Experimental evidence has shown that the implantation of stem cells might trigger angiogenesis (new cell growth) in damaged heart tissue. Gustav Steinhoff and colleagues from the University of Rostock, Germany, injected six heart-attack patients with bone-marrow cells into areas of the heart which had died as a result of myocardial infarction; patients also received conventional bypass surgery . All patients were alive and well after surgery, and five patients had strikingly improved blood flow to the heart, suggesting that the stem cells may have generated cell growth in previously damaged areas.
Gustav Rostock comments: "We have shown that local bone-marrow stem-cell implantation for myocardial regeneration together with CABG is safe. However, whether a larger number of cells than that which we used will be tolerated is unclear. We emphasise that all reported attempts of clinical cell transplantation for myocardial regeneration, including our study, have been done in association with surgical or interventional revascularisation, so that the effectiveness of cell transplantation alone cannot be readily assessed. Controlled studies are needed to clarify the role of cell transplantation in myocardial regeneration."
A second research letter (p 47) also highlights the potential benefits of stem-cell implantation for heart-tissue regeneration. Hung-Fat Tse from the University of Hong Kong and colleagues report the early success of a catheter-based stem-cell transplantation among eight patients, all of whom had improved heart function at three months follow-up.
Hung-Fat Tse comments: "We have demonstrated that catheter-based percutaneous delivery of the patient's own bone-marrow stem-cells into the heart muscle for blood-vessel regeneration is a safe and feasible procedure for patients with coronary heart disease which cannot be treated by medical or interventional therapy. We have observed an improvement in blood flow to the heart after the procedure, and further studies are planned to evaluate the clinical impact of this therapy in larger, controlled populations. Furthermore, the exact type of marrow stem-cells effective in heart-tissue regeneration will need to be defined."
An accompanying Commentary (p 11) by Roger J Laham and Peter Oettgen from Harvard Medical School, USA, urges caution in the interpretation of these preliminary findings. They conclude: "Wherever this field leads, it is likely to follow the well-known pathway of incredible results leading to unrealistic expectations followed by sobering complications and disappointments and ultimately, cautious optimism. There is the opportunity with stem-cell therapy to alter this pathway at its onset by prescribing a healthy dose of scepticism to accompany a realisation of the promise of such therapies for patients with cardiovascular disease."
Journal
The Lancet