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The Essential Facts about Umbilical Cord Blood

A Lay Summary

Hematopoietic stem cell therapy (HSCT) is usually used in situations of life threatening illness. Although HSCT is a high risk procedure (because of possible incompatibility reactions between the donor and recipient), it is the preferred treatment today for patients suffering from malignant disease or immune system disorders.

In theory, transplantation of a patient’s own hematopoietic stem cells (HSCs) harvested in adulthood, eliminates the risk posed by possible incompatibility reactions. But, this is not really a practical approach since adult hematopoietic stem cells can be damaged during harvest, and other potentially dangerous cell types like tumor cells or auto-immune cells might also be collected as well. A good alternative to adult HSCs (cells that give rise to the immune and blood systems) are those harvested from umbilical cord blood (UCB).

UCB was first used to treat bone marrow diseases like leukemia, thirty four years ago. Stem cells from umbilical cord blood are intermediary between those found in fetal liver blood (the most desirable stem cells to use for therapy) and those produced in the bone marrow (BM). UCB is taken from the infant umbilical cord or maternal placenta and is stored in transplant banks for later use(1). Since HSCs are found in cord blood, UCB can be used to treat patients that have damaged or suppressed blood or immune systems (2).

However, when donating cord blood, certain procedural guidelines must be followed. The collected blood must be negative for pathogens (viral and bacterial) and for genetic disorders(3). And, should the harvested UCB not fulfill these stipulations, the collected blood cannot be used to treat patients.

Currently, patients can only be given UCB if an appropriate BM match is unavailable. But, this procedure may soon change. With the increase in understanding of these cell types, UCB may become a great curative tool for both young and old patients. Recent studies have reported good results and reduced overall risk of complication in children who received UCB transplants. And this was true regardless of who donated the UCB, or whether or not the UCB was a match for the child. UCB transplantation results in adults, on the other hand are not as encouraging. But, this may be because the umbilical cord only has enough stem cells to treat younger, lower body weight patients.

Nevertheless, many scientists today are finding new ways of producing better results in adults. One method under investigation is the combination of as many UCB units as are necessary for a successful transplant. Another is the use of one umbilical cord to produce more of the harvested cells (via a process called expansion), without this procedure resulting in injury to the transplant recipient. Researchers are also exploring the value of co-transplantation techniques whereby UCB is given to patients along with other nurturing bone marrow stem cells (called mesenchymal stem cells).

Although a donor-recipient incompatibility disease known as graft versus host disease (GVHD) is a significant concern in UCB transplantation, UCB still shows higher growth potential and better engraftment success than adult bone marrow. Numerous UCB transplant banks have therefore been established in the United States and around the world to feed the growing need for these stem cells. And, with the establishment of these banks, ethnic minorities who might otherwise have experienced little success in finding an appropriate donor now have a very good chance of finding a UCB match.

As research in the field progresses, other uses for UCB will continue to surface. So far, neuron and pancreatic cell regeneration has been investigated. And, other important applications are certain to be added to these. It is clear that although there are still many issues to consider (both biomedical and ethical), UCB is a good alternative to bone marrow transplantation, when a suitable bone marrow match is unavailable.

REFERENCES

1. Cohen, Y., Nagler, A. Umbilical Cord Blood Transplantation – How, When and for Whom? Blood Reviews. 2004. 18: 167-179.

2. Mayani H, Lansdrop PM. Biology of Human Umbilical Cord Blood-derived Hematopoietic Stem/Progenitor Cells. Stem Cells. 1998. 16: 153-65.

3. Tamruini, A., Malerba, C., Picardi A., et al. Placental/Umbilical Cord Blood: Experience of St. Eugenio Hospital Collection Center. Transplantation Proceedings. 2005. 37: 2670-2672.

Acknowledgements

This review was prepared by the following graduate students in the Stem Cell Biology Class, Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey: Monique H. Johnson, Katherine Liu, Christopher Komurek, George Lambrinos, Raghavendra A Shamanna (in alphabetical order).

Teaching Assistant: Edward Garay