Recent years have seen a tremendous improvement of possibilities to restore normal cardiac perfusion of the coronary arteries both by surgical and interventional techniques. In addition, several pharmacological approaches are available to block the mal-adaptive molecular signaling initiated by the Renin/Angiotensin/Aldosteron (RAAS) system. Device therapy achieving resychronisation has lowered morbidity and mortality. However, heart failure therapy still falls short to address the underlying disease of the heart muscle: loss of contractile force.
To achieve this aim and restore contractile force a regenerative approach is required. Early experimental studies suggested bone marrow cells to be able to differentiate towards functional cardiomyocytes when injected into the scar area after ischemic injury.2 These and other studies lead to clinical trials, where bone marrow cells were injected into the coronary circulation. Lately, the first completed multi-center, placebo-controlled, double-blinded study found several end points to be improved including global left ventricular function 3. At the same time genetically labelled experimental mouse models demonstrated differentiation of bone marrow cells towards a cardiomyocyte lineage to be a rare event,4 questioning at least the proposed molecular and cellular mechanism of intra-coronary cell therapy. Furthermore, several other clinical trials recently performed did either find no or a very limited effect of intra-coronary applied bone marrow cells. The effect appears to be related to improved angiogenesis. Our group has recently shown that in mammals endogenous regeneration of myocardium does occur after injury and can be enhanced via specific signaling pathways.5 Whether intra-coronary cell therapy is the ideal approach to enhance this process is currently unclear.
References:
1. Nieminen MS, Brutsaert D, Dickstein K, Drexler H, Follath F, Harjola VP, Hochadel M, Komajda M, Lassus J, Lopez-Sendon JL, Ponikowski P, Tavazzi L. EuroHeart Failure Survey II (EHFS II): a survey on hospitalized acute heart failure patients: description of population. Eur Heart J. 2006;27:2725-2736.
2. Orlic D, Kajstura J, Chimenti S, Limana F, Jakoniuk I, Quaini F, Nadal-Ginard B, Bodine DM, Leri A, Anversa P. Mobilized bone marrow cells repair the infarcted heart, improving function and survival. Proc Natl Acad Sci U S A. 2001;98:10344-10349.
3. Schachinger V, Erbs S, Elsasser A, Haberbosch W, Hambrecht R, Holschermann H, Yu J, Corti R, Mathey DG, Hamm CW, Suselbeck T, Assmus B, Tonn T, Dimmeler S, Zeiher AM, the R-AMII. Intracoronary Bone Marrow-Derived Progenitor Cells in Acute Myocardial Infarction. N Engl J Med. 2006;355:1210-1221.
4. Murry CE, Soonpaa MH, Reinecke H, Nakajima H, Nakajima HO, Rubart M, Pasumarthi KB, Virag JI, Bartelmez SH, Poppa V, Bradford G, Dowell JD, Williams DA, Field LJ. Haematopoietic stem cells do not transdifferentiate into cardiac myocytes in myocardial infarcts. Nature. 2004;428:664-668.
5. Zelarayan L, Noack C, Sekkali B, Kmecova J, Gehrke C, Renger A, Zafiriou MP, Nagel Rvd, Dietz R, Windt LJd, Balligand J-L, Bergmann MW. beta-catenin downregulation attenuates ischemic cardiac remodeling through enhanced resident precursor cell differentiation. Proc Natl Acad Sci U S A. 2008;105:19762-19767.
6. Krause KT, Jaquet K, Geidel S, Schneider C, Mandel C, Stoll HP, Hertting K, Harle T, Kuck KH. Percutaneous endocardial injection of erythropoietin: assessment of cardioprotection by electromechanical mapping. Eur J Heart Fail. 2006;8:443-450.
