As the debate surrounding the use of embryonic stem cells in therapy rages on, new findings hint that an ethically viable alternative could be to enlist our own bone marrow cells as a cellular 'repair squad'.

Reports by two independent groups, both published online in the Proceedings of the National Academy of Sciences, have shown that transplanted bone marrow cells can make their way to the brain and become brain cells. The findings have obvious implications for the treatment of diseases such as Parkinson's and Alzheimer's.

The discovery came from the post-mortem examination of brains from female leukaemia patients who had received bone marrow transplants from male donors after chemotherapy. Not surprisingly, blood cells in the brain originated from the bone marrow transplant, but the telltale Y chromosome of the male donors was also detected in neurons. Éva Mezey, lead researcher of the team from the US National Institute of Neurological Diseases and Stroke, said “...some kind of cell in bone marrow, most likely a stem cell, has the capacity to enter the brain and form neurons”.

Helen Blau's group, based at Stanford University, believes that the cells travel the bloodstream, responding to stress and repairing damaged tissues, such as brain, muscle and possibly others, throughout the body. “The next steps are to learn which cells in the bone marrow act ... how these cells are lured to tissues and how they repair damage once there.”, adding, “...we may be able to direct the repair cells to where they are needed” (Science Daily, 4th February, 2003).