Small molecule inhibitors and culture conditions enhance therapeutic cell and EV potency via activation of beta-catenin and suppression of THY1

Primary cell therapy continues to face significant hurdles to therapeutic translation including the inherent variations that exist from donor to donor, batch to batch, and scale-up driven modifications to the manufacturing process. Cardiosphere-derived cells (CDCs) are stromal/progenitor cells with clinically demonstrated tissue reparative capabilities. Mechanistic investigations have identified canonical Wnt/β-catenin signaling as a therapeutic potency marker, and THY1 (CD90) expression as inversely correlated with potency. Here we demonstrate that the cardiosphere formation process increases β-catenin levels and enriches for therapeutic miR content in the extracellular vesicles of these cells, namely miR-146a and miR-22. We further find that loss of potency is correlated with impaired cardiosphere formation. Finally, our data show that small GSK3β inhibitors including CHIR, and BIO and “pro-canonical Wnt” culturing conditions can rescue β-catenin signaling and reduce CD90 expression. These findings identify strategies that could be used to maintain CDC potency and therapeutic consistency.