Cord blood has been shown to contain ‘stem cells’. Stem cells are immature cells that have the potential to develop into different cell types. There are various conditions for which a cord blood stem cell transplant may be used, and there are also many potential uses under investigation.
Disorders of the blood (including certain blood cancers and immune deficiencies), and inherited metabolic diseases are currently the only indications for which a cord blood stem cell transplant is generally accepted by the medical community as an established treatment (EBMT 2015 and Gluckman 2011). In some cases, a person’s own cord blood may not be a suitable treatment for him or her, for example if certain malignancies or other genetic problems are present. In this guidance, when we talk about ‘transplants’ we mean these established treatments.
The quantity and quality of cells in units stored at a cord blood bank will differ, and these factors are influenced by natural variation in the cord blood itself and the way that the cord blood is collected, transported, processed and stored. Well-controlled procedures during all phases of cord blood banking are important to the success of a cord blood stem cell transplant.
For a cord blood unit to be used in a transplant, it must contain enough stem cells (Querol 2010). In some cases where a cord blood unit does not contain enough cells, cord blood units from two different donors may be combined to treat one patient. Both public and private cord blood banks in the UK set their own thresholds for the number of cells a cord blood unit must contain in order for it to be banked. Public banks will store only cord blood units that are likely to contain enough cells for a transplant, because they aim to bank as many cord blood units as possible for use in established treatments. Private cord blood banks will usually store the cord blood unit even if it does not contain enough cells for a transplant, because private cord blood banks store cord blood units for transplants, clinical trials and for ‘potential future use’ (i.e. for as yet unknown therapies that may be available in the future).