The Essential Need for a Validated Potency Assay for Cell-Based Therapies in Cardiac Regenerative and Reparative Medicine. A Practical Approach to Test Development.

Biological treatments are one of the medical breakthroughs in the twenty-first century. The initial enthusiasm pushed the field towards indiscriminatory use of cell therapy regardless of the pathophysiological particularities of underlying conditions. In the reparative and regenerative cardiovascular field, the results of the over two decades of research in cell-based therapies, although promising still could not be translated into clinical scenario. Now, when we identified possible deficiencies and try to rebuild its foundations rigorously on scientific evidence, development of potency assays for the potential therapeutic product is one of the steps which will bring our goal of clinical translation closer. Although, highly challenging, the potency tests for cell products are considered as a priority by the regulatory agencies. In this paper we describe the main characteristics and challenges for a cell therapy potency test focusing on the cardiovascular field. Moreover, we discuss different steps and types of assays that should be taken into consideration for an eventual potency test development by tying together two fundamental concepts: target disease and expected mechanism of action. Development of potency assays for cell-based products consists in understanding the pathophysiology of the disease, identifying potential mechanisms of action (MoA) to counteract it and finding the most suitable cell-based product that exhibits these MoA. When applied, the potency assay needs to correlate bioactivity of the product, via a measurement related to the MoA, with treatment efficacy. However, in the cardiovascular field, the process faces several challenges and high requirements.