Transplantation and other uses of human umbilical cord blood and stem cells.

Human umbilical cord blood (CB) has established itself as a legitimate source for hematopoeitic stem cell transplantations. Since the first transplantation was performed in 1988, it is estimated that approximately 4,000 patients, with malignant and non-malignant diseases, were transplanted with CB. Comparing to bone marrow transplants, cord blood's collection is easier and safer. It is also quicker to perform CB transplantation from the time of beginning of donor search. One of the major advantages of it is the naïve nature of newborn's immune system. This allows transplantations with less restriction of the HLA system, and with fewer graft versus host disease (GVHD) cases. A true setback of CB transplantations is the slow pace of engraftment. This fact has negative impact on treatment related mortality and is related to the amount of stem cell infused. Since CB has limited nucleated cell dose, transplanting it to heavier patients, namely adults, poses many difficulties. But the skepticism about the possibility that CB might be used in adult hematopoetic stem cell transplantations, can decline after few large scale trials have shown that it is definitely a feasible procedure. Few fields of research might help to improve the outcome of CB transplantations. While some strategies are at different investigational stages, others are at advanced phases of clinical studies. Main strategies are based on expansion of the number of the stem cells in CB grafts, induction of a temporary engraftment with other stem cell sources, or reduction of the toxicity of the conditioning regimens. It is encouraging to witness that the outcome of CB transplantations is improving constantly. Other potential uses of CB are also discussed. It was used for gene transfer for primary immune deficiency, and it was also demonstrated in animal models that its stem cell could serve as regenerative cells in non-hematopoeitic injured tissues. CB has broad spectrum of possible uses, but hematopoeitic stem cell transplantation is still the major indication. In an era where 30-40% of patients will not have a matched related or unrelated donor, CB is a major alternative, which provide a true chance for cure for a wide variety of diseases.