Umbilical Cord Blood Collection Protocol and the Impact on the Nucleated and Progenitor Cell

Abstract

The number of cells available in a single cord blood unit (CBU), in particular, the CD34+? and total nucleated cell (TNC) content influences the transplantation clinical outcome. By optimizing the CB collection, the quantity and quality of umbilical cord blood (UCB) for storage can be improved and increase the likelihood of its use for transplantation. Cord blood collection is the first step in cord blood banking and impacts significantly on the volume and quality of the collected blood. The Standard Operating Procedure (SOP) on cord blood banking recommends that education should be provided to a potential mother/donor of an umbilical cord blood unit so that she can make an informed choice on donation of her infant's cord blood. Parents need to be aware of the options that exist for their infant's cord blood and have access to the relevant information to inform their choice. Informed consent has been identified as one of the ethical issues confronting umbilical cord blood donation and banking. Some workers have opined that informed consent could be optimized by (1) having those personnel who obtain consent emphasize that banking involves research and to explain the true benefits of donation, (2) ensuring that parents know how and when to contact the umbilical cord blood bank after donation, and (3) using phone surveys to continue assessments and to monitor changes in the process. The degree to which the donated cord blood stem cells are molecularly similar to the recipient cells is measured by human leukocyte antigen. The current consensus is that CB should be at least 4/6 HLA matching for HLA-A, -B at the antigen level, and HLA-DRB1 at the allelic level. The collection could be in utero or ex utero usually by either a syringe or bag method. The interval between placenta delivery and CB collection has significantly influenced the volume of cord blood units and it has been shown that collection within not greater than 5 minutes of placental delivery produced higher volume and TNC count. Concerns have been raised about reduced red cell mass in the neonate resulting from early clamping of the umbilical cord that is necessary to maximize volume of UCB collection. Delayed cord clamping has been formally endorsed by a number of medical societies; however, it has not yet been universally adopted by obstetricians and neonatologists. Umbilical cord blood is always collected in sterile bags containing anticoagulant-based citrate, such as citrate phosphate dextrose (CPD) or CPD-adenine 1 (CPD-Al) to prevent coagulation and to maintain viability during transport to the processing facility. The TNC yield and viability of samples collected in lyophilized heparin (LH) compared to CPD suggest that UCB quality was impacted by anticoagulant selection. Some workers have done some analyses to determine the correlation between cell number, cell type, volume, and time between collection and processing. They reported significant losses of nucleated and CD34+ cells after storage at room temperature for up to 24 hours. Another group of workers studies the possible effect of time between collecting and processing umbilical cord blood samples on the quality of the sample. Their findings showed that an increase in the time interval between collection and processing negatively affects the quality of the UCB sample. The effect of storage temperature before processing on the quantity of recovered cells has been studied and results show the optimum temperature to be between 2’°C to 8°C. Inall cases the loss of cells increased with the number of days of storage before processing.