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A team of scientists from Duke University in the US have revealed evidence indicating that stem cell transplants from umbilical cord blood cells can successfully replace damaged tissue in target organs. Stem cells derived from umbilical cord blood have been successfully used to treat children with rare genetic diseases (resulting in heart, brain and liver defects) for several years, but without evidence that the stem cells were directly responsible.

However, heart tissue from a child who received a successful stem cell transplant but later died from an infection has been used to demonstrate the presence of heart muscle cells of donor origin. The boy suffered from Sanfilippo Syndrome B, a rare metabolic genetic disease that arises due to the absence of a key enzyme needed to break down complex sugars. As sugars accumulate in vital organs such as the liver, heart and brain, cells become damaged and die. The boy had been treated with stem cells from the cord blood of a baby girl; by using differential staining of X and Y chromosomes, researchers were able to identify the origin of each heart muscle cell. A small number of female heart cells were identified among the male heart cells. Presenting their findings to the International Association of Bone Marrow Transplantation Research meeting in Orlando this week, the researchers proposed that even the presence of a few heart cells derived from healthy donor stem cells can provide sufficient levels of enzyme to restore function to the damaged tissue.

Private companies in the UK are already offering a service for collection and storage of cord blood from newborn babies for a fee of around £1000, but there are concerns about inappropriate marketing of these services to prospective parents. Banking of stem cells from umbilical cord blood has been undertaken by NHS facilities within the National Blood Service since 1996, primarily for research and development purposes; there is no routine collection and storage (see the Royal College of Obstetricians and Gynaecologists Scientific Advisory Committee report). Currently, there is some provision for donation of umbilical cord blood to public stem cell banks, with a view to providing a resource for matching stem cells for people who develop diseases requiring transplants. This is viewed as an ethically acceptable alternative to private stem cell banks, which store cells for the sole future use of their donor. Some transplant centres may provide collection and storage of cord blood in families with known genetic diseases.