These findings suggest that while total cfDNA reflects some inflammatory activity, it lacks the specificity of dd-cfDNA in clinical transplant monitoring. Larger studies and fraction-specific analysis are warranted.