Study for Detection of Donor-derived Cell-free DNA After Renal Transplantation Using Devysers NGS-based Chimerism Assay.

Each year 40-60 patients undergo renal transplant with a living donor (LD) at Karolinska University Hospital. Prior to transplantation, these patients and their donors are investigated for their immunological compatibility. This includes cytotoxic- and flow cytometric crossmatches, HLA typing as well as determination of possible presence of panel-reactive HLA antibodies (PRA). Normally these investigations are performed 2-3 months prior to renal transplantation. Once a patient has been accepted for transplantation with a given living donor, they will, prior to transplantation be asked whether they are interested in taking part of the present study. If the patient and the donor do accept, we will collect 15 mL of blood prior to transplantation using suitable sample collection tubes (Cell-Free BCT tubes). This sample will be used for screening patient and donor for specific genetic markers. Furthermore, the pretransplant samples will be used for determining the presence or absence of HLA antibodies for each patient. We aim to include up to 50 patients in the current study.

During the first 24-48 hrs after transplantation, two more samples (10 mL) from the patient will be collected to measure the potential presence of dd-cfDNA including cell-free particles such as exosomes. The cell-free DNA and RNA from all samples will be extracted, stored frozen and later sequenced. Following transplantation and initiation of the immunosuppressive therapy, samples for analysis will be obtained once every week for up to 3 months. All collected samples will be either analysed immediately or frozen for future analysis. Stored frozen samples could, at a later time point, be thawed, batched and analysed using molecular techniques including sequencing for measuring dd-cfDNA or analysis of the presence of HLA-antibodies using commercial bead-technologies (Luminex or Immucor). Results from these assays will be added to a dedicated database. The obtained laboratory results will be compared to clinical outcome including graft survival, patient survival, clinical and subclinical rejections etc. as well as other laboratory data (e.g. results from pathological examination of the graft, clinical chemistry, concentration of immunosuppressive drugs etc).