Soft Hydrogels Support Differentiation of Induced Pluripotent Stem Cells toward Mesenchymal Stromal Cells [expression]

Induced pluripotent stem cells (iPSCs) can be differentiated toward mesenchymal stromal cells (MSCs), but at least on epigenetic level this transition remains incomplete with the current culture conditions. Hydrogels provide a more physiologic three-dimensional environment for in vitro cell culture than conventional tissue culture plastic (TCP). In this study, we followed the hypothesis that growth and differentiation of primary MSCs and of iPSC-derived MSCs (iMSCs) can be enhanced on hydrogels. To this end, we used a hydrogel made of human platelet lysate (hPL). MSCs were effectively cultured on and inside hPL-gel and demonstrated more structured deposition of extracellular matrix (ECM) components than TCP. Furthermore, hPL-gel supported differentiation of iPSCs toward MSCs. Unexpectedly, the differentiation process seemed to be hardly affected by the substrate: iMSCs generated either on TCP or hPL-gel did not reveal differences in morphology, immunophenotype, or differentiation potential. Moreover, global gene expression and DNA-methylation profiles were almost identical in iMSCs generated on TCP or hPL-gel. Our results indicate that matrix elasticity is less crucial for directed lineage-specific differentiation toward MSCs than expected. MSCs and iMSCs were either cultured with human platelet lysate (hPL) gel or tissue culture plastic (TCP) as substrate to compare impact on gene expression profiles with Illumina HT-12 v4 Expression BeadChip.