Allogenic benefit in stem cell therapy: cardiac repair and regeneration.

Stem cell (SC)-based therapies are a developing mean to repair, restore, maintain, or enhance organ functioning through life span. They are in particular a fast track to restore function in failing heart. Various types of SCs have been used in experimental and clinical studies showing the potential of these cells to revolutionize the treatment of heart diseases. Autologous cells have been privileged to overpass immunological barriers. The field has progressed tremendously and the hurdles, which have been largely overlooked in the excitement over the expected benefit the immunogenicity, have been revealed. Also, manufacturing of patient-specific clinical grade SC product, whether adult stem or reprogrammed induced pluripotent SCs, and the availability of these cells in sufficient amounts and status when needed is questionable. In contrast, adult SCs derived from healthy donors, thus allogeneic, have the advantage to be immediately available as an 'off-the-shelf' therapeutic product. The challenge is to overcome the immunological barriers to their transplantation. Recent research provided new insights into the mode of action and immune behavior of SCs in autologous as well as allogeneic settings. Lessons are learned and immune paradigms are changing: allogenicity, if balanced could be part of the dynamic and durable mechanisms that are critical to sustain cardiac regeneration and repair. We discuss the hurdles, lessons, and advances accomplished in the field through the progressive journey of cardiac-derived stem/progenitor cells toward allogeneic cardiac regenerative/reparative therapy.