Cell therapies and regenerative medicine - the dawn of a new age or more hype than hope?

The treatment of myocardial disease using intracoronary or intramyocardial bone marrow derived stem cells provides a fascinating insight into the challenges of using cell suspensions as drugs. Strauer and Steinhoff recently reviewed the first 10？years of this novel approach to the care of patients with heart disease [2]. They describe the first treatment in 2001 of a patient with a failing left ventricle, using unfractionated mononuclear bone marrow cells. In 2003 the first attempt was made to use a purified stem cell fraction [3]. This short report described the use of an anti-CD133 antibody to isolate bone marrow stem cells with potential angiogenic properties. This was a departure from the original concept of implanting cells that would restore contractility of the myocardium and instead focused on restoring the myocardial vascular supply. However it is becoming apparent that the same stem cells may both restore contractility (directly or indirectly) and improve the cardiac circulation [2]. Despite this lack of clarity on the proposed mechanism of action of stem cells, the extent of clinical improvement with these techniques is gradually becoming clear. Clinical results are highly variable and can be difficult to compare between studies because of huge variations in cell source, preparation and implantation methodology. Nevertheless there is merging evidence of a modest but significant improvement in ventricular performance in the treatment of acute myocardial infarction and increased ventricular performance and increased patient survival in the treatment of chronic infarction [2].The rapid progression from laboratory to clinic in the treatment of myocardial disease has not been without controversy. In a 2004 Nature paper Murray et al provided evidence to oppose the idea that haematopoietic stem cells can transdifferentiate into cardiac myocytes [4]. Murray has publicly debated this issue with Sussman who is a proponent of the use of bone marrow cells for heart d