Bio-Rad Droplet Digital™ PCR and Organ Transplant Rejection

Researchers at Chronix Biomedical applied Bio-Rad's ddPCR™ technology to quantify graft-derived cell-free DNA (cfDNA) in recent liver transplant patients and in stable patients who had undergone a transplant procedure more than six months earlier. ddPCR technology allowed Chronix to develop a fast and cost-effective laboratory test to detect cfDNA released into the blood stream by dying cells from the transplanted organ.

Sequencing methods typically require batch sampling, but using ddPCR assays, researchers are able to run single samples. Additionally, this method reduces test time from three days or more to one day, and reduces costs by 90 percent. The study authors were able to address the need for donor DNA by preselecting single-nucleotide polymorphisms (SNPs) that ensure enough heterogeneity between donor and recipient. The new blood test can also deliver results up to several days earlier than the conventional aspartate aminotransferase (AST) and bilirubin tests for liver transplantation rejection, with the potential for an immediate positive impact on patient care.

Chronix Biomedical is a molecular diagnostics company developing blood tests primarily for cancer, including companion diagnostics and tests for detecting minimal residual disease. Chronix is preparing to offer its pioneering tests through its own laboratories under CLIA certification in North America and the CE mark in Europe. The Company's initial product is a test to be used by cancer treatment centers and oncologists in the treatment of breast cancer patients. Chronix is privately held with headquarters in San Jose, California, and laboratories in Göttingen, Germany and Brookings, South Dakota.

The Droplet Digital PCR system enables the quantification of target DNA with unrivaled precision by partitioning samples into 20,000 nanoliter-sized droplets. After PCR on a thermal cycler, PCR-positive and PCR-negative droplets are counted to provide absolute quantification of the target DNA. The QX200™ system, Bio-Rad's second-generation digital PCR system, provides absolute quantification of target DNA or RNA molecules using EvaGreen or TaqMan hydrolysis probes, yielding unmatched sensitivity and precision for a wide variety of applications.