Biomaterials directed activation of a cryostable therapeutic secretome in induced pluripotent stem cell derived mesenchymal stromal cells.

Mesenchymal stem cell therapy has suffered from wide variability in clinical efficacy, largely due to heterogeneous starting cell populations and large-scale cell death during and after implantation. Optimizing the manufacturing process has led to reproducible cell populations that can be cryopreserved for clinical applications. Nevertheless, ensuring a reproducible cell state that persists after cryopreservation remains a significant challenge, and is necessary to ensure reproducible clinical outcomes. Here we demonstrate how matrix-conjugated hydrogel cell culture materials can normalize a population of induced pluripotent stem cell derived mesenchymal stem cells (iPSC-MSCs) to display a defined secretory profile that promotes enhanced neovascularization in vitro and in vivo. Using a protein-conjugated biomaterials screen we identified two conditions-1 kPa collagen and 10 kPa fibronectin coated polyacrylamide gels-that promote reproducible secretion of pro-angiogenic and immunomodulatory cytokines from iPSC-MSCs that enhance tubulogenesis of endothelial cells in Geltrex and neovascularization in chick chorioallantoic membranes. Using defined culture substrates alone, we demonstrate maintenance of secretory activity after cryopreservation for the first time. This advance provides a simple and scalable approach for cell engineering and subsequent manufacturing, toward normalizing and priming a desired cell activity for clinical regenerative medicine.