Search

Exosome-based regenerative therapies are potentially easier to manufacture and safer to apply compared to cell-based therapies. However, many questions remain about how to bio-manufacture reproducible and potent exosomes using animal-free reagents. Here we evaluate the hypothesis that designer biomaterial substrates can be used to alter the potency of exosomes secreted by human induced pluripotent stem cells (iPSCs). Two animal-free designer matrices were fabricated based on recombinant elastin-like polypeptides (ELPs): one including a cell-adhesive RGD ligand and a second with a non-adhesive RDG peptide. While iPSCs cultured on these two substrates and Matrigel-coated controls had similar levels of proliferation, the RDG-ELP substrate significantly increased protein expression of stemness markers OCT4 and SOX2 and suppressed spontaneous differentiation compared to those on RGD-ELP. The pro-survival potency of iPSC-derived exosomes was evaluated using three distinct stress tests: serum starvation in murine fibroblasts, hypoxia in human endothelial cells, and hyperosmolarity in canine kidney cells. In all three cases, exosomes produced by iPSCs grown on RDG-ELP substrates had similar pro-survival effects to those produced using iPSCs grown on Matrigel, while use of RGD-ELP substrates led to significantly reduced exosome potency. These data demonstrate that recombinant substrates can be designed for the robust bio-manufacturing of iPSC-derived, pro-survival exosomes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Currently, no medical therapies exist to augment stroke recovery. Stem cells are an intriguing treatment option being evaluated, but cell-based therapies have several challenges including developing a stable cell product with long term reproducibility. Since much of the improvement observed from cellular therapeutics is believed to result from trophic factors the stem cells release over time, biomaterials are well-positioned to deliver these important molecules in a similar fashion. Here we show that essential trophic factors secreted from stem cells can be effectively released from a multi-component hydrogel system into the post-stroke environment. Using our polymeric system to deliver VEGF-A and MMP-9, we improved recovery after stroke to an equivalent degree as observed with traditional stem cell treatment in a rodent model. While VEGF-A and MMP-9 have many unique mechanisms of action, connective tissue growth factor (CTGF) interacts with both VEGF-A and MMP-9. With our hydrogel system as well as with stem cell delivery, the CTGF pathway is shown to be downregulated with improved stroke recovery., (Copyright © 2018 Elsevier Ltd. All rights reserved.)