Embryo Project Encyclopedia

Edward Donnall Thomas, an American physician and scientist, gained recognition in the scientific community for conducting the first bone marrow transplant, a pioneering form of hematopoietic stem cell transplantation (HSCT). Bone marrow transplants are considered to be the first successful example of tissue engineering, a field within regenerative medicine that uses hematopoietic stem cells (HSCs) as a vehicle for treatment. Prior to Thomas's groundbreaking work, most blood-borne diseases, including certain inherited and autoimmune diseases, were considered lethal.

The purpose of regenerative medicine, especially tissue engineering, is to replace damaged tissue with new tissue that will allow the body to resume normal function. The uniqueness of tissue engineering is that it can restore normal structure in addition to repairing tissue function, and is often accomplished using stem cells. The first type of tissue engineering using stem cells was hematopoietic stem cell transplantation (HSCT), a surgical procedure in which hematopoietic stem cells (HSCs) are infused into a host to treat a variety of blood diseases, cancers, and immunodeficiencies. While there is a standard procedure for the infusion of these cells into a donor, variations in the sources of hematopoietic stem cells, and in the relationship between donor and recipient, do produce some variability in the procedure.

The discovery of hematopoietic stem cells (HSCs) provided a pioneering step in stem cell research. HSCs are a type of multipotent adult stem cell, characterized by their ability to self-renew and differentiate into erythrocyte (red blood cell) and leukocyte (white blood cell) cell lineages. In terms of function, these cells are responsible for the continual renewal of the erythrocytes, leukocytes, and platelets in the body through a process called hematopoiesis. They also play an important role in the formation of vital organs such as the liver and spleen during fetal development. The early biological knowledge obtained from the studies of HSCs established the base of knowledge for understanding other stem cell systems. In addition, these cells have a vital role in furthering stem cell research for clinical applications. Regenerative medicine is a field of medicine that has applied HSCs to the treatment of blood-borne diseases such as leukemia and lymphoma and of cancer patients undergoing chemotherapy.

Umbilical cord blood (UCB) stem cells are hematopoietic stem cells (HSC) that are recovered from the blood of the umbilical cord and placenta after birth. Umbilical cord blood is rich in cells that express the CD34 molecule, a surface protein that identifies cells as stem cells. Prior to the discovery of UCB stem cells, it was standard procedure to discard the umbilical cord and placenta; now much effort is devoted to raising public awareness and to encouraging people to store or donate cord blood. The importance of these cells lies in potential clinical treatments of blood-borne diseases, as well as the possibility of restoring cells of other lineages, such as cardiac and neural cells. These possible uses have given rise to cord blood stem cell banking, both private and public, where cells can be frozen and stored for later use.

Cord blood banks are institutions designed to store umbilical cord blood (UCB) stem cells. UCB, a source of hematopoietic stem cells (HSCs), has garnered attention from scientific and medical communities since its first successful use in a hematopoietic stem cell transplant (HSCT) in 1988. The umbilical cord is the lifeline by which the growing fetus is nourished by the mother. Once regarded as medical waste, the umbilical cord has become a source of lifesaving treatment. The extraction of HSCs from umbilical cord is non-invasive since the umbilical cord is delivered immediately after the baby exits the womb. The most common application of umbilical cord blood derived stem cells is in unrelated (between donor and host) HSCT. Since these cells are not often needed at the time of delivery, cord blood banks have been established to preserve these cells for future use. In addition to harvesting a supply of cells for treatment, UCB stem cells can be used in research.