Stem cells are present, albeit in small amounts, in most tissues of the adult body. This is most clearly evinced by the ability of tissues to heal themselves e.g. skin, bone, liver etc. For most of these tissues, however, identification and moreover isolation of the stem cell component is far from trivial. In addition, adult stem cells have a greatly restricted potential, only giving rise to a limited set of cell types. Or so it was thought…

Work by Catherine Verfaillie’s group (Minneapolis, USA) has now revealed that truly multipotent stem cells might exist in adult tissues too. The most accessible and therefore best researched sources of adult stem cells are bone marrow and umbilical cord. Bone marrow transplants are well known for their ability to treat patients with blood disorders due to their haemopoietic (blood) stem cell component, and bone marrow also contains a source of mesenchymal stem cells (MSCs). MSCs grown in culture can make bone, cartilage muscle and other connective tissue cells. Verfaillie and colleagues have found that within MSCs there exists a small group of multipotent stem cells. This sub-population can give rise to a much wider variety of cell types, including those that could form brain cells. It seems that adult stem cells might be more malleable after all.

Umbilical cord, although a more limited source of stem cells than bone marrow, contains proportionally more MSCs and also more of the multipotent kind. Biotech company BioE, in the US, has grown and developed umbilical cord cells into nerve, liver, fat and bone cells and is selling vials of these fully characterised cultures, at present for research, but possibly for therapeutic use in future.

The measly fractions of multipotent MSCs available from bone marrow throw a bit of a spanner in the clinical works. But they are retrievable and patients’ own cells can be used for therapy. Umbilical cord, although a richer source of adult stem cells than bone marrow, is less applicable for patient-identical therapies (few patients still have umbilical cords but they do have bones!).

The American company, Viacord, is now offering what might turn out to be the best of both worlds. Although umbilical stem cells are not yet used in therapy, while waiting for the technology to catch-up, customers are taking out a form of ‘stem cell insurance’ for their offspring. According to Nature Biotechnology magazine, at a cost of $125 per month Viacord will bank your baby’s umbilical cord blood cells as a source of ‘self’ cells to insure against possible future diseases. So far approximately 70,000 (wealthy) families have signed-up.