Early insights into donor-derived cell-free DNA in a preclinical model of face vascularized composite allotransplantation

Acute rejection remains a major challenge following face vascularized composite allotransplantation (VCA) and can lead to allograft dysfunction or loss. Donor-derived cell-free DNA (ddcfDNA) has emerged as a promising noninvasive biomarker for allograft injury and rejection monitoring in solid organ transplantation. However, its application to VCA remains largely unexplored, and data characterizing ddcfDNA dynamics following face transplantation are limited.

In this exploratory study, the authors performed face transplantation in a rodent model and analyzed plasma and tissue samples at the time of graft injury, confirmed by histology and immunofluorescence. Cell-free DNA was extracted and analyzed using next-generation sequencing. Donor-derived cfDNA was identified based on single nucleotide polymorphisms (SNPs) unique to the donor genome and was assessed in relation to graft injury.

SNPs corresponding to donor-but not recipient-genomic sequences were identified in circulating cfDNA, supporting the feasibility of detecting ddcfDNA following face transplantation. Elevated levels of donor-derived cfDNA were observed at the time of clinically apparent graft injury, with donor-specific SNPs comprising approximately 0.31% of total sequenced fragments. Across donor-recipient pairings, 313 donor-specific SNPs mapping to 49 genes were consistently detectable, suggesting reproducible donor-specific cfDNA signals in this model.

This pilot study demonstrates the feasibility of detecting and characterizing donor-derived cell-free DNA following face transplantation in a rodent model. While preliminary, these findings support further investigation of ddcfDNA as a potential biomarker of allograft injury in VCA. Larger, controlled studies will be required to define its specificity, kinetics, and clinical relevance for rejection monitoring.