It would be nice if it were that easy. It is true that bone marrow does contain stem cells. However, these age in the same way as the body, potentially losing both their vitality and usefulness and could be affected by the same diseases as the rest of the body (e.g. type II diabetes). In contrast, stem cells from the
umbilical cord are young, fresher and relatively unaffected by diseases, thus offering much more flexibility. The umbilical cord also contains a wider range of stem cell types than bone marrow.