Stem Cell Delivery into the Myocardial Wall

Stem cells have been proposed as a powerful tool for the treatment of cardiac diseases. Indeed, the identification of a small number of progenitor cells virtually within every tissue of the body opened new perspectives to setup specific therapeutic protocols for cardiac diseases. To this end, a number of pre-clinical and clinical trials have been already completed, in which different stem cell subsets were directly injected into the myocardium or delivered via bloodstream to the heart. Despite the evidence of little, but significant improvements in cardiac outcome, the results demonstrated that no or few cells were retained within the host tissue few weeks after cell administration. The mild beneficial effects on the host tissue were thus ascribable to paracrine factors released by the implanted cells before they are washed away or removed by the immune system. Such results suggest that additional efforts are needed to setup efficient systems to deliver stem cells to the injured site. Among others, cardiac tissue engineering concepts could represent an efficient and cost/effective solution. However, their application requires cutting edge technologies to fabricate synthetic and hybrid scaffolds to be used as cell delivery systems. In this respect, particular attention must be paid to determine the role of the scaffold surface physical, mechanical and chemical properties and their effects on stem cells.