Decellularized Extracellular Matrix Produced by <scp>iPSC</scp> ‐Derived <scp>MSCs</scp> Promotes <scp>iPSC</scp> ‐ <scp>MSC</scp> Proliferation and Differentiation and Regulates Secreted Factors

The in vitro expansion of mesenchymal stromal cells (MSCs) is essential to produce clinically relevant quantities of cells while preserving therapeutic potential. Currently, premature senescence of the MSCs during in vitro expansion is a significant limitation that inflates costs and reduces the efficacy of treatments. Culture environments that maintain MSC properties during in vitro expansion are urgently needed. In this study, we explored the use of the decellularized extracellular matrix (dECM) deposited from different sources of MSCs for induced pluripotent stem cell (iPSC-MSC) expansion. Specifically, we compared dECMs derived from primary bone marrow (BMSCs), a placenta-derived MSC cell line (DMSC23s), and iPSC-MSCs, against conventional substrates including tissue culture plastic (TCP), collagen type I, fibronectin, and Matrigel. We demonstrated for the first time that iPSC-MSCs deposit substantially greater amounts of dECM than BMSCs and DMSC23s (35- and 2-fold, respectively). Additionally, the dECM produced by the iPSC-MSCs demonstrated superior properties in promoting MSC proliferation and lineage-specific differentiation. Furthermore, enzyme-linked immunosorbent assays revealed that dECM culture could modulate the MSC secretome. These findings suggest that iPSC-MSCs and their ECM are suitable for optimizing and upscaling the in vitro expansion of iPSC-MSCs, offering potential advantages in regenerative therapies.