The role and potential of umbilical cord blood in an era of new therapies: a review

Abstract

In light of pioneering findings in the 1980s and an estimation of more than 130 million global annual births, umbilical cord blood (UCB) is considered to be the most plentiful reservoir of cells and to have regenerative potential for many clinical applications. Although UCB is used mainly against blood disorders, the spectrum of diseases for which it provides effective therapy has been expanded to include non-hematopoietic conditions; UCB has also been used as source for regenerative cell therapy and immune modulation. Thus, collection and banking of UCB-derived cells have become a popular option. However, there are questions regarding the cost versus the benefits of UCB banking, and it also raises complex ethical and legal issues. This review discusses many issues surrounding the conservation of UCB-derived cells and the great potential and current clinical applications of UCB in an era of new therapies. In particular, we describe the practical issues inherent in UCB collection, processing, and long-term storage as well as the different types of 'stem' or progenitor cells circulating in UCB and their uses in multiple clinical settings. Given these considerations, the trend toward UCB will continue to provide growing assistance to health care worldwide.

Fig. 1

Umbilical cord: a tube containing highly ‘stem’ cell-enriched blood. Representative images show a the fetal face of a placenta from which an umbilical cord grows as a flexible, spongy-looking, tube-like structure usually around 55 cm or 2 feet, b a transversal section of umbilical cord showing two arteries (A) and one vein (V), and c a Masson’s trichrome staining of a complete umbilical cord microsection. At the structural level, amniotic membrane (AM), Wharton’s jelly (WJ), and smooth musculature (SM) associated with a blood vessel’s wall (VW) and lumen (VL) can be clearly distinguished. d The blood entrapped in the umbilical cord is recognized as a highly enriched source of valuable cells which can be visualized by, for example, fluorescence in situ hybridization using specific probes for X (green) and Y (red) chromosome

Fig. 2

Umbilical cord blood collecting, processing, and banking: basic steps. In brief, once the umbilical cord blood extraction kit (temperature-insulated and padded for safety during transport) arrives at the processing laboratory, the blood bag’s external surfaces are disinfected prior to entrance in Cleanroom type B. Here, under highly sterile conditions, a pre-cryopreserved cell suspension enriched with mononuclear cells is collected following hydroxyethyl starch-based sedimentation of red blood cells (RBCs) and centrifugation. The resultant cell product is finally cryopreserved in a freezing bag cassette following a controlled-rate freezing process to slowly reduce the temperature to −180 °C and is stored in commercially available liquid nitrogen dewars. Routinely, quality controls based on the estimation of total nucleated cells (TNCs), percentage of CD34⁺ and CD45⁺ cells, and cell viability are performed throughout sample processing. The figure was designed and hand-drawn by CG-M

Fig. 3

Sedimentation of red blood cells (RBCs). Representative photographs show umbilical cord blood collections at the beginning (a) and at the end (b) of the process of RBC sedimentation. Note that a yellow modified buffy coat, enriched in mononuclear cells, is obtained at the top of the bag. This procedure is central to reduce volume sample, storage space, and the cytotoxicity caused by the thawing of RBCs

Fig. 4

Current clinical applications of umbilical cord blood. The blood in the umbilical cord after the birth of a child is a readily available source of regenerative ‘stem’ or progenitor cells—for example, hematopoietic progenitor cells (HPCs) and mesenchymal stem cells (MSCs)—for use against many human diseases. The figure was designed and hand-drawn by CG-M