Umbilical cord blood stem cell banking
Hematological (blood) cancers are the fifth major cause of cancer in the United Kingdom with over 30,000 new cases being reported annually (http://leukaemialymphomaresearch.org.uk). Of the other hematological disorders, the inherited hemoglobinopathies are the most common monogenic diseases worldwide. A potentially curative therapy for severe hematological malignancies and other severe disorders of the blood and bone marrow is hematopoietic stem cell transplantation (HSCT), with its usage having increased rapidly over the past 25 years and with the one millionth HSCT being performed in 2013. Worldwide, more than 60,000 patients p.a. receive HSCT. This equates to over 36,000 individuals in Europe. Although around 58% of HSCT use autologous HSC donations in Europe, a significant proportion of HSCs are sourced from related and unrelated allogeneic donors either from the bone marrow, from peripheral blood after induced mobilization, or from cord blood. In the past 25 years to 2012, the number of HSCTs using cord blood increased substantially and accounted for 5% of HSCT in Europe and substantially more in the USA and Japan. By 2014-15, 2% and 8% of allogeneic HSCTs used cord blood in Europe and worldwide, respectively, as assessed by CIBMTR. Cord blood units are banked prior to transplantation in public, private, or hybrid public-private cord blood banks. Banked normal cord blood units that are sourced from HLA-identical allogeneic siblings or HLA-matched unrelated allogeneic donors are used to transplant patients with a variety of severe inherited or acquired diseases following myeloablative or reduced intensity conditioning. Outcomes vary, but success depends on the numbers and quality of HSCs and hematopoietic progenitors in the graft, HLA-matching at the allele level, disease status, conditioning and the ability of the HSCs and their progeny to efficiently engraft in specific bone marrow niches where they regenerate normal blood cells over an individual’s lifetime. Autologous cord blood transplants have been less common, but the recent development of novel genome editing technologies opens the way to using this new technology to correct certain inherited gene disorders in autologous hematopoietic stem cells (HSCs) sourced from cord blood at birth (or alternatively as appropriate subsequently from mobilized peripheral blood and bone marrow) and carrying these inherited disorders and to then transplant these cells into the affected individual to correct the disease. HLA matching of the HSCs has not to date been a problem for autologous transplants, and the earlier the patient is treated the better the outcome. However, cord blood has the disadvantage of limited HSC content and shows delayed hematological reconstitution. Since most cord blood transplants have been from unrelated donors, this article will concentrate principally on unrelated public cord blood banking, covering recent clinical advances, recommendations for improving cord blood unit quality, and regulations governing cord blood acquisition and provision for human use, and will briefly discuss autologous cord blood transplants and approaches that may enhance their use.