An improved method for the isolation of free-circulating plasma DNA and cell-free DNA from other body fluids.

Cell-free DNA is of increasing interest in different fields, such as cancer research, prenatal diagnosis, and the diagnosis of nonmalignant diseases. The quantity of free-circulating DNA in plasma, serum, and other body fluids is usually low and its isolation is still a challenge. Here we evaluate the application of the new commercially available NucleoSpin Plasma XS Kit for the isolation of cell-free DNA from plasma, serum, and cell-free bronchial lavage samples. The NucleoSpin columns proved superior to the QIAamp system in terms of DNA yield, purity, and retrieval of small DNA fragments. The procedure is fast and easy to standardize and might be valuable for laboratories working in the field of CNAPS.