Cardiac performance after myocardial infarction (MI) is compromised by ventricular remodelling, which represents a major cause of late infarct-related chronic heart failure and death. Clinical studies have shown recently that bone marrow mononuclear cells may restore damaged myocardium in humans1 2 with variable certainty.3 4 Stem cells have the important properties of self-regeneration and differentiational plasticity. Human bone marrow contains CD34-positive haematopoietic and CD34-negative mesenchymal stem cells and both these types of stem cells may contribute to heart muscle repair.

Clinical studies with direct intracoronary transplantation of bone marrow cells until now have been concerned mainly with three clinically relevant situations:

• treatment for acute MI1^–6;

• treatment for old MI (⩾8 years, with heart failure)7;

• treatment for congestive heart failure (dilatative cardiomyopathy).6 8

The study in this issue of Heart by van Ramshorst et al9 focuses on important aspects of bone marrow cell-related therapy in chronic heart dysfunction: (a) the route of cell delivery; (b) the relationship between improved left ventricular (LV) function and synchronicity of wall motion in chronic infarction; (c) the possible mechanism of bone marrow cell action in heart failure (see page 119).

WHAT IS THE OPTIMUM WAY OF CELL DELIVERY?

When given intravenously, only a very small fraction of infused cells can reach the infarct region after the following injection; assuming normal coronary blood flow of 80 ml/min per 100 g of LV weight, a quantity of 160 ml per left ventricle (assuming a regular LV mass of ≈200 g) will flow per minute. This corresponds to only around 3% of cardiac output (assuming a cardiac …