Stem cell research and technology represent a major challenge for treating otherwise non-curable patients. A decade of intensive research has demonstrated that initial hopes based more on the will to succeed than on solid scientific bases can be translated into factual techniques only by adopting more rigorous procedures and strategies. Among other major impediments, the failure so far experienced in applying stem cell technologies to repair parenchymal organs can be ascribed to the lack of sufficient knowledge of basic mechanisms but also to the lack of standardized criteria and protocols....