Australian researchers performed microbial recovery studies on Cord Blood Units (CBUs) by screening contaminated units after thaw, and also by performing spiking studies on fresh CBUs evaluating recovery both before freeze and again after thaw. These results were reported in the J. of Transfusion March 2014.
The study demonstrated that a majority of contaminating organisms isolated in pre-freeze samples of CB can survive cryopreservation process, frozen storage and thawing. One of the more interesting conclusions reported from the spiking studies was the apparent higher recovery rates of certain organisms after thaw as opposed to fresh. This lead to the conclusion that CBUs reported as microbial free could possibly contain contamination which could result in transplantation of contaminated CB and be potentially deleterious to a patient.