Repeated Cell Therapy A Paradigm Shift Whose Time Has Come

Although treatment with stem/progenitor cells is a promising approach to heart disease, enthusiasm for cell therapy has been dampened by the inconsistent, modest, borderline, or undetectable benefits reported in clinical trials (all of which have used 1 dose of cells). 1-4 As a result, clinical translation has not occurred (no cell-based therapy is close to being approved for heart disease), and a rising tide of skepticism has bedeviled the field, 5,6 leading some critics even to question whether clinical studies should continue. Here, I propose that a major reason for the modest, borderline, or disappointing results is the administration of only 1 dose of cells, which causes the benefits of cell therapy to be underestimated. I argue that just as most pharmacological agents are ineffective when given once but can be highly effective when given repeatedly, so a cell product may be ineffective, or modestly effective, when given as a single treatment, but may turn out to be quite efficacious if given repeatedly. This concept constitutes a major paradigm shift (a "game changer"), with potentially vast implications for the entire field of reparative medicine.