Utility and limitations of the use of donor-derived cell-free DNA in kidney transplantation

Table 3 Overview of different cell-free DNA biomarkers

Biomarker	Characteristics and clinical utility
Total (plasma/serum cfDNA)	Donor plus recipient-derived cfDNA
	Reflects total cell damage, not limited to the allograft[21]
	Possible release of recipient-derived cfDNA by recipient’s immunological effector cells activated during rejection[22]
Donor-derived plasma/serum cfDNA	Directly interrogates graft integrity[23]
	Increased in cases of graft damage[24]
Urinary cfDNA	Tr-DNA
	Molecules crossing the kidney barrier and appearing in urine as a soluble fraction[25]
	Reflects increased burden of tissue injury and apoptosis[24]
	Donor-derived or recipient derived

cfDNA: Cell-free DNA; Tr-DNA: Transrenal DNA.